WO2011099509A1 - Mobile communication system - Google Patents
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- WO2011099509A1 WO2011099509A1 PCT/JP2011/052721 JP2011052721W WO2011099509A1 WO 2011099509 A1 WO2011099509 A1 WO 2011099509A1 JP 2011052721 W JP2011052721 W JP 2011052721W WO 2011099509 A1 WO2011099509 A1 WO 2011099509A1
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- backhaul link
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/0005—Control or signalling for completing the hand-off
- H04W36/0083—Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
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- H04W36/0088—Scheduling hand-off measurements
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- H—ELECTRICITY
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- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W36/00—Hand-off or reselection arrangements
- H04W36/24—Reselection being triggered by specific parameters
- H04W36/30—Reselection being triggered by specific parameters by measured or perceived connection quality data
- H04W36/302—Reselection being triggered by specific parameters by measured or perceived connection quality data due to low signal strength
Definitions
- the present invention relates to a mobile communication system that performs wireless communication between a plurality of mobile terminals and a base station.
- the W-CDMA Wideband Code Division Multiple Access
- HS-DSCH High-Speed-Downlink Shared Channel
- HSDPA High Speed Down Link Link Packet Access
- HSUPA High Speed Up Link Link Packet Access
- W-CDMA is a communication system defined by 3GPP (3rd Generation Partnership Project), which is a standardization organization for mobile communication systems, and standardized release 8 editions are compiled.
- W-CDMA uses code division multiple access (Code-Division-Multiple-Access)
- LTE uses OFDM (Orthogonal Frequency-Division-Multiplexing) in the downlink direction and SC-FDMA (Single in the uplink direction).
- Code-Division-Multiple-Access code division multiple access
- LTE uses OFDM (Orthogonal Frequency-Division-Multiplexing) in the downlink direction and SC-FDMA (Single in the uplink direction).
- SC-FDMA Single in the uplink direction.
- LTE is defined as an independent radio access network separate from the W-CDMA network because the communication system is configured using a new core network different from the W-CDMA core network (General Packet Radio Service: GPRS). Is done. Therefore, in order to distinguish from the W-CDMA communication system, in the LTE communication system, a base station (Base station) that communicates with a mobile terminal (User Equipment: UE) is referred to as an eNB (E-UTRAN NodeB). A base station controller (Radio Network Controller) that exchanges control data and user data with the base station is called EPC (Evolved Packet Core) or aGW (Access Gateway).
- EPC Evolved Packet Core
- GW Access Gateway
- a unicast service and an E-MBMS service (Evolved Multimedia Broadcast Multicast Service) are provided.
- the E-MBMS service is a broadcast-type multimedia service and may be simply referred to as MBMS. Mass broadcast contents such as news, weather forecasts, and mobile broadcasts are transmitted to a plurality of mobile terminals. This is also called a point-to-multipoint service.
- Non-Patent Document 1 (Chapter 4.6.1) describes the current decisions regarding the overall architecture of the LTE system in 3GPP. The overall architecture will be described with reference to FIG. FIG. 1 is an explanatory diagram illustrating a configuration of an LTE communication system.
- a control protocol for the mobile terminal 101 such as RRC (Radio Resource Control) and a user plane such as PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), PHY (Physical Layer) E-UTRAN (Evolved102Universal Terrestrial Radio Access) is composed of one or more base stations 102.
- RRC Radio Resource Control
- PDCP Packet Data Convergence Protocol
- RLC Radio Link Control
- MAC Medium Access Control
- PHY Physical Layer
- E-UTRAN Evolved102Universal Terrestrial Radio Access
- the base station 102 performs scheduling and transmission of a paging signal (also called paging signaling or paging message) notified from an MME (Mobility Management Entity) 103.
- Base stations 102 are connected to each other via an X2 interface.
- the base station 102 is connected to an EPC (Evolved Packet Core) via an S1 interface. More specifically, the base station 102 is connected to an MME (Mobility Management Entity) 103 via an S1_MME interface, and is connected to an S-GW (Serving Gateway) 104 via an S1_U interface.
- EPC Evolved Packet Core
- the MME 103 distributes a paging signal to a plurality or a single base station 102. Further, the MME 103 performs mobility control (Mobility control) in a standby state (Idle State). The MME 103 manages a tracking area (Tracking Area) list when the mobile terminal is in a standby state and an active state (Active State).
- Mobility control mobility control
- Idle State standby state
- the MME 103 manages a tracking area (Tracking Area) list when the mobile terminal is in a standby state and an active state (Active State).
- the S-GW 104 transmits / receives user data to / from one or a plurality of base stations 102.
- the S-GW 104 becomes a local mobility anchor point (Mobility Anchor Point) during handover between base stations.
- the EPC further includes a P-GW (PDN Gateway), which performs packet filtering and UE-ID address allocation for each user.
- PDN Gateway PDN Gateway
- the control protocol RRC between the mobile terminal 101 and the base station 102 performs broadcast, paging, RRC connection management (RRC connection management), and the like.
- RRC_Idle and RRC_CONNECTED are states of the base station and the mobile terminal in RRC.
- RRC_IDLE PLMN (Public Land Mobile Mobile Network) selection, system information (System Information: SI) notification, paging, cell re-selection, mobility, and the like are performed.
- RRC_CONNECTED a mobile terminal has an RRC connection (connection), can transmit and receive data to and from the network, and performs handover (Handover: HO), measurement of a neighbor cell (Neighbour cell), and the like.
- Non-Patent Document 1 (Chapter 5) describes the current decisions regarding the frame configuration in the LTE system in 3GPP, with reference to FIG.
- FIG. 2 is an explanatory diagram showing a configuration of a radio frame used in the LTE communication system.
- one radio frame (Radio frame) is 10 ms.
- the radio frame is divided into 10 equally sized sub-frames.
- the subframe is divided into two equally sized slots.
- a downlink synchronization signal (Downlink Synchronization Signal: SS) is included in the first and sixth subframes for each radio frame.
- the synchronization signal includes a first synchronization signal (Primary Synchronization Signal: P-SS) and a second synchronization signal (Secondary Synchronization Signal: S-SS).
- MBSFN Multimedia (Broadcast multicast service Single Frequency Network) and channels other than MBSFN are performed on a subframe basis.
- MBSFN subframe MBSFN subframe
- Non-Patent Document 2 describes a signaling example at the time of MBSFN subframe allocation.
- FIG. 3 is an explanatory diagram showing the configuration of the MBSFN frame.
- an MBSFN subframe is allocated for each MBSFN frame (MBSFN frame).
- a set of MBSFN frames (MBSFN frame Cluster) is scheduled.
- a repetition period (Repetition Period) of a set of MBSFN frames is assigned.
- Non-Patent Document 1 (Chapter 5) describes the current decisions regarding the channel configuration in the LTE system in 3GPP. It is assumed that the CSG cell (ClosednSubscriber Group ⁇ ⁇ ⁇ ⁇ cell) uses the same channel configuration as the non-CSG cell.
- a physical channel will be described with reference to FIG.
- FIG. 4 is an explanatory diagram illustrating physical channels used in the LTE communication system.
- a physical broadcast channel (PBCH) 401 is a downlink channel transmitted from the base station 102 to the mobile terminal 101.
- a BCH transport block (transport block) is mapped to four subframes in a 40 ms interval. There is no obvious signaling of 40ms timing.
- a physical control channel format indicator channel (Physical-Control-Format-Indicator-Channel: PCFICH) 402 is transmitted from the base station 102 to the mobile terminal 101.
- PCFICH notifies base station 102 to mobile terminal 101 about the number of OFDM symbols used for PDCCHs.
- PCFICH is transmitted for each subframe.
- a physical downlink control channel (Physical Downlink Control Channel: PDCCH) 403 is a downlink channel transmitted from the base station 102 to the mobile terminal 101.
- the PDCCH is resource allocation, HARQ information regarding DL-SCH (a downlink shared channel that is one of the transport channels shown in FIG. 5 described later), and PCH (one of the transport channels shown in FIG. 5).
- the PDCCH carries an uplink scheduling grant (Uplink Scheduling Grant).
- the PDCCH carries Ack (Acknowledgement) / Nack (Negative Acknowledgment) which is a response signal for uplink transmission.
- the PDCCH is also called an L1 / L2 control signal.
- a physical downlink shared channel (PDSCH) 404 is a downlink channel transmitted from the base station 102 to the mobile terminal 101.
- PDSCH Downlink shared channel
- DL-SCH downlink shared channel
- PCH transport channel
- a physical multicast channel (Physical Multicast Channel: PMCH) 405 is a downlink channel transmitted from the base station 102 to the mobile terminal 101.
- the PMCH is mapped with an MCH (multicast channel) which is a transport channel.
- a physical uplink control channel (Physical Uplink Control Channel: PUCCH) 406 is an uplink channel transmitted from the mobile terminal 101 to the base station 102.
- the PUCCH carries Ack / Nack which is a response signal (response) to downlink transmission.
- the PUCCH carries a CQI (Channel Quality Indicator) report.
- CQI is quality information indicating the quality of received data or channel quality.
- the PUCCH carries a scheduling request (SR).
- a physical uplink shared channel (Physical Uplink Shared Channel: PUSCH) 407 is an uplink channel transmitted from the mobile terminal 101 to the base station 102.
- the PUSCH is mapped with UL-SCH (uplink shared channel which is one of the transport channels shown in FIG. 5).
- a Physical HARQ indicator channel (Physical Hybrid ARQ Indicator Channel: PHICH) 408 is a downlink channel transmitted from the base station 102 to the mobile terminal 101.
- PHICH carries Ack / Nack which is a response to uplink transmission.
- a physical random access channel (Physical Random Access Channel: PRACH) 409 is an uplink channel transmitted from the mobile terminal 101 to the base station 102.
- the PRACH carries a random access preamble.
- RSRP Reference Symbol Received Power
- FIG. 5 is an explanatory diagram for explaining a transport channel used in an LTE communication system.
- FIG. 5A shows the mapping between the downlink transport channel and the downlink physical channel.
- FIG. 5B shows mapping between the uplink transport channel and the uplink physical channel.
- the broadcast channel (Broadcast Channel: BCH) is broadcast to the entire base station (cell) regarding the downlink transport channel.
- the BCH is mapped to the physical broadcast channel (PBCH).
- HARQ Hybrid ARQ
- DL-SCH downlink shared channel
- the DL-SCH can be broadcast to the entire base station (cell).
- DL-SCH supports dynamic or semi-static resource allocation. Quasi-static resource allocation is also referred to as persistent scheduling.
- DL-SCH supports DRX (Discontinuous reception) of a mobile terminal in order to reduce power consumption of the mobile terminal.
- the DL-SCH is mapped to the physical downlink shared channel (PDSCH).
- the Paging Channel supports DRX of the mobile terminal in order to enable low power consumption of the mobile terminal.
- the PCH is required to be broadcast to the entire base station (cell).
- the PCH is mapped to a physical resource such as a physical downlink shared channel (PDSCH) that can be dynamically used for traffic, or a physical resource such as a physical downlink control channel (PDCCH) of another control channel.
- PDSCH physical downlink shared channel
- PDCCH physical downlink control channel
- a multicast channel (Multicast Channel: MCH) is used for broadcast to the entire base station (cell).
- the MCH supports SFN combining of MBMS services (MTCH and MCCH) in multi-cell transmission.
- the MCH supports quasi-static resource allocation.
- MCH is mapped to PMCH.
- Retransmission control by HARQ is applied to the uplink shared channel (Uplink Shared Channel: UL-SCH).
- UL-SCH supports dynamic or semi-static resource allocation.
- UL-SCH is mapped to a physical uplink shared channel (PUSCH).
- the random access channel (Random Access Channel: RACH) shown in FIG. 5B is limited to control information.
- RACH is at risk of collision.
- the RACH is mapped to a physical random access channel (PRACH).
- HARQ is a technique for improving the communication quality of a transmission path by combining automatic retransmission (AutomaticAutoRepeat reQuest) and error correction (Forward Error Correction).
- error correction functions effectively by retransmission even for transmission paths in which communication quality changes.
- further quality improvement can be obtained by combining the initial transmission reception result and the retransmission reception result upon retransmission.
- Chase combining is a method in which the same data sequence is transmitted for initial transmission and retransmission, and the gain is improved by combining the initial transmission data sequence and the retransmission data sequence in retransmission. This means that even if there is an error in the initial transmission data, the data is partially accurate, and the data is transmitted with higher accuracy by combining the correct initial transmission data and the retransmission data. It is based on the idea that it can be done.
- IR Intelligent Redundancy
- IR is to increase redundancy, and by transmitting parity bits in retransmission, the redundancy is increased in combination with initial transmission, and the quality is improved by an error correction function.
- FIG. 6 is an explanatory diagram illustrating logical channels used in the LTE communication system.
- FIG. 6A shows mapping between the downlink logical channel and the downlink transport channel.
- FIG. 6B shows mapping between the uplink logical channel and the uplink transport channel.
- the broadcast control channel (Broadcast Control Channel: BCCH) is a downlink channel for broadcast system control information.
- BCCH Broadcast Control Channel
- the BCCH that is a logical channel is mapped to a broadcast channel (BCH) that is a transport channel or a downlink shared channel (DL-SCH).
- the paging control channel is a downlink channel for transmitting a paging signal.
- PCCH is used when the network does not know the cell location of the mobile terminal.
- the PCCH that is a logical channel is mapped to a paging channel (PCH) that is a transport channel.
- the common control channel (Common Control Channel: CCCH) is a channel for transmission control information between the mobile terminal and the base station.
- CCCH is used when the mobile terminal does not have an RRC connection with the network.
- the CCCH is mapped to a downlink shared channel (DL-SCH) that is a transport channel.
- DL-SCH downlink shared channel
- UL-SCH uplink shared channel
- the multicast control channel (Multicast Control Channel: MCCH) is a downlink channel for one-to-many transmission.
- the MCCH is used for transmission of MBMS control information for one or several MTCHs from the network to the mobile terminal.
- MCCH is used only for mobile terminals that are receiving MBMS.
- the MCCH is mapped to the downlink shared channel (DL-SCH) or multicast channel (MCH) which is a transport channel.
- DL-SCH downlink shared channel
- MCH multicast channel
- the dedicated control channel (Dedicated Control Channel: DCCH) is a channel for transmitting dedicated control information between the mobile terminal and the network.
- the DCCH is mapped to the uplink shared channel (UL-SCH) in the uplink, and is mapped to the downlink shared channel (DL-SCH) in the downlink.
- the dedicated traffic channel (Dedicate Traffic Channel: DTCH) is a channel for one-to-one communication to individual mobile terminals for transmitting user information.
- DTCH exists for both uplink and downlink.
- the DTCH is mapped to the uplink shared channel (UL-SCH) in the uplink, and is mapped to the downlink shared channel (DL-SCH) in the downlink.
- UL-SCH uplink shared channel
- DL-SCH downlink shared channel
- the multicast traffic channel is a downlink channel for transmitting traffic data from the network to the mobile terminal.
- MTCH is a channel used only for a mobile terminal that is receiving MBMS.
- the MTCH is mapped to a downlink shared channel (DL-SCH) or a multicast channel (MCH).
- DL-SCH downlink shared channel
- MCH multicast channel
- GCI is a global cell identifier (Global Cell Identity).
- CSG cells Cell (Closed Subscriber Group Cell) are introduced. CSG will be described below (see Non-Patent Document 3, Chapter 3.1).
- CSG Cell
- PLMN Public Land Mobile Mobile Network
- One or more E-UTRAN cells to which the identified subscribers are allowed access are referred to as “CSG cell (s)”.
- PLMN has access restrictions.
- a CSG cell is a part of a PLMN that broadcasts a unique CSG identity (CSG identity: CSG ID; CSG-ID). Members of the subscriber group who have been registered in advance and permitted access the CSG cell using the CSG-ID as access permission information.
- CSG identity CSG ID; CSG-ID.
- the CSG-ID is broadcast by the CSG cell or cell. There are a plurality of CSG-IDs in a mobile communication system. The CSG-ID is then used by the mobile terminal (UE) to facilitate access of CSG related members.
- the location tracking of a mobile terminal is performed in units of areas composed of one or more cells. The position tracking is to enable tracking of the position of the mobile terminal and calling (the mobile terminal receives a call) even in the standby state. This area for tracking the location of the mobile terminal is called a tracking area.
- the CSG white list (CSG white list) is a list stored in a USIM (Universal Subscriber Identity Module) in which all CSG IDs of CSG cells to which the subscriber belongs are recorded. The CSG white list may be referred to as an allowed CSG list (Allowed CSG ID List).
- Suitable cell will be described below (see Non-Patent Document 3, Chapter 4.3).
- a “suitable cell” is a cell that the UE camps on to receive normal service. Such a cell shall satisfy the following conditions:
- the cell is a selected PLMN or a registered PLMN, or a part of the PLMN in the “Equivalent PLMN list”.
- the cell is not a barred cell.
- B And not a part of the “Forbidden LAs” list, but a part of at least one tracking area (TA). In that case, the cell needs to satisfy the above (1).
- C The cell satisfies the cell selection evaluation criteria.
- D The cell is a CSG cell according to system information (SI). For the identified cell, the CSG-ID shall be part of the UE's “CSG WhiteList” (included in the UE's CSG WhiteList).
- “Acceptable cell” will be described below (see Non-Patent Document 3, Chapter 4.3). This is a cell where the UE camps on in order to receive a limited service (emergency call). Such a cell shall satisfy all the following requirements: That is, the minimum set of requirements for initiating an emergency call in an E-UTRAN network is shown below. (1) The cell is not a barred cell. (2) The cell satisfies the cell selection evaluation criteria.
- camping on a cell means that the UE has completed cell selection / reselection processing and the UE has selected a cell for monitoring system information and paging information.
- Non-Patent Document 4 discloses three different modes of access to HeNB and HNB. Specifically, an open access mode (Open access mode), a closed access mode (Closed access mode), and a hybrid access mode (Hybrid access mode).
- Open access mode Open access mode
- closed access mode closed access mode
- Hybrid access mode Hybrid access mode
- Each mode has the following characteristics.
- the HeNB or HNB In the open access mode, the HeNB or HNB is operated as a normal cell of a normal operator.
- the closed access mode the HeNB or HNB is operated as a CSG cell. This is a CSG cell accessible only to CSG members.
- a non-CSG member In the hybrid access mode, a non-CSG member is a CSG cell to which access is permitted at the same time.
- a cell in hybrid access mode (also referred to as a hybrid cell) is a cell that supports both an open access mode and a closed access mode.
- Non-Patent Document 5 discloses a basic operation of a mobile terminal using PCI split.
- a mobile terminal that does not have PCI split information needs to perform a cell search using all PCIs (for example, using all 504 codes).
- a mobile terminal having PCI split information can perform a cell search using the PCI split information.
- LTE-A Long Term Evolution Advanced
- relay relay node
- the relay node is wirelessly connected to the radio access network via a donor cell (Donor cell; Donor eNB; DeNB).
- Donor cell Donor cell; Donor eNB; DeNB
- the network (NW) to relay link shares the same frequency band as the network to UE link.
- a Release 8 UE can also be connected to the donor cell.
- a link between the donor cell and the relay node is referred to as a backhaul link, and a link between the relay node and the UE is referred to as an access link.
- transmission from DeNB to RN is performed in a downlink (DL) frequency band
- transmission from RN to DeNB is performed in an uplink (UL) frequency band.
- DL downlink
- UL uplink
- a link from DeNB to RN and a link from RN to UE are time-division multiplexed in one frequency band
- a link from RN to DeNB and a link from UE to RN are also one frequency band. Is time-division multiplexed. By doing so, it is possible to prevent the relay transmission from interfering with the reception of the own relay in the relay.
- Heterogeneous Networks has been added as one of the technologies studied in LTE-A (see Non-Patent Document 8).
- Heterogeneous networks are networks in which one or more local area range nodes such as HeNBs and relay nodes are incorporated in a normal eNB (macro cell).
- Non-Patent Document 8 proposes that cell selection considering the quality of the backhaul link, measurement of a cell with weak received power, and a trigger mechanism are necessary to solve these problems.
- Non-Patent Document 9 discloses a cell selection method considering the communication quality of a relay node backhaul link.
- Non-Patent Document 10 discloses that an uplink and a downlink are independently connected to different cells.
- Non-Patent Document 8 proposes that cell selection taking into account the quality of the backhaul link, measurement of a cell with weak reception power, and a trigger mechanism are necessary to solve the above-described problems. However, these specific methods are not described at all.
- Non-Patent Document 9 describes that the relay node broadcasts the quality of the backhaul link, and the UE performs cell selection in consideration thereof. However, there is no disclosure of a specific method by which the quality of the backhaul link is taken into consideration.
- Non-Patent Document 10 discloses that an uplink and a downlink are connected independently to different cells, but this specific method is not described at all. In addition, connecting to different cells in the uplink and the downlink is considered to make communication control very complicated because the UE has a plurality of serving cells.
- An object of the present invention is to provide a mobile communication system that enables operation of a huge number of local area range nodes and their flexible arrangement.
- the mobile communication system of the present invention includes a plurality of base station devices connected to a core network and mobile terminal devices capable of wireless communication with each of the base station devices, and a communicable range of the plurality of base station devices
- the cell of the base station apparatus to be communicated is selected from the plurality of cells based on selection information including the communication quality of the communication line.
- the mobile communication system of the present invention includes a plurality of base station devices, a mobile terminal device capable of wireless communication with each of the base station devices, at least one base station device of the plurality of base station devices, and the mobile A mobile communication system in which at least a part of a plurality of cells that are communicable ranges of the plurality of base station devices overlap each other, including a relay device that relays wireless communication with the terminal device
- the apparatus is configured to select from among the plurality of cells based on selection information including reception quality of a signal from the base station apparatus in each cell and communication quality of a communication line between the base station apparatus and the relay apparatus.
- the base station apparatus cell to be communicated is selected.
- the mobile communication system of the present invention includes a plurality of base station devices and a mobile terminal device capable of wireless communication with each of the base station devices, and a plurality of cells that are communicable ranges of the plurality of base station devices.
- a portion of the mobile terminal apparatus overlaps the reception quality of the signal from the base station apparatus in each cell and the uplink communication line from the mobile terminal apparatus to the base station apparatus in each cell.
- a cell of a base station apparatus to be a communication target is selected from the plurality of cells based on selection information including a state.
- the mobile terminal apparatus selects the reception quality of the signal from the base station apparatus in each cell and the communication quality of the communication line between the base station apparatus and the core network. Based on the information, a cell of the base station apparatus to be communicated is selected from a plurality of cells. Thereby, in addition to the reception quality of each cell, the communication quality of the communication line between the base station apparatus and the core network can be taken into consideration, and the cell of the base station apparatus to be communicated can be selected. Therefore, for example, since it is possible to improve the interference problem and the capacity problem in heterogeneous networks, it is possible to operate a large number of local area range nodes and flexibly arrange them.
- the mobile terminal apparatus selects information including the reception quality of the signal from the base station apparatus in each cell and the communication quality of the communication line between the base station apparatus and the relay apparatus. Based on the above, a cell of a base station apparatus to be a communication target is selected from a plurality of cells. Thereby, in addition to the reception quality of each cell, the communication quality of the communication line between the base station apparatus and the relay apparatus can be taken into consideration, and the cell of the base station apparatus to be communicated can be selected. Therefore, for example, since it is possible to improve the interference problem and the capacity problem in heterogeneous networks, it is possible to operate a large number of local area range nodes and flexibly arrange them.
- the mobile terminal apparatus determines the reception quality of the signal from the base station apparatus in each cell and the state of the uplink communication line from the mobile terminal apparatus to the base station apparatus in each cell. Based on the selection information included, a cell of a base station apparatus to be communicated is selected from a plurality of cells. Thereby, in addition to the reception quality of each cell, the state of the uplink communication line of each cell can be taken into consideration, and the cell of the base station apparatus to be communicated can be selected. Therefore, for example, since it is possible to improve the interference problem and the capacity problem in heterogeneous networks, it is possible to operate a large number of local area range nodes and flexibly arrange them.
- FIG. 2 is an explanatory diagram showing a configuration of a radio frame used in an LTE communication system. It is explanatory drawing which shows the structure of a MBSFN frame. It is explanatory drawing explaining the physical channel used with the communication system of a LTE system. It is explanatory drawing explaining the transport channel used with the communication system of a LTE system. It is explanatory drawing explaining the logical channel used with the communication system of a LTE system. It is a block diagram which shows the whole structure of the mobile communication system of the LTE system currently discussed in 3GPP. It is a block diagram which shows the structure of the mobile terminal (mobile terminal 71 of FIG. 7) which concerns on this invention.
- FIG. 7 It is a block diagram which shows the structure of the base station (base station 72 of FIG. 7) based on this invention. It is a block diagram which shows the structure of MME which concerns on this invention (MME part 73 of FIG. 7). It is a block diagram which shows the structure of HeNBGW74 shown in FIG. 7 which is HeNBGW which concerns on this invention.
- 5 is a flowchart illustrating an outline from a cell search to a standby operation performed by a mobile terminal (UE) in an LTE communication system. It is a flowchart which shows the process sequence of the celery selection of UE by the technique of a nonpatent literature 3.
- FIG. 10 is a sequence diagram illustrating a normal HO processing procedure according to the technique of Non-Patent Document 1. It is a flowchart which shows an example of the selection procedure of the target cell by a serving cell. It is a flowchart which shows the communication procedure of the cell backhaul link disclosed in this Embodiment, and the process procedure of HO which considered the state of the uplink.
- FIG. 7 is a block diagram showing the overall configuration of an LTE mobile communication system currently under discussion in 3GPP.
- CSG Cell Subscriber Group
- E-UTRAN Home-eNodeB Home-eNodeB
- HeNB HeNB
- UTRAN Home-NB HNB
- non-CSG cells E-UTRAN eNodeB
- eNB UTRAN NodeB
- GERAN BSS GERAN BSS
- a mobile terminal device (hereinafter referred to as “mobile terminal” or “UE”) 71 is capable of wireless communication with a base station device (hereinafter referred to as “base station”) 72, and transmits and receives signals by wireless communication.
- the base station 72 is classified into an eNB 72-1 and a Home-eNB 72-2.
- the eNB 72-1 is connected to the MME, S-GW, or the MME / S-GW unit (hereinafter referred to as “MME unit”) 73 including the MME and the S-GW via the S1 interface. Control information is communicated between the two.
- the eNB 72-1 is connected to the core network via the MME unit 73.
- a plurality of MME units 73 may be connected to one eNB 72-1.
- the eNBs 72-1 are connected by the X2 interface, and control information is communicated between the eNBs 72-1.
- the Home-eNB 72-2 is connected to the MME unit 73 via the S1 interface, and control information is communicated between the Home-eNB 72-2 and the MME unit 73.
- a plurality of Home-eNBs 72-2 are connected to one MME unit 73.
- the Home-eNB 72-2 is connected to the MME unit 73 via a HeNBGW (Home-eNB GateWay) 74.
- Home-eNB 72-2 and HeNBGW 74 are connected via an S1 interface, and HeNBGW 74 and MME unit 73 are connected via an S1 interface.
- the Home-eNB 72-2 is connected to the core network via the MME unit 73 or the MME unit 73 and the HeNBGW 74.
- One or a plurality of Home-eNBs 72-2 are connected to one HeNBGW 74, and information is communicated through the S1 interface.
- the HeNBGW 74 is connected to one or a plurality of MME units 73, and information is communicated through the S1 interface.
- the X2 interface between Home-eNB 72-2 is not supported. From the MME unit 73, the HeNBGW 74 appears as an eNB 72-1. From the Home-eNB 72-2, the HeNBGW 74 appears as the MME unit 73. Regardless of whether or not the Home-eNB 72-2 is connected to the MME unit 73 via the HeNBGW 74, the interface between the Home-eNB 72-2 and the MME unit 73 is the same in the S1 interface. Mobility to the Home-eNB 72-2 or mobility from the Home-eNB 72-2 that spans a plurality of MME units 73 is not supported. Home-eNB 72-2 supports only one cell.
- FIG. 8 is a block diagram showing a configuration of a mobile terminal (mobile terminal 71 in FIG. 7) according to the present invention.
- a transmission process of the mobile terminal 71 shown in FIG. 8 will be described.
- control data from the protocol processing unit 801 and user data from the application unit 802 are stored in the transmission data buffer unit 803.
- the data stored in the transmission data buffer unit 803 is transferred to the encoder unit 804 and subjected to encoding processing such as error correction.
- the data encoded by the encoder unit 804 is modulated by the modulation unit 805.
- the modulated data is converted into a baseband signal, and then output to the frequency conversion unit 806, where it is converted into a radio transmission frequency.
- a transmission signal is transmitted from the antenna 807 to the base station 72.
- the reception process of the mobile terminal 71 is executed as follows.
- a radio signal from the base station 72 is received by the antenna 807.
- the reception signal is converted from a radio reception frequency to a baseband signal by the frequency conversion unit 806, and demodulated by the demodulation unit 808.
- the demodulated data is passed to the decoder unit 809 and subjected to decoding processing such as error correction.
- control data is passed to the protocol processing unit 801, and user data is passed to the application unit 802.
- a series of processing of the mobile terminal 71 is controlled by the control unit 810. Therefore, the control unit 810 is connected to the respective units 801 to 809, which is omitted in FIG.
- FIG. 9 is a block diagram showing the configuration of the base station (base station 72 in FIG. 7) according to the present invention.
- the transmission process of the base station 72 shown in FIG. 9 will be described.
- the EPC communication unit 901 transmits and receives data between the base station 72 and the EPC (MME unit 73, HeNBGW 74, etc.).
- the other base station communication unit 902 transmits / receives data to / from other base stations. Since the X2 interface between the Home-eNB 72-2 is a direction that is not supported, the Home-eNB 72-2 may not include the other base station communication unit 902.
- the EPC communication unit 901 and the other base station communication unit 902 exchange information with the protocol processing unit 903, respectively. Control data from the protocol processing unit 903 and user data and control data from the EPC communication unit 901 and the other base station communication unit 902 are stored in the transmission data buffer unit 904.
- the data stored in the transmission data buffer unit 904 is transferred to the encoder unit 905 and subjected to encoding processing such as error correction. There may exist data that is directly output from the transmission data buffer unit 904 to the modulation unit 906 without performing the encoding process.
- the encoded data is subjected to modulation processing by the modulation unit 906.
- the modulated data is converted into a baseband signal, and then output to the frequency conversion unit 907 to be converted into a radio transmission frequency. Thereafter, a transmission signal is transmitted from the antenna 908 to one or a plurality of mobile terminals 71.
- the reception process of the base station 72 is executed as follows. Radio signals from one or a plurality of mobile terminals 71 are received by the antenna 908. The reception signal is converted from a radio reception frequency to a baseband signal by the frequency conversion unit 907, and demodulated by the demodulation unit 909. The demodulated data is transferred to the decoder unit 910 and subjected to decoding processing such as error correction. Of the decoded data, the control data is passed to the protocol processing unit 903 or the EPC communication unit 901 and the other base station communication unit 902, and the user data is passed to the EPC communication unit 901 and the other base station communication unit 902. A series of processing of the base station 72 is controlled by the control unit 911. Therefore, although not shown in FIG. 9, the control unit 911 is connected to the units 901 to 910.
- the functions of Home-eNB 72-2 currently being discussed in 3GPP are shown below (see Non-Patent Document 1, Chapter 4.6.2).
- the Home-eNB 72-2 has the same function as the eNB 72-1.
- the Home-eNB 72-2 has a function of finding an appropriate serving HeNBGW 74.
- the Home-eNB 72-2 is only connected to one HeNBGW 74. That is, in the case of connection with the HeNBGW 74, the Home-eNB 72-2 does not use the Flex function in the S1 interface.
- the Home-eNB 72-2 is not simultaneously connected to another HeNBGW 74 or another MME unit 73.
- the TAC and PLMN ID of the Home-eNB 72-2 are supported by the HeNBGW 74.
- the selection of the MME unit 73 in “UE attachment” is performed by the HeNBGW 74 instead of the Home-eNB 72-2.
- Home-eNB 72-2 may be deployed without network planning. In this case, Home-eNB 72-2 is moved from one geographic region to another. Therefore, the Home-eNB 72-2 in this case needs to be connected to different HeNBGW 74 depending on the position.
- FIG. 10 is a block diagram showing the configuration of the MME (MME unit 73 in FIG. 7) according to the present invention.
- the PDN GW communication unit 1001 transmits and receives data between the MME unit 73 and the PDN GW.
- the base station communication unit 1002 performs data transmission / reception between the MME unit 73 and the base station 72 through the S1 interface. If the data received from the PDN GW is user data, the user data is passed from the PDN GW communication unit 1001 to the base station communication unit 1002 via the user plane communication unit 1003 to one or a plurality of base stations 72. Sent. When the data received from the base station 72 is user data, the user data is passed from the base station communication unit 1002 to the PDN GW communication unit 1001 via the user plane communication unit 1003 and transmitted to the PDN GW.
- control data is passed from the PDN GW communication unit 1001 to the control plane control unit 1005.
- control data is transferred from the base station communication unit 1002 to the control plane control unit 1005.
- the HeNBGW communication unit 1004 is provided when the HeNBGW 74 exists, and transmits and receives data through an interface (IF) between the MME unit 73 and the HeNBGW 74 depending on the information type.
- the control data received from the HeNBGW communication unit 1004 is passed from the HeNBGW communication unit 1004 to the control plane control unit 1005.
- the result of processing in the control plane control unit 1005 is transmitted to the PDN GW via the PDN GW communication unit 1001. Further, the result processed by the control plane control unit 1005 is transmitted to one or a plurality of base stations 72 via the S1 interface via the base station communication unit 1002, and to one or a plurality of HeNBGWs 74 via the HeNBGW communication unit 1004. Sent.
- the control plane control unit 1005 includes a NAS security unit 1005-1, an SAE bearer control unit 1005-2, an idle state mobility management unit 1005-3, and the like, and performs overall processing for the control plane.
- the NAS security unit 1005-1 performs security of a NAS (Non-Access Stratum) message.
- the SAE bearer control unit 1005-2 manages a bearer of SAE (System Architecture) Evolution.
- the idle state mobility management unit 1005-3 manages mobility in a standby state (LTE-IDLE state, also simply referred to as idle), generation and control of a paging signal in the standby state, and one or more mobile terminals 71 being served thereby Add, delete, update, search, and track area list (TA ⁇ ⁇ ⁇ List) management.
- the MME unit 73 initiates the paging protocol by transmitting a paging message to a cell belonging to a tracking area (tracking area: Tracking Area: TA) in which the UE is registered.
- the idle state mobility management unit 1005-3 may perform CSG management, CSG-ID management, and white list management of the Home-eNB 72-2 connected to the MME unit 73.
- the relationship between the mobile terminal corresponding to the CSG-ID and the CSG cell is managed (added, deleted, updated, searched). For example, it may be a relationship between one or a plurality of mobile terminals registered for user access with a certain CSG-ID and a CSG cell belonging to the CSG-ID.
- white list management the relationship between a mobile terminal and a CSG-ID is managed (added, deleted, updated, searched). For example, one or a plurality of CSG-IDs registered by a certain mobile terminal as a user may be stored in the white list. Management related to these CSGs may be performed in other parts of the MME unit 73. A series of processing of the MME unit 73 is controlled by the control unit 1006. Therefore, although not shown in FIG. 10, the control unit 1006 is connected to the units 1001 to 1005.
- the functions of MME currently being discussed in 3GPP are shown below (refer to Chapter 4.6.2 of Non-Patent Document 1).
- the MME performs access control of one or a plurality of mobile terminals of CSG (Closed Subscriber Groups).
- the MME accepts paging optimization as an option.
- FIG. 11 is a block diagram showing a configuration of the HeNBGW 74 shown in FIG. 7 which is the HeNBGW according to the present invention.
- the EPC communication unit 1101 performs data transmission / reception between the HeNBGW 74 and the MME unit 73 through the S1 interface.
- the base station communication unit 1102 performs data transmission / reception between the HeNBGW 74 and the Home-eNB 72-2 via the S1 interface.
- the location processing unit 1103 performs a process of transmitting registration information and the like among the data from the MME unit 73 delivered via the EPC communication unit 1101 to the plurality of Home-eNBs 72-2.
- the data processed by the location processing unit 1103 is passed to the base station communication unit 1102 and transmitted to one or more Home-eNBs 72-2 via the S1 interface.
- Data that does not require processing in the location processing unit 1103 and is simply passed (transmitted) is passed from the EPC communication unit 1101 to the base station communication unit 1102 and sent to one or more Home-eNBs 72-2 via the S1 interface. Sent.
- a series of processing of the HeNBGW 74 is controlled by the control unit 1104. Therefore, although not shown in FIG. 11, the control unit 1104 is connected to the units 1101 to 1103.
- HeNBGW74 The functions of HeNBGW74 currently being discussed in 3GPP are shown below (see Non-Patent Document 1, Chapter 4.6.2).
- the HeNBGW 74 relays for the S1 application. Although part of the procedure of the MME unit 73 to the Home-eNB 72-2, the HeNBGW 74 terminates the S1 application not related to the mobile terminal 71.
- the HeNBGW 74 When the HeNBGW 74 is arranged, procedures unrelated to the mobile terminal 71 are communicated between the Home-eNB 72-2 and the HeNBGW 74, and between the HeNBGW 74 and the MME unit 73.
- the X2 interface is not set between the HeNBGW 74 and other nodes.
- the HeNBGW 74 recognizes execution of paging optimization (Paging optimization) as an option.
- Paging optimization paging optimization
- FIG. 12 is a flowchart showing an outline from a cell search to a standby operation performed by a mobile terminal (UE) in an LTE communication system.
- the mobile terminal uses the first synchronization signal (P-SS) and the second synchronization signal (S-SS) transmitted from the neighboring base stations in step ST1201, and the slot timing, frame Synchronize timing.
- the synchronization signal (SS) is assigned a synchronization code corresponding to one-to-one PCI (Physical Cell Identity) assigned to each cell.
- PCI Physical Cell Identity
- a reference signal RS Reference signal
- the reference signal RS uses a code corresponding to the PCI one-to-one, and can be separated from other cells by taking a correlation with the code.
- a cell having the best RS reception quality (for example, a cell having the highest RS reception power, that is, the best cell) is selected from one or more cells detected up to step ST1202.
- the PBCH of the best cell is received and the BCCH that is broadcast information is obtained.
- MIB Master Information Block
- the MIB information includes, for example, DL (downlink) system bandwidth (also called transmission bandwidth setting (transmission bandwidth configuration: dl-bandwidth)), the number of transmission antennas, SFN (System frame number), and the like.
- SIB1 System Information Block 1 in the broadcast information BCCH.
- SIB1 includes information related to access to the cell, information related to cell selection, and scheduling information of other SIBs (SIBk; an integer of k ⁇ 2). Also, SIB1 includes TAC (Tracking Area Code).
- step ST1206 the mobile terminal compares the TAC of SIB1 received in step ST1205 with the TAC already held by the mobile terminal. If the result of the comparison is the same, a standby operation is started in the cell. If they are different from each other, the mobile terminal requests a change of TA to perform TAU (Tracking Area Update) to the core network (Core-Network, EPC) (including MME) through the cell.
- the core network updates the TA based on the identification number (UE-ID or the like) of the mobile terminal sent from the mobile terminal together with the TAU request signal. After updating the TA, the core network transmits a TAU receipt signal to the mobile terminal.
- the mobile terminal rewrites (updates) the TAC (or TAC list) held by the mobile terminal with the TAC of the cell. Thereafter, the mobile terminal enters a standby operation in the cell.
- CSG Cell Subscriber Group
- access is permitted only to one or a plurality of mobile terminals registered in the CSG cell.
- a CSG cell and one or more registered mobile terminals constitute one CSG.
- a CSG configured in this way is given a unique identification number called CSG-ID.
- a single CSG may have a plurality of CSG cells. If a mobile terminal registers in any one CSG cell, it can access another CSG cell to which the CSG cell belongs.
- Home-eNB in LTE and Home-NB in UMTS may be used as CSG cells.
- the mobile terminal registered in the CSG cell has a white list.
- the white list is stored in SIM (Subscriber Identity Module) / USIM.
- the white list stores CSG information of CSG cells registered by the mobile terminal.
- CSG-ID, TAI (Tracking Area Identity), TAC, etc. can be considered as the CSG information.
- Either of the CSG-ID and the TAC may be used as long as they are associated with each other.
- GCI may be used as long as CSG-ID and TAC are associated with GCI (Global Cell Identity).
- a mobile terminal that does not have a white list cannot access a CSG cell, and only accesses a non-CSG cell. Can not.
- a mobile terminal having a white list can access both a CSG cell of a registered CSG-ID and a non-CSG cell.
- Non-Patent Document 5 discloses a basic operation of a mobile terminal using PCI split.
- a mobile terminal that does not have PCI split information needs to perform a cell search using all PCIs (for example, using all 504 codes).
- a mobile terminal having PCI split information can perform a cell search using the PCI split information.
- PCI for hybrid cells is not included in the PCI range for CSG cells (see Non-Patent Document 1, Chapter 10.7).
- the HeNB and HNB are required to support various services. For example, an operator increases a radio resource that can be used by a mobile terminal by allowing the mobile terminal to be registered in a certain HeNB and HNB and allowing only the registered mobile terminal to access the HeNB and HNB cells. To enable high-speed communication. Accordingly, the service is such that the operator sets the charging fee higher than usual.
- CSG Cell
- Many CSG (Closed Subscriber Group Cell) cells are required to be installed in shopping streets, condominiums, schools, companies, and the like.
- a CSG cell is installed for each store in a shopping street, each room in a condominium, each classroom in a school, and each section in a company, and only a user registered in each CSG cell can use the CSG cell.
- HeNB / HNB is required not only to complement communication outside the coverage of the macro cell, but also to support various services as described above. For this reason, a case where the HeNB / HNB is installed in the coverage of the macro cell may occur.
- Heterogeneous networks was added as one of the technologies to be studied in LTE-A.
- a low output power local area range such as a pico eNB (pico cell), a node for a hot zone cell, a HeNB / HNB / CSG cell, a relay node, a remote radio head (RRH) range) network nodes (local area range node (local area node), local area node (local area node), local node (local node)). Therefore, it is required to operate a network in which one or more such local area range nodes are incorporated in a normal eNB (macro cell).
- a network in which one or more such local area range nodes are incorporated in a normal eNB (macro cell) is called heterogeneous networks, and an interference reduction method, a capacity improvement method, and the like are studied.
- Non-patent document 8 describes the technology of heterogeneous networks.
- the cell selection is performed to the cell having the strongest reception power (strongest cell, best cell).
- strongest cell, best cell strongest cell
- the best cell cannot be selected due to the limitation by CSG.
- the best cell is not necessarily the optimal cell for communication.
- the UE should not connect to a cell with poor backhaul link communication quality.
- the femtocell (HeNB) is assumed to be home use, and is connected to the core network side through a general broadband line. Therefore, the use band is limited and the reliability is deteriorated in the backhaul link.
- the backhaul link of the relay node is a communication line between the relay node and the base station device.
- a backhaul link of a base station apparatus such as a pico cell and a femto cell (HeNB) is a communication line between the base station apparatus and the core network.
- Non-Patent Document 8 proposes that cell selection considering the quality of the backhaul link, measurement of a cell with weak received power, and a trigger mechanism are necessary to solve these problems. However, these specific methods are not described at all.
- Non-Patent Document 9 discloses a cell selection method considering a backhaul link of a relay node. It is described that the relay node broadcasts the quality of the backhaul link and the UE performs cell selection in consideration thereof. However, there is no disclosure of a specific method by which the quality of the backhaul link is taken into consideration.
- Non-Patent Document 9 describes that the donor eNB reports the quality of the backhaul link of all the relay nodes, and that the link quality between the relay node and the donor eNB is inserted into Qoffset.
- Qoffset is an offset value added to the received power measurement value of the adjacent cell at the time of cell reselection. Therefore, in the method disclosed here, the communication quality of the backhaul link is not included in the cell selection. Further, since Qoffset is an offset value given to the received power measurement value of the adjacent cell, the communication quality of the serving cell backhaul link cannot be incorporated into the received power of the serving cell.
- FIG. 13 is a flowchart showing a celery selection processing procedure of the UE according to the technique of Non-Patent Document 3.
- the UE measures the received power of the serving cell for cell reselection.
- the received power measurement value of the serving cell is Sx.
- step ST1301 the UE compares Sx with a measurement start threshold (S_intrasearch) for celery selection.
- S_intrasearch is notified in advance from the serving cell.
- the UE compares Sx and S_intrasearch, and when Sx is equal to or less than S_intrasearch, the UE determines that the reception power of the serving cell is low and starts measurement for celery selection (step ST1302). If Sx is larger than S_intrasearch, the UE determines that the received power of the serving cell is sufficient, does not start measurement for cell reselection, measures Sx, returns to step ST1301, and again returns to Sx and S_intrasearch. And compare.
- step ST1302 the UE measures received power of neighboring cells. At this time, the reception power of the serving cell may be measured.
- Step ST1303 the UE calculates a value (Srxlev) in which a correction value in the received power is inserted from the measured value for each cell. This correction value and calculation method are described in Non-Patent Document 3.
- the UE that has calculated Srxlev determines whether or not the Srxlev is greater than 0 in step ST1304. If the Srxlev is greater than 0, the process of step ST1306 described later is performed with the cell as a candidate for best cell selection. When the Srxlev is 0 or less, the cell is not regarded as a best cell selection candidate.
- step ST1303 performs the process of above-mentioned step ST1303 and step ST1304 with respect to the one or some cell obtained by the measurement for the cell reselection of step ST1302.
- step ST1305 when no cell having Srxlev greater than 0 is obtained, the process moves to step ST1305 and becomes out of range. If a cell having Srxlev greater than 0 is obtained, the process proceeds to step ST1306.
- step ST1306 the UE calculates Rs and Rn using the following equations (see Non-Patent Document 3).
- the UE uses the calculated Rs and Rn to select the cell (best cell) with the highest received power. Then, the UE performs celery selection on the best cell selected in step ST1306.
- Non-Patent Document 9 Since the cell reselection is performed as described above, the method disclosed in Non-Patent Document 9 has a problem in that the communication quality of the serving cell backhaul link cannot be included in the received power of the serving cell.
- Non-Patent Document 9 does not describe this at all.
- the communication quality of the backhaul link of the serving cell cannot be considered at all in determining whether or not to perform the measurement of the neighboring cell for celery selection shown in step ST1301. .
- the serving cell when the serving cell is a relay, the reception quality of the access link is good, but the communication quality of the backhaul link may be bad. If the communication quality of the backhaul link of the serving cell is not taken into consideration in the determination of whether to perform the measurement of the neighboring cell for cell reselection in step ST1301, the communication quality of the backhaul link is poor. , Celery selection will not be performed. As a result, the communication speed is reduced, and in the worst case, communication is interrupted.
- the backhaul link is a broadband line that connects the HeNB and the core network.
- the same problem occurs when communication quality deteriorates due to congestion of this broadband line.
- this embodiment discloses a method in which the communication quality of the backhaul link of at least one of the serving cell and the neighboring cell is taken into consideration for cell reselection.
- the communication quality of the backhaul link is taken into account in the criteria for starting measurement for the cell reselection, that is, the reference value.
- the communication quality of the serving cell backhaul link is inserted into the measurement start threshold for celery selection.
- FIG. 14 is a flowchart showing the processing procedure of celery selection in which the communication quality of the backhaul link of the serving cell is inserted in the measurement start threshold for celery selection.
- the process of the flowchart shown in FIG. 14 is similar to the process of the flowchart shown in FIG. 13, so only the different processes will be described, the corresponding parts will be denoted by the same step numbers, and the description of the processes will be omitted. .
- UE measures the received power of the serving cell for celery selection.
- a measurement start threshold (S_intrasearch_total) for celery selection considering the communication quality of the backhaul link of the serving cell is newly provided.
- step ST1401 the UE compares the received power measurement value (Sx) of the serving cell with a measurement start threshold value (S_intrasearch_total) for cell reselection considering the communication quality of the backhaul link of the serving cell.
- Sx received power measurement value
- S_intrasearch_total measurement start threshold value
- the UE compares Sx and S_intrasearch_total, and when Sx is equal to or less than S_intrasearch_total, the UE determines that the reception quality of the serving cell including the communication quality of the backhaul link is poor and starts measurement for celery selection ( Step ST1302). If Sx is larger than S_intrasearch_total, the UE determines that the reception quality of the serving cell including the communication quality of the backhaul link is sufficient, does not start measurement for cell reselection, measures Sx, Returning to ST1401, Sx is again compared with S_intrasearch_total.
- the communication quality of the backhaul link of the serving cell is included in the measurement start threshold for celery selection, so that the communication quality of the backhaul link is taken into consideration for the measurement start criteria for celery selection.
- the serving cell measures the communication quality of the backhaul link and determines a measurement start threshold (S_intrasearch_total) for new cell reselection in consideration of the measurement result.
- the serving cell notifies the S_intrasearch_total in advance.
- the UE receives the S_intrasearch_total broadcast from the serving cell in advance and uses it as a measurement start threshold for cell reselection in step ST1401.
- S_intrasearch_total is newly provided separately from S_intrasearch of FIG. This makes it possible to use different threshold values depending on whether or not the backhaul link is considered.
- a measurement start threshold for cell reselection considering the communication quality of the backhaul link derived by the serving cell may be set in S_intrasearch.
- the communication quality of the backhaul link can always be inserted into S_intrasearch, and the number of parameters to be notified can be reduced.
- the communication quality of the backhaul link may be received power (RSRP, RSRQ: Reference Signal Received Quality), communication speed, communication capacity, line quality, and the like.
- RSRP, RSRQ Reference Signal Received Quality
- S_intrasearch_total can be directly calculated by a certain function. This makes it easy to derive S_intrasearch_total in the serving cell. Instead of calculating and deriving with a certain function, it may be derived using a correspondence table between the communication quality of the backhaul link and the corresponding threshold value S_intrasearch_total.
- the communication quality of the backhaul link should be the communication speed, communication capacity, line quality, etc.
- the unit is different from the conventional threshold (S_intrasearch).
- S_intrasearch a function having the communication quality of the backhaul link as a variable may be provided, and S_intrasearch_total may be derived by the function. Or you may make it derive
- These functions or correspondence tables may be determined statically in advance.
- the serving cell may be notified by including a measurement start threshold value (S_intrasearch_total) for new cell reselection in SIB3, or may be included in SIB1.
- SIB3 since the cell reselection parameter is included, the UE can receive it together with other cell reselection parameters. For this reason, the reception operation of the UE can be simplified, and the control malfunction can be reduced.
- SIB1 since the timing to be notified in advance is determined, the UE can receive at an early stage during measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE.
- the serving cell derives a measurement start threshold (S_intrasearch_total) for a new cell reselection.
- the present invention is not limited to this, and the UE may derive a measurement start threshold value (S_intrasearch_total) for a new celery selection.
- the serving cell may notify the UE of the communication quality of the backhaul link of the serving cell.
- the UE derives the threshold S_intrasearch_total using the notified communication quality of the backhaul link of the serving cell.
- the communication quality of the backhaul link varies. Therefore, when the communication quality of the backhaul link is changed and notified, the notification information may be corrected.
- the serving cell may report the average value or the value after filtering by averaging or filtering the communication quality of the backhaul link for a certain period. You may make it match this certain period with the timing when alerting
- the serving cell may notify the communication quality of the backhaul link of the serving cell by including it in SIB3 or may be notified by including it in SIB1. In each case, the same effect as when S_intrasearch_total is notified can be obtained.
- a method similar to the method derived by the serving cell can be applied.
- the same method can be applied to celery selection to cells in other frequency carriers and celery selection to other systems such as W-CDMA.
- the measurement start threshold (S_intrasearch) for celery selection the communication quality of the backhaul link may be considered in the measurement start threshold (S_nonintrasearch) for celery selection for other frequency carriers or other systems.
- a similar method may be used by separately providing a measurement start threshold (S_nonintrasearch_total) for cell reselection for a new other frequency carrier or another system considering the communication quality of the backhaul link.
- cell reselection can be performed in consideration of the communication quality of the backhaul link in addition to the reception quality of each cell.
- the reception quality of the serving cell is good, cell reselection is started depending on the communication quality of the backhaul link of the serving cell, so the communication speed due to the deterioration of the communication quality of the backhaul link of the serving cell. And the occurrence of communication interruption can be suppressed. Therefore, since it is possible to improve the interference problem and capacity problem in heterogeneous networks, it is possible to operate a large number of local area range nodes and to arrange them flexibly.
- Embodiment 1 Modification 1 As another example of taking the communication quality of the backhaul link into consideration for the measurement start criteria for celery selection, a case will be described in which the communication quality of the backhaul link of the serving cell is included in the measurement value of the serving cell.
- FIG. 15 is a flowchart showing a processing procedure of cell reselection in which the communication quality of the serving cell backhaul link is inserted into the measured value of the serving cell.
- the processing of the flowchart shown in FIG. 15 is similar to the processing of the flowchart shown in FIG. 13, so only the different processing will be described, the corresponding steps will be given the same step numbers, and the description of the processing will be omitted. .
- the UE measures the received power of the serving cell for celery selection.
- the UE derives a value (Sx_total) obtained by inserting the communication quality of the backhaul link of the serving cell into the received power measurement value (Sx) of the serving cell.
- the serving cell measures the communication quality of the backhaul link and informs the UE.
- the UE receives the communication quality broadcast from the serving cell in advance and uses it when deriving the above-described Sx_total.
- step ST1501 the UE compares Sx_total with a measurement start threshold (S_intrasearch) for celery selection.
- the UE compares Sx_total and S_intrasearch, and when Sx_total is equal to or lower than S_intrasearch, the UE determines that the reception quality of the serving cell including the communication quality of the backhaul link is poor and starts measurement for celery selection ( Step ST1302).
- Sx_total is larger than S_intrasearch, the UE determines that the reception quality of the serving cell including the communication quality of the backhaul link is sufficient, does not start measurement for cell reselection, and returns to step ST1501.
- Sx is measured again, Sx_total is derived and compared with S_intrasearch.
- a value (Sx_total) in which the communication quality of the backhaul link of the serving cell is inserted into the received power measurement value (Sx) of the serving cell measured by the UE is derived, and Sx_total is measured for cell reselection.
- the communication quality of the serving cell backhaul link is taken into account.
- the communication quality of the backhaul link may be received power (RSRP, RSRQ), communication speed, communication capacity, line quality, and the like.
- the received power (RSRP, RSRQ) or the like is aligned with the measured value (Sx) of the access link, and Sx_total can be directly calculated by a certain function. This makes it easy to derive Sx_total at the UE. Further, it may be derived using a correspondence table instead of being calculated using a certain function.
- the communication quality of the backhaul link may be the communication speed, communication capacity, line quality, etc.
- the unit is different from the received power measurement value (Sx) of the conventional serving cell, in that case, a certain function with the communication quality of the backhaul link as a variable is provided, and Sx_total is derived by the function. It may be. Alternatively, it may be derived using a correspondence table between the communication quality of the backhaul link and the corresponding measurement value Sx_total. These functions or correspondence tables may be determined statically in advance.
- the serving cell reports the communication quality of the backhaul link, but the communication quality of the backhaul link varies. Therefore, when the communication quality of the backhaul link is changed and notified, the notification information may be corrected.
- the serving cell may report the average value or the value after filtering by averaging or filtering the communication quality of the backhaul link for a certain period. You may make it match this certain period with the timing when alerting
- the UE may average or filter the communication quality of the backhaul link for a certain period.
- the serving cell may notify the UE of the communication quality measurement value of the backhaul link without averaging, and may average or filter the communication quality measurement value of the backhaul link notified by the UE.
- the serving cell may be notified by including the communication quality of the backhaul link in SIB3 or may be included in SIB1.
- SIB3 since the cell reselection parameter is included, the UE can receive it together with other cell reselection parameters. For this reason, the reception operation of the UE can be simplified, and the control malfunction can be reduced.
- SIB1 since the timing to be notified in advance is determined, the UE can receive early at the time of measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE.
- the following effects can be obtained by adopting the method of the present modification.
- the UE By inserting the communication quality of the backhaul link of the serving cell into the reception power measurement value of the serving cell, the UE can derive the total reception quality from the network to the UE via the serving cell. For this reason, it becomes possible to appropriately consider the effect of the communication quality of the backhaul link, and even when the communication quality of the backhaul link becomes dominant, the measurement for celery selection is started with high accuracy. It becomes possible.
- Embodiment 1 Modification 2 As another example of taking into account the communication quality of the backhaul link in the measurement start criteria for celery selection, the communication quality threshold of the serving cell backhaul link (hereinafter, “ A backhaul threshold (start) ”).
- FIG. 16 is a flowchart showing a processing procedure of celery selection in which a backhaul threshold value (start) is provided as a measurement start threshold value for celery selection.
- the process of the flowchart shown in FIG. 16 is similar to the process of the flowchart shown in FIG. 13, so only the different processes will be described, the corresponding parts will be denoted by the same step numbers, and the description of the processes will be omitted. .
- Step ST1301 the UE measures the received power of the serving cell for celery selection.
- the UE compares the received power measurement value (Sx) of the serving cell with a measurement start threshold value (S_intrasearch) for cell reselection.
- S_intrasearch is notified in advance from the serving cell.
- the UE compares Sx and S_intrasearch, and when Sx is equal to or lower than S_intrasearch, the UE determines that the reception power of the serving cell is low, and starts measurement for cell reselection (step ST1302). If Sx is larger than S_intrasearch, the UE compares the communication quality of the backhaul link of the serving cell with the communication quality threshold (backhaul threshold (start)) of the backhaul link of the serving cell in step ST1601. The communication quality of the backhaul link of the serving cell and the communication quality threshold of the backhaul link of the serving cell are each notified beforehand from the serving cell.
- step ST1601 when the communication quality of the backhaul link of the serving cell is equal to or lower than the backhaul threshold (start), the UE determines that the communication quality of the backhaul link is low and performs measurement for cell reselection. Start (step ST1302). If the communication quality of the serving cell backhaul link is greater than the backhaul threshold (start), the UE determines that the communication quality of the backhaul link is sufficient and does not start the measurement for celery selection, Returning to step ST1301, Sx is measured, and Sx and S_intrasearch are compared.
- the comparison of the communication quality of the backhaul link of the serving cell and the backhaul threshold (start) in step ST1601 is a comparison between the received power measurement value (Sx) of the normal serving cell and the threshold of received power (S_intrasearch) in step ST1301. It should be done under or conditions. Thereby, when any of the conditions becomes insufficient for communication, measurement for celery selection can be started.
- a communication quality threshold for the backhaul link of the serving cell is provided, and used to determine whether or not to start measurement for celery selection, and the determination is put into measurement start conditions for celery selection.
- the communication quality of the serving cell backhaul link is taken into account.
- the coping method may be the same as that disclosed in the first modification of the first embodiment.
- the backhaul link communication quality and the backhaul link communication quality threshold may be received power (RSRP, RSRQ), communication speed, communication capacity, line quality, and the like.
- the communication quality of the backhaul link and the communication quality threshold value of the backhaul link may be different indicators, but may be the same. In the case of the same, the unit becomes the same, so that direct comparison is possible, and thus the control at the UE is simplified.
- the serving cell may notify the communication quality of the backhaul link and the communication quality threshold of the backhaul link together or separately in the SIB3, or may be notified in the SIB1.
- SIB3 since the cell reselection parameter is included, the UE can receive it together with other cell reselection parameters. For this reason, the reception operation of the UE can be simplified, and the control malfunction can be reduced.
- SIB1 since the timing to be notified in advance is determined, the UE can receive early at the time of measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE.
- the communication quality threshold value of the serving cell backhaul link may be determined in advance as a static value instead of being notified.
- the UE can use a predetermined value. Thereby, broadcast information can be reduced and signaling load can be reduced.
- the notified backhaul link A communication quality threshold may be used.
- the serving cell may notify the backhaul link communication quality threshold as necessary.
- the following effects can be obtained by adopting the method of the present modification. Since the reception quality of the serving cell and the communication quality of the backhaul link can be individually set, it is possible to make a highly flexible and precise setting. Therefore, even when the number of cells that need to consider the communication quality of the backhaul link increases, cell reselection that suppresses the decrease in communication speed and the occurrence of communication disconnection is possible.
- FIG. The aforementioned non-patent document 9 discloses that the link quality between the relay node and the donor eNB is inserted into Qoffset.
- the communication quality of the backhaul link of the serving cell cannot be inserted at the time of cell ranking in celery selection.
- the cell ranking if the communication quality of the backhaul link of the serving cell is not taken into consideration, when the reception power of the serving cell is good, the possibility of selecting the serving cell as the best cell increases.
- the communication quality of the backhaul link of the serving cell is poor, the communication speed is lowered and the communication is interrupted even after the best cell is selected.
- the backhaul link of at least one of the serving cell and the neighboring cell in the cell reselection at the time of cell ranking, the backhaul link of at least one of the serving cell and the neighboring cell is selected. Incorporate communication quality.
- the communication quality of the backhaul link of each cell is inserted into the measured value of the cell at the time of cell ranking.
- FIG. 17 is a flowchart showing a processing procedure of cell reselection in which the communication quality of the backhaul link of each cell is included in the cell measurement value at the time of cell ranking.
- the processing of the flowchart shown in FIG. 17 is similar to the processing of the flowchart shown in FIG. 13 and FIG. 16, so only the different processing will be described, and the corresponding steps will be denoted by the same step numbers and the description of the processing. Is omitted.
- the operation until the measurement for celery selection is started uses the method disclosed in the second modification of the first embodiment, but is not limited thereto. The method disclosed in the first embodiment or the first modification of the first embodiment may be used.
- the UE performs the process of step ST1701 for the cell in which Srxlev is greater than 0 in step ST1304.
- Step ST1701 the UE derives a reception quality obtained by inserting the communication quality of the backhaul link of the serving cell into the reception power measurement value of the serving cell.
- the reception quality including the communication quality of the backhaul link of the serving cell is Rs_total.
- the UE derives reception quality obtained by inserting the communication quality of the backhaul link of the adjacent cell into the reception power measurement value of the adjacent cell.
- Rn_total is the reception quality including the communication quality of the backhaul link of the adjacent cell.
- the UE uses the derived Rs_total and Rn_total to select the cell (best cell) with the best reception quality including the communication quality of the backhaul link. Then, the UE performs celery selection on the best cell selected in step ST1701.
- the serving cell notifies the UE of the communication quality of the backhaul link of the own cell, and the UE receives the information notified from the serving cell and uses it for derivation of Rs_total in step ST1701.
- the serving cell to notify the information the method disclosed in the first modification of the first embodiment may be used.
- the serving cell notifies the UE of the communication quality of the backhaul link of the neighboring cell, and the UE receives the information notified from the serving cell and uses it for derivation of Rn_total in step ST1701.
- each cell measures the communication quality of the backhaul link of its own cell, and notifies the neighbor cell of the result together with or in association with the identity (PCI, GCI) of the cell.
- PCI PCI, GCI
- An X2 interface or an S1 interface may be used as the notification interface.
- the donor eNB may be notified using an uplink backhaul link (link from the relay to the DeNB).
- the DeNB may notify the relays being served thereby. By doing so, the relay can recognize the communication quality of the backhaul link of the adjacent relay.
- the DeNB may measure the communication quality of the uplink backhaul link and use the result as the communication quality of the backhaul link of the relay. This eliminates the need to notify the DeNB from the relay. In this way, the serving cell can recognize the communication quality of the backhaul link of the adjacent cell.
- the HeNBGW may measure the communication quality of the backhaul link of the HeNB being served, and the HeNBGW may notify the measurement value to the HeNB being served.
- the method in which the serving cell reports the communication quality of the backhaul link of the neighboring cell may be the same as the method of reporting the communication quality of the backhaul link of the serving cell disclosed in the first modification of the first embodiment.
- the derivation of the average value of the communication quality of the backhaul link or the value after filtering may be performed by the serving cell, the UE, or may be performed for each cell. Each cell should be performed in its own cell. As a result, the information after averaging or filtering may be notified every certain period. You may make it match this certain period with the timing when alerting
- the serving cell may be notified by including the communication quality of the backhaul link of the adjacent cell in the SIB4. Since SIB4 includes information on neighboring cells, the UE can receive information associated with other neighboring cells, for example, PCI. For this reason, the reception operation of the UE can be simplified, and the control malfunction can be reduced.
- the index used for the communication quality of the backhaul link, the derivation method using the index, and the derivation method when the units of the received power measurement values of the cells are different are the same as those disclosed in the first modification of the first embodiment. Use it.
- the method disclosed in the present embodiment enables cell reselection in consideration of the communication quality of the backhaul link of the neighboring cell and the communication quality of the backhaul link of the serving cell. Even if the reception quality of the serving cell is good, if the communication quality of the backhaul link of the serving cell is bad, cell reselection to another cell can be performed. For this reason, it becomes possible to suppress the reduction in communication speed and the occurrence of communication disconnection due to the deterioration of the communication quality of the backhaul link of the serving cell.
- cell reselection is not performed on cells with poor communication quality on the backhaul link, so that it is possible to suppress a decrease in communication speed and occurrence of communication disconnection after reselection.
- the communication quality of the backhaul link of the serving cell and the communication quality of the backhaul link for each neighboring cell individually, and deriving the total cell communication quality it varies depending on the cell.
- the communication quality of the backhaul link can be individually entered. A cell having no change in the communication quality of the backhaul link does not need to notify the changed communication quality, so the number of notifications using the X2 interface or the S1 interface can be reduced. Therefore, it is possible to reduce the signaling load and the power consumption of the UE.
- the communication quality of the backhaul link may be an offset value that can be expressed in units of received power of the serving cell.
- the offset value taking into account the communication quality of the backhaul link of the serving cell may be Qoffset, s, and the offset value taking into account the communication quality of the backhaul link of the neighboring cell may be set to Qoffset, n.
- the serving cell notifies the UE of the offset value.
- the UE calculates Rs_total and Rn_total using the following equations.
- each cell since the serving cell recognizes the communication quality of the backhaul link of the neighboring cell, each cell measures the communication quality of the backhaul link of its own cell, and the result is obtained as an X2 interface or an S1 interface. Is used to notify neighboring cells.
- each cell may broadcast the communication quality of its own backhaul link on a plurality of frequency carriers.
- Each cell receives broadcast information of an adjacent cell on a frequency carrier different from the frequency carrier used by the own cell among the plurality of frequency carriers.
- a dedicated frequency carrier for broadcasting the broadcast information may be statically determined in advance.
- Each cell measures a neighboring cell with respect to a frequency carrier to which the broadcast information is transmitted periodically or at any time, and receives broadcast information of a cell whose received power is larger than a certain threshold. In this way, each cell can recognize the broadcast information of neighboring cells.
- an LTE-A compatible mobile terminal receives one or a plurality of component carriers (Component : Carrier: CC) at the same time. You may make it perform the above-mentioned method using this component carrier.
- Each cell broadcasts the communication quality of its own backhaul link on a plurality of component carriers, and each cell reports broadcast information on neighboring cells on the component carrier used by the own cell among the plurality of component carriers. What is necessary is just to make it receive.
- the component carrier to which the broadcast information is transmitted can also be used for communication with the UE.
- the HeNB currently does not have an X2 interface. Therefore, by using this method in a heterogeneous network in which a HeNB is present, it is possible to obtain information on neighboring cells through an air interface without an X2 interface. For example, when the HeNB exists in the macro cell range, the communication quality of the backhaul link of the own cell is increased from the macro cell to the HeNB or from the HeNB to the macro cell using the above-described method. You may make it notify. As a result, notification can be made earlier than notification via the S1 interface. The communication quality of the backhaul link that varies with time can be notified to the neighboring cell with a delay time smaller than that of the S1 interface.
- the notification information becomes enormous.
- the signaling load increases and the power consumption of the UE also increases.
- the serving cell does not report the communication quality of the backhaul link of the neighboring cell, but the cell notifies the communication quality of the backhaul link of its own cell, and the UE The communication quality is used for cell ranking in celery selection.
- the UE which starts the measurement of the cell for celery selection starts the measurement of a cell in step ST1302 shown in FIG. At this time, the UE not only measures the reception power of each cell, but also receives the communication quality of the backhaul link of the own cell broadcast by each cell.
- step ST1701 the UE derives Rs_total and Rn_total of each cell using the communication quality of the backhaul link of each cell received in step ST1302.
- the backhaul link communication quality index and the derivation method, and the derivation method when the unit of the cell received power measurement value is different may be performed in the same manner as in the second embodiment.
- Each cell reports the communication quality of its own backhaul link, but the communication quality of the backhaul link varies. Therefore, when the communication quality of the backhaul link is changed and notified, the notification information may be corrected.
- the derivation of the average value of the communication quality of the backhaul link or the value after filtering may be performed by the UE or may be performed for each cell, but each cell is preferably performed in its own cell. By doing so, it is only necessary to notify the information after averaging or after filtering every certain period. Therefore, it is possible to reduce the amount of information that each cell notifies the serving cell and the amount of information that the serving cell notifies the UE. You may make it match this certain period with the timing when alerting
- Each cell reports the communication quality of the backhaul link of its own cell, but at this time, it may be reported in SIB1.
- SIB1 since the timing to be notified in advance is determined, the UE can receive early at the time of measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE.
- the best cell selection in step ST1203 may be performed after receiving SIB1 in step ST1205.
- Neighboring cell information can be reduced from information broadcast by the serving cell.
- each cell does not need to notify the neighboring cell of the communication quality of the backhaul link of the own cell and the identity (PCI, GCI) of the cell. Accordingly, it is possible to reduce the signaling load on the air interface, the X2 interface, and the S1 interface. For this reason, it is possible to construct a system with a simple configuration even in a network including a large amount of HeNBs installed in an arbitrary place.
- each cell may broadcast an offset value taking into account the communication quality of the backhaul link of its own cell or Qoffset disclosed in Non-Patent Document 9. Even if it does in this way, the effect equivalent to this modification is acquired.
- Embodiment 2 Modification 2 an indicator is provided that indicates whether or not to be subject to celery selection.
- the serving cell broadcasts an indicator that indicates whether or not the own cell is allowed to be subject to celery selection, and an indicator that indicates whether or not neighboring cells are allowed to be subject to celery selection.
- the indicator of the adjacent cell may be provided for each cell and notified.
- the operation of the UE at the time of celery selection is made possible by changing a part of the flowchart shown in FIG.
- the UE receives the indicator broadcast from the serving cell in advance, and at the time of cell reselection, in step ST1303 of FIG. 17, only the cell that is allowed to be subject to cell reselection by the indicator is Srxlev. Is calculated.
- step ST1303 the UE performs cell ranking in step ST1701 from the cells in which Srxlev is greater than 0 in step ST1304, and selects the best cell. Good. By doing so, it is possible to select the best cell from the cells that are permitted to be subject to celery selection.
- the UE performs cell ranking and best cell selection in Step ST1306 from among cells in which Srxlev is greater than 0 in Step ST1304. By doing so, it is possible to select the best cell from the cells that are permitted to be subject to celery selection.
- the indicator is a cell that is not permitted to be subject to celery selection
- the indicator is excluded from the targets for calculating Srxlev in step ST1303.
- selecting the best cell a cell that is not permitted to be subject to celery selection is not selected.
- Srxlev is calculated only for the cells permitted to be subject to celery selection by the indicator in step ST1303, but the present invention is not limited to this.
- only the cell permitted to be subject to celery selection by the indicator may be measured.
- Rs, Rn may be calculated.
- Rs_total and Rn_total may be calculated only for the cells that are permitted to be subject to cell reselection by the indicator in step ST1701. The best cell may be selected from the cells permitted to be subject to celery selection by the indicator.
- the serving cell needs to recognize the indicator of the neighboring cell.
- This method may be the same as the method disclosed in Embodiment 2 in which the serving cell recognizes the communication quality of the backhaul link of the neighboring cell.
- the method of notifying the indicator by the serving cell may be the same as the method of notifying the communication quality of the backhaul link of the adjacent cell disclosed by the second embodiment.
- Each cell measures the communication quality of its own backhaul link and sets the value of the indicator according to the measurement result. In this way, when the backhaul link communication quality is poor and the backhaul link communication is not sufficient, the indicator can be used to prevent the cell reselection from being permitted. In addition, it is possible to prevent the UE from selecting the cell.
- the following effects can be obtained by using the method disclosed in the present modification.
- the cell When there is a cell with extremely poor communication quality of the backhaul link, the cell can be removed from the cell reselection target, so that the cell reselection control can be simplified. In addition, the power consumption of the UE can be reduced.
- the indicator can have a smaller amount of information than the communication quality of the backhaul link of each cell described in Embodiment 2, the amount of information notified from each cell to the serving cell and the amount of information broadcast from the serving cell can be reduced. It becomes possible.
- the indicator may be 1 bit. 1 (or 0) indicates that it is permitted to become a celery selection target, and 0 (or 1) indicates that it is not permitted to be a celery selection target. As a result, it can be realized with a minimum amount of information.
- the serving cell broadcasts an indicator that indicates whether the own cell is permitted to be subject to celery selection, and an indicator that indicates whether neighboring cells are allowed to be subject to celery selection.
- each cell may notify an indicator indicating whether or not each cell is permitted to be subject to celery selection.
- the UE that starts measuring the cell for celery selection performs each cell measurement in step ST1302 illustrated in FIG.
- the indicator broadcast by the cell may be received. This eliminates the need for the serving cell to report the indicator of the neighboring cell.
- the method for notifying each cell of the indicator may be the same as the method of the first modification of the second embodiment.
- the following effects can be further obtained by notifying each cell of an indicator indicating whether or not each cell is permitted to be subject to celery selection. Neighboring cell information can be reduced from information broadcast by the serving cell. In addition, each cell does not need to notify the neighboring cell of the communication quality of the backhaul link of the own cell and the identity (PCI, GCI) of the cell. Accordingly, it is possible to reduce the signaling load on the air interface, the X2 interface, and the S1 interface. For this reason, it is possible to construct a system having a simple configuration even in a network including a large amount of HeNBs installed at an arbitrary place.
- Embodiment 2 Modification 3 In this modified example, another method of incorporating the communication quality of the backhaul link of at least one of the serving cell and the neighboring cell at the time of cell ranking is disclosed.
- cell ranking is performed in consideration of the reception quality of the backhaul link.
- a reception quality threshold value (reference value) is provided as the certain value.
- FIG. 18 is a flowchart showing a processing procedure of cell reselection in which cell ranking is performed in consideration of the reception quality of the backhaul link when there is a cell whose reception quality is a certain value or more.
- the process of the flowchart shown in FIG. 18 is similar to the process of the flowcharts shown in FIGS. 13 and 16, so only the different processes will be described, and the corresponding parts will be denoted by the same step numbers and the description of the processes Is omitted.
- the operation until the measurement for celery selection is started uses the method disclosed in the second modification of the first embodiment, but is not limited thereto. The method disclosed in the first embodiment or the first modification of the first embodiment may be used.
- the UE performs the process of step ST1801 for the cell in which Srxlev is greater than 0 in step ST1304.
- Step ST1801 the UE determines whether the reception quality of the cell is equal to or higher than the reception quality threshold (reference value), specifically, whether the received power measurement value indicating the reception quality of the cell is equal to or higher than the reception quality threshold (reference value). Determine whether.
- the mobile terminal makes a transition to step ST1803.
- the received power measurement value is smaller than the reception quality threshold value (reference value)
- the mobile terminal makes a transition to step ST1802.
- step ST1304 Among the cells in which Srxlev is greater than 0 in step ST1304, if there is a cell whose received power measurement value is equal to or greater than the reception quality threshold (reference value) in step ST1801, in step ST1803, the UE Cell ranking is performed based on the communication quality of the backhaul link, and the cell with the best communication quality of the backhaul link is selected as the best cell. Then, the UE performs celery selection on the best cell selected in step ST1803.
- the reception quality threshold reference value
- the cell backhaul is received from the cells whose reception quality measurement values satisfy the required reception quality.
- the best cell can be selected according to the communication quality of the link.
- step ST1304 Among the cells in which Srxlev is greater than 0 in step ST1304, if there is no cell whose received power measurement value is equal to or greater than the reception quality threshold (reference value) in step ST1801, in step ST1802, the UE Cell ranking is performed based on the reception quality, specifically, the received power measurement value.
- This cell ranking method can be the same as the conventional cell ranking method.
- the UE selects the cell with the best received power measurement value as the best cell. Then, the UE performs celery selection on the best cell selected in step ST1802.
- the reception quality threshold value may be one or plural, for example, for each cell. For example, when a reception quality threshold (reference value) is provided for each cell, the reception quality threshold (reference value) may be used for each cell to be determined in step ST1801. When the reception quality threshold value (reference value) is provided for each cell, it may be associated with the cell identity (PCI, GCI). By doing so, since the situation for each cell can be taken into consideration, more precise celery selection becomes possible.
- PCI cell identity
- the serving cell may notify the reception quality threshold (reference value), or each cell may notify.
- the serving cell may be included in SIB3, notified in SIB1, or included in SIB4.
- SIB3 since the celery selection parameter is included, it can be received together with other celery selection parameters. For this reason, the reception operation of the UE can be simplified, and the control malfunction can be reduced.
- SIB1 since the timing to be notified in advance is determined, the UE can receive early at the time of measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE.
- broadcasting by SIB4 since information on neighboring cells is included, it is possible to receive information in association with information on other neighboring cells, for example, PCI. Broadcasting by SIB4 is suitable when the reception quality threshold value (reference value) is provided for each cell, and has an advantage that the reception operation of the UE can be simplified and the control malfunction can be reduced.
- each cell When each cell broadcasts the reception quality threshold (reference value), it may be broadcast by including it in SIB1.
- SIB1 since the timing to be notified in advance is determined, the UE can receive early at the time of measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE.
- the reception quality threshold (reference value) may be determined in advance as a static value instead of being notified. In this case, the UE can use a predetermined value. Since the UE does not need to be notified of the reception quality threshold (reference value), the signaling load can be reduced and the power consumption of the UE can be reduced.
- reception quality threshold when a predetermined value is used as the initial value for the reception quality threshold (reference value), and the reception quality threshold (reference value) is reported from the serving cell or each cell, it is notified instead of the initial value.
- the reception quality threshold value (reference value) of each cell may be used. In this case, the serving cell or each cell may notify the reception quality threshold (reference value) as necessary.
- step ST1803 the UE selects the best cell based on the communication quality of the backhaul link. Therefore, the UE needs to recognize the communication quality of the serving cell and the backhaul link of each cell.
- Embodiment 2, Modification 1 of Embodiment 2, or the like may be used.
- the following effects can be obtained in addition to the effects described in the second embodiment and the first modification of the second embodiment.
- the best cell can be selected depending on the communication quality of the backhaul link. Since the cell to be selected with priority on the reception quality can be determined, the cell can be easily found. Further, it is not necessary for the UE to derive the total reception quality using the communication quality of the backhaul link. Therefore, the celery selection control of the UE becomes easy, and the power consumption of the UE can be reduced.
- step ST1801 apart from the determination by Srxlev in step ST1304, it is determined in step ST1801 whether or not the reception quality is equal to or higher than the reception quality threshold (reference value).
- the processing of step ST1801 and step ST1802 may be eliminated. In this case, the following is performed.
- step ST1304 it was described that Srxlev was derived in consideration of a certain offset value for the received power measurement value for each cell.
- a new offset may be provided, and a value considering the reception quality threshold (reference value) may be used as the new offset value.
- the reception quality threshold value (reference value) can be taken into consideration.
- a value considering the reception quality threshold value (reference value) may be inserted into the existing offset.
- the determination by Srxlev in step ST1304 and the determination of whether the reception quality in step ST1801 is equal to or higher than the reception quality threshold (reference value) are performed in one step, thereby simplifying the determination in the UE. It becomes possible. Further, it can be performed in the same manner as the conventional cell ranking method.
- Embodiment 2 Modification 4 In this modified example, another method of incorporating the communication quality of the backhaul link of at least one of the serving cell and the neighboring cell at the time of cell ranking is disclosed.
- cell ranking is performed in consideration of the reception quality of the cell.
- a backhaul threshold value reference value
- FIG. 19 is a flowchart showing a processing procedure of cell reselection in which cell ranking is performed in consideration of the reception quality of a cell when the communication quality of the backhaul link exceeds a certain value.
- the processing of the flowchart shown in FIG. 19 is similar to the processing of the flowcharts shown in FIGS. 13 and 16, so only the different processing will be described, and the corresponding steps will be denoted by the same step numbers and the description of the processing. Is omitted.
- the operation until the measurement for celery selection is started uses the method disclosed in the second modification of the first embodiment, but is not limited thereto. The method disclosed in the first embodiment or the first modification of the first embodiment may be used.
- the UE performs the process of step ST1901 for the cell in which Srxlev is greater than 0 in step ST1304.
- Step ST1901 the UE determines whether or not the communication quality of the cell backhaul link is equal to or higher than a backhaul threshold (reference value).
- a backhaul threshold reference value
- the communication quality of a backhaul link is more than a backhaul threshold value (reference value)
- the communication quality of a backhaul link is smaller than a backhaul threshold value (reference value)
- step ST1903 If there is a cell in which the communication quality of the backhaul link is greater than or equal to the backhaul threshold (reference value) in step ST1901 among the cells in which Srxlev is greater than 0 in step ST1304, in step ST1903, the UE Then, cell ranking is performed based on the reception quality, specifically, the received power measurement value, and the cell having the best reception quality, specifically, the received power measurement value, is selected as the best cell.
- This cell ranking method can be the same as the conventional cell ranking method.
- UE performs celery selection to the best cell selected by step ST1903.
- the communication quality of the backhaul link satisfies the required communication quality of the backhaul link.
- the best cell can be selected from the received cells according to the reception quality of the cell, specifically, the received power measurement value.
- step ST1902 If there is no cell whose backhaul link communication quality is equal to or higher than the backhaul threshold (reference value) in step ST1901 among the cells in which Srxlev is greater than 0 in step ST1304, in step ST1902, the UE Cell ranking is performed according to the communication quality of the backhaul link. In step ST1902, the UE selects the cell with the best communication quality of the backhaul link as the best cell. And UE performs celery selection to the best cell selected by step ST1902.
- the setting method of the backhaul threshold value (reference value), the notification method to the UE, and the like may be set similarly to the reception quality threshold value (reference value) described in the third modification of the second embodiment.
- the communication quality of the backhaul link between the serving cell and each cell may be the same as the method described in the third modification of the second embodiment.
- the following effects can be obtained in addition to the effects described in the second embodiment and the first modification of the second embodiment.
- the communication quality of the backhaul link sufficient for communication it is possible to select the best cell according to the reception quality of the cell, specifically, the received power measurement value. Since it is possible to determine a cell to be selected with priority on the communication quality of the backhaul link, it is possible to easily find a cell in which a reliable link can be set.
- the UE it is not necessary for the UE to derive the total reception quality using the communication quality of the backhaul link. Therefore, the celery selection control of the UE becomes easy, and the power consumption of the UE can be reduced.
- Embodiment 3 FIG.
- another method is disclosed in which the communication quality of the backhaul link of at least one of the serving cell and the neighboring cell is taken into consideration for cell reselection.
- the communication quality of the backhaul link according to the communication speed of the UE is taken into consideration.
- the UE performs cell ranking among cells satisfying the required communication quality of the backhaul link according to the desired communication speed of the own UE.
- the communication quality of the desired backhaul link varies depending on the communication speed. For example, high backhaul communication quality is required for high speed and large capacity communication, and low backhaul link communication quality may be used for low speed and small capacity communication. Therefore, cell ranking is performed among cells satisfying the required communication quality of the backhaul link according to the desired communication speed of the UE.
- a threshold value of required backhaul link communication quality according to the communication speed of the UE may be provided.
- the UE derives a threshold value of the backhaul link communication quality corresponding to the communication speed from the desired communication speed of the own UE, and selects a cell by cell ranking from cells having a communication quality of the backhaul link higher than the threshold value. To do.
- the correspondence relationship between the UE communication speed and the backhaul link communication quality threshold value may be determined in advance as a static value, or may be reported from the serving cell or each cell.
- a static value may be set as the initial value, and then notified from the serving cell or each cell, and the notified value may be used instead of the initial value.
- the correspondence relationship between the communication speed of the UE and the threshold value of the communication quality of the backhaul link may be provided with a correspondence table, or may be derived from the communication speed of the UE using an appropriate function. When an appropriate function is used, the function may be determined in advance.
- the present invention is not limited thereto, and the UE's transmission buffer state and the UE's capability indicating how much communication speed the UE can support may be taken into consideration. . In this case, what is necessary is just to make it match
- Non-Patent Document 8 proposes that measurement of a cell with a weak reception power and a trigger mechanism are necessary. There is no mention of a practical method.
- Non-Patent Document 10 describes that in heterogeneous networks, there is a problem that the optimum cell in the downlink is different from the optimum cell in the uplink.
- the downlink transmission power of the macro cell is larger than the downlink transmission power of the HeNB.
- the macro cell may be better than the HeNB as downlink reception quality.
- the HeNB is better than the macro cell as uplink communication quality.
- Non-Patent Document 10 discloses that the uplink and the downlink are independently connected to different cells, but this specific method is not described at all. Absent. In addition, connecting to different cells in the uplink and the downlink is considered to make communication control very complicated because the UE has a plurality of serving cells.
- the present embodiment discloses a method that enables reselection to a cell with weak received power by taking the uplink state into consideration in cell reselection.
- the uplink state corresponds to selection information
- the uplink corresponds to an uplink communication line.
- the optimal cell in the downlink is different from the optimal cell in the uplink, the optimal cell in the uplink may be a cell with weak received power in the downlink.
- cell ranking is performed based on downlink received power, and in such a case, cell reselection to an optimal cell in the uplink cannot be performed. Therefore, in the present embodiment, the uplink state is also taken into consideration in celery selection.
- the cell loss threshold of the measurement start serving cell for celery selection (hereinafter also referred to as “path loss threshold (start)”)
- the cell A path loss threshold value for each cell for ranking hereinafter sometimes referred to as “path loss threshold value (reference value)”.
- the path loss the more optimal the cell can be determined on the uplink. This is because if the path loss is small, the cell can obtain reception power necessary for demodulating the uplink signal with a small UE transmission power. Therefore, the UE can operate with low power consumption, and the uplink interference can be reduced as a system.
- an uplink path loss may be used, but since it is complicated for the UE to recognize the uplink path loss, a downlink path loss may be used. Since the relative value of the path loss mainly depends on the route (path) of the link caused by the positions of the cell and the UE, it can also be determined using the downlink path loss. Therefore, in order to take the uplink state into consideration, downlink path loss is used here.
- FIG. 20 is a flowchart showing the processing procedure of celery selection taking into account the uplink state.
- the processing of the flowchart shown in FIG. 20 is similar to the processing of the flowchart shown in FIG. 13, so only the different processing will be described, the corresponding steps will be denoted by the same step numbers, and the description of the processing will be omitted. .
- the UE measures the received power of the serving cell for celery selection.
- the UE compares Sx and S_intrasearch, and when Sx is equal to or lower than S_intrasearch, the UE determines that the reception power of the serving cell is low and starts measurement for celery selection (step ST1302).
- Sx is larger than S_intrasearch
- the UE compares the path loss of the serving cell with the path loss threshold (start) in step ST2001.
- the UE measures the path loss of the serving cell.
- the path loss may be measured when measuring the received power of the serving cell for cell reselection.
- step ST2001 when the path loss of the serving cell is equal to or greater than the path loss threshold (start), the UE determines that the uplink state is bad and starts measurement for cell reselection (step ST1302). If the serving cell path loss is smaller than the path loss threshold (start), the UE determines that the uplink state is sufficient for communication, does not start measurement for cell reselection, returns to step ST1301, and sets Sx Measure and compare Sx and S_intrasearch.
- the comparison between the path loss of the serving cell in step ST2001 and the path loss threshold (start) is based on the comparison between the received power measurement value (Sx) of the normal serving cell in step ST1301 and the threshold (S_intrasearch) of the received power, and the OR condition. It should be done. Thereby, when any of the conditions becomes insufficient for communication, measurement for celery selection can be started.
- a path loss threshold for the serving cell it is used to determine whether or not to start measurement for celery selection, and by inserting this determination into the measurement start condition for celery selection, Uplink conditions can be taken into account.
- the UE that has started measurement for cell reselection in step ST1302 calculates Srxlev from the received power measurement value of each cell in step ST1303. For the cell in which Srxlev is greater than 0 in step ST1304, the UE performs step ST2002. Perform the process. When there is no cell in which Srxlev is greater than 0 in Step ST1304, the UE moves to Step ST1305 and enters an out-of-service state.
- step ST2002 the UE determines whether or not the cell path loss measurement value is equal to or less than the path loss threshold (reference value).
- the UE measures the path loss of each cell.
- the path loss may be measured when the UE performs measurement for celery selection in step ST1302.
- the process proceeds to step ST2004.
- the path loss measurement value of the cell is larger than the path loss threshold value (reference value)
- the process proceeds to step ST2003.
- Step ST1304 Among the cells in which Srxlev is greater than 0 in Step ST1304, if there is a cell whose path loss measurement value is equal to or less than the path loss threshold (reference value) in Step ST2002, in Step ST2004, the UE determines reception quality among the cells. Based on cell ranking, the cell with the best reception quality is selected as the best cell. This cell ranking method can be the same as the conventional cell ranking method. And UE performs celery selection to the best cell selected by step ST2004. By setting the path loss threshold (reference value) to the uplink state of the cell necessary for the UE to perform cell reselection, the reception quality of the cell can be selected from the cells that satisfy the required uplink state. The best cell can be selected accordingly.
- the path loss threshold reference value
- step ST2003 the UE determines the path loss measurement value from the cells. Perform cell ranking with.
- step ST2003 the UE selects the cell with the smallest path loss measurement value as the best cell. Then, the UE performs celery selection on the best cell selected in step ST2003.
- the UE may average or filter the path loss measurement result for a certain period.
- the average value or the value after filtering may be compared with a path loss threshold value (reference value) in step ST2002.
- the serving cell notifies the path loss threshold (start).
- the notification may be included in SIB3 or may be notified in SIB1.
- SIB3 since the cell reselection parameter is included, the UE can receive it together with other cell reselection parameters. For this reason, the reception operation of the UE can be simplified, and the control malfunction can be reduced.
- SIB1 since the timing to be notified in advance is determined, the UE can receive at an early stage during measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE.
- the path loss threshold (start) may not be notified but may be determined in advance as a static value.
- the UE can use a predetermined value. Thereby, broadcast information can be reduced and signaling load can be reduced.
- the serving cell may notify the path loss threshold (start) as necessary.
- the path loss threshold value may be one or plural, for example, for each cell. For example, when a path loss threshold value (reference value) is provided for each cell, the path loss threshold value (reference value) may be used for each cell to be determined in step ST2002. When the path loss threshold value (reference value) is provided for each cell, it may be associated with the cell identity (PCI, GCI). By doing so, since the uplink situation for each cell can be taken into account, more precise cell reselection is possible.
- PCI cell identity
- the serving cell may notify the path loss threshold (reference value), or each cell may notify.
- the serving cell may notifies, it may be notified by being included in SIB3, may be notified by being included in SIB1, or may be notified by being included in SIB4.
- the UE can receive it together with other celery selection parameters. For this reason, the reception operation of the UE can be simplified, and the control malfunction can be reduced.
- SIB1 since the timing to be notified in advance is determined, the UE can receive early at the time of measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE.
- SIB4 since information on neighboring cells is included, it is possible to receive information in association with information on other neighboring cells, for example, PCI. Broadcasting with SIB4 is suitable when the path loss threshold value (reference value) is provided for each cell, and can simplify the reception operation of the UE and reduce control malfunctions.
- each cell When each cell notifies the path loss threshold (reference value), it may be included in SIB1 and notified.
- SIB1 since the timing to be notified in advance is determined, the UE can receive early at the time of measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE.
- the path loss threshold (reference value) may not be notified but may be determined in advance as a static value. In this case, the UE can use a predetermined value. Since the UE does not need to be notified of the path loss threshold (reference value), the signaling load can be reduced and the power consumption of the UE can be reduced.
- the path loss threshold value (reference value) of the cell may be used.
- the serving cell or each cell may notify the path loss threshold (reference value) as necessary.
- the path loss threshold (start) and the path loss threshold (reference value) are provided, but either one may be used. Either the determination in step ST2001 or step ST2002 may be performed.
- a path loss is used as an index indicating the uplink state between the cell and the UE, but an actual distance may be used as an index indicating the uplink state.
- the present invention is not limited to these, and any index that represents the uplink state may be used.
- the actual distance may be derived by, for example, the following method.
- the cell measures the position of its own cell by GPS (Global Positioning System) or the like, and notifies the position information.
- the UE measures the position of its own cell by GPS or the like.
- UE receives the positional information on the cell alert
- the UE derives the distance between each cell and the UE based on the measured location information of the own UE and the received location information of each cell. This makes it possible to use the actual distance between each cell and the UE as an index representing the uplink state.
- cell reselection can be performed in consideration of uplink communication quality in addition to reception quality of each cell.
- the reception quality of the serving cell is good, depending on the path loss of the serving cell, cell reselection is started, so the communication speed decreases due to the increase of the serving cell path loss, the occurrence of communication disconnection, the UE An increase in power consumption can be suppressed.
- uplink transmission power of the UE can be suppressed, uplink interference can be avoided as a system. Therefore, since it is possible to improve the interference problem and capacity problem in heterogeneous networks, it is possible to operate a large number of local area range nodes and to arrange them flexibly.
- the method disclosed in the present embodiment it is possible to take into account the path loss of the serving cell and the path loss of the neighboring cell in cell ranking. As a result, even if the reception quality of the serving cell is good, if the path loss of the serving cell is large, it is possible to perform cell reselection to another cell. For this reason, it becomes possible to suppress a decrease in communication speed due to an increase in path loss of the serving cell, occurrence of communication disconnection, and an increase in power consumption of the UE.
- uplink interference can be avoided as a system.
- Embodiment 4 Modification 1 In this modification, another method that takes the uplink state into consideration in celery selection is disclosed. When there is a cell whose reception quality is a certain value or higher, cell ranking is performed in consideration of the uplink state.
- a reception quality threshold value (reference value) is provided as the certain value.
- the reception quality threshold (reference value) may be different from the reception quality threshold (reference value) disclosed in the third modification of the second embodiment, but the reception quality of the cell obtains reception quality sufficient for communication. Since it is a threshold value that is an index of whether or not it is set, it may be the same. In the case of the same, the parameter indicating the reception quality threshold value (reference value) can be made one.
- FIG. 21 is a flowchart showing a processing procedure of cell reselection in which cell ranking is performed in consideration of path loss when there is a cell whose reception quality exceeds a certain value.
- the process of the flowchart shown in FIG. 21 is similar to the process of the flowcharts shown in FIGS. 13 and 20, so only the different processes will be described, and the corresponding parts will be denoted by the same step numbers and the description of the processes Is omitted.
- the operation until the measurement for celery selection is started is the method disclosed in the fourth embodiment.
- the UE performs the process of step ST2101 for the cell where Srxlev is greater than 0 in step ST1304.
- Step ST2101 the UE determines whether or not the reception quality of the cell, specifically, the received power measurement value is equal to or higher than the reception quality threshold (reference value).
- the received power measurement value is greater than or equal to the reception quality threshold (reference value)
- the mobile terminal makes a transition to step ST2103.
- the received power measurement value is smaller than the reception quality threshold value (reference value)
- the mobile terminal makes a transition to step ST2102.
- step ST1304 Among the cells in which Srxlev is greater than 0 in step ST1304, if there is a cell whose received power measurement value is equal to or higher than the reception quality threshold (reference value) in step ST2101, the UE in step ST2103 Cell ranking is performed by path loss, and the cell with the smallest path loss is selected as the best cell. Then, the UE performs celery selection on the best cell selected in step ST2103.
- the reception quality threshold reference value
- the reception quality measurement value is changed from the cell that satisfies the required reception quality to the path loss of the cell. The best cell can be selected accordingly.
- the UE receives the received cell from the cell in step ST2102.
- Cell ranking is performed using the measured power value.
- This cell ranking method can be the same as the conventional cell ranking method.
- the cell with the best received power measurement value is selected as the best cell.
- the UE performs celery selection on the best cell selected in Step ST2102.
- the reception quality threshold (reference value) may be the same as the method disclosed in the third modification of the second embodiment.
- the determination by Srxlev in step ST1304 and the determination in step ST2101 whether or not the reception quality is equal to or higher than the reception quality threshold (reference value) may be combined.
- This method may be the same as the method disclosed in the third modification of the second embodiment. This makes it possible to simplify the determination at the UE.
- the UE selects the best cell based on the path loss in step ST2103. Therefore, the UE needs to recognize the serving cell and the path loss of each cell.
- the method disclosed in Embodiment 4 may be used.
- the following effects can be obtained by using the method disclosed in the present modification. If reception quality sufficient for communication is obtained, the best cell can be selected by path loss. Since the cell to be selected with priority on the reception quality can be determined, the cell can be easily found.
- Embodiment 5 In order to solve the problem in the heterogeneous networks, the methods disclosed in the first modification of the first to fourth embodiments may be combined.
- FIG. 22 is an example of a flowchart showing a processing procedure of celery selection combining the methods disclosed in the first modification of the first to fourth embodiments of the present invention.
- the processing of the flowchart shown in FIG. 22 is similar to the processing of the flowcharts shown in FIGS. 13, 16, 18, 19, and 20, so only the different processing will be described, and the corresponding steps will be the same step. A number is attached and explanation of processing is omitted.
- the UE takes into consideration the communication quality of the backhaul link of the serving cell and the path loss of the serving cell, as shown in Step ST1601 and Step ST2001, as a determination of whether to start measurement for celery selection. Together with the serving cell reception power shown in step ST1301, these determinations are set to an OR condition so that measurement for cell reselection is started when any of the conditions becomes insufficient for communication. it can.
- step ST1801 the UE takes into account the reception quality of the cell, takes into account the cell path loss in step ST2002, takes into account the communication quality of the cell backhaul link in step ST1901, In step ST2201, the desired communication speed of the UE is taken into consideration.
- step ST2201 If a cell that satisfies the communication quality threshold of the backhaul link corresponding to the desired communication speed of the UE cannot be obtained in step ST2201, the mobile station moves to step ST2202, performs cell ranking based on the reception quality of the cell, and performs the best reception. Select the quality cell (best cell). Alternatively, cell ranking may be performed based on the cell path loss, and the cell with the smallest path loss (best cell) may be selected.
- the method of associating the desired communication speed of the UE and the communication quality of the backhaul link disclosed in Embodiment 3 is not limited to the communication quality of the backhaul, but is associated with the uplink state. You may do it. Both may be performed.
- the path loss or distance disclosed in the fourth embodiment may be used.
- path loss a path loss threshold value corresponding to the desired communication speed of the UE is provided, and it is determined in step ST2201 whether the path loss threshold value corresponding to the desired communication speed of the UE is satisfied.
- the correspondence between the UE communication speed and the uplink path loss threshold may be the same as the method disclosed in the third embodiment. This makes it possible to consider the desired communication speed of the UE when taking the uplink state into consideration.
- step ST2201 If a cell that satisfies the communication quality threshold of the backhaul link corresponding to the desired communication speed of the UE is obtained in step ST2201, the mobile terminal moves to step ST2203 and performs cell ranking based on the communication quality of the cell backhaul link.
- the cell with the best communication quality of the backhaul link (best cell) is selected.
- the UE performs celery selection on the best cell selected in step ST1802, step ST2003, step ST1902, step ST2202 or step ST2203.
- the quality of the backhaul link of at least one of the serving cell and the neighboring cell is considered by combining the methods disclosed in the first modification of the first to fourth embodiments.
- Cell reselection and cell reselection to a cell with weak received power are possible, and it is possible to improve interference problems and capacity problems in heterogeneous networks.
- Embodiment 6 FIG.
- Non-Patent Document 8 proposes that measurement of a cell with weak received power and a trigger mechanism are necessary, but no specific method is described.
- Non-Patent Document 9 discloses a cell selection method that considers the backhaul link of the relay node, but what kind of mechanism is taken into consideration the quality of the backhaul link, for a specific method, Nothing is disclosed. Further, in the method disclosed in Non-Patent Document 10, communication control becomes very complicated.
- this embodiment discloses a specific method for taking into account at least one of the communication quality of the cell backhaul link and the uplink state in the cell selection.
- this embodiment a case will be described in which both the communication quality of the cell backhaul link and the uplink state are taken into consideration.
- FIG. 23 is a flowchart showing a UE cell selection processing procedure according to the technique of Non-Patent Document 3.
- the UE measures received power of neighboring cells for cell selection.
- the UE calculates a value (Srxlev) obtained by inserting a certain correction value into the received power from the measurement value for each cell. This correction value and its calculation method are described in Non-Patent Document 3.
- the UE that has calculated Srxlev determines whether or not the Srxlev is greater than 0 in step ST2303. If the Srxlev is greater than 0, the cell is determined as a best cell selection candidate, and the process moves to step ST2305. When the Srxlev is 0 or less, the cell is not regarded as a best cell selection candidate.
- Step ST2302 the UE performs each process of step ST2302 and step ST2303 with respect to the one or some cell obtained by the measurement for cell selection.
- the mobile terminal shifts to step ST2304 to enter an out-of-service state.
- the process of step ST2305 is performed.
- the UE selects a cell (best cell) having the highest received power from the cells having Srxlev greater than 0. Then, the UE camps on the selected best cell.
- FIG. 24 is a flowchart showing a cell selection processing procedure that takes into consideration the communication quality of the cell backhaul link and the uplink state, disclosed in the present embodiment.
- the processing of the flowchart shown in FIG. 24 is similar to the processing of the flowchart shown in FIG. 18, FIG. 19, FIG. 20, FIG. 22 and FIG. A number is attached and explanation of processing is omitted.
- step ST2303 when a cell having Srxlev greater than 0 is obtained in step ST2303, the UE takes into account the reception quality of the cell in step ST1801 when selecting the best cell, and in step ST2002, the cell In step ST1901, the communication quality of the cell backhaul link is taken into consideration, and in step ST2201, the desired communication speed of the UE is taken into consideration.
- Step ST2201 If a cell that satisfies the communication quality threshold of the backhaul link corresponding to the desired communication speed of the UE cannot be obtained in Step ST2201, the process proceeds to Step ST2202, and the cell with the best cell reception quality (best cell) Make a selection. Alternatively, the cell with the smallest cell path loss (best cell) may be selected.
- step ST2201 If a cell satisfying the communication quality threshold of the backhaul link corresponding to the desired communication speed of the UE is obtained in step ST2201, the cell moves to step ST2203 and the cell with the best communication quality of the cell backhaul link is obtained.
- Select (Best Cell). The UE selects the best cell selected in Step ST1802, Step ST2003, Step ST1902, Step ST2202 or Step ST2203 as a cell to camp on.
- the cell ranking method of the cell reselection disclosed in the second embodiment to the fifth embodiment after the start of measurement for cell reselection can be applied.
- Embodiment 7 FIG.
- the method of taking into account at least one of the communication quality of the cell backhaul link and the uplink state in celery selection and cell selection has been disclosed.
- a method of taking into account at least one of the communication quality of the cell backhaul link and the uplink state in handover (HO) is disclosed.
- the above-described problems occur not only in cell selection and cell reselection, but also in the case of handover (HO). This is because the aforementioned problem occurs when the serving cell is selected or changed. In HO, a target cell to be a HO destination must be selected. Therefore, the selection of the target cell becomes a problem.
- FIG. 25 is a sequence diagram showing a normal HO processing procedure according to the technique of Non-Patent Document 1.
- the serving cell becomes the source cell.
- a case where communication between the source cell and the target cell is performed using the X2 interface is shown.
- the source cell notifies the UE of a measurement control message, and causes the UE to perform measurement, that is, measurement. Specifically, reception power representing reception quality is measured.
- the UE notifies the source cell of the measurement result, that is, the measurement result, as a measurement report (Measurement report). Specifically, the reception quality measurement result, more specifically, the received power measurement value is notified as a measurement report.
- the source cell determines a target cell using a measurement report from the UE. In this way, in normal HO, each cell determines whether the UE needs HO and to which cell to make HO mainly based on the reception quality measurement result of the UE. That is, the source cell activates the HO procedure using the measurement report received from the UE in step ST2502 as a trigger.
- step ST2504 the source cell that has determined the target cell notifies the target cell of a HO request message.
- the HO request message includes UE context (UE context) information, which is information related to the UE to be HOed.
- Step ST2505 the target cell determines whether to permit HO to the UE in consideration of the state of the own cell and information on the UE.
- FIG. 25 shows a case where the target cell permits HO to the UE.
- the target cell In the case of HO permission, the target cell notifies the source cell of a permission message (HO request Ack) for the HO request in step ST2506.
- the source cell that has received the permission message notifies the UE of Mobility (HO) control information.
- the source cell In step ST2509, the source cell notifies the target cell of data necessary for continuing communication with HO and PDCP SN status (SN (status) information related thereto.
- the UE that has received the HO control information in step ST2507 performs detachment from the source cell in step ST2508, and synchronizes with the target cell in step ST2510 based on the target cell information included in the HO control information. Process.
- the target cell notifies the UE of uplink resource allocation information and TA (Timing Advance) information that is transmission timing information.
- Step ST2512 the UE that has received the uplink resource allocation information and TA information notifies the target cell of an RRC connection reconfiguration complete (RRC connection reconfiguration complete) message. Thereby, data communication between the UE and the target cell is started.
- Step ST2513 the target cell that has received the RRC connection reconfiguration completion message in Step ST2512 completes HO (HO ⁇ ⁇ ⁇ completion) with the source cell via the MME and serving GW (S-GW) that are higher-level devices. Process for.
- the source cell releases the resources used for the control associated with the information on the UE in step ST2514.
- FIG. 26 is a flowchart illustrating an example of a target cell selection procedure by the serving cell.
- the serving cell receives the measurement report (Measurement Report) notified from the UE.
- step ST2602 the serving cell that has received the measurement report notified from the UE in step ST2601 selects a cell having the best reception quality as a target cell based on the reception quality of the UE from the result of the measurement report.
- At the time of selection of a target cell by the serving cell at least one of the communication quality of the cell backhaul link and the uplink state is taken into account in the HO.
- at the time of selection of a target cell by the serving cell at least one of the communication quality of the cell backhaul link and the uplink state is taken into account in the HO.
- both the communication quality of the cell backhaul link and the uplink state are taken into consideration.
- FIG. 27 is a flowchart showing the processing procedure of HO taking into consideration the communication quality of the cell backhaul link and the uplink state, disclosed in the present embodiment.
- the processing of the flowchart shown in FIG. 27 is similar to the processing of the flowcharts shown in FIGS. 18, 19, 20, 22, and 26, so only the different processing will be described, and the corresponding steps will be the same step. A number is attached and explanation of processing is omitted.
- step ST2601 the serving cell that has received the measurement report notified from the UE takes the cell reception quality into consideration in step ST1801 and the cell path loss in step ST2002 when selecting the target cell.
- step ST2201 the desired communication speed of the UE is taken into consideration in step ST2201.
- step ST2201 If a cell that satisfies the communication quality threshold of the backhaul link corresponding to the desired communication speed of the UE cannot be obtained in step ST2201, the process proceeds to step ST2704, and the cell with the best cell reception quality is selected as the target cell. To do. Alternatively, the cell with the smallest cell path loss may be selected as the target cell.
- step ST2201 When a cell that satisfies the communication quality threshold of the backhaul link corresponding to the desired communication speed of the UE is obtained in step ST2201, the cell moves to step ST2705, and the cell having the best communication quality of the cell backhaul link As the target cell.
- the serving cell selects, as a target cell, the cell selected in step ST2701, step ST2702, step ST2703, step ST2704, and step ST2705.
- the cell ranking method after the start of measurement for celery selection in the celery selection disclosed in the second to fifth embodiments is the target cell by the serving cell in HO. Can be applied to the choice of.
- the serving cell needs to recognize the communication quality of the backhaul link of the neighboring cell.
- the method disclosed in the second embodiment may be used.
- the serving cell needs to recognize a path loss between the UE and the cell. It is necessary to recognize not only the serving cell path loss but also the neighboring cell path loss.
- a measurement configuration for path loss is provided.
- the serving cell notifies the UE to measure the path loss of the adjacent cell using the measurement configuration for path loss as the measurement control shown in Step ST2501 of FIG.
- the UE For a cell whose measured path loss satisfies a certain condition, the UE notifies the serving cell of the path loss value together with the identity (PCI, GCI) of the cell in the measurement report corresponding to the measurement configuration.
- the serving cell notifies the UE of the threshold for path loss in the measurement configuration.
- the UE that has received the measurement configuration measures the path loss of at least one of the serving cell and the neighboring cell, and notifies the serving cell of the measurement report for the cell whose path loss measurement result is greater than the threshold.
- the UE measures the path loss of at least one of the serving cell and the neighboring cell, and notifies the serving cell of the measurement report for the cell with the smallest path loss.
- the serving cell may measure the uplink received power from the UE and derive it using the transmission power of the UE and the received power measurement value.
- the serving cell sets the transmission power of the UE
- the serving cell recognizes the transmission power of the UE.
- the UE may notify the serving cell of the transmission power information together with the transmission data. Thereby, the serving cell can recognize the transmission power information.
- an actual distance may be used as the uplink state instead of a path loss.
- a measurement configuration for position measurement is provided.
- the UE that has received the measurement configuration measures the position of the own UE by GPS or the like.
- the UE notifies the serving cell of the measured position through a measurement report corresponding to the measurement configuration.
- the serving cell needs to recognize not only the UE but also the location of its own cell and neighboring cells.
- Each cell may measure the position of its own cell by GPS or the like, and notify the neighboring cell of the position information in advance. The notification may be performed when each cell is installed or initialized, that is, at initialization.
- the serving cell can recognize the position of the neighboring cell, and therefore, the actual distance between each cell and the UE can be derived using the position of the UE described above. .
- the serving cell needs to recognize the desired communication speed of the UE.
- the UE notifies the serving cell of such information in advance.
- the UE may notify the serving cell of these pieces of information when requesting the RRC connection or when in the RRC_connected state.
- the serving cell may be notified together with the measurement report shown in step ST2502 of FIG. 25 or included in the measurement report message.
- RRC signaling may be used, or MAC signaling may be used.
- the methods disclosed in the first embodiment to the present embodiment may be combined, and in this case, when the serving cell is selected or changed regardless of the UE state (RRC_Idle state and RRC_Connected state), the cell back It becomes possible to take into consideration at least one of the communication quality of the hall link and the uplink state, and it becomes possible to improve the interference problem and the capacity problem in the heterogeneous network.
- the method disclosed in the present invention is not limited to a network in which one or more local nodes are incorporated in a normal eNB (macro cell), but also in a macro cell only network or a local node only network. It is possible to apply for For example, in a macro cell, a dedicated line is used for many of the backhaul links, but the communication quality of the dedicated line varies from cell to cell. When an event is being performed in a certain cell, the communication load of the cell increases, and the communication quality of the backhaul dedicated line of the cell may deteriorate accordingly. Even in such a case, by selecting the serving cell in consideration of the communication quality of the backhaul link, it is possible to select a different cell while avoiding the cell. Therefore, it is possible to distribute the capacity among the cells, and it is possible to prevent the communication speed from being lowered and the communication interruption that occurs in the worst case.
- the LTE system (E-UTRAN) has been mainly described.
- the mobile communication system of the present invention can be applied to any communication system using one or a plurality of types of nodes.
- the present invention can be applied to a W-CDMA system (UTRAN, UMTS) or LTE-Advanced.
- 71 mobile terminals 72 base stations, 72-1 eNB, 72-2 Home-eNB, 73 MME / S-GW unit, 74 HeNBGW.
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Abstract
Provided is a mobile communication system wherein it is possible to operate a plurality of local area range nodes and to flexibly arrange same. A value in which the communication quality of the backhaul link of a serving cell is considered is used as the measurement start threshold value (S_intrasearch_total) for cell reselection. In step (ST1401), a mobile terminal (71) compares the measurement start threshold value (S_intrasearch_total) with the reception power measurement value (Sx) of the serving cell. If Sx is equal to or less than S_intrasearch_total, it is determined that the reception quality of the serving cell including the communication quality of the backhaul link is bad, and in step (ST1302), the measurement for cell reselection is started.
Description
本発明は、複数の移動端末と基地局との間で無線通信を実施する移動体通信システムに関する。
The present invention relates to a mobile communication system that performs wireless communication between a plurality of mobile terminals and a base station.
第3世代と呼ばれる通信方式のうち、W-CDMA(Wideband Code division Multiple Access)方式が2001年から日本で商用サービスが開始されている。また、下りリンク(個別データチャネル、個別制御チャネル)にパケット伝送用のチャネル(High Speed-Downlink Shared Channel:HS-DSCH)を追加することにより、下りリンクを用いたデータ送信の更なる高速化を実現するHSDPA(High Speed Down Link Packet Access)のサービスが開始されている。さらに、上り方向のデータ送信をより高速化するためHSUPA(High Speed Up Link Packet Access)方式についてもサービスが開始されている。W-CDMAは、移動体通信システムの規格化団体である3GPP(3rd Generation Partnership Project)により定められた通信方式であり、リリース8版の規格書がとりまとめられている。
Among the communication systems called third generation, the W-CDMA (Wideband Code Division Multiple Access) system has been commercialized in Japan since 2001. In addition, by adding a packet transmission channel (High-Speed-Downlink Shared Channel: HS-DSCH) to the downlink (dedicated data channel, dedicated control channel), further speeding up data transmission using the downlink Realized HSDPA (High Speed Down Link Link Packet Access) services have been started. Furthermore, in order to further increase the speed of data transmission in the uplink direction, a service has also been started for the HSUPA (High Speed Up Link Link Packet Access) system. W-CDMA is a communication system defined by 3GPP (3rd Generation Partnership Project), which is a standardization organization for mobile communication systems, and standardized release 8 editions are compiled.
また、3GPPにおいて、W-CDMAとは別の通信方式として、無線区間についてはロングタームエボリューション(Long Term Evolution:LTE)、コアネットワーク(単にネットワークとも称する)を含めたシステム全体構成については、システムアーキテクチャエボリューション(System Architecture Evolution:SAE)と称される新たな通信方式が検討されている。
Further, in 3GPP, as a communication method different from W-CDMA, the entire system configuration including a long term evolution (LTE) and a core network (also simply referred to as a network) is used for the radio section. A new communication method called Evolution (System Architecture Evolution: SAE) is being studied.
LTEでは、アクセス方式、無線のチャネル構成やプロトコルが、現在のW-CDMA(HSDPA/HSUPA)とは全く異なるものになる。例えば、アクセス方式は、W-CDMAが符号分割多元接続(Code Division Multiple Access)を用いているのに対して、LTEは下り方向はOFDM(Orthogonal Frequency Division Multiplexing)、上り方向はSC-FDMA(Single Career Frequency Division Multiple Access)を用いる。また、帯域幅は、W-CDMAが5MHzであるのに対し、LTEでは1.4MHz,3MHz,5MHz,10MHz,15MHz,20MHzの中で基地局毎に選択可能となっている。また、LTEでは、W-CDMAのように回線交換を含まず、パケット通信方式のみになる。
In LTE, the access method, wireless channel configuration, and protocol are completely different from the current W-CDMA (HSDPA / HSUPA). For example, W-CDMA uses code division multiple access (Code-Division-Multiple-Access), whereas LTE uses OFDM (Orthogonal Frequency-Division-Multiplexing) in the downlink direction and SC-FDMA (Single in the uplink direction). Career Frequency Division Multiple Access). The bandwidth is 5 MHz for W-CDMA, whereas the bandwidth can be selected for each base station from 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, and 20 MHz in LTE. Also, LTE does not include circuit switching as in W-CDMA, and only packet communication is used.
LTEは、W-CDMAのコアネットワーク(General Packet Radio Service:GPRS)とは異なる新たなコアネットワークを用いて通信システムが構成されるため、W-CDMA網とは別の独立した無線アクセス網として定義される。したがって、W-CDMAの通信システムと区別するため、LTEの通信システムでは、移動端末(User Equipment:UE)と通信を行う基地局(Base station)はeNB(E-UTRAN NodeB)と称され、複数の基地局と制御データやユーザデータのやり取りを行う基地局制御装置(Radio Network Controller)は、EPC(Evolved Packet Core)またはaGW(Access Gateway)と称される。このLTEの通信システムでは、ユニキャスト(Unicast)サービスとE-MBMSサービス(Evolved Multimedia Broadcast Multicast Service)とが提供される。E-MBMSサービスとは、放送型マルチメディアサービスであり、単にMBMSと称される場合もある。複数の移動端末に対してニュースや天気予報、モバイル放送などの大容量放送コンテンツが送信される。これを1対多(Point to Multipoint)サービスともいう。
LTE is defined as an independent radio access network separate from the W-CDMA network because the communication system is configured using a new core network different from the W-CDMA core network (General Packet Radio Service: GPRS). Is done. Therefore, in order to distinguish from the W-CDMA communication system, in the LTE communication system, a base station (Base station) that communicates with a mobile terminal (User Equipment: UE) is referred to as an eNB (E-UTRAN NodeB). A base station controller (Radio Network Controller) that exchanges control data and user data with the base station is called EPC (Evolved Packet Core) or aGW (Access Gateway). In this LTE communication system, a unicast service and an E-MBMS service (Evolved Multimedia Broadcast Multicast Service) are provided. The E-MBMS service is a broadcast-type multimedia service and may be simply referred to as MBMS. Mass broadcast contents such as news, weather forecasts, and mobile broadcasts are transmitted to a plurality of mobile terminals. This is also called a point-to-multipoint service.
3GPPでの、LTEシステムにおける全体的なアーキテクチャ(Architecture)に関する現在の決定事項が、非特許文献1(4.6.1章)に記載されている。全体的なアーキテクチャについて図1を用いて説明する。図1は、LTE方式の通信システムの構成を示す説明図である。図1において、移動端末101に対する制御プロトコル、例えばRRC(Radio Resource Control)と、ユーザプレイン、例えばPDCP(Packet Data Convergence Protocol)、RLC(Radio Link Control)、MAC(Medium Access Control)、PHY(Physical layer)とが基地局102で終端するならば、E-UTRAN(Evolved Universal Terrestrial Radio Access)は1つあるいは複数の基地局102によって構成される。
Non-Patent Document 1 (Chapter 4.6.1) describes the current decisions regarding the overall architecture of the LTE system in 3GPP. The overall architecture will be described with reference to FIG. FIG. 1 is an explanatory diagram illustrating a configuration of an LTE communication system. In FIG. 1, a control protocol for the mobile terminal 101 such as RRC (Radio Resource Control) and a user plane such as PDCP (Packet Data Convergence Protocol), RLC (Radio Link Control), MAC (Medium Access Control), PHY (Physical Layer) E-UTRAN (Evolved102Universal Terrestrial Radio Access) is composed of one or more base stations 102.
基地局102は、MME(Mobility Management Entity)103から通知されるページング信号(Paging Signaling、ページングメッセージ(paging messages)とも称される)のスケジューリング(Scheduling)および送信を行う。基地局102は、X2インタフェースにより、互いに接続される。また基地局102は、S1インタフェースによりEPC(Evolved Packet Core)に接続される。より明確には、基地局102は、S1_MMEインタフェースによりMME(Mobility Management Entity)103に接続され、S1_UインタフェースによりS-GW(Serving Gateway)104に接続される。
The base station 102 performs scheduling and transmission of a paging signal (also called paging signaling or paging message) notified from an MME (Mobility Management Entity) 103. Base stations 102 are connected to each other via an X2 interface. The base station 102 is connected to an EPC (Evolved Packet Core) via an S1 interface. More specifically, the base station 102 is connected to an MME (Mobility Management Entity) 103 via an S1_MME interface, and is connected to an S-GW (Serving Gateway) 104 via an S1_U interface.
MME103は、複数あるいは単数の基地局102へのページング信号の分配を行う。また、MME103は待受け状態(Idle State)のモビリティ制御(Mobility control)を行う。MME103は、移動端末が待ち受け状態および、アクティブ状態(Active State)の際に、トラッキングエリア(Tracking Area)リストの管理を行う。
The MME 103 distributes a paging signal to a plurality or a single base station 102. Further, the MME 103 performs mobility control (Mobility control) in a standby state (Idle State). The MME 103 manages a tracking area (Tracking Area) list when the mobile terminal is in a standby state and an active state (Active State).
S-GW104は、ひとつまたは複数の基地局102とユーザデータの送受信を行う。S-GW104は、基地局間のハンドオーバの際、ローカルな移動性のアンカーポイント(Mobility Anchor Point)となる。EPCには、さらにP-GW(PDN Gateway)が存在し、ユーザ毎のパケットフィルタリングやUE-IDアドレスの割当などを行う。
The S-GW 104 transmits / receives user data to / from one or a plurality of base stations 102. The S-GW 104 becomes a local mobility anchor point (Mobility Anchor Point) during handover between base stations. The EPC further includes a P-GW (PDN Gateway), which performs packet filtering and UE-ID address allocation for each user.
移動端末101と基地局102との間の制御プロトコルRRCは、報知(Broadcast)、ページング(paging)、RRC接続マネージメント(RRC connection management)などを行う。RRCにおける基地局と移動端末の状態として、RRC_Idle、RRC_CONNECTEDがある。RRC_IDLEでは、PLMN(Public Land Mobile Network)選択、システム情報(System Information:SI)の報知、ページング(paging)、セル再選択(cell re-selection)、モビリティ等が行われる。RRC_CONNECTEDでは、移動端末はRRC接続(connection)を有し、ネットワークとのデータの送受信を行うことができ、また、ハンドオーバ(Handover:HO)、隣接セル(Neighbour cell)のメジャメント等が行われる。
The control protocol RRC between the mobile terminal 101 and the base station 102 performs broadcast, paging, RRC connection management (RRC connection management), and the like. There are RRC_Idle and RRC_CONNECTED as states of the base station and the mobile terminal in RRC. In RRC_IDLE, PLMN (Public Land Mobile Mobile Network) selection, system information (System Information: SI) notification, paging, cell re-selection, mobility, and the like are performed. In RRC_CONNECTED, a mobile terminal has an RRC connection (connection), can transmit and receive data to and from the network, and performs handover (Handover: HO), measurement of a neighbor cell (Neighbour cell), and the like.
非特許文献1(5章)に記載される3GPPでの、LTEシステムにおけるフレーム構成に関する現在の決定事項について、図2を用いて説明する。図2は、LTE方式の通信システムで使用される無線フレームの構成を示す説明図である。図2において、1つの無線フレーム(Radio frame)は10msである。無線フレームは10個の等しい大きさのサブフレーム(Sub-frame)に分割される。サブフレームは、2個の等しい大きさのスロット(slot)に分割される。無線フレーム毎に1番目と6番目のサブフレームに下り同期信号(Downlink Synchronization Signal:SS)が含まれる。同期信号には、第一同期信号(Primary Synchronization Signal:P-SS)と、第二同期信号(Secondary Synchronization Signal:S-SS)とがある。サブフレーム単位にてMBSFN(Multimedia Broadcast multicast service Single Frequency Network)用とMBSFN以外のチャネルの多重が行われる。以降、MBSFN送信用のサブフレームをMBSFNサブフレーム(MBSFN sub-frame)と称する。
Non-Patent Document 1 (Chapter 5) describes the current decisions regarding the frame configuration in the LTE system in 3GPP, with reference to FIG. FIG. 2 is an explanatory diagram showing a configuration of a radio frame used in the LTE communication system. In FIG. 2, one radio frame (Radio frame) is 10 ms. The radio frame is divided into 10 equally sized sub-frames. The subframe is divided into two equally sized slots. A downlink synchronization signal (Downlink Synchronization Signal: SS) is included in the first and sixth subframes for each radio frame. The synchronization signal includes a first synchronization signal (Primary Synchronization Signal: P-SS) and a second synchronization signal (Secondary Synchronization Signal: S-SS). Channels other than MBSFN (Multimedia (Broadcast multicast service Single Frequency Network) and channels other than MBSFN are performed on a subframe basis. Hereinafter, a subframe for MBSFN transmission is referred to as an MBSFN subframe (MBSFN sub-frame).
非特許文献2に、MBSFNサブフレームの割り当て時のシグナリング例が記載されている。図3は、MBSFNフレームの構成を示す説明図である。図3において、MBSFNフレーム(MBSFN frame)毎にMBSFNサブフレームが割り当てられる。MBSFNフレームの集合(MBSFN frame Cluster)がスケジュールされる。MBSFNフレームの集合の繰り返し周期(Repetition Period)が割り当てられる。
Non-Patent Document 2 describes a signaling example at the time of MBSFN subframe allocation. FIG. 3 is an explanatory diagram showing the configuration of the MBSFN frame. In FIG. 3, an MBSFN subframe is allocated for each MBSFN frame (MBSFN frame). A set of MBSFN frames (MBSFN frame Cluster) is scheduled. A repetition period (Repetition Period) of a set of MBSFN frames is assigned.
3GPPでの、LTEシステムにおけるチャネル構成に関する現在の決定事項が、非特許文献1(5章)に記載されている。CSGセル(Closed Subscriber Group cell)においてもnon-CSGセルと同じチャネル構成が用いられると想定されている。物理チャネル(Physical channel)について、図4を用いて説明する。図4は、LTE方式の通信システムで使用される物理チャネルを説明する説明図である。図4において、物理報知チャネル(Physical Broadcast channel:PBCH)401は、基地局102から移動端末101へ送信される下りチャネルである。BCHトランスポートブロック(transport block)は、40ms間隔中の4個のサブフレームにマッピングされる。40msタイミングの明白なシグナリングはない。物理制御チャネルフォーマットインジケータチャネル(Physical Control Format Indicator Channel:PCFICH)402は、基地局102から移動端末101へ送信される。PCFICHは、PDCCHsのために用いるOFDMシンボルの数について基地局102から移動端末101へ通知する。PCFICHは、サブフレーム毎に送信される。
Non-Patent Document 1 (Chapter 5) describes the current decisions regarding the channel configuration in the LTE system in 3GPP. It is assumed that the CSG cell (ClosednSubscriber Group に お い て cell) uses the same channel configuration as the non-CSG cell. A physical channel will be described with reference to FIG. FIG. 4 is an explanatory diagram illustrating physical channels used in the LTE communication system. In FIG. 4, a physical broadcast channel (PBCH) 401 is a downlink channel transmitted from the base station 102 to the mobile terminal 101. A BCH transport block (transport block) is mapped to four subframes in a 40 ms interval. There is no obvious signaling of 40ms timing. A physical control channel format indicator channel (Physical-Control-Format-Indicator-Channel: PCFICH) 402 is transmitted from the base station 102 to the mobile terminal 101. PCFICH notifies base station 102 to mobile terminal 101 about the number of OFDM symbols used for PDCCHs. PCFICH is transmitted for each subframe.
物理下り制御チャネル(Physical Downlink Control Channel:PDCCH)403は、基地局102から移動端末101へ送信される下りチャネルである。PDCCHは、リソース割り当て(allocation)、DL-SCH(後述の図5に示されるトランスポートチャネルの1つである下り共有チャネル)に関するHARQ情報、PCH(図5に示されるトランスポートチャネルの1つであるページングチャネル)を通知する。PDCCHは、上りスケジューリンググラント(Uplink Scheduling Grant)を運ぶ。PDCCHは、上り送信に対する応答信号であるAck(Acknowledgement)/Nack(Negative Acknowledgement)を運ぶ。PDCCHは、L1/L2制御信号とも呼ばれる。
A physical downlink control channel (Physical Downlink Control Channel: PDCCH) 403 is a downlink channel transmitted from the base station 102 to the mobile terminal 101. The PDCCH is resource allocation, HARQ information regarding DL-SCH (a downlink shared channel that is one of the transport channels shown in FIG. 5 described later), and PCH (one of the transport channels shown in FIG. 5). A certain paging channel). The PDCCH carries an uplink scheduling grant (Uplink Scheduling Grant). The PDCCH carries Ack (Acknowledgement) / Nack (Negative Acknowledgment) which is a response signal for uplink transmission. The PDCCH is also called an L1 / L2 control signal.
物理下り共有チャネル(Physical Downlink Shared Channel:PDSCH)404は、基地局102から移動端末101へ送信される下りチャネルである。PDSCHは、トランスポートチャネルであるDL-SCH(下り共有チャネル)やトランスポートチャネルであるPCHがマッピングされている。物理マルチキャストチャネル(Physical Multicast Channel:PMCH)405は、基地局102から移動端末101へ送信される下りチャネルである。PMCHは、トランスポートチャネルであるMCH(マルチキャストチャネル)がマッピングされている。
A physical downlink shared channel (PDSCH) 404 is a downlink channel transmitted from the base station 102 to the mobile terminal 101. In PDSCH, DL-SCH (downlink shared channel) which is a transport channel and PCH which is a transport channel are mapped. A physical multicast channel (Physical Multicast Channel: PMCH) 405 is a downlink channel transmitted from the base station 102 to the mobile terminal 101. The PMCH is mapped with an MCH (multicast channel) which is a transport channel.
物理上り制御チャネル(Physical Uplink Control Channel:PUCCH)406は、移動端末101から基地局102へ送信される上りチャネルである。PUCCHは、下り送信に対する応答信号(response)であるAck/Nackを運ぶ。PUCCHは、CQI(Channel Quality Indicator)レポートを運ぶ。CQIとは受信したデータの品質、もしくは通信路品質を示す品質情報である。またPUCCHは、スケジューリングリクエスト(Scheduling Request:SR)を運ぶ。物理上り共有チャネル(Physical Uplink Shared Channel:PUSCH)407は、移動端末101から基地局102へ送信される上りチャネルである。PUSCHは、UL-SCH(図5に示されるトランスポートチャネルの1つである上り共有チャネル)がマッピングされている。
A physical uplink control channel (Physical Uplink Control Channel: PUCCH) 406 is an uplink channel transmitted from the mobile terminal 101 to the base station 102. The PUCCH carries Ack / Nack which is a response signal (response) to downlink transmission. The PUCCH carries a CQI (Channel Quality Indicator) report. CQI is quality information indicating the quality of received data or channel quality. The PUCCH carries a scheduling request (SR). A physical uplink shared channel (Physical Uplink Shared Channel: PUSCH) 407 is an uplink channel transmitted from the mobile terminal 101 to the base station 102. The PUSCH is mapped with UL-SCH (uplink shared channel which is one of the transport channels shown in FIG. 5).
物理HARQインジケータチャネル(Physical Hybrid ARQ Indicator Channel:PHICH)408は、基地局102から移動端末101へ送信される下りチャネルである。PHICHは、上り送信に対する応答であるAck/Nackを運ぶ。物理ランダムアクセスチャネル(Physical Random Access Channel:PRACH)409は、移動端末101から基地局102へ送信される上りチャネルである。PRACHは、ランダムアクセスプリアンブル(random access preamble)を運ぶ。
A Physical HARQ indicator channel (Physical Hybrid ARQ Indicator Channel: PHICH) 408 is a downlink channel transmitted from the base station 102 to the mobile terminal 101. PHICH carries Ack / Nack which is a response to uplink transmission. A physical random access channel (Physical Random Access Channel: PRACH) 409 is an uplink channel transmitted from the mobile terminal 101 to the base station 102. The PRACH carries a random access preamble.
下りリファレンスシグナル(Reference signal)は、移動体通信システムとして既知のシンボルが、毎スロットの最初、3番目、最後のOFDMシンボルに挿入される。移動端末の物理レイヤの測定として、リファレンスシンボルの受信電力(Reference Symbol Received Power:RSRP)がある。
As a downlink reference signal (Reference signal), a symbol known as a mobile communication system is inserted into the first, third and last OFDM symbols of each slot. As a measurement of the physical layer of the mobile terminal, there is a received power of a reference symbol (Reference Symbol Received Power: RSRP).
非特許文献1(5章)に記載されるトランスポートチャネル(Transport channel)について、図5を用いて説明する。図5は、LTE方式の通信システムで使用されるトランスポートチャネルを説明する説明図である。図5(A)には、下りトランスポートチャネルと下り物理チャネルとの間のマッピングを示す。図5(B)には、上りトランスポートチャネルと上り物理チャネルとの間のマッピングを示す。下りトランスポートチャネルについて報知チャネル(Broadcast Channel:BCH)は、その基地局(セル)全体に報知される。BCHは、物理報知チャネル(PBCH)にマッピングされる。
The transport channel described in Non-Patent Document 1 (Chapter 5) will be described with reference to FIG. FIG. 5 is an explanatory diagram for explaining a transport channel used in an LTE communication system. FIG. 5A shows the mapping between the downlink transport channel and the downlink physical channel. FIG. 5B shows mapping between the uplink transport channel and the uplink physical channel. The broadcast channel (Broadcast Channel: BCH) is broadcast to the entire base station (cell) regarding the downlink transport channel. The BCH is mapped to the physical broadcast channel (PBCH).
下り共有チャネル(Downlink Shared Channel:DL-SCH)には、HARQ(Hybrid ARQ)による再送制御が適用される。DL-SCHは、基地局(セル)全体への報知が可能である。DL-SCHは、ダイナミックあるいは準静的(Semi-static)なリソース割り当てをサポートする。準静的なリソース割り当ては、パーシステントスケジューリング(Persistent Scheduling)とも言われる。DL-SCHは、移動端末の低消費電力化のために移動端末のDRX(Discontinuous reception)をサポートする。DL-SCHは、物理下り共有チャネル(PDSCH)へマッピングされる。
Retransmission control by HARQ (Hybrid ARQ) is applied to the downlink shared channel (DL-SCH). The DL-SCH can be broadcast to the entire base station (cell). DL-SCH supports dynamic or semi-static resource allocation. Quasi-static resource allocation is also referred to as persistent scheduling. DL-SCH supports DRX (Discontinuous reception) of a mobile terminal in order to reduce power consumption of the mobile terminal. The DL-SCH is mapped to the physical downlink shared channel (PDSCH).
ページングチャネル(Paging Channel:PCH)は、移動端末の低消費電力を可能とするために移動端末のDRXをサポートする。PCHは、基地局(セル)全体への報知が要求される。PCHは、動的にトラフィックに利用できる物理下り共有チャネル(PDSCH)のような物理リソース、あるいは他の制御チャネルの物理下り制御チャネル(PDCCH)のような物理リソースへマッピングされる。マルチキャストチャネル(Multicast Channel:MCH)は、基地局(セル)全体への報知に使用される。MCHは、マルチセル送信におけるMBMSサービス(MTCHとMCCH)のSFN合成をサポートする。MCHは、準静的なリソース割り当てをサポートする。MCHは、PMCHへマッピングされる。
The Paging Channel (PCH) supports DRX of the mobile terminal in order to enable low power consumption of the mobile terminal. The PCH is required to be broadcast to the entire base station (cell). The PCH is mapped to a physical resource such as a physical downlink shared channel (PDSCH) that can be dynamically used for traffic, or a physical resource such as a physical downlink control channel (PDCCH) of another control channel. A multicast channel (Multicast Channel: MCH) is used for broadcast to the entire base station (cell). The MCH supports SFN combining of MBMS services (MTCH and MCCH) in multi-cell transmission. The MCH supports quasi-static resource allocation. MCH is mapped to PMCH.
上り共有チャネル(Uplink Shared Channel:UL-SCH)には、HARQ(Hybrid ARQ)による再送制御が適用される。UL-SCHは、ダイナミックあるいは準静的(Semi-static)なリソース割り当てをサポートする。UL-SCHは、物理上り共有チャネル(PUSCH)へマッピングされる。図5(B)に示されるランダムアクセスチャネル(Random Access Channel:RACH)は、制御情報に限られている。RACHは、衝突のリスクがある。RACHは、物理ランダムアクセスチャネル(PRACH)へマッピングされる。
Retransmission control by HARQ (Hybrid ARQ) is applied to the uplink shared channel (Uplink Shared Channel: UL-SCH). UL-SCH supports dynamic or semi-static resource allocation. UL-SCH is mapped to a physical uplink shared channel (PUSCH). The random access channel (Random Access Channel: RACH) shown in FIG. 5B is limited to control information. RACH is at risk of collision. The RACH is mapped to a physical random access channel (PRACH).
HARQについて説明する。HARQとは、自動再送(Automatic Repeat reQuest)と誤り訂正(Forward Error Correction)との組み合わせにより、伝送路の通信品質を向上させる技術である。通信品質が変化する伝送路に対しても、再送により誤り訂正が有効に機能するという利点がある。特に、再送にあたって初送の受信結果と再送の受信結果との合成をすることで、更なる品質向上を得ることも可能である。
HARQ will be described. HARQ is a technique for improving the communication quality of a transmission path by combining automatic retransmission (AutomaticAutoRepeat reQuest) and error correction (Forward Error Correction). There is also an advantage that error correction functions effectively by retransmission even for transmission paths in which communication quality changes. In particular, further quality improvement can be obtained by combining the initial transmission reception result and the retransmission reception result upon retransmission.
再送の方法の一例を説明する。受信側にて、受信データが正しくデコードできなかった場合、換言すればCRC(Cyclic Redundancy Check)エラーが発生した場合(CRC=NG)、受信側から送信側へ「Nack」を送信する。「Nack」を受信した送信側は、データを再送する。受信側にて、受信データが正しくデコードできた場合、換言すればCRCエラーが発生しない場合(CRC=OK)、受信側から送信側へ「Ack」を送信する。「Ack」を受信した送信側は次のデータを送信する。
An example of the retransmission method will be described. When the reception side cannot decode the received data correctly, in other words, when a CRC (Cyclic Redundancy Check) error occurs (CRC = NG), “Nack” is transmitted from the reception side to the transmission side. The transmitting side that has received “Nack” retransmits the data. When the reception side can correctly decode the received data, in other words, when no CRC error occurs (CRC = OK), “Ack” is transmitted from the reception side to the transmission side. The transmitting side that has received “Ack” transmits the next data.
HARQ方式の一例として、チェースコンバイニング(Chase Combining)がある。チェースコンバイニングとは、初送と再送に同じデータ系列を送信するもので、再送において初送のデータ系列と再送のデータ系列との合成を行うことで、利得を向上させる方式である。これは、初送データに誤りがあったとしても、部分的に正確なものも含まれており、正確な部分の初送データと再送データとを合成することで、より高精度にデータを送信できるという考え方に基づいている。また、HARQ方式の別の例として、IR(Incremental Redundancy)がある。IRとは、冗長度を増加させるものであり、再送においてパリティビットを送信することで、初送と組み合わせて冗長度を増加させ、誤り訂正機能により品質を向上させるものである。
As an example of the HARQ method, there is chase combining. Chase combining is a method in which the same data sequence is transmitted for initial transmission and retransmission, and the gain is improved by combining the initial transmission data sequence and the retransmission data sequence in retransmission. This means that even if there is an error in the initial transmission data, the data is partially accurate, and the data is transmitted with higher accuracy by combining the correct initial transmission data and the retransmission data. It is based on the idea that it can be done. Another example of the HARQ method is IR (Incremental Redundancy). IR is to increase redundancy, and by transmitting parity bits in retransmission, the redundancy is increased in combination with initial transmission, and the quality is improved by an error correction function.
非特許文献1(6章)に記載される論理チャネル(Logical channel、以下「ロジカルチャネル」という場合がある)について、図6を用いて説明する。図6は、LTE方式の通信システムで使用される論理チャネルを説明する説明図である。図6(A)には、下りロジカルチャネルと下りトランスポートチャネルとの間のマッピングを示す。図6(B)には、上りロジカルチャネルと上りトランスポートチャネルとの間のマッピングを示す。報知制御チャネル(Broadcast Control Channel:BCCH)は、報知システム制御情報のための下りチャネルである。論理チャネルであるBCCHは、トランスポートチャネルである報知チャネル(BCH)、あるいは下り共有チャネル(DL-SCH)へマッピングされる。
The logical channel described in Non-Patent Document 1 (Chapter 6) will be described with reference to FIG. FIG. 6 is an explanatory diagram illustrating logical channels used in the LTE communication system. FIG. 6A shows mapping between the downlink logical channel and the downlink transport channel. FIG. 6B shows mapping between the uplink logical channel and the uplink transport channel. The broadcast control channel (Broadcast Control Channel: BCCH) is a downlink channel for broadcast system control information. The BCCH that is a logical channel is mapped to a broadcast channel (BCH) that is a transport channel or a downlink shared channel (DL-SCH).
ページング制御チャネル(Paging Control Channel:PCCH)は、ページング信号を送信するための下りチャネルである。PCCHは、移動端末のセルロケーションをネットワークが知らない場合に用いられる。論理チャネルであるPCCHは、トランスポートチャネルであるページングチャネル(PCH)へマッピングされる。共有制御チャネル(Common Control Channel:CCCH)は、移動端末と基地局との間の送信制御情報のためのチャネルである。CCCHは、移動端末がネットワークとの間でRRC接続(connection)を持っていない場合に用いられる。下り方向では、CCCHは、トランスポートチャネルである下り共有チャネル(DL-SCH)へマッピングされる。上り方向では、CCCHは、トランスポートチャネルである上り共有チャネル(UL-SCH)へマッピングされる。
The paging control channel (Paging Control Channel: PCCH) is a downlink channel for transmitting a paging signal. PCCH is used when the network does not know the cell location of the mobile terminal. The PCCH that is a logical channel is mapped to a paging channel (PCH) that is a transport channel. The common control channel (Common Control Channel: CCCH) is a channel for transmission control information between the mobile terminal and the base station. CCCH is used when the mobile terminal does not have an RRC connection with the network. In the downlink direction, the CCCH is mapped to a downlink shared channel (DL-SCH) that is a transport channel. In the uplink direction, the CCCH is mapped to an uplink shared channel (UL-SCH) that is a transport channel.
マルチキャスト制御チャネル(Multicast Control Channel:MCCH)は、1対多の送信のための下りチャネルである。MCCHは、ネットワークから移動端末への1つあるいはいくつかのMTCH用のMBMS制御情報の送信のために用いられる。MCCHは、MBMS受信中の移動端末のみに用いられる。MCCHは、トランスポートチャネルである下り共有チャネル(DL-SCH)あるいはマルチキャストチャネル(MCH)へマッピングされる。
The multicast control channel (Multicast Control Channel: MCCH) is a downlink channel for one-to-many transmission. The MCCH is used for transmission of MBMS control information for one or several MTCHs from the network to the mobile terminal. MCCH is used only for mobile terminals that are receiving MBMS. The MCCH is mapped to the downlink shared channel (DL-SCH) or multicast channel (MCH) which is a transport channel.
個別制御チャネル(Dedicated Control Channel:DCCH)は、移動端末とネットワークとの間の個別制御情報を送信するチャネルである。DCCHは、上りでは上り共有チャネル(UL-SCH)へマッピングされ、下りでは下り共有チャネル(DL-SCH)にマッピングされる。
The dedicated control channel (Dedicated Control Channel: DCCH) is a channel for transmitting dedicated control information between the mobile terminal and the network. The DCCH is mapped to the uplink shared channel (UL-SCH) in the uplink, and is mapped to the downlink shared channel (DL-SCH) in the downlink.
個別トラフィックチャネル(Dedicate Traffic Channel:DTCH)は、ユーザ情報の送信のための個別移動端末への1対1通信のチャネルである。DTCHは、上りおよび下りともに存在する。DTCHは、上りでは上り共有チャネル(UL-SCH)へマッピングされ、下りでは下り共有チャネル(DL-SCH)へマッピングされる。
The dedicated traffic channel (Dedicate Traffic Channel: DTCH) is a channel for one-to-one communication to individual mobile terminals for transmitting user information. DTCH exists for both uplink and downlink. The DTCH is mapped to the uplink shared channel (UL-SCH) in the uplink, and is mapped to the downlink shared channel (DL-SCH) in the downlink.
マルチキャストトラフィックチャネル(Multicast Traffic channel:MTCH)は、ネットワークから移動端末へのトラフィックデータ送信のための下りチャネルである。MTCHは、MBMS受信中の移動端末のみに用いられるチャネルである。MTCHは、下り共有チャネル(DL-SCH)あるいはマルチキャストチャネル(MCH)へマッピングされる。
The multicast traffic channel (MTCH) is a downlink channel for transmitting traffic data from the network to the mobile terminal. MTCH is a channel used only for a mobile terminal that is receiving MBMS. The MTCH is mapped to a downlink shared channel (DL-SCH) or a multicast channel (MCH).
GCIとは、グローバルセル識別子(Global Cell Identity)のことである。LTEおよびUMTS(Universal Mobile Telecommunication System)において、CSGセル(Closed Subscriber Group cell)が導入される。CSGについて以下に説明する(非特許文献3 3.1章参照)。CSG(Closed Subscriber Group)とは、利用可能な加入者をオペレータが特定しているセルである(特定加入者用セル)。特定された加入者は、PLMN(Public Land Mobile Network)の1つ以上のE-UTRANセルにアクセスすることが許可される。特定された加入者がアクセスを許可されている1つ以上のE-UTRANセルを「CSG cell(s)」と呼ぶ。ただし、PLMNにはアクセス制限がある。CSGセルとは、固有のCSGアイデンティティ(CSG identity:CSG ID;CSG-ID)を報知するPLMNの一部である。予め利用登録し、許可された加入者グループのメンバーは、アクセス許可情報であるところのCSG-IDを用いてCSGセルにアクセスする。
GCI is a global cell identifier (Global Cell Identity). In LTE and UMTS (Universal Mobile Telecommunication System), CSG cells (Closed Subscriber Group Cell) are introduced. CSG will be described below (see Non-Patent Document 3, Chapter 3.1). CSG (Closed Subscriber Group) is a cell in which an operator identifies an available subscriber (a cell for a specific subscriber). The identified subscribers are allowed to access one or more E-UTRAN cells of the PLMN (Public Land Mobile Mobile Network). One or more E-UTRAN cells to which the identified subscribers are allowed access are referred to as “CSG cell (s)”. However, PLMN has access restrictions. A CSG cell is a part of a PLMN that broadcasts a unique CSG identity (CSG identity: CSG ID; CSG-ID). Members of the subscriber group who have been registered in advance and permitted access the CSG cell using the CSG-ID as access permission information.
CSG-IDは、CSGセルまたはセルによって報知される。移動体通信システムにCSG-IDは複数存在する。そして、CSG-IDは、CSG関連のメンバーのアクセスを容易にするために、移動端末(UE)によって使用される。移動端末の位置追跡は、1つ以上のセルからなる区域を単位に行われる。位置追跡は、待受け状態であっても移動端末の位置を追跡し、呼び出す(移動端末が着呼する)ことを可能にするためである。この移動端末の位置追跡のための区域をトラッキングエリアと呼ぶ。CSGホワイトリスト(CSG White List)とは、加入者が属するCSGセルのすべてのCSG IDが記録されている、USIM(Universal Subscriber Identity Module)に格納されたリストである。CSGホワイトリストは、許可CSGリスト(Allowed CSG ID List)と呼ばれることもある。
The CSG-ID is broadcast by the CSG cell or cell. There are a plurality of CSG-IDs in a mobile communication system. The CSG-ID is then used by the mobile terminal (UE) to facilitate access of CSG related members. The location tracking of a mobile terminal is performed in units of areas composed of one or more cells. The position tracking is to enable tracking of the position of the mobile terminal and calling (the mobile terminal receives a call) even in the standby state. This area for tracking the location of the mobile terminal is called a tracking area. The CSG white list (CSG white list) is a list stored in a USIM (Universal Subscriber Identity Module) in which all CSG IDs of CSG cells to which the subscriber belongs are recorded. The CSG white list may be referred to as an allowed CSG list (Allowed CSG ID List).
「適切なセル」(Suitable cell)について以下に説明する(非特許文献3 4.3章参照)。「適切なセル」(Suitable cell)とは、UEが通常(normal)サービスを受けるためにキャンプオン(Camp ON)するセルである。そのようなセルは、以下の条件を満たすものとする。
“Suitable cell” will be described below (see Non-Patent Document 3, Chapter 4.3). A “suitable cell” is a cell that the UE camps on to receive normal service. Such a cell shall satisfy the following conditions:
(1)セルは、選択されたPLMNもしくは登録されたPLMN、または「Equivalent PLMNリスト」のPLMNの一部であること。
(1) The cell is a selected PLMN or a registered PLMN, or a part of the PLMN in the “Equivalent PLMN list”.
(2)NAS(Non-Access Stratum)によって提供された最新情報にて、さらに以下の条件を満たすこと
(a)そのセルが禁じられた(barred)セルでないこと
(b)そのセルが「ローミングのための禁止されたLAs」リストの一部ではなく、少なくとも1つのトラッキングエリア(Tracking Area:TA)の一部であること。その場合、そのセルは上記(1)を満たす必要がある
(c)そのセルが、セル選択評価基準を満たしていること
(d)そのセルが、CSGセルとしてシステム情報(System Information:SI)によって特定されたセルに関しては、CSG-IDはUEの「CSGホワイトリスト」(CSG WhiteList)の一部であること(UEのCSG WhiteList中に含まれること)。 (2) In the latest information provided by NAS (Non-Access Stratum), the following conditions must be satisfied. (A) The cell is not a barred cell. (B) And not a part of the “Forbidden LAs” list, but a part of at least one tracking area (TA). In that case, the cell needs to satisfy the above (1). (C) The cell satisfies the cell selection evaluation criteria. (D) The cell is a CSG cell according to system information (SI). For the identified cell, the CSG-ID shall be part of the UE's “CSG WhiteList” (included in the UE's CSG WhiteList).
(a)そのセルが禁じられた(barred)セルでないこと
(b)そのセルが「ローミングのための禁止されたLAs」リストの一部ではなく、少なくとも1つのトラッキングエリア(Tracking Area:TA)の一部であること。その場合、そのセルは上記(1)を満たす必要がある
(c)そのセルが、セル選択評価基準を満たしていること
(d)そのセルが、CSGセルとしてシステム情報(System Information:SI)によって特定されたセルに関しては、CSG-IDはUEの「CSGホワイトリスト」(CSG WhiteList)の一部であること(UEのCSG WhiteList中に含まれること)。 (2) In the latest information provided by NAS (Non-Access Stratum), the following conditions must be satisfied. (A) The cell is not a barred cell. (B) And not a part of the “Forbidden LAs” list, but a part of at least one tracking area (TA). In that case, the cell needs to satisfy the above (1). (C) The cell satisfies the cell selection evaluation criteria. (D) The cell is a CSG cell according to system information (SI). For the identified cell, the CSG-ID shall be part of the UE's “CSG WhiteList” (included in the UE's CSG WhiteList).
「アクセプタブルセル」(Acceptable cell)について以下に説明する(非特許文献3 4.3章参照)。これは、UEが限られたサービス(緊急通報)を受けるためにキャンプオンするセルである。そのようなセルは、以下のすべての要件を充足するものとする。つまり、E-UTRANネットワークで緊急通報を開始するための最小のセットの要件を以下に示す。(1)そのセルが禁じられた(barred)セルでないこと。(2)そのセルが、セル選択評価基準を満たしていること。
“Acceptable cell” will be described below (see Non-Patent Document 3, Chapter 4.3). This is a cell where the UE camps on in order to receive a limited service (emergency call). Such a cell shall satisfy all the following requirements: That is, the minimum set of requirements for initiating an emergency call in an E-UTRAN network is shown below. (1) The cell is not a barred cell. (2) The cell satisfies the cell selection evaluation criteria.
セルにキャンプオン(camp on)するとは、UEがセル選択/再選択(cell selection/reselection)処理を完了し、UEがシステム情報とページング情報をモニタするセルを選択した状態である。
Camping on a cell means that the UE has completed cell selection / reselection processing and the UE has selected a cell for monitoring system information and paging information.
3GPPにおいて、Home-NodeB(Home-NB;HNB)、Home-eNodeB(Home-eNB;HeNB)と称される基地局が検討されている。UTRANにおけるHNB、またはE-UTRANにおけるHeNBは、例えば家庭、法人、商業用のアクセスサービス向けの基地局である。非特許文献4には、HeNBおよびHNBへのアクセスの3つの異なるモードが開示されている。具体的には、オープンアクセスモード(Open access mode)と、クローズドアクセスモード(Closed access mode)と、ハイブリッドアクセスモード(Hybrid access mode)である。
In 3GPP, base stations called Home-NodeB (Home-NB; HNB) and Home-eNodeB (Home-eNB; HeNB) are being studied. The HNB in UTRAN or the HeNB in E-UTRAN is a base station for, for example, home, corporate, and commercial access services. Non-Patent Document 4 discloses three different modes of access to HeNB and HNB. Specifically, an open access mode (Open access mode), a closed access mode (Closed access mode), and a hybrid access mode (Hybrid access mode).
各々のモードは、以下のような特徴を有する。オープンアクセスモードでは、HeNBやHNBは通常のオペレータのノーマルセルとして操作される。クローズドアクセスモードでは、HeNBやHNBがCSGセルとして操作される。これはCSGメンバーのみアクセス可能なCSGセルである。ハイブリッドアクセスモードでは、非CSGメンバーも同時にアクセス許可されているCSGセルである。ハイブリッドアクセスモードのセル(ハイブリッドセルとも称する)は、言い換えれば、オープンアクセスモードとクローズドアクセスモードの両方をサポートするセルである。
Each mode has the following characteristics. In the open access mode, the HeNB or HNB is operated as a normal cell of a normal operator. In the closed access mode, the HeNB or HNB is operated as a CSG cell. This is a CSG cell accessible only to CSG members. In the hybrid access mode, a non-CSG member is a CSG cell to which access is permitted at the same time. In other words, a cell in hybrid access mode (also referred to as a hybrid cell) is a cell that supports both an open access mode and a closed access mode.
3GPPでは、全PCI(Physical Cell Identity)を、CSGセル用とnon-CSGセル用とに分割(PCIスプリットと称する)することが議論されている(非特許文献5参照)。またPCIスプリット情報は、システム情報にて基地局から傘下の移動端末に対して報知されることが議論されている。非特許文献5は、PCIスプリットを用いた移動端末の基本動作を開示する。PCIスプリット情報を有していない移動端末は、全PCIを用いて(例えば504コード全てを用いて)セルサーチを行う必要がある。これに対して、PCIスプリット情報を有する移動端末は、当該PCIスプリット情報を用いてセルサーチを行うことが可能である。
3GPP discusses dividing all PCI (Physical Cell Identity) into a CSG cell and a non-CSG cell (referred to as PCI split) (see Non-Patent Document 5). Further, it is discussed that the PCI split information is reported from the base station to the mobile terminals being served by the system information. Non-Patent Document 5 discloses a basic operation of a mobile terminal using PCI split. A mobile terminal that does not have PCI split information needs to perform a cell search using all PCIs (for example, using all 504 codes). On the other hand, a mobile terminal having PCI split information can perform a cell search using the PCI split information.
また3GPPでは、リリース10として、ロングタームエボリューションアドヴァンスド(Long Term Evolution Advanced:LTE-A)の規格策定が進められている(非特許文献6、非特許文献7参照)。
In 3GPP, the Long Term Evolution Advanced (LTE-A) standard is being developed as Release 10 (see Non-Patent Document 6 and Non-Patent Document 7).
LTE-Aシステムでは、高い通信速度、セルエッジでの高いスループット、新たなカバレッジエリアなどを得るために、リレー(Relay:リレーノード(RN))をサポートすることが検討されている。リレーノードは、ドナーセル(Donor cell;Donor eNB;DeNB)を介して無線アクセスネットワークに無線で接続される。ドナーセルの範囲内で、ネットワーク(Network:NW)からリレーへのリンクは、ネットワークからUEへのリンクと同じ周波数バンドを共用する。この場合、リリース8のUEも該ドナーセルに接続することを可能とする。ドナーセルとリレーノードとの間のリンクをバックホールリンク(backhaul link)と称し、リレーノードとUEとの間のリンクをアクセスリンク(access link)と称す。
In the LTE-A system, in order to obtain a high communication speed, a high throughput at the cell edge, a new coverage area, etc., it is considered to support a relay (Relay: relay node (RN)). The relay node is wirelessly connected to the radio access network via a donor cell (Donor cell; Donor eNB; DeNB). Within the donor cell, the network (NW) to relay link shares the same frequency band as the network to UE link. In this case, a Release 8 UE can also be connected to the donor cell. A link between the donor cell and the relay node is referred to as a backhaul link, and a link between the relay node and the UE is referred to as an access link.
FDD(Frequency Division Duplex)におけるバックホールリンクの多重方法として、DeNBからRNへの送信は下り(DL)周波数バンドで行われ、RNからDeNBへの送信は上り(UL)周波数バンドで行われる。リレーにおけるリソースの分割方法として、DeNBからRNへのリンクおよびRNからUEへのリンクが一つの周波数バンドで時分割多重され、RNからDeNBへのリンクおよびUEからRNへのリンクも一つの周波数バンドで時分割多重される。こうすることで、リレーにおいて、リレーの送信が自リレーの受信へ干渉することを防ぐことができる。
As a backhaul link multiplexing method in FDD (Frequency Division Duplex), transmission from DeNB to RN is performed in a downlink (DL) frequency band, and transmission from RN to DeNB is performed in an uplink (UL) frequency band. As a resource division method in the relay, a link from DeNB to RN and a link from RN to UE are time-division multiplexed in one frequency band, and a link from RN to DeNB and a link from UE to RN are also one frequency band. Is time-division multiplexed. By doing so, it is possible to prevent the relay transmission from interfering with the reception of the own relay in the relay.
LTE-Aで検討される技術の一つとして、ヘテロジーニアスネットワークス(Heterogeneous Networks:HetNets)が加えられた(非特許文献8参照)。ヘテロジーニアスネットワークスは、通常のeNB(マクロセル)に、HeNBやリレーノードのようなローカルエリアレンジノードを一つ以上組み入れたネットワークである。
Heterogeneous Networks (HetNets) has been added as one of the technologies studied in LTE-A (see Non-Patent Document 8). Heterogeneous networks are networks in which one or more local area range nodes such as HeNBs and relay nodes are incorporated in a normal eNB (macro cell).
ヘテロジーニアスネットワークスにおいては、最も受信電力の強いセルへセルセレクションを行うことが必ずしも最適になるとは限らないという問題が存在する。また、バックホールリンクの通信品質が悪いセルには接続しない方がよい場合があるが、従来のセルセレクションにおいては、バックホールリンクの通信品質を考慮に入れていないという問題がある。さらに、ヘテロジーニアスネットワークでは、下りリンクで最適なセルと、上りリンクで最適なセルとは異なるという問題がある。従来のセルセレクションでは、下りリンクで最適なセルへのセルセレクションが行われるため、上りリンクについて何ら考慮されていない。これらの問題は、セルセレクションに限らず、セルリセレクションやハンドオーバなどのサービングセルの選択あるいは変更の際に生じる。
In heterogeneous networks, there is a problem that cell selection to the cell with the strongest reception power is not always optimal. Further, although it may be better not to connect to a cell with poor communication quality of the backhaul link, the conventional cell selection has a problem that the communication quality of the backhaul link is not taken into consideration. Further, in the heterogeneous network, there is a problem that the optimum cell in the downlink is different from the optimum cell in the uplink. In the conventional cell selection, since cell selection to the optimum cell is performed in the downlink, no consideration is given to the uplink. These problems occur not only in cell selection but also in selection or change of a serving cell such as cell reselection or handover.
これらの問題は、ヘテロジーニアスネットワークにおけるUEあるいはノード間の干渉の増大や、各ノードのキャパシティの低減という問題につながる。将来の膨大な数のローカルエリアレンジノードの運用やそれらの柔軟な配置を可能とするためには、これらの問題を解決することが重要な課題となっている。
These problems lead to problems such as increased interference between UEs or nodes in a heterogeneous network and reduced capacity of each node. In order to enable the operation of a huge number of local area range nodes in the future and their flexible arrangement, it is important to solve these problems.
非特許文献8では、これらの問題を解消するために、バックホールリンクの品質を考慮したセルセレクションや、弱受信電力のセルの測定とトリガメカニズムとが必要であることが提案されている。非特許文献9には、リレーノードのバックホールリンクの通信品質を考慮したセルセレクション方法が開示されている。非特許文献10には、上りリンクと下りリンクとで異なるセルに独立に接続させることが開示されている。
Non-Patent Document 8 proposes that cell selection considering the quality of the backhaul link, measurement of a cell with weak received power, and a trigger mechanism are necessary to solve these problems. Non-Patent Document 9 discloses a cell selection method considering the communication quality of a relay node backhaul link. Non-Patent Document 10 discloses that an uplink and a downlink are independently connected to different cells.
非特許文献8では、前述の問題を解消するために、バックホールリンクの品質を考慮したセルセレクションや、弱受信電力のセルの測定とトリガメカニズムとが必要であることが提案されている。しかし、これらの具体的な方法については、何ら記載されていない。
Non-Patent Document 8 proposes that cell selection taking into account the quality of the backhaul link, measurement of a cell with weak reception power, and a trigger mechanism are necessary to solve the above-described problems. However, these specific methods are not described at all.
非特許文献9には、リレーノードがバックホールリンクの品質を報知して、UEはそれを考慮してセルセレクションを行うと記載されている。しかし、どのようなメカニズムで該バックホールリンクの品質を考慮に入れるのか、具体的な方法については、何ら開示されていない。
Non-Patent Document 9 describes that the relay node broadcasts the quality of the backhaul link, and the UE performs cell selection in consideration thereof. However, there is no disclosure of a specific method by which the quality of the backhaul link is taken into consideration.
非特許文献10には、上りリンクと下りリンクとで異なるセルに独立に接続させることが開示されているが、この具体的方法については、何ら記載されていない。また、上りリンクと下りリンクとで異なるセルに接続させることは、UEがサービングセルを複数有することになるため、通信制御が非常に複雑になってしまうと考えられる。
Non-Patent Document 10 discloses that an uplink and a downlink are connected independently to different cells, but this specific method is not described at all. In addition, connecting to different cells in the uplink and the downlink is considered to make communication control very complicated because the UE has a plurality of serving cells.
本発明の目的は、膨大な数のローカルエリアレンジノードの運用やそれらの柔軟な配置を可能とする移動通信システムを提供することである。
An object of the present invention is to provide a mobile communication system that enables operation of a huge number of local area range nodes and their flexible arrangement.
本発明の移動体通信システムは、コアネットワークに接続される複数の基地局装置と、各前記基地局装置と無線通信可能な移動端末装置とを含み、前記複数の基地局装置の通信可能な範囲である複数のセルの少なくとも一部分が重複する移動体通信システムであって、前記移動端末装置は、各セルにおける基地局装置からの信号の受信品質と、前記基地局装置と前記コアネットワークとの間の通信回線の通信品質とを含む選択情報に基づいて、前記複数のセルの中から、通信対象となる基地局装置のセルを選択することを特徴とする。
The mobile communication system of the present invention includes a plurality of base station devices connected to a core network and mobile terminal devices capable of wireless communication with each of the base station devices, and a communicable range of the plurality of base station devices A mobile communication system in which at least a part of a plurality of cells overlap, wherein the mobile terminal apparatus receives a signal reception quality from a base station apparatus in each cell, and between the base station apparatus and the core network. The cell of the base station apparatus to be communicated is selected from the plurality of cells based on selection information including the communication quality of the communication line.
また本発明の移動体通信システムは、複数の基地局装置と、各前記基地局装置と無線通信可能な移動端末装置と、前記複数の基地局装置のうちの少なくとも1つの基地局装置と前記移動端末装置との間の無線通信を中継する中継装置とを含み、前記複数の基地局装置の通信可能な範囲である複数のセルの少なくとも一部分が重複する移動体通信システムであって、前記移動端末装置は、各セルにおける基地局装置からの信号の受信品質と、前記基地局装置と前記中継装置との間の通信回線の通信品質とを含む選択情報に基づいて、前記複数のセルの中から、通信対象となる基地局装置のセルを選択することを特徴とする。
The mobile communication system of the present invention includes a plurality of base station devices, a mobile terminal device capable of wireless communication with each of the base station devices, at least one base station device of the plurality of base station devices, and the mobile A mobile communication system in which at least a part of a plurality of cells that are communicable ranges of the plurality of base station devices overlap each other, including a relay device that relays wireless communication with the terminal device The apparatus is configured to select from among the plurality of cells based on selection information including reception quality of a signal from the base station apparatus in each cell and communication quality of a communication line between the base station apparatus and the relay apparatus. The base station apparatus cell to be communicated is selected.
また本発明の移動体通信システムは、複数の基地局装置と、各前記基地局装置と無線通信可能な移動端末装置とを含み、前記複数の基地局装置の通信可能な範囲である複数のセルの少なくとも一部分が重複する移動体通信システムであって、前記移動端末装置は、各セルにおける基地局装置からの信号の受信品質と、各セルにおける移動端末装置から基地局装置への上り通信回線の状態とを含む選択情報に基づいて、前記複数のセルの中から、通信対象となる基地局装置のセルを選択することを特徴とする。
The mobile communication system of the present invention includes a plurality of base station devices and a mobile terminal device capable of wireless communication with each of the base station devices, and a plurality of cells that are communicable ranges of the plurality of base station devices. In which at least a portion of the mobile terminal apparatus overlaps the reception quality of the signal from the base station apparatus in each cell and the uplink communication line from the mobile terminal apparatus to the base station apparatus in each cell. A cell of a base station apparatus to be a communication target is selected from the plurality of cells based on selection information including a state.
また本発明の移動体通信システムによれば、移動端末装置は、各セルにおける基地局装置からの信号の受信品質と、基地局装置とコアネットワークとの間の通信回線の通信品質とを含む選択情報に基づいて、複数のセルの中から、通信対象となる基地局装置のセルを選択する。これによって、各セルの受信品質に加えて、基地局装置とコアネットワークとの間の通信回線の通信品質を考慮に入れて、通信対象となる基地局装置のセルを選択することができる。したがって、たとえば、ヘテロジーニアスネットワークスにおける干渉問題およびキャパシティ問題を改善することが可能となるので、膨大な数のローカルエリアレンジノードの運用およびそれらの柔軟な配置が可能となる。
Further, according to the mobile communication system of the present invention, the mobile terminal apparatus selects the reception quality of the signal from the base station apparatus in each cell and the communication quality of the communication line between the base station apparatus and the core network. Based on the information, a cell of the base station apparatus to be communicated is selected from a plurality of cells. Thereby, in addition to the reception quality of each cell, the communication quality of the communication line between the base station apparatus and the core network can be taken into consideration, and the cell of the base station apparatus to be communicated can be selected. Therefore, for example, since it is possible to improve the interference problem and the capacity problem in heterogeneous networks, it is possible to operate a large number of local area range nodes and flexibly arrange them.
本発明の移動体通信システムによれば、移動端末装置は、各セルにおける基地局装置からの信号の受信品質と、基地局装置と中継装置との間の通信回線の通信品質とを含む選択情報に基づいて、複数のセルの中から、通信対象となる基地局装置のセルを選択する。これによって、各セルの受信品質に加えて、基地局装置と中継装置との間の通信回線の通信品質を考慮に入れて、通信対象となる基地局装置のセルを選択することができる。したがって、たとえば、ヘテロジーニアスネットワークスにおける干渉問題およびキャパシティ問題を改善することが可能となるので、膨大な数のローカルエリアレンジノードの運用およびそれらの柔軟な配置が可能となる。
According to the mobile communication system of the present invention, the mobile terminal apparatus selects information including the reception quality of the signal from the base station apparatus in each cell and the communication quality of the communication line between the base station apparatus and the relay apparatus. Based on the above, a cell of a base station apparatus to be a communication target is selected from a plurality of cells. Thereby, in addition to the reception quality of each cell, the communication quality of the communication line between the base station apparatus and the relay apparatus can be taken into consideration, and the cell of the base station apparatus to be communicated can be selected. Therefore, for example, since it is possible to improve the interference problem and the capacity problem in heterogeneous networks, it is possible to operate a large number of local area range nodes and flexibly arrange them.
また本発明の移動体通信システムによれば、移動端末装置は、各セルにおける基地局装置からの信号の受信品質と、各セルにおける移動端末装置から基地局装置への上り通信回線の状態とを含む選択情報に基づいて、複数のセルの中から、通信対象となる基地局装置のセルを選択する。これによって、各セルの受信品質に加えて、各セルの上り通信回線の状態を考慮に入れて、通信対象となる基地局装置のセルを選択することができる。したがって、たとえば、ヘテロジーニアスネットワークスにおける干渉問題およびキャパシティ問題を改善することが可能となるので、膨大な数のローカルエリアレンジノードの運用およびそれらの柔軟な配置が可能となる。
Further, according to the mobile communication system of the present invention, the mobile terminal apparatus determines the reception quality of the signal from the base station apparatus in each cell and the state of the uplink communication line from the mobile terminal apparatus to the base station apparatus in each cell. Based on the selection information included, a cell of a base station apparatus to be communicated is selected from a plurality of cells. Thereby, in addition to the reception quality of each cell, the state of the uplink communication line of each cell can be taken into consideration, and the cell of the base station apparatus to be communicated can be selected. Therefore, for example, since it is possible to improve the interference problem and the capacity problem in heterogeneous networks, it is possible to operate a large number of local area range nodes and flexibly arrange them.
この発明の目的、特徴、局面、および利点は、以下の詳細な説明と添付図面とによって、より明白となる。
The objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.
実施の形態1.
図7は、現在3GPPにおいて議論されているLTE方式の移動体通信システムの全体的な構成を示すブロック図である。現在3GPPにおいては、CSG(Closed Subscriber Group)セル(E-UTRANのHome-eNodeB(Home-eNB;HeNB)、UTRANのHome-NB(HNB))と、non-CSGセル(E-UTRANのeNodeB(eNB)、UTRANのNodeB(NB)、GERANのBSS)とを含めたシステムの全体的な構成が検討されており、E-UTRANについては、図7のような構成が提案されている(非特許文献1 4.6.1.章参照)。Embodiment 1 FIG.
FIG. 7 is a block diagram showing the overall configuration of an LTE mobile communication system currently under discussion in 3GPP. Currently, in 3GPP, CSG (Closed Subscriber Group) cells (E-UTRAN Home-eNodeB (Home-eNB; HeNB), UTRAN Home-NB (HNB)) and non-CSG cells (E-UTRAN eNodeB ( eNB), UTRAN NodeB (NB), and GERAN BSS) are being studied, and a configuration as shown in FIG. 7 has been proposed for E-UTRAN (non-patent document).Reference 1 see Chapter 4.6.1.).
図7は、現在3GPPにおいて議論されているLTE方式の移動体通信システムの全体的な構成を示すブロック図である。現在3GPPにおいては、CSG(Closed Subscriber Group)セル(E-UTRANのHome-eNodeB(Home-eNB;HeNB)、UTRANのHome-NB(HNB))と、non-CSGセル(E-UTRANのeNodeB(eNB)、UTRANのNodeB(NB)、GERANのBSS)とを含めたシステムの全体的な構成が検討されており、E-UTRANについては、図7のような構成が提案されている(非特許文献1 4.6.1.章参照)。
FIG. 7 is a block diagram showing the overall configuration of an LTE mobile communication system currently under discussion in 3GPP. Currently, in 3GPP, CSG (Closed Subscriber Group) cells (E-UTRAN Home-eNodeB (Home-eNB; HeNB), UTRAN Home-NB (HNB)) and non-CSG cells (E-UTRAN eNodeB ( eNB), UTRAN NodeB (NB), and GERAN BSS) are being studied, and a configuration as shown in FIG. 7 has been proposed for E-UTRAN (non-patent document).
図7について説明する。移動端末装置(以下「移動端末」または「UE」という)71は、基地局装置(以下「基地局」という)72と無線通信可能であり、無線通信で信号の送受信を行う。基地局72は、eNB72-1と、Home-eNB72-2とに分類される。eNB72-1は、MME、あるいはS-GW、あるいはMMEおよびS-GWを含むMME/S-GW部(以下「MME部」という)73とS1インタフェースにより接続され、eNB72-1とMME部73との間で制御情報が通信される。eNB72-1は、MME部73を介してコアネットワークに接続される。ひとつのeNB72-1に対して、複数のMME部73が接続されてもよい。eNB72-1間は、X2インタフェースにより接続され、eNB72-1間で制御情報が通信される。
Referring to FIG. A mobile terminal device (hereinafter referred to as “mobile terminal” or “UE”) 71 is capable of wireless communication with a base station device (hereinafter referred to as “base station”) 72, and transmits and receives signals by wireless communication. The base station 72 is classified into an eNB 72-1 and a Home-eNB 72-2. The eNB 72-1 is connected to the MME, S-GW, or the MME / S-GW unit (hereinafter referred to as “MME unit”) 73 including the MME and the S-GW via the S1 interface. Control information is communicated between the two. The eNB 72-1 is connected to the core network via the MME unit 73. A plurality of MME units 73 may be connected to one eNB 72-1. The eNBs 72-1 are connected by the X2 interface, and control information is communicated between the eNBs 72-1.
Home-eNB72-2は、MME部73とS1インタフェースにより接続され、Home-eNB72-2とMME部73との間で制御情報が通信される。ひとつのMME部73に対して、複数のHome-eNB72-2が接続される。あるいは、Home-eNB72-2は、HeNBGW(Home-eNB GateWay)74を介してMME部73と接続される。Home-eNB72-2とHeNBGW74とは、S1インタフェースにより接続され、HeNBGW74とMME部73とはS1インタフェースを介して接続される。Home-eNB72-2は、MME部73、またはMME部73およびHeNBGW74を介して、コアネットワークに接続される。ひとつまたは複数のHome-eNB72-2がひとつのHeNBGW74と接続され、S1インタフェースを通して情報が通信される。HeNBGW74は、ひとつまたは複数のMME部73と接続され、S1インタフェースを通して情報が通信される。
The Home-eNB 72-2 is connected to the MME unit 73 via the S1 interface, and control information is communicated between the Home-eNB 72-2 and the MME unit 73. A plurality of Home-eNBs 72-2 are connected to one MME unit 73. Alternatively, the Home-eNB 72-2 is connected to the MME unit 73 via a HeNBGW (Home-eNB GateWay) 74. Home-eNB 72-2 and HeNBGW 74 are connected via an S1 interface, and HeNBGW 74 and MME unit 73 are connected via an S1 interface. The Home-eNB 72-2 is connected to the core network via the MME unit 73 or the MME unit 73 and the HeNBGW 74. One or a plurality of Home-eNBs 72-2 are connected to one HeNBGW 74, and information is communicated through the S1 interface. The HeNBGW 74 is connected to one or a plurality of MME units 73, and information is communicated through the S1 interface.
さらに現在3GPPでは、以下のような構成が検討されている。Home-eNB72-2間のX2インタフェースはサポートされない。MME部73からは、HeNBGW74はeNB72-1として見える。Home-eNB72-2からは、HeNBGW74はMME部73として見える。Home-eNB72-2が、HeNBGW74を介してMME部73に接続されるか否かに関係なく、Home-eNB72-2とMME部73との間のインタフェースは、S1インタフェースで同じである。複数のMME部73にまたがるような、Home-eNB72-2へのモビリティ、あるいはHome-eNB72-2からのモビリティはサポートされない。Home-eNB72-2は、唯一のセルをサポートする。
Furthermore, the following configurations are currently being studied in 3GPP. The X2 interface between Home-eNB 72-2 is not supported. From the MME unit 73, the HeNBGW 74 appears as an eNB 72-1. From the Home-eNB 72-2, the HeNBGW 74 appears as the MME unit 73. Regardless of whether or not the Home-eNB 72-2 is connected to the MME unit 73 via the HeNBGW 74, the interface between the Home-eNB 72-2 and the MME unit 73 is the same in the S1 interface. Mobility to the Home-eNB 72-2 or mobility from the Home-eNB 72-2 that spans a plurality of MME units 73 is not supported. Home-eNB 72-2 supports only one cell.
図8は、本発明に係る移動端末(図7の移動端末71)の構成を示すブロック図である。図8に示す移動端末71の送信処理を説明する。まず、プロトコル処理部801からの制御データ、およびアプリケーション部802からのユーザデータが、送信データバッファ部803へ保存される。送信データバッファ部803に保存されたデータは、エンコーダー部804へ渡され、誤り訂正などのエンコード処理が施される。エンコード処理を施さずに、送信データバッファ部803から変調部805へ直接出力されるデータが存在してもよい。エンコーダー部804でエンコード処理されたデータは、変調部805にて変調処理が行われる。変調されたデータは、ベースバンド信号に変換された後、周波数変換部806へ出力され、無線送信周波数に変換される。その後、アンテナ807から基地局72に送信信号が送信される。
FIG. 8 is a block diagram showing a configuration of a mobile terminal (mobile terminal 71 in FIG. 7) according to the present invention. A transmission process of the mobile terminal 71 shown in FIG. 8 will be described. First, control data from the protocol processing unit 801 and user data from the application unit 802 are stored in the transmission data buffer unit 803. The data stored in the transmission data buffer unit 803 is transferred to the encoder unit 804 and subjected to encoding processing such as error correction. There may exist data directly output from the transmission data buffer unit 803 to the modulation unit 805 without performing the encoding process. The data encoded by the encoder unit 804 is modulated by the modulation unit 805. The modulated data is converted into a baseband signal, and then output to the frequency conversion unit 806, where it is converted into a radio transmission frequency. Thereafter, a transmission signal is transmitted from the antenna 807 to the base station 72.
また、移動端末71の受信処理は、以下のとおりに実行される。基地局72からの無線信号がアンテナ807により受信される。受信信号は、周波数変換部806にて無線受信周波数からベースバンド信号に変換され、復調部808において復調処理が行われる。復調後のデータは、デコーダー部809へ渡され、誤り訂正などのデコード処理が行われる。デコードされたデータのうち、制御データはプロトコル処理部801へ渡され、ユーザデータはアプリケーション部802へ渡される。移動端末71の一連の処理は、制御部810によって制御される。よって制御部810は、図8では省略しているが、各部801~809と接続している。
Also, the reception process of the mobile terminal 71 is executed as follows. A radio signal from the base station 72 is received by the antenna 807. The reception signal is converted from a radio reception frequency to a baseband signal by the frequency conversion unit 806, and demodulated by the demodulation unit 808. The demodulated data is passed to the decoder unit 809 and subjected to decoding processing such as error correction. Of the decoded data, control data is passed to the protocol processing unit 801, and user data is passed to the application unit 802. A series of processing of the mobile terminal 71 is controlled by the control unit 810. Therefore, the control unit 810 is connected to the respective units 801 to 809, which is omitted in FIG.
図9は、本発明に係る基地局(図7の基地局72)の構成を示すブロック図である。図9に示す基地局72の送信処理を説明する。EPC通信部901は、基地局72とEPC(MME部73、HeNBGW74など)との間のデータの送受信を行う。他基地局通信部902は、他の基地局との間のデータの送受信を行う。Home-eNB72-2間のX2インタフェースはサポートされない方向であるため、Home-eNB72-2では、他基地局通信部902が存在しないことも考えられる。EPC通信部901および他基地局通信部902は、それぞれプロトコル処理部903と情報の受け渡しを行う。プロトコル処理部903からの制御データ、ならびにEPC通信部901および他基地局通信部902からのユーザデータおよび制御データは、送信データバッファ部904へ保存される。
FIG. 9 is a block diagram showing the configuration of the base station (base station 72 in FIG. 7) according to the present invention. The transmission process of the base station 72 shown in FIG. 9 will be described. The EPC communication unit 901 transmits and receives data between the base station 72 and the EPC (MME unit 73, HeNBGW 74, etc.). The other base station communication unit 902 transmits / receives data to / from other base stations. Since the X2 interface between the Home-eNB 72-2 is a direction that is not supported, the Home-eNB 72-2 may not include the other base station communication unit 902. The EPC communication unit 901 and the other base station communication unit 902 exchange information with the protocol processing unit 903, respectively. Control data from the protocol processing unit 903 and user data and control data from the EPC communication unit 901 and the other base station communication unit 902 are stored in the transmission data buffer unit 904.
送信データバッファ部904に保存されたデータは、エンコーダー部905へ渡され、誤り訂正などのエンコード処理が施される。エンコード処理を施さずに、送信データバッファ部904から変調部906へ直接出力されるデータが存在してもよい。エンコードされたデータは、変調部906にて変調処理が行われる。変調されたデータは、ベースバンド信号に変換された後、周波数変換部907へ出力され、無線送信周波数に変換される。その後、アンテナ908より一つもしくは複数の移動端末71に対して送信信号が送信される。
The data stored in the transmission data buffer unit 904 is transferred to the encoder unit 905 and subjected to encoding processing such as error correction. There may exist data that is directly output from the transmission data buffer unit 904 to the modulation unit 906 without performing the encoding process. The encoded data is subjected to modulation processing by the modulation unit 906. The modulated data is converted into a baseband signal, and then output to the frequency conversion unit 907 to be converted into a radio transmission frequency. Thereafter, a transmission signal is transmitted from the antenna 908 to one or a plurality of mobile terminals 71.
また、基地局72の受信処理は以下のとおりに実行される。ひとつもしくは複数の移動端末71からの無線信号が、アンテナ908により受信される。受信信号は、周波数変換部907にて無線受信周波数からベースバンド信号に変換され、復調部909で復調処理が行われる。復調されたデータは、デコーダー部910へ渡され、誤り訂正などのデコード処理が行われる。デコードされたデータのうち、制御データはプロトコル処理部903あるいはEPC通信部901、他基地局通信部902へ渡され、ユーザデータはEPC通信部901および他基地局通信部902へ渡される。基地局72の一連の処理は、制御部911によって制御される。よって制御部911は、図9では省略しているが、各部901~910と接続している。
Further, the reception process of the base station 72 is executed as follows. Radio signals from one or a plurality of mobile terminals 71 are received by the antenna 908. The reception signal is converted from a radio reception frequency to a baseband signal by the frequency conversion unit 907, and demodulated by the demodulation unit 909. The demodulated data is transferred to the decoder unit 910 and subjected to decoding processing such as error correction. Of the decoded data, the control data is passed to the protocol processing unit 903 or the EPC communication unit 901 and the other base station communication unit 902, and the user data is passed to the EPC communication unit 901 and the other base station communication unit 902. A series of processing of the base station 72 is controlled by the control unit 911. Therefore, although not shown in FIG. 9, the control unit 911 is connected to the units 901 to 910.
現在3GPPにおいて議論されているHome-eNB72-2の機能を以下に示す(非特許文献1 4.6.2章参照)。Home-eNB72-2は、eNB72-1と同じ機能を有する。加えて、HeNBGW74と接続する場合、Home-eNB72-2は、適当なサービングHeNBGW74を発見する機能を有する。Home-eNB72-2は、1つのHeNBGW74に唯一接続する。つまり、HeNBGW74との接続の場合は、Home-eNB72-2は、S1インタフェースにおけるFlex機能を使用しない。Home-eNB72-2は、1つのHeNBGW74に接続されると、同時に別のHeNBGW74や別のMME部73に接続しない。
The functions of Home-eNB 72-2 currently being discussed in 3GPP are shown below (see Non-Patent Document 1, Chapter 4.6.2). The Home-eNB 72-2 has the same function as the eNB 72-1. In addition, when connecting to the HeNBGW 74, the Home-eNB 72-2 has a function of finding an appropriate serving HeNBGW 74. The Home-eNB 72-2 is only connected to one HeNBGW 74. That is, in the case of connection with the HeNBGW 74, the Home-eNB 72-2 does not use the Flex function in the S1 interface. When the Home-eNB 72-2 is connected to one HeNBGW 74, the Home-eNB 72-2 is not simultaneously connected to another HeNBGW 74 or another MME unit 73.
Home-eNB72-2のTACとPLMN IDは、HeNBGW74によってサポートされる。Home-eNB72-2をHeNBGW74に接続すると、「UE attachment」でのMME部73の選択は、Home-eNB72-2の代わりに、HeNBGW74によって行われる。Home-eNB72-2は、ネットワーク計画なしで配備される可能性がある。この場合、Home-eNB72-2は、1つの地理的な領域から別の地理的な領域へ移される。したがって、この場合のHome-eNB72-2は、位置によって、異なったHeNBGW74に接続する必要がある。
The TAC and PLMN ID of the Home-eNB 72-2 are supported by the HeNBGW 74. When the Home-eNB 72-2 is connected to the HeNBGW 74, the selection of the MME unit 73 in “UE attachment” is performed by the HeNBGW 74 instead of the Home-eNB 72-2. Home-eNB 72-2 may be deployed without network planning. In this case, Home-eNB 72-2 is moved from one geographic region to another. Therefore, the Home-eNB 72-2 in this case needs to be connected to different HeNBGW 74 depending on the position.
図10は、本発明に係るMME(図7のMME部73)の構成を示すブロック図である。PDN GW通信部1001は、MME部73とPDN GWとの間のデータの送受信を行う。基地局通信部1002は、MME部73と基地局72との間のS1インタフェースによるデータの送受信を行う。PDN GWから受信したデータがユーザデータであった場合、ユーザデータは、PDN GW通信部1001から、ユーザプレイン通信部1003経由で基地局通信部1002に渡され、1つあるいは複数の基地局72へ送信される。基地局72から受信したデータがユーザデータであった場合、ユーザデータは、基地局通信部1002から、ユーザプレイン通信部1003経由でPDN GW通信部1001に渡され、PDN GWへ送信される。
FIG. 10 is a block diagram showing the configuration of the MME (MME unit 73 in FIG. 7) according to the present invention. The PDN GW communication unit 1001 transmits and receives data between the MME unit 73 and the PDN GW. The base station communication unit 1002 performs data transmission / reception between the MME unit 73 and the base station 72 through the S1 interface. If the data received from the PDN GW is user data, the user data is passed from the PDN GW communication unit 1001 to the base station communication unit 1002 via the user plane communication unit 1003 to one or a plurality of base stations 72. Sent. When the data received from the base station 72 is user data, the user data is passed from the base station communication unit 1002 to the PDN GW communication unit 1001 via the user plane communication unit 1003 and transmitted to the PDN GW.
PDN GWから受信したデータが制御データであった場合、制御データは、PDN GW通信部1001から制御プレイン制御部1005へ渡される。基地局72から受信したデータが制御データであった場合、制御データは、基地局通信部1002から制御プレイン制御部1005へ渡される。
When the data received from the PDN GW is control data, the control data is passed from the PDN GW communication unit 1001 to the control plane control unit 1005. When the data received from the base station 72 is control data, the control data is transferred from the base station communication unit 1002 to the control plane control unit 1005.
HeNBGW通信部1004は、HeNBGW74が存在する場合に設けられ、情報種別によって、MME部73とHeNBGW74との間のインタフェース(IF)によるデータの送受信を行う。HeNBGW通信部1004から受信した制御データは、HeNBGW通信部1004から制御プレイン制御部1005へ渡される。制御プレイン制御部1005での処理の結果は、PDN GW通信部1001経由でPDN GWへ送信される。また、制御プレイン制御部1005で処理された結果は、基地局通信部1002経由でS1インタフェースにより1つあるいは複数の基地局72へ送信され、またHeNBGW通信部1004経由で1つあるいは複数のHeNBGW74へ送信される。
The HeNBGW communication unit 1004 is provided when the HeNBGW 74 exists, and transmits and receives data through an interface (IF) between the MME unit 73 and the HeNBGW 74 depending on the information type. The control data received from the HeNBGW communication unit 1004 is passed from the HeNBGW communication unit 1004 to the control plane control unit 1005. The result of processing in the control plane control unit 1005 is transmitted to the PDN GW via the PDN GW communication unit 1001. Further, the result processed by the control plane control unit 1005 is transmitted to one or a plurality of base stations 72 via the S1 interface via the base station communication unit 1002, and to one or a plurality of HeNBGWs 74 via the HeNBGW communication unit 1004. Sent.
制御プレイン制御部1005には、NASセキュリティ部1005-1、SAEベアラコントロール部1005-2、アイドルステート(Idle State)モビリティ管理部1005―3などが含まれ、制御プレインに対する処理全般を行う。NASセキュリティ部1005―1は、NAS(Non-Access Stratum)メッセージのセキュリティなどを行う。SAEベアラコントロール部1005―2は、SAE(System Architecture Evolution)のベアラの管理などを行う。アイドルステートモビリティ管理部1005―3は、待受け状態(LTE-IDLE状態、単にアイドルとも称される)のモビリティ管理、待受け状態時のページング信号の生成および制御、傘下の1つあるいは複数の移動端末71のトラッキングエリア(TA)の追加、削除、更新、検索、トラッキングエリアリスト(TA List)管理などを行う。
The control plane control unit 1005 includes a NAS security unit 1005-1, an SAE bearer control unit 1005-2, an idle state mobility management unit 1005-3, and the like, and performs overall processing for the control plane. The NAS security unit 1005-1 performs security of a NAS (Non-Access Stratum) message. The SAE bearer control unit 1005-2 manages a bearer of SAE (System Architecture) Evolution. The idle state mobility management unit 1005-3 manages mobility in a standby state (LTE-IDLE state, also simply referred to as idle), generation and control of a paging signal in the standby state, and one or more mobile terminals 71 being served thereby Add, delete, update, search, and track area list (TA エ リ ア List) management.
MME部73は、UEが登録されている(registered)追跡領域(トラッキングエリア:Tracking Area:TA)に属するセルへ、ページングメッセージを送信することで、ページングプロトコルに着手する。MME部73に接続されるHome-eNB72-2のCSGの管理やCSG-IDの管理、そしてホワイトリスト管理は、アイドルステートモビリティ管理部1005―3で行ってもよい。
The MME unit 73 initiates the paging protocol by transmitting a paging message to a cell belonging to a tracking area (tracking area: Tracking Area: TA) in which the UE is registered. The idle state mobility management unit 1005-3 may perform CSG management, CSG-ID management, and white list management of the Home-eNB 72-2 connected to the MME unit 73.
CSG-IDの管理では、CSG-IDに対応する移動端末とCSGセルとの関係が管理(追加、削除、更新、検索)される。例えば、あるCSG-IDにユーザアクセス登録された一つまたは複数の移動端末と該CSG-IDに属するCSGセルとの関係であってもよい。ホワイトリスト管理では、移動端末とCSG-IDとの関係が管理(追加、削除、更新、検索)される。例えば、ホワイトリストには、ある移動端末がユーザ登録した一つまたは複数のCSG-IDが記憶されてもよい。これらのCSGに関する管理は、MME部73の中の他の部分で行われてもよい。MME部73の一連の処理は、制御部1006によって制御される。よって制御部1006は、図10では省略しているが、各部1001~1005と接続している。
In the management of CSG-ID, the relationship between the mobile terminal corresponding to the CSG-ID and the CSG cell is managed (added, deleted, updated, searched). For example, it may be a relationship between one or a plurality of mobile terminals registered for user access with a certain CSG-ID and a CSG cell belonging to the CSG-ID. In white list management, the relationship between a mobile terminal and a CSG-ID is managed (added, deleted, updated, searched). For example, one or a plurality of CSG-IDs registered by a certain mobile terminal as a user may be stored in the white list. Management related to these CSGs may be performed in other parts of the MME unit 73. A series of processing of the MME unit 73 is controlled by the control unit 1006. Therefore, although not shown in FIG. 10, the control unit 1006 is connected to the units 1001 to 1005.
現在3GPPにおいて議論されているMMEの機能を以下に示す(非特許文献1 4.6.2章参照)。MMEは、CSG(Closed Subscriber Groups)のメンバーの1つ、あるいは複数の移動端末のアクセスコントロールを行う。MMEは、ページングの最適化(Paging optimization)の実行をオプションとして認める。
The functions of MME currently being discussed in 3GPP are shown below (refer to Chapter 4.6.2 of Non-Patent Document 1). The MME performs access control of one or a plurality of mobile terminals of CSG (Closed Subscriber Groups). The MME accepts paging optimization as an option.
図11は、本発明に係るHeNBGWである図7に示すHeNBGW74の構成を示すブロック図である。EPC通信部1101は、HeNBGW74とMME部73との間のS1インタフェースによるデータの送受信を行う。基地局通信部1102は、HeNBGW74とHome-eNB72-2との間のS1インタフェースによるデータの送受信を行う。ロケーション処理部1103は、EPC通信部1101経由で渡されたMME部73からのデータのうちレジストレーション情報などを、複数のHome-eNB72-2に送信する処理を行う。ロケーション処理部1103で処理されたデータは、基地局通信部1102に渡され、ひとつまたは複数のHome-eNB72-2にS1インタフェースを介して送信される。
FIG. 11 is a block diagram showing a configuration of the HeNBGW 74 shown in FIG. 7 which is the HeNBGW according to the present invention. The EPC communication unit 1101 performs data transmission / reception between the HeNBGW 74 and the MME unit 73 through the S1 interface. The base station communication unit 1102 performs data transmission / reception between the HeNBGW 74 and the Home-eNB 72-2 via the S1 interface. The location processing unit 1103 performs a process of transmitting registration information and the like among the data from the MME unit 73 delivered via the EPC communication unit 1101 to the plurality of Home-eNBs 72-2. The data processed by the location processing unit 1103 is passed to the base station communication unit 1102 and transmitted to one or more Home-eNBs 72-2 via the S1 interface.
ロケーション処理部1103での処理を必要とせず通過(透過)させるだけのデータは、EPC通信部1101から基地局通信部1102に渡され、ひとつまたは複数のHome-eNB72-2にS1インタフェースを介して送信される。HeNBGW74の一連の処理は、制御部1104によって制御される。よって制御部1104は、図11では省略しているが、各部1101~1103と接続している。
Data that does not require processing in the location processing unit 1103 and is simply passed (transmitted) is passed from the EPC communication unit 1101 to the base station communication unit 1102 and sent to one or more Home-eNBs 72-2 via the S1 interface. Sent. A series of processing of the HeNBGW 74 is controlled by the control unit 1104. Therefore, although not shown in FIG. 11, the control unit 1104 is connected to the units 1101 to 1103.
現在3GPPにおいて議論されているHeNBGW74の機能を以下に示す(非特許文献1 4.6.2章参照)。HeNBGW74は、S1アプリケーションについてリレーする。Home-eNB72-2へのMME部73の手順の一部分であるが、HeNBGW74は、移動端末71に関係しないS1アプリケーションについて終端する。HeNBGW74が配置されるとき、移動端末71に無関係な手順がHome-eNB72-2とHeNBGW74との間、そしてHeNBGW74とMME部73との間を通信される。HeNBGW74と他のノードとの間でX2インタフェースは設定されない。HeNBGW74は、ページングの最適化(Paging optimization)の実行をオプションとして認める。
The functions of HeNBGW74 currently being discussed in 3GPP are shown below (see Non-Patent Document 1, Chapter 4.6.2). The HeNBGW 74 relays for the S1 application. Although part of the procedure of the MME unit 73 to the Home-eNB 72-2, the HeNBGW 74 terminates the S1 application not related to the mobile terminal 71. When the HeNBGW 74 is arranged, procedures unrelated to the mobile terminal 71 are communicated between the Home-eNB 72-2 and the HeNBGW 74, and between the HeNBGW 74 and the MME unit 73. The X2 interface is not set between the HeNBGW 74 and other nodes. The HeNBGW 74 recognizes execution of paging optimization (Paging optimization) as an option.
次に移動体通信システムにおける一般的なセルサーチ方法の一例を示す。図12は、LTE方式の通信システムにおいて移動端末(UE)が行うセルサーチから待ち受け動作までの概略を示すフローチャートである。移動端末は、セルサーチを開始すると、ステップST1201で、周辺の基地局から送信される第一同期信号(P-SS)、および第二同期信号(S-SS)を用いて、スロットタイミング、フレームタイミングの同期をとる。P-SSとS-SSとを合わせて、同期信号(SS)には、セル毎に割り当てられたPCI(Physical Cell Identity)に1対1に対応するシンクロナイゼーションコードが割り当てられている。PCIの数は現在504通りが検討されており、この504通りのPCIを用いて同期をとるとともに、同期がとれたセルのPCIを検出(特定)する。
Next, an example of a general cell search method in a mobile communication system is shown. FIG. 12 is a flowchart showing an outline from a cell search to a standby operation performed by a mobile terminal (UE) in an LTE communication system. When starting the cell search, the mobile terminal uses the first synchronization signal (P-SS) and the second synchronization signal (S-SS) transmitted from the neighboring base stations in step ST1201, and the slot timing, frame Synchronize timing. In combination with P-SS and S-SS, the synchronization signal (SS) is assigned a synchronization code corresponding to one-to-one PCI (Physical Cell Identity) assigned to each cell. Currently, 504 PCIs are being studied, and the 504 PCIs are used for synchronization, and the PCI of the synchronized cell is detected (specified).
次に同期がとれたセルに対して、ステップST1202で、基地局からセル毎に送信される参照信号RS(Reference Signal)を検出し受信電力の測定を行う。参照信号RSには、PCIと1対1に対応したコードが用いられており、そのコードで相関をとることによって他セルと分離できる。ステップST1201で特定したPCIから、該セルのRS用のコードを導出することによって、RSを検出し、RS受信電力を測定することが可能となる。
For the next synchronized cell, in step ST1202, a reference signal RS (Reference signal) transmitted from the base station for each cell is detected, and the received power is measured. The reference signal RS uses a code corresponding to the PCI one-to-one, and can be separated from other cells by taking a correlation with the code. By deriving the RS code of the cell from the PCI specified in step ST1201, it is possible to detect the RS and measure the RS received power.
次にステップST1203で、ステップST1202までで検出されたひとつ以上のセルの中から、RSの受信品質が最も良いセル(例えば、RSの受信電力が最も高いセル、つまりベストセル)を選択する。
Next, in step ST1203, a cell having the best RS reception quality (for example, a cell having the highest RS reception power, that is, the best cell) is selected from one or more cells detected up to step ST1202.
次にステップST1204で、ベストセルのPBCHを受信して、報知情報であるBCCHを得る。PBCH上のBCCHには、セル構成情報が含まれるMIB(Master Information Block)がのる。したがってPBCHを受信してBCCHを得ることで、MIBが得られる。MIBの情報としては、例えば、DL(ダウンリンク)システム帯域幅(送信帯域幅設定(transmission bandwidth configuration:dl-bandwidth)とも呼ばれる)、送信アンテナ数、SFN(System Frame Number)などがある。
Next, in step ST1204, the PBCH of the best cell is received and the BCCH that is broadcast information is obtained. MIB (Master Information Block) including cell configuration information is carried on BCCH on PBCH. Therefore, the MIB is obtained by receiving the PBCH and obtaining the BCCH. The MIB information includes, for example, DL (downlink) system bandwidth (also called transmission bandwidth setting (transmission bandwidth configuration: dl-bandwidth)), the number of transmission antennas, SFN (System frame number), and the like.
次にステップST1205で、MIBのセル構成情報をもとに該セルのDL-SCHを受信して、報知情報BCCHの中のSIB(System Information Block)1を得る。SIB1には、該セルへのアクセスに関する情報や、セルセレクションに関する情報、他のSIB(SIBk;k≧2の整数)のスケジューリング情報が含まれる。また、SIB1には、TAC(Tracking Area Code)が含まれる。
Next, in step ST1205, the DL-SCH of the cell is received based on the MIB cell configuration information to obtain SIB (System Information Block) 1 in the broadcast information BCCH. SIB1 includes information related to access to the cell, information related to cell selection, and scheduling information of other SIBs (SIBk; an integer of k ≧ 2). Also, SIB1 includes TAC (Tracking Area Code).
次にステップST1206で、移動端末は、ステップST1205で受信したSIB1のTACと、移動端末が既に保有しているTACとを比較する。比較した結果、同じならば、該セルで待ち受け動作に入る。比較して異なる場合は、移動端末は該セルを通してコアネットワーク(Core Network,EPC)(MMEなどが含まれる)へ、TAU(Tracking Area Update)を行うためにTAの変更を要求する。コアネットワークは、TAU要求信号とともに移動端末から送られてくる該移動端末の識別番号(UE-IDなど)をもとに、TAの更新を行う。コアネットワークは、TAの更新後、移動端末にTAU受領信号を送信する。移動端末は、該セルのTACで、移動端末が保有するTAC(あるいはTACリスト)を書き換える(更新する)。その後、移動端末は、該セルで待ち受け動作に入る。
Next, in step ST1206, the mobile terminal compares the TAC of SIB1 received in step ST1205 with the TAC already held by the mobile terminal. If the result of the comparison is the same, a standby operation is started in the cell. If they are different from each other, the mobile terminal requests a change of TA to perform TAU (Tracking Area Update) to the core network (Core-Network, EPC) (including MME) through the cell. The core network updates the TA based on the identification number (UE-ID or the like) of the mobile terminal sent from the mobile terminal together with the TAU request signal. After updating the TA, the core network transmits a TAU receipt signal to the mobile terminal. The mobile terminal rewrites (updates) the TAC (or TAC list) held by the mobile terminal with the TAC of the cell. Thereafter, the mobile terminal enters a standby operation in the cell.
LTEやUMTS(Universal Mobile Telecommunication System)においては、CSG(Closed Subscriber Group)セルの導入が検討されている。前述したように、CSGセルに登録したひとつまたは複数の移動端末のみにアクセスが許される。CSGセルと登録されたひとつまたは複数の移動端末とがひとつのCSGを構成する。このように構成されたCSGには、CSG-IDと呼ばれる固有の識別番号が付される。なお、ひとつのCSGには、複数のCSGセルがあってもよい。移動端末は、どれかひとつのCSGセルに登録すれば、そのCSGセルが属するCSGの他のCSGセルにはアクセス可能となる。
In LTE and UMTS (Universal Mobile Telecommunication System), introduction of CSG (Closed Subscriber Group) cells is being studied. As described above, access is permitted only to one or a plurality of mobile terminals registered in the CSG cell. A CSG cell and one or more registered mobile terminals constitute one CSG. A CSG configured in this way is given a unique identification number called CSG-ID. A single CSG may have a plurality of CSG cells. If a mobile terminal registers in any one CSG cell, it can access another CSG cell to which the CSG cell belongs.
また、LTEでのHome-eNBやUMTSでのHome-NBが、CSGセルとして使われることがある。CSGセルに登録した移動端末は、ホワイトリストを有する。具体的には、ホワイトリストはSIM(Subscriber Identity Module)/USIMに記憶される。ホワイトリストには、移動端末が登録したCSGセルのCSG情報が格納される。CSG情報として具体的には、CSG-ID、TAI(Tracking Area Identity)、TACなどが考えられる。CSG-IDとTACとが対応付けられていれば、どちらか一方でよい。また、CSG-IDおよびTACと、GCI(Global Cell Identity)とが対応付けられていればGCIでもよい。
In addition, Home-eNB in LTE and Home-NB in UMTS may be used as CSG cells. The mobile terminal registered in the CSG cell has a white list. Specifically, the white list is stored in SIM (Subscriber Identity Module) / USIM. The white list stores CSG information of CSG cells registered by the mobile terminal. Specifically, CSG-ID, TAI (Tracking Area Identity), TAC, etc. can be considered as the CSG information. Either of the CSG-ID and the TAC may be used as long as they are associated with each other. Further, GCI may be used as long as CSG-ID and TAC are associated with GCI (Global Cell Identity).
以上から、ホワイトリストを有しない(本発明においては、ホワイトリストが空(empty)の場合も含める)移動端末は、CSGセルにアクセスすることは不可能であり、non-CSGセルのみにしかアクセスできない。一方、ホワイトリストを有する移動端末は、登録したCSG-IDのCSGセルにも、non-CSGセルにもアクセスすることが可能となる。
From the above, a mobile terminal that does not have a white list (including a case where the white list is empty in the present invention) cannot access a CSG cell, and only accesses a non-CSG cell. Can not. On the other hand, a mobile terminal having a white list can access both a CSG cell of a registered CSG-ID and a non-CSG cell.
3GPPでは、全PCI(Physical Cell Identity)を、CSGセル用とnon-CSGセル用とに分割(PCIスプリットと称する)することが議論されている(非特許文献5参照)。またPCIスプリット情報は、システム情報にて基地局から傘下の移動端末に対して報知されることが議論されている。非特許文献5は、PCIスプリットを用いた移動端末の基本動作を開示する。PCIスプリット情報を有していない移動端末は、全PCIを用いて(例えば504コード全てを用いて)セルサーチを行う必要がある。これに対して、PCIスプリット情報を有する移動端末は、当該PCIスプリット情報を用いてセルサーチを行うことが可能である。
3GPP discusses dividing all PCI (Physical Cell Identity) into a CSG cell and a non-CSG cell (referred to as PCI split) (see Non-Patent Document 5). Further, it is discussed that the PCI split information is reported from the base station to the mobile terminals being served by the system information. Non-Patent Document 5 discloses a basic operation of a mobile terminal using PCI split. A mobile terminal that does not have PCI split information needs to perform a cell search using all PCIs (for example, using all 504 codes). On the other hand, a mobile terminal having PCI split information can perform a cell search using the PCI split information.
また3GPPでは、ハイブリッドセルのためのPCIは、CSGセル用のPCI範囲の中には含まれないことが決定されている(非特許文献1 10.7章参照)。
In 3GPP, it has been determined that PCI for hybrid cells is not included in the PCI range for CSG cells (see Non-Patent Document 1, Chapter 10.7).
HeNBおよびHNBに対しては、様々なサービスへの対応が求められている。例えば、オペレータは、ある決められたHeNBおよびHNBに移動端末を登録させ、登録した移動端末のみにHeNBおよびHNBのセルへのアクセスを許可することで、該移動端末が使用できる無線リソースを増大させて、高速に通信を行えるようにする。その分、オペレータは、課金料を通常よりも高く設定する、といったサービスである。
The HeNB and HNB are required to support various services. For example, an operator increases a radio resource that can be used by a mobile terminal by allowing the mobile terminal to be registered in a certain HeNB and HNB and allowing only the registered mobile terminal to access the HeNB and HNB cells. To enable high-speed communication. Accordingly, the service is such that the operator sets the charging fee higher than usual.
このようなサービスを実現するため、登録した(加入した、メンバーとなった)移動端末のみがアクセスできるCSG(Closed Subscriber Group cell)セルが導入されている。CSG(Closed Subscriber Group cell)セルは、商店街やマンション、学校、会社などへ数多く設置されることが要求される。例えば、商店街では店舗毎、マンションでは部屋毎、学校では教室毎、会社ではセクション毎にCSGセルを設置し、各CSGセルに登録したユーザのみが該CSGセルを使用可能とするような使用方法が要求されている。HeNB/HNBは、マクロセルのカバレッジ外での通信を補完するためだけでなく、上述したような様々なサービスへの対応が求められている。このため、HeNB/HNBがマクロセルのカバレッジ内に設置される場合も生じる。
In order to realize such a service, a CSG (Closed Subscriber Group Cell) cell that can be accessed only by registered (subscribed, member) mobile terminals has been introduced. Many CSG (Closed Subscriber Group Cell) cells are required to be installed in shopping streets, condominiums, schools, companies, and the like. For example, a CSG cell is installed for each store in a shopping street, each room in a condominium, each classroom in a school, and each section in a company, and only a user registered in each CSG cell can use the CSG cell. Is required. HeNB / HNB is required not only to complement communication outside the coverage of the macro cell, but also to support various services as described above. For this reason, a case where the HeNB / HNB is installed in the coverage of the macro cell may occur.
LTE-Aで検討される技術の一つとして、ヘテロジーニアスネットワークス(Heterogeneous networks:HetNets)が加えられた。3GPPでは、ピコeNB(ピコセル(pico cell))、ホットゾーンセル用のノード、HeNB/HNB/CSGセル、リレーノード、リモートラジオヘッド(RRH)のような低出力電力のローカルエリアレンジ(Local-area range)のネットワークノード(ローカルエリアレンジノード(local area range node)、ローカルエリアノード(local area node)、ローカルノード(local node))を扱う。したがって、通常のeNB(マクロセル)に、このようなローカルエリアレンジノードを一つ以上組み入れたネットワークの運用が要求される。通常のeNB(マクロセル)に、このようなローカルエリアレンジノードを一つ以上組み入れたネットワークがヘテロジーニアスネットワークスと呼ばれ、干渉低減方法、キャパシティ改善方法などが検討される。
Heterogeneous networks (HetNets) was added as one of the technologies to be studied in LTE-A. In 3GPP, a low output power local area range such as a pico eNB (pico cell), a node for a hot zone cell, a HeNB / HNB / CSG cell, a relay node, a remote radio head (RRH) range) network nodes (local area range node (local area node), local area node (local area node), local node (local node)). Therefore, it is required to operate a network in which one or more such local area range nodes are incorporated in a normal eNB (macro cell). A network in which one or more such local area range nodes are incorporated in a normal eNB (macro cell) is called heterogeneous networks, and an interference reduction method, a capacity improvement method, and the like are studied.
非特許文献8に、ヘテロジーニアスネットワークスの技術が記載されている。従来のセルセレクションのアルゴリズムでは、周辺セルを測定した後、最も受信電力の強いセル(ストロンゲストセル、ベストセル)へセルセレクションを行う。しかし、HeNBの場合、CSGによる制限のために、ベストセルをセル選択できないという問題が生じる。またマクロセルとピコセルとが存在するネットワークでは、必ずしもベストセルが通信に最適なセルになるとは限らないという問題が存在する。
Non-patent document 8 describes the technology of heterogeneous networks. In the conventional cell selection algorithm, after the neighboring cells are measured, the cell selection is performed to the cell having the strongest reception power (strongest cell, best cell). However, in the case of HeNB, there is a problem that the best cell cannot be selected due to the limitation by CSG. Further, in a network in which macro cells and pico cells exist, there is a problem that the best cell is not necessarily the optimal cell for communication.
さらに、UEは、バックホールリンクの通信品質が悪いセルに接続しない方がよい場合がある。このことは、中継装置であるリレーノードのバックホールリンクだけでなく、ピコセルやフェムトセル(HeNB)のような有線のバックホールリンクを有するノードにも該当する。特に、フェムトセル(HeNB)は、ホームユースが想定されており、一般的なブロードバンド回線を通してコアネットワーク側に接続されるため、バックホールリンクにおいて使用帯域の制限や信頼性の劣化が生じてしまう。リレーノードのバックホールリンクは、リレーノードと基地局装置との間の通信回線である。ピコセルおよびフェムトセル(HeNB)などの基地局装置のバックホールリンクは、基地局装置とコアネットワークとの間の通信回線である。
Furthermore, there are cases where the UE should not connect to a cell with poor backhaul link communication quality. This applies not only to a backhaul link of a relay node that is a relay device, but also to a node having a wired backhaul link such as a pico cell or a femto cell (HeNB). In particular, the femtocell (HeNB) is assumed to be home use, and is connected to the core network side through a general broadband line. Therefore, the use band is limited and the reliability is deteriorated in the backhaul link. The backhaul link of the relay node is a communication line between the relay node and the base station device. A backhaul link of a base station apparatus such as a pico cell and a femto cell (HeNB) is a communication line between the base station apparatus and the core network.
非特許文献8では、これらの問題を解消するために、バックホールリンクの品質を考慮したセルセレクションや、弱受信電力のセルの測定とトリガメカニズムとが必要であることが提案されている。しかし、これらの具体的な方法については、何ら記載されていない。
Non-Patent Document 8 proposes that cell selection considering the quality of the backhaul link, measurement of a cell with weak received power, and a trigger mechanism are necessary to solve these problems. However, these specific methods are not described at all.
またこれらの問題は、セルセレクションに限らず、セルリセレクションやハンドオーバ(HO)などのサービングセルの選択あるいは変更の際に生じてしまう。
These problems occur not only in cell selection but also in selection or change of a serving cell such as cell reselection or handover (HO).
非特許文献9に、リレーノードのバックホールリンクを考慮したセルセレクション方法が開示されている。リレーノードがバックホールリンクの品質を報知して、UEはそれを考慮してセルセレクションを行うと記載されている。しかし、どのようなメカニズムで該バックホールリンクの品質を考慮に入れるのか、具体的な方法については、何ら開示されていない。
Non-Patent Document 9 discloses a cell selection method considering a backhaul link of a relay node. It is described that the relay node broadcasts the quality of the backhaul link and the UE performs cell selection in consideration thereof. However, there is no disclosure of a specific method by which the quality of the backhaul link is taken into consideration.
また非特許文献9に、ドナーeNBが全てのリレーノードのバックホールリンクの品質を報知すること、およびQoffsetに、リレーノードとドナーeNBとの間のリンク品質を入れ込むことが記載されている。しかし、非特許文献3に示されるように、Qoffsetは、セルリセレクションの際に隣接セルの受信電力測定値に加えるオフセット値である。したがって、ここで開示された方法では、セルセレクションの際に、バックホールリンクの通信品質を入れ込めていない。また、Qoffsetは、隣接セルの受信電力測定値に対して与えられるオフセット値であるので、サービングセルの受信電力に対して、サービングセルのバックホールリンクの通信品質を入れ込むことができていない。
Further, Non-Patent Document 9 describes that the donor eNB reports the quality of the backhaul link of all the relay nodes, and that the link quality between the relay node and the donor eNB is inserted into Qoffset. However, as shown in Non-Patent Document 3, Qoffset is an offset value added to the received power measurement value of the adjacent cell at the time of cell reselection. Therefore, in the method disclosed here, the communication quality of the backhaul link is not included in the cell selection. Further, since Qoffset is an offset value given to the received power measurement value of the adjacent cell, the communication quality of the serving cell backhaul link cannot be incorporated into the received power of the serving cell.
図13は、非特許文献3の技術によるUEのセルリセレクションの処理手順を示すフローチャートである。UEは、セルリセレクションのために、サービングセルの受信電力を測定する。該サービングセルの受信電力測定値をSxとする。
FIG. 13 is a flowchart showing a celery selection processing procedure of the UE according to the technique of Non-Patent Document 3. The UE measures the received power of the serving cell for cell reselection. The received power measurement value of the serving cell is Sx.
ステップST1301で、UEは、Sxとセルリセレクションのための測定開始用閾値(S_intrasearch)とを比較する。S_intrasearchは、予めサービングセルから報知される。UEは、SxとS_intrasearchとを比較し、SxがS_intrasearch以下となった場合に、サービングセルの受信電力が低いと判断し、セルリセレクションのための測定を開始する(ステップST1302)。UEは、SxがS_intrasearchよりも大きい場合は、サービングセルの受信電力は十分であると判断し、セルリセレクションのための測定を開始せず、Sxを測定し、ステップST1301に戻って、再度SxとS_intrasearchとを比較する。
In step ST1301, the UE compares Sx with a measurement start threshold (S_intrasearch) for celery selection. S_intrasearch is notified in advance from the serving cell. The UE compares Sx and S_intrasearch, and when Sx is equal to or less than S_intrasearch, the UE determines that the reception power of the serving cell is low and starts measurement for celery selection (step ST1302). If Sx is larger than S_intrasearch, the UE determines that the received power of the serving cell is sufficient, does not start measurement for cell reselection, measures Sx, returns to step ST1301, and again returns to Sx and S_intrasearch. And compare.
ステップST1302で、UEは、隣接セルの受信電力の測定を行う。この際、サービングセルの受信電力の測定も行ってもよい。ステップST1303で、UEは、セル毎の測定値から、受信電力にある補正値を入れ込んだ値(Srxlev)を算出する。この補正値および算出方法は、非特許文献3に記載されている。
In step ST1302, the UE measures received power of neighboring cells. At this time, the reception power of the serving cell may be measured. In Step ST1303, the UE calculates a value (Srxlev) in which a correction value in the received power is inserted from the measured value for each cell. This correction value and calculation method are described in Non-Patent Document 3.
Srxlevを算出したUEは、ステップST1304で、該Srxlevが0より大きいか否か判断する。該Srxlevが0より大きい場合、該セルをベストセル選択の候補として、後述するステップST1306の処理を行う。該Srxlevが0以下の場合は、該セルはベストセル選択の候補としない。
The UE that has calculated Srxlev determines whether or not the Srxlev is greater than 0 in step ST1304. If the Srxlev is greater than 0, the process of step ST1306 described later is performed with the cell as a candidate for best cell selection. When the Srxlev is 0 or less, the cell is not regarded as a best cell selection candidate.
UEは、ステップST1302のセルリセレクションのための測定で得られた一つまたは複数のセルに対して、前述のステップST1303およびステップST1304の処理を行う。その結果、Srxlevが0より大きくなるセルが全く得られなかった場合は、ステップST1305に移行し、圏外となる。Srxlevが0より大きくなるセルが得られた場合は、ステップST1306に移行する。
UE performs the process of above-mentioned step ST1303 and step ST1304 with respect to the one or some cell obtained by the measurement for the cell reselection of step ST1302. As a result, when no cell having Srxlev greater than 0 is obtained, the process moves to step ST1305 and becomes out of range. If a cell having Srxlev greater than 0 is obtained, the process proceeds to step ST1306.
Srxlevが0より大きくなったセルについて、ステップST1306で、UEは以下の式を用いてRs,Rnを算出する(非特許文献3参照)。
For a cell in which Srxlev is greater than 0, in step ST1306, the UE calculates Rs and Rn using the following equations (see Non-Patent Document 3).
Rs=Qmeas,s+Qhyst
Rn=Qmeas,n-Qoffset
Qmeas,sは、セルリセレクション用のサービングセルの受信電力測定値で、Qmeas,nは、セルリセレクション用の隣接セル(サービングセルでないセル)の受信電力測定値である。Qhystは、ヒステリシスを与えるオフセット値である。Qoffsetは、同一周波数キャリア内でのセルリセレクションにおいては、セル間補正用オフセット値、異周波数キャリアあるいは他システムへのリセレクションにおいては、セル間補正用と周波数間補正用のオフセット値である。 Rs = Qmeas, s + Qhyst
Rn = Qmeas, n-Qoffset
Qmeas, s is a received power measurement value of a serving cell for celery selection, and Qmeas, n is a received power measurement value of an adjacent cell for celery selection (a cell that is not a serving cell). Qhyst is an offset value giving a hysteresis. Qoffset is an offset value for correction between cells in cell reselection within the same frequency carrier, and is an offset value for correction between cells and correction between frequencies in reselection to a different frequency carrier or another system.
Rn=Qmeas,n-Qoffset
Qmeas,sは、セルリセレクション用のサービングセルの受信電力測定値で、Qmeas,nは、セルリセレクション用の隣接セル(サービングセルでないセル)の受信電力測定値である。Qhystは、ヒステリシスを与えるオフセット値である。Qoffsetは、同一周波数キャリア内でのセルリセレクションにおいては、セル間補正用オフセット値、異周波数キャリアあるいは他システムへのリセレクションにおいては、セル間補正用と周波数間補正用のオフセット値である。 Rs = Qmeas, s + Qhyst
Rn = Qmeas, n-Qoffset
Qmeas, s is a received power measurement value of a serving cell for celery selection, and Qmeas, n is a received power measurement value of an adjacent cell for celery selection (a cell that is not a serving cell). Qhyst is an offset value giving a hysteresis. Qoffset is an offset value for correction between cells in cell reselection within the same frequency carrier, and is an offset value for correction between cells and correction between frequencies in reselection to a different frequency carrier or another system.
UEは、算出したRs、Rnを用いて、最も高い受信電力となるセル(ベストセル)を選択する。そして、UEがステップST1306で選択したベストセルにセルリセレクションを行う。
The UE uses the calculated Rs and Rn to select the cell (best cell) with the highest received power. Then, the UE performs celery selection on the best cell selected in step ST1306.
セルリセレクションは、以上のように行われるので、非特許文献9に開示された方法では、サービングセルの受信電力に対して、サービングセルのバックホールリンクの通信品質を入れ込めないという問題が生じる。
Since the cell reselection is performed as described above, the method disclosed in Non-Patent Document 9 has a problem in that the communication quality of the serving cell backhaul link cannot be included in the received power of the serving cell.
さらに、非特許文献3に開示されたセルリセレクションでは、隣接セルの受信電力測定の前に、サービングセルの受信電力を測定し、その値に応じてセルリセレクションのための測定を行うか否かを判断するが、非特許文献9にはこのことについては全く記載されていない。非特許文献9に開示された方法では、ステップST1301に示すセルリセレクションのための隣接セルの測定を行うか否かの判断に、サービングセルのバックホールリンクの通信品質を全く考慮できていないことになる。
Furthermore, in the cell reselection disclosed in Non-Patent Document 3, the reception power of the serving cell is measured before the reception power measurement of the neighboring cell, and it is determined whether or not the measurement for the cell reselection is performed according to the measured value. However, Non-Patent Document 9 does not describe this at all. In the method disclosed in Non-Patent Document 9, the communication quality of the backhaul link of the serving cell cannot be considered at all in determining whether or not to perform the measurement of the neighboring cell for celery selection shown in step ST1301. .
例えば、サービングセルがリレーの場合、アクセスリンクの受信品質は良いが、バックホールリンクの通信品質が悪い場合がある。ステップST1301のセルリセレクションのための隣接セルの測定を行うか否かの判断に、サービングセルのバックホールリンクの通信品質を考慮に入れていない場合は、バックホールリンクの通信品質が悪いにもかかわらず、セルリセレクションを行わなくなる。これにより、通信速度の低下や、最悪の場合、通信断が生じることになる。
For example, when the serving cell is a relay, the reception quality of the access link is good, but the communication quality of the backhaul link may be bad. If the communication quality of the backhaul link of the serving cell is not taken into consideration in the determination of whether to perform the measurement of the neighboring cell for cell reselection in step ST1301, the communication quality of the backhaul link is poor. , Celery selection will not be performed. As a result, the communication speed is reduced, and in the worst case, communication is interrupted.
このことは、リレーだけでなく、他のローカルノードにおいても生じる。例えば、HeNBにおいて、バックホールリンクはHeNBとコアネットワークとを接続するブロードバンド回線である。このブロードバンド回線が混雑して通信品質が劣化した場合などには、同じ問題が生じる。
This occurs not only at the relay but also at other local nodes. For example, in the HeNB, the backhaul link is a broadband line that connects the HeNB and the core network. The same problem occurs when communication quality deteriorates due to congestion of this broadband line.
これらの問題を解消するために、本実施の形態では、セルリセレクションにサービングセルおよび隣接セルの少なくともいずれか一方のバックホールリンクの通信品質を考慮に入れる方法を開示する。
In order to solve these problems, this embodiment discloses a method in which the communication quality of the backhaul link of at least one of the serving cell and the neighboring cell is taken into consideration for cell reselection.
本実施の形態では、セルリセレクションに、サービングセルのバックホールリンクの通信品質を考慮に入れる方法として、セルリセレクションのための測定開始用クライテリア、すなわち基準値に、バックホールリンクの通信品質を考慮に入れる。
In the present embodiment, as a method of taking into account the communication quality of the serving cell backhaul link in the cell reselection, the communication quality of the backhaul link is taken into account in the criteria for starting measurement for the cell reselection, that is, the reference value. .
セルリセレクションのための測定開始用クライテリアにバックホールリンクの通信品質を考慮に入れる一例として、セルリセレクションのための測定開始用閾値にサービングセルのバックホールリンクの通信品質を入れ込む。
As an example of taking the backhaul link communication quality into consideration in the measurement start criteria for celery selection, the communication quality of the serving cell backhaul link is inserted into the measurement start threshold for celery selection.
図14は、セルリセレクションのための測定開始用閾値に、サービングセルのバックホールリンクの通信品質を入れ込んだセルリセレクションの処理手順を示すフローチャートである。図14に示すフローチャートの処理は、図13に示すフローチャートの処理と類似しているので、異なる処理についてのみ説明し、対応する部分については同一のステップ番号を付して、処理の説明を省略する。
FIG. 14 is a flowchart showing the processing procedure of celery selection in which the communication quality of the backhaul link of the serving cell is inserted in the measurement start threshold for celery selection. The process of the flowchart shown in FIG. 14 is similar to the process of the flowchart shown in FIG. 13, so only the different processes will be described, the corresponding parts will be denoted by the same step numbers, and the description of the processes will be omitted. .
UEは、セルリセレクションのために、サービングセルの受信電力を測定する。ここで、サービングセルのバックホールリンクの通信品質を考慮したセルリセレクションのための測定開始用閾値(S_intrasearch_total)を新たに設けておく。
UE measures the received power of the serving cell for celery selection. Here, a measurement start threshold (S_intrasearch_total) for celery selection considering the communication quality of the backhaul link of the serving cell is newly provided.
ステップST1401で、UEは、該サービングセルの受信電力測定値(Sx)とサービングセルのバックホールリンクの通信品質を考慮したセルリセレクションのための測定開始用閾値(S_intrasearch_total)とを比較する。サービングセルの受信品質およびバックホールリンクの通信品質は、選択情報に相当する。
In step ST1401, the UE compares the received power measurement value (Sx) of the serving cell with a measurement start threshold value (S_intrasearch_total) for cell reselection considering the communication quality of the backhaul link of the serving cell. The reception quality of the serving cell and the communication quality of the backhaul link correspond to selection information.
UEは、SxとS_intrasearch_totalとを比較し、SxがS_intrasearch_total以下となった場合に、バックホールリンクの通信品質を含めたサービングセルの受信品質が悪いと判断し、セルリセレクションのための測定を開始する(ステップST1302)。UEは、SxがS_intrasearch_totalよりも大きい場合は、バックホールリンクの通信品質を含めたサービングセルの受信品質が十分であると判断し、セルリセレクションのための測定を開始せず、Sxを測定し、ステップST1401に戻って、再度SxとS_intrasearch_totalとを比較する。
The UE compares Sx and S_intrasearch_total, and when Sx is equal to or less than S_intrasearch_total, the UE determines that the reception quality of the serving cell including the communication quality of the backhaul link is poor and starts measurement for celery selection ( Step ST1302). If Sx is larger than S_intrasearch_total, the UE determines that the reception quality of the serving cell including the communication quality of the backhaul link is sufficient, does not start measurement for cell reselection, measures Sx, Returning to ST1401, Sx is again compared with S_intrasearch_total.
このように、セルリセレクションのための測定開始用閾値に、サービングセルのバックホールリンクの通信品質を入れ込むことで、セルリセレクションのための測定開始用クライテリアにバックホールリンクの通信品質を考慮に入れる。
In this way, the communication quality of the backhaul link of the serving cell is included in the measurement start threshold for celery selection, so that the communication quality of the backhaul link is taken into consideration for the measurement start criteria for celery selection.
サービングセルは、バックホールリンクの通信品質を測定し、該測定結果を考慮して新たなセルリセレクションのための測定開始用閾値(S_intrasearch_total)を決定する。サービングセルは、予め該S_intrasearch_totalを報知しておく。UEは、予めサービングセルから報知された該S_intrasearch_totalを受信しておき、ステップST1401で、セルリセレクションのための測定開始用閾値として用いる。
The serving cell measures the communication quality of the backhaul link and determines a measurement start threshold (S_intrasearch_total) for new cell reselection in consideration of the measurement result. The serving cell notifies the S_intrasearch_total in advance. The UE receives the S_intrasearch_total broadcast from the serving cell in advance and uses it as a measurement start threshold for cell reselection in step ST1401.
図14では、図13のS_intrasearchとは別に、新たにS_intrasearch_totalを設けることとした。これにより、バックホールリンクを考慮する場合と考慮しない場合とで、異なる閾値を用いることが可能となる。
In FIG. 14, S_intrasearch_total is newly provided separately from S_intrasearch of FIG. This makes it possible to use different threshold values depending on whether or not the backhaul link is considered.
一方、新たにS_intrasearch_totalを設けずに、サービングセルが導出したバックホールリンクの通信品質を考慮したセルリセレクションのための測定開始用閾値をS_intrasearchに設定するようにしてもよい。常にバックホールリンクを考慮するセルのような場合は、常にS_intrasearchにバックホールリンクの通信品質を入れ込むことができ、報知するパラメータの数を減らすことが可能となる。
On the other hand, instead of newly providing S_intrasearch_total, a measurement start threshold for cell reselection considering the communication quality of the backhaul link derived by the serving cell may be set in S_intrasearch. In the case of a cell that always considers the backhaul link, the communication quality of the backhaul link can always be inserted into S_intrasearch, and the number of parameters to be notified can be reduced.
バックホールリンクの通信品質としては、受信電力(RSRP、RSRQ:Reference Signal Received Quality)、通信速度、通信容量、回線品質などとすればよい。リレーでは、バックホールリンクの通信品質として受信電力(RSRP、RSRQ)などとして、従来の閾値(S_intrasearch)と単位を揃え、ある関数により直接S_intrasearch_totalを計算できるようにするとよい。これによって、サービングセルにおけるS_intrasearch_totalの導出を容易にすることが可能となる。また、ある関数により計算して導出するのではなく、バックホールリンクの通信品質とそれに対応する閾値S_intrasearch_totalとの対応表を用いて導出するようにしてもよい。
The communication quality of the backhaul link may be received power (RSRP, RSRQ: Reference Signal Received Quality), communication speed, communication capacity, line quality, and the like. In the relay, as the communication quality of the backhaul link, the received power (RSRP, RSRQ) and the like are aligned with the conventional threshold (S_intrasearch), and S_intrasearch_total can be directly calculated by a certain function. This makes it easy to derive S_intrasearch_total in the serving cell. Instead of calculating and deriving with a certain function, it may be derived using a correspondence table between the communication quality of the backhaul link and the corresponding threshold value S_intrasearch_total.
バックホールリンクが有線の場合は、バックホールリンクの通信品質を、通信速度、通信容量、回線品質などとするとよい。この場合、従来の閾値(S_intrasearch)と単位が異なることになるが、その場合、バックホールリンクの通信品質を変数とするある関数を設けて、該関数によってS_intrasearch_totalを導出するようにしてもよい。あるいは、バックホールリンクの通信品質とそれに対応する閾値S_intrasearch_totalとの対応表を用いて導出するようにしてもよい。これらの関数あるいは対応表は、予め静的に決めておくとよい。
If the backhaul link is wired, the communication quality of the backhaul link should be the communication speed, communication capacity, line quality, etc. In this case, the unit is different from the conventional threshold (S_intrasearch). In that case, a function having the communication quality of the backhaul link as a variable may be provided, and S_intrasearch_total may be derived by the function. Or you may make it derive | lead-out using the correspondence table of the communication quality of a backhaul link, and the threshold value S_intrasearch_total corresponding to it. These functions or correspondence tables may be determined statically in advance.
サービングセルは、新たなセルリセレクションのための測定開始用閾値(S_intrasearch_total)をSIB3に含めて報知してもよいし、あるいはSIB1に含めて報知してもよい。SIB3の場合、セルリセレクション用パラメータが含まれるので、UEは、他のセルリセレクション用パラメータと一緒に受信することが可能となる。このため、UEの受信動作を簡略化でき、また、制御誤動作の削減が可能となる。SIB1の場合、予め報知されるタイミングが決められているので、UEは、メジャメント時に早期に受信可能となる。このため、UEのメジャメント動作において制御遅延を小さくすることが可能となる。
The serving cell may be notified by including a measurement start threshold value (S_intrasearch_total) for new cell reselection in SIB3, or may be included in SIB1. In the case of SIB3, since the cell reselection parameter is included, the UE can receive it together with other cell reselection parameters. For this reason, the reception operation of the UE can be simplified, and the control malfunction can be reduced. In the case of SIB1, since the timing to be notified in advance is determined, the UE can receive at an early stage during measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE.
上記に開示した方法では、新たなセルリセレクションのための測定開始用閾値(S_intrasearch_total)をサービングセルが導出することとした。これに限らず、UEが新たなセルリセレクションのための測定開始用閾値(S_intrasearch_total)を導出するようにしてもよい。この場合、サービングセルは、該サービングセルのバックホールリンクの通信品質をUEに報知するようにすればよい。UEは、報知された該サービングセルのバックホールリンクの通信品質を用いて、該閾値S_intrasearch_totalを導出する。
In the method disclosed above, the serving cell derives a measurement start threshold (S_intrasearch_total) for a new cell reselection. However, the present invention is not limited to this, and the UE may derive a measurement start threshold value (S_intrasearch_total) for a new celery selection. In this case, the serving cell may notify the UE of the communication quality of the backhaul link of the serving cell. The UE derives the threshold S_intrasearch_total using the notified communication quality of the backhaul link of the serving cell.
バックホールリンクの通信品質は変動する。したがって、該バックホールリンクの通信品質を変更して報知する場合は、報知情報の修正により行えばよい。サービングセルは、該バックホールリンクの通信品質を、ある期間平均する、あるいはフィルタリングするなどして、該平均値あるいはフィルタリング後の値を報知するようにしてもよい。該ある期間を報知情報が修正されるタイミングに合わせるようにしてもよい。
The communication quality of the backhaul link varies. Therefore, when the communication quality of the backhaul link is changed and notified, the notification information may be corrected. The serving cell may report the average value or the value after filtering by averaging or filtering the communication quality of the backhaul link for a certain period. You may make it match this certain period with the timing when alerting | reporting information is corrected.
サービングセルは、該サービングセルのバックホールリンクの通信品質をSIB3に含めて報知してもよいし、あるいはSIB1に含めて報知してもよい。それぞれの場合において、S_intrasearch_totalを報知する場合と同等の効果が得られる。
The serving cell may notify the communication quality of the backhaul link of the serving cell by including it in SIB3 or may be notified by including it in SIB1. In each case, the same effect as when S_intrasearch_total is notified can be obtained.
UEが、サービングセルから報知された該サービングセルのバックホールリンクの通信品質を用いて、該閾値S_intrasearch_totalを導出する方法としては、前述のサービングセルが導出する方法と同様の方法を適用できる。
As a method for the UE to derive the threshold S_intrasearch_total using the communication quality of the backhaul link of the serving cell broadcast from the serving cell, a method similar to the method derived by the serving cell can be applied.
ここでは、同じ周波数キャリア内でのセルリセレクションについて記載したが、他周波数キャリア内のセルへのセルリセレクションや、W-CDMAなど他システムへのセルリセレクションにおいても同様の方法とすることができる。セルリセレクションのための測定開始用閾値(S_intrasearch)の代わりに、他周波数キャリア用あるいは他システム用のセルリセレクションのための測定開始用閾値(S_nonintrasearch)にバックホールリンクの通信品質を考慮すればよい。バックホールリンクの通信品質を考慮した新たな他周波数キャリア用あるいは他システム用のセルリセレクションのための測定開始用閾値(S_nonintrasearch_total)を、別途設けて同様の方法としてもよい。
Here, celery selection within the same frequency carrier has been described, but the same method can be applied to celery selection to cells in other frequency carriers and celery selection to other systems such as W-CDMA. Instead of the measurement start threshold (S_intrasearch) for celery selection, the communication quality of the backhaul link may be considered in the measurement start threshold (S_nonintrasearch) for celery selection for other frequency carriers or other systems. A similar method may be used by separately providing a measurement start threshold (S_nonintrasearch_total) for cell reselection for a new other frequency carrier or another system considering the communication quality of the backhaul link.
本実施の形態に開示した方法とすることで、各セルの受信品質に加えて、バックホールリンクの通信品質を考慮に入れて、セルリセレクションを行うことができる。これによって、たとえサービングセルの受信品質が良好であったとしても、サービングセルのバックホールリンクの通信品質によっては、セルリセレクションを開始することになるため、サービングセルのバックホールリンクの通信品質の劣化による通信速度の低下や通信断の発生を抑制することが可能となる。したがって、ヘテロジーニアスネットワークスにおける干渉問題およびキャパシティ問題を改善することが可能となるので、膨大な数のローカルエリアレンジノードの運用およびそれらの柔軟な配置が可能となる。
By adopting the method disclosed in the present embodiment, cell reselection can be performed in consideration of the communication quality of the backhaul link in addition to the reception quality of each cell. As a result, even if the reception quality of the serving cell is good, cell reselection is started depending on the communication quality of the backhaul link of the serving cell, so the communication speed due to the deterioration of the communication quality of the backhaul link of the serving cell. And the occurrence of communication interruption can be suppressed. Therefore, since it is possible to improve the interference problem and capacity problem in heterogeneous networks, it is possible to operate a large number of local area range nodes and to arrange them flexibly.
実施の形態1 変形例1.
セルリセレクションのための測定開始用クライテリアに、バックホールリンクの通信品質を考慮に入れる別の例として、サービングセルの測定値にサービングセルのバックホールリンクの通信品質を入れ込む場合について説明する。Embodiment 1 Modification 1
As another example of taking the communication quality of the backhaul link into consideration for the measurement start criteria for celery selection, a case will be described in which the communication quality of the backhaul link of the serving cell is included in the measurement value of the serving cell.
セルリセレクションのための測定開始用クライテリアに、バックホールリンクの通信品質を考慮に入れる別の例として、サービングセルの測定値にサービングセルのバックホールリンクの通信品質を入れ込む場合について説明する。
As another example of taking the communication quality of the backhaul link into consideration for the measurement start criteria for celery selection, a case will be described in which the communication quality of the backhaul link of the serving cell is included in the measurement value of the serving cell.
図15は、サービングセルの測定値にサービングセルのバックホールリンクの通信品質を入れ込んだセルリセレクションの処理手順を示すフローチャートである。図15に示すフローチャートの処理は、図13に示すフローチャートの処理と類似しているので、異なる処理についてのみ説明し、対応する部分については同一のステップ番号を付して、処理の説明を省略する。
FIG. 15 is a flowchart showing a processing procedure of cell reselection in which the communication quality of the serving cell backhaul link is inserted into the measured value of the serving cell. The processing of the flowchart shown in FIG. 15 is similar to the processing of the flowchart shown in FIG. 13, so only the different processing will be described, the corresponding steps will be given the same step numbers, and the description of the processing will be omitted. .
UEは、セルリセレクションのために、サービングセルの受信電力を測定する。UEは、該サービングセルの受信電力測定値(Sx)にサービングセルのバックホールリンクの通信品質を入れ込んだ値(Sx_total)を導出する。
UE measures the received power of the serving cell for celery selection. The UE derives a value (Sx_total) obtained by inserting the communication quality of the backhaul link of the serving cell into the received power measurement value (Sx) of the serving cell.
サービングセルは、バックホールリンクの通信品質を測定し、UEに報知しておく。UEは、予めサービングセルから報知された該通信品質を受信しておき、上述したSx_totalの導出の際に用いる。
The serving cell measures the communication quality of the backhaul link and informs the UE. The UE receives the communication quality broadcast from the serving cell in advance and uses it when deriving the above-described Sx_total.
ステップST1501で、UEは、Sx_totalとセルリセレクションのための測定開始用閾値(S_intrasearch)とを比較する。UEは、Sx_totalとS_intrasearchとを比較し、Sx_totalがS_intrasearch以下となった場合に、バックホールリンクの通信品質を含めたサービングセルの受信品質が悪いと判断し、セルリセレクションのための測定を開始する(ステップST1302)。UEは、Sx_totalがS_intrasearchよりも大きい場合は、バックホールリンクの通信品質を含めたサービングセルの受信品質が十分であると判断し、セルリセレクションのための測定を開始せず、ステップST1501に戻って、再度Sxを測定し、Sx_totalを導出してS_intrasearchと比較する。
In step ST1501, the UE compares Sx_total with a measurement start threshold (S_intrasearch) for celery selection. The UE compares Sx_total and S_intrasearch, and when Sx_total is equal to or lower than S_intrasearch, the UE determines that the reception quality of the serving cell including the communication quality of the backhaul link is poor and starts measurement for celery selection ( Step ST1302). When Sx_total is larger than S_intrasearch, the UE determines that the reception quality of the serving cell including the communication quality of the backhaul link is sufficient, does not start measurement for cell reselection, and returns to step ST1501. Sx is measured again, Sx_total is derived and compared with S_intrasearch.
このように、UEが測定するサービングセルの受信電力測定値(Sx)にサービングセルのバックホールリンクの通信品質を入れ込んだ値(Sx_total)を導出して、Sx_totalをセルリセレクションのための測定を開始するか否かの判断に用いることで、サービングセルのバックホールリンクの通信品質を考慮に入れる。
In this way, a value (Sx_total) in which the communication quality of the backhaul link of the serving cell is inserted into the received power measurement value (Sx) of the serving cell measured by the UE is derived, and Sx_total is measured for cell reselection. The communication quality of the serving cell backhaul link is taken into account.
バックホールリンクの通信品質としては、受信電力(RSRP、RSRQ)、通信速度、通信容量、回線品質などとすればよい。リレーでは、バックホールリンクの通信品質として受信電力(RSRP、RSRQ)などとして、アクセスリンクの測定値(Sx)と単位を揃え、ある関数により直接Sx_totalを計算できるようにするとよい。これによって、UEにおけるSx_totalの導出を容易にすることが可能となる。また、ある関数により計算して導出するのではなく、対応表を用いて導出するようにしてもよい。
The communication quality of the backhaul link may be received power (RSRP, RSRQ), communication speed, communication capacity, line quality, and the like. In the relay, as the communication quality of the backhaul link, the received power (RSRP, RSRQ) or the like is aligned with the measured value (Sx) of the access link, and Sx_total can be directly calculated by a certain function. This makes it easy to derive Sx_total at the UE. Further, it may be derived using a correspondence table instead of being calculated using a certain function.
バックホールリンクが有線の場合は、バックホールリンクの通信品質としては、通信速度、通信容量、回線品質などとするとよい。この場合、従来のサービングセルの受信電力測定値(Sx)と単位が異なることになるが、その場合、バックホールリンクの通信品質を変数とするある関数を設けて、該関数によってSx_totalを導出するようにしてもよい。あるいは、バックホールリンクの通信品質とそれに対応する測定値Sx_totalとの対応表を用いて導出するようにしてもよい。これらの関数あるいは対応表は、予め静的に決めておくとよい。
If the backhaul link is wired, the communication quality of the backhaul link may be the communication speed, communication capacity, line quality, etc. In this case, although the unit is different from the received power measurement value (Sx) of the conventional serving cell, in that case, a certain function with the communication quality of the backhaul link as a variable is provided, and Sx_total is derived by the function. It may be. Alternatively, it may be derived using a correspondence table between the communication quality of the backhaul link and the corresponding measurement value Sx_total. These functions or correspondence tables may be determined statically in advance.
サービングセルは、バックホールリンクの通信品質を報知するが、該バックホールリンクの通信品質は変動する。したがって、該バックホールリンクの通信品質を変更して報知する場合は、報知情報の修正により行えばよい。サービングセルは、該バックホールリンクの通信品質を、ある期間平均する、あるいはフィルタリングするなどして、該平均値あるいはフィルタリング後の値を報知するようにしてもよい。該ある期間を報知情報が修正されるタイミングに合わせるようにしてもよい。
The serving cell reports the communication quality of the backhaul link, but the communication quality of the backhaul link varies. Therefore, when the communication quality of the backhaul link is changed and notified, the notification information may be corrected. The serving cell may report the average value or the value after filtering by averaging or filtering the communication quality of the backhaul link for a certain period. You may make it match this certain period with the timing when alerting | reporting information is corrected.
UEがバックホールリンクの通信品質を、ある期間平均する、あるいはフィルタリングしてもよい。サービングセルは、バックホールリンクの通信品質測定値を平均などせずにUEに報知して、UEが報知されたバックホールリンクの通信品質測定値を平均あるいはフィルタリングするようにしてもよい。
The UE may average or filter the communication quality of the backhaul link for a certain period. The serving cell may notify the UE of the communication quality measurement value of the backhaul link without averaging, and may average or filter the communication quality measurement value of the backhaul link notified by the UE.
サービングセルは、バックホールリンクの通信品質をSIB3に含めて報知してもよいし、あるいはSIB1に含めて報知してもよい。SIB3の場合、セルリセレクション用パラメータが含まれるので、UEは、他のセルリセレクション用パラメータと一緒に受信することが可能となる。このため、UEの受信動作を簡略化でき、また、制御誤動作の削減が可能となる。SIB1の場合、予め報知されるタイミングが決められているので、UEはメジャメント時に早期に受信可能となる。このため、UEのメジャメント動作において制御遅延を小さくすることが可能となる。
The serving cell may be notified by including the communication quality of the backhaul link in SIB3 or may be included in SIB1. In the case of SIB3, since the cell reselection parameter is included, the UE can receive it together with other cell reselection parameters. For this reason, the reception operation of the UE can be simplified, and the control malfunction can be reduced. In the case of SIB1, since the timing to be notified in advance is determined, the UE can receive early at the time of measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE.
本変形例の方法とすることで、実施の形態1で記載した効果に加えて、以下の効果を得ることが可能となる。サービングセルの受信電力測定値にサービングセルのバックホールリンクの通信品質を入れ込むことで、UEがネットワークからサービングセルを介して、UEまでのトータルの受信品質を導出することができるようになる。このため、バックホールリンクの通信品質の効果を適切に考慮することが可能となり、たとえバックホールリンクの通信品質が支配的となるような場合にも、精度良くセルリセレクションのための測定を開始させることが可能となる。
In addition to the effects described in the first embodiment, the following effects can be obtained by adopting the method of the present modification. By inserting the communication quality of the backhaul link of the serving cell into the reception power measurement value of the serving cell, the UE can derive the total reception quality from the network to the UE via the serving cell. For this reason, it becomes possible to appropriately consider the effect of the communication quality of the backhaul link, and even when the communication quality of the backhaul link becomes dominant, the measurement for celery selection is started with high accuracy. It becomes possible.
実施の形態1 変形例2.
セルリセレクションのための測定開始用クライテリアに、バックホールリンクの通信品質を考慮に入れる別の例として、セルリセレクションのための測定開始用閾値として、サービングセルのバックホールリンクの通信品質閾値(以降、「バックホール閾値(開始)」と表す)を設ける。Embodiment 1 Modification 2
As another example of taking into account the communication quality of the backhaul link in the measurement start criteria for celery selection, the communication quality threshold of the serving cell backhaul link (hereinafter, “ A backhaul threshold (start) ”).
セルリセレクションのための測定開始用クライテリアに、バックホールリンクの通信品質を考慮に入れる別の例として、セルリセレクションのための測定開始用閾値として、サービングセルのバックホールリンクの通信品質閾値(以降、「バックホール閾値(開始)」と表す)を設ける。
As another example of taking into account the communication quality of the backhaul link in the measurement start criteria for celery selection, the communication quality threshold of the serving cell backhaul link (hereinafter, “ A backhaul threshold (start) ”).
図16は、セルリセレクションのための測定開始用閾値として、バックホール閾値(開始)を設けたセルリセレクションの処理手順を示すフローチャートである。図16に示すフローチャートの処理は、図13に示すフローチャートの処理と類似しているので、異なる処理についてのみ説明し、対応する部分については同一のステップ番号を付して、処理の説明を省略する。
FIG. 16 is a flowchart showing a processing procedure of celery selection in which a backhaul threshold value (start) is provided as a measurement start threshold value for celery selection. The process of the flowchart shown in FIG. 16 is similar to the process of the flowchart shown in FIG. 13, so only the different processes will be described, the corresponding parts will be denoted by the same step numbers, and the description of the processes will be omitted. .
UEは、セルリセレクションのために、サービングセルの受信電力を測定する。ステップST1301で、UEは、該サービングセルの受信電力測定値(Sx)とセルリセレクションのための測定開始用閾値(S_intrasearch)とを比較する。S_intrasearchは、予めサービングセルから報知される。
UE measures the received power of the serving cell for celery selection. In Step ST1301, the UE compares the received power measurement value (Sx) of the serving cell with a measurement start threshold value (S_intrasearch) for cell reselection. S_intrasearch is notified in advance from the serving cell.
UEは、SxとS_intrasearchとを比較し、SxがS_intrasearch以下となった場合に、サービングセルの受信電力が低いと判断し、セルリセレクションのための測定を開始する(ステップST1302)。UEは、SxがS_intrasearchよりも大きい場合は、ステップST1601で、サービングセルのバックホールリンクの通信品質と、サービングセルのバックホールリンクの通信品質閾値(バックホール閾値(開始))とを比較する。サービングセルのバックホールリンクの通信品質と、サービングセルのバックホールリンクの通信品質閾値とは、各々予めサービングセルから報知される。
The UE compares Sx and S_intrasearch, and when Sx is equal to or lower than S_intrasearch, the UE determines that the reception power of the serving cell is low, and starts measurement for cell reselection (step ST1302). If Sx is larger than S_intrasearch, the UE compares the communication quality of the backhaul link of the serving cell with the communication quality threshold (backhaul threshold (start)) of the backhaul link of the serving cell in step ST1601. The communication quality of the backhaul link of the serving cell and the communication quality threshold of the backhaul link of the serving cell are each notified beforehand from the serving cell.
ステップST1601で、UEは、サービングセルのバックホールリンクの通信品質が、バックホール閾値(開始)以下となった場合は、バックホールリンクの通信品質が低いと判断して、セルリセレクションのための測定を開始する(ステップST1302)。UEは、サービングセルのバックホールリンクの通信品質が、バックホール閾値(開始)より大きい場合は、バックホールリンクの通信品質が十分であると判断して、セルリセレクションのための測定を開始せず、ステップST1301に戻り、Sxを測定し、SxとS_intrasearchとを比較する。
In step ST1601, when the communication quality of the backhaul link of the serving cell is equal to or lower than the backhaul threshold (start), the UE determines that the communication quality of the backhaul link is low and performs measurement for cell reselection. Start (step ST1302). If the communication quality of the serving cell backhaul link is greater than the backhaul threshold (start), the UE determines that the communication quality of the backhaul link is sufficient and does not start the measurement for celery selection, Returning to step ST1301, Sx is measured, and Sx and S_intrasearch are compared.
ステップST1601におけるサービングセルのバックホールリンクの通信品質とバックホール閾値(開始)との比較は、ステップST1301における通常のサービングセルの受信電力測定値(Sx)と受信電力の閾値(S_intrasearch)との比較と、オア(or)条件で行われるようにするとよい。これによって、いずれかの条件が通信に不十分となった場合に、セルリセレクションのための測定を開始するようにできる。
The comparison of the communication quality of the backhaul link of the serving cell and the backhaul threshold (start) in step ST1601 is a comparison between the received power measurement value (Sx) of the normal serving cell and the threshold of received power (S_intrasearch) in step ST1301. It should be done under or conditions. Thereby, when any of the conditions becomes insufficient for communication, measurement for celery selection can be started.
このように、サービングセルのバックホールリンクの通信品質閾値を設けて、セルリセレクションのための測定を開始するか否かの判断に用い、また、該判断をセルリセレクションのための測定開始条件に入れ込むことで、サービングセルのバックホールリンクの通信品質を考慮に入れる。
In this way, a communication quality threshold for the backhaul link of the serving cell is provided, and used to determine whether or not to start measurement for celery selection, and the determination is put into measurement start conditions for celery selection. Thus, the communication quality of the serving cell backhaul link is taken into account.
バックホールリンクの通信品質は変動するが、その対処方法は実施の形態1の変形例1で開示したのと同様の方法とすればよい。
Although the communication quality of the backhaul link varies, the coping method may be the same as that disclosed in the first modification of the first embodiment.
バックホールリンクの通信品質およびバックホールリンクの通信品質閾値として、受信電力(RSRP、RSRQ)、通信速度、通信容量、回線品質などとすればよい。バックホールリンクの通信品質とバックホールリンクの通信品質閾値とを別の指標としてもよいが、同じとしてもよい。同じ場合は、単位が同じになるので直接比較が可能となるため、UEでの制御が簡易になる。
The backhaul link communication quality and the backhaul link communication quality threshold may be received power (RSRP, RSRQ), communication speed, communication capacity, line quality, and the like. The communication quality of the backhaul link and the communication quality threshold value of the backhaul link may be different indicators, but may be the same. In the case of the same, the unit becomes the same, so that direct comparison is possible, and thus the control at the UE is simplified.
サービングセルは、バックホールリンクの通信品質とバックホールリンクの通信品質閾値とを、一緒にあるいは別々に、SIB3に含めて報知してもよいし、あるいはSIB1に含めて報知してもよい。SIB3の場合、セルリセレクション用パラメータが含まれるので、UEは、他のセルリセレクション用パラメータと一緒に受信することが可能となる。このため、UEの受信動作を簡略化でき、また、制御誤動作の削減が可能となる。SIB1の場合、予め報知されるタイミングが決められているので、UEはメジャメント時に早期に受信可能となる。このため、UEのメジャメント動作において制御遅延を小さくすることが可能となる。
The serving cell may notify the communication quality of the backhaul link and the communication quality threshold of the backhaul link together or separately in the SIB3, or may be notified in the SIB1. In the case of SIB3, since the cell reselection parameter is included, the UE can receive it together with other cell reselection parameters. For this reason, the reception operation of the UE can be simplified, and the control malfunction can be reduced. In the case of SIB1, since the timing to be notified in advance is determined, the UE can receive early at the time of measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE.
サービングセルのバックホールリンクの通信品質閾値は、報知されるのではなく、静的な値として予め決められていてもよい。この場合、UEは、予め決められた値を用いることができる。これにより、報知情報を削減できシグナリング負荷を低減できる。
The communication quality threshold value of the serving cell backhaul link may be determined in advance as a static value instead of being notified. In this case, the UE can use a predetermined value. Thereby, broadcast information can be reduced and signaling load can be reduced.
また、バックホールリンクの通信品質閾値に、初期値として予め決められた値を用い、バックホールリンクの通信品質閾値が報知された場合に、初期値に代えて、報知された該バックホールリンクの通信品質閾値を用いるようにしてもよい。この場合、該バックホールリンクの通信品質閾値を、サービングセルが必要に応じて報知すればよい。
In addition, when the communication quality threshold of the backhaul link is notified as the initial value by using a predetermined value as the communication quality threshold of the backhaul link, instead of the initial value, the notified backhaul link A communication quality threshold may be used. In this case, the serving cell may notify the backhaul link communication quality threshold as necessary.
本変形例の方法とすることで、実施の形態1で記載した効果に加えて、以下の効果を得ることが可能となる。サービングセルの受信品質とバックホールリンクの通信品質とを各々個別に設定できるため、柔軟性が高く緻密な設定が可能となる。したがって、バックホールリンクの通信品質を考慮する必要のあるセルが増大した場合にも、通信速度の低下や通信断の発生を抑制したセルリセレクションが可能となる。
In addition to the effects described in the first embodiment, the following effects can be obtained by adopting the method of the present modification. Since the reception quality of the serving cell and the communication quality of the backhaul link can be individually set, it is possible to make a highly flexible and precise setting. Therefore, even when the number of cells that need to consider the communication quality of the backhaul link increases, cell reselection that suppresses the decrease in communication speed and the occurrence of communication disconnection is possible.
実施の形態2.
前述の非特許文献9には、Qoffsetに、リレーノードとドナーeNBとの間のリンク品質を入れ込むことが開示されている。しかし、非特許文献9に開示された方法では、セルリセレクションにおけるセルランキングの際に、サービングセルのバックホールリンクの通信品質を入れ込むことができていない。セルランキングにおいて、サービングセルのバックホールリンクの通信品質を考慮に入れないと、サービングセルの受信電力が良い場合、該サービングセルをベストセルとして選択する可能性が大きくなる。該サービングセルのバックホールリンクの通信品質が悪い場合は、ベストセル選択後も通信速度の低下や、さらには通信断が生じることになる。Embodiment 2. FIG.
The aforementioned non-patent document 9 discloses that the link quality between the relay node and the donor eNB is inserted into Qoffset. However, in the method disclosed in Non-Patent Document 9, the communication quality of the backhaul link of the serving cell cannot be inserted at the time of cell ranking in celery selection. In the cell ranking, if the communication quality of the backhaul link of the serving cell is not taken into consideration, when the reception power of the serving cell is good, the possibility of selecting the serving cell as the best cell increases. When the communication quality of the backhaul link of the serving cell is poor, the communication speed is lowered and the communication is interrupted even after the best cell is selected.
前述の非特許文献9には、Qoffsetに、リレーノードとドナーeNBとの間のリンク品質を入れ込むことが開示されている。しかし、非特許文献9に開示された方法では、セルリセレクションにおけるセルランキングの際に、サービングセルのバックホールリンクの通信品質を入れ込むことができていない。セルランキングにおいて、サービングセルのバックホールリンクの通信品質を考慮に入れないと、サービングセルの受信電力が良い場合、該サービングセルをベストセルとして選択する可能性が大きくなる。該サービングセルのバックホールリンクの通信品質が悪い場合は、ベストセル選択後も通信速度の低下や、さらには通信断が生じることになる。
The aforementioned non-patent document 9 discloses that the link quality between the relay node and the donor eNB is inserted into Qoffset. However, in the method disclosed in Non-Patent Document 9, the communication quality of the backhaul link of the serving cell cannot be inserted at the time of cell ranking in celery selection. In the cell ranking, if the communication quality of the backhaul link of the serving cell is not taken into consideration, when the reception power of the serving cell is good, the possibility of selecting the serving cell as the best cell increases. When the communication quality of the backhaul link of the serving cell is poor, the communication speed is lowered and the communication is interrupted even after the best cell is selected.
本実施の形態では、セルリセレクションに、サービングセルおよび隣接セルの少なくともいずれか一方のバックホールリンクの通信品質を考慮に入れる方法として、セルランキング時にサービングセルおよび隣接セルの少なくともいずれか一方のバックホールリンクの通信品質を入れこむ。
In the present embodiment, as a method for taking into account the communication quality of the backhaul link of at least one of the serving cell and the neighboring cell in the cell reselection, at the time of cell ranking, the backhaul link of at least one of the serving cell and the neighboring cell is selected. Incorporate communication quality.
ここでは、セルランキング時にサービングセルおよび隣接セルの少なくともいずれか一方のバックホールリンクの通信品質を入れこむ一例として、セルランキング時のセルの測定値に各セルのバックホールリンクの通信品質を入れ込む。
Here, as an example of incorporating the communication quality of the backhaul link of at least one of the serving cell and the neighboring cell at the time of cell ranking, the communication quality of the backhaul link of each cell is inserted into the measured value of the cell at the time of cell ranking.
図17は、セルランキング時のセルの測定値に各セルのバックホールリンクの通信品質を入れこんだセルリセレクションの処理手順を示すフローチャートである。図17に示すフローチャートの処理は、図13および図16に示すフローチャートの処理と類似しているので、異なる処理についてのみ説明し、対応する部分については同一のステップ番号を付して、処理の説明を省略する。セルリセレクションのための測定を開始するまでの動作は、実施の形態1の変形例2で開示した方法を用いているが、これに限らない。実施の形態1または実施の形態1の変形例1で開示した方法であってもよい。
FIG. 17 is a flowchart showing a processing procedure of cell reselection in which the communication quality of the backhaul link of each cell is included in the cell measurement value at the time of cell ranking. The processing of the flowchart shown in FIG. 17 is similar to the processing of the flowchart shown in FIG. 13 and FIG. 16, so only the different processing will be described, and the corresponding steps will be denoted by the same step numbers and the description of the processing. Is omitted. The operation until the measurement for celery selection is started uses the method disclosed in the second modification of the first embodiment, but is not limited thereto. The method disclosed in the first embodiment or the first modification of the first embodiment may be used.
本実施の形態では、ステップST1304で、Srxlevが0より大きくなったセルについて、UEは、ステップST1701の処理を行う。ステップST1701で、UEは、サービングセルの受信電力測定値にサービングセルのバックホールリンクの通信品質を入れ込んだ受信品質を導出する。該サービングセルのバックホールリンクの通信品質を入れ込んだ受信品質をRs_totalとする。
In this embodiment, the UE performs the process of step ST1701 for the cell in which Srxlev is greater than 0 in step ST1304. In Step ST1701, the UE derives a reception quality obtained by inserting the communication quality of the backhaul link of the serving cell into the reception power measurement value of the serving cell. The reception quality including the communication quality of the backhaul link of the serving cell is Rs_total.
さらにステップST1701で、UEは、隣接セルの受信電力測定値に隣接セルのバックホールリンクの通信品質を入れ込んだ受信品質を導出する。該隣接セルのバックホールリンクの通信品質を入れ込んだ受信品質をRn_totalとする。
Further, in step ST1701, the UE derives reception quality obtained by inserting the communication quality of the backhaul link of the adjacent cell into the reception power measurement value of the adjacent cell. Rn_total is the reception quality including the communication quality of the backhaul link of the adjacent cell.
UEは、導出したRs_totalとRn_totalとを用いて、バックホールリンクの通信品質を入れ込んだ受信品質が最良のセル(ベストセル)を選択する。そして、UEがステップST1701で選択したベストセルにセルリセレクションを行う。
The UE uses the derived Rs_total and Rn_total to select the cell (best cell) with the best reception quality including the communication quality of the backhaul link. Then, the UE performs celery selection on the best cell selected in step ST1701.
サービングセルは、自セルのバックホールリンクの通信品質をUEに報知し、UEは、サービングセルから報知される該情報を受信して、ステップST1701のRs_totalの導出に用いる。サービングセルが該情報を報知する方法は、実施の形態1の変形例1で開示した方法を用いればよい。
The serving cell notifies the UE of the communication quality of the backhaul link of the own cell, and the UE receives the information notified from the serving cell and uses it for derivation of Rs_total in step ST1701. As a method for the serving cell to notify the information, the method disclosed in the first modification of the first embodiment may be used.
サービングセルは、隣接セルのバックホールリンクの通信品質をUEに報知し、UEは、サービングセルから報知される該情報を受信して、ステップST1701のRn_totalの導出に用いる。
The serving cell notifies the UE of the communication quality of the backhaul link of the neighboring cell, and the UE receives the information notified from the serving cell and uses it for derivation of Rn_total in step ST1701.
サービングセルが該情報を報知するため、サービングセルは、隣接セルのバックホールリンクの通信品質を認識する必要がある。この方法として、セルは各々、自セルのバックホールリンクの通信品質を測定し、その結果を、該セルのアイデンティティ(PCI、GCI)とともに、あるいは関連付けて、隣接セルに通知する。該通知のためのインタフェースには、X2インタフェースあるいはS1インタフェースなどを用いればよい。
Since the serving cell broadcasts the information, the serving cell needs to recognize the communication quality of the backhaul link of the neighboring cell. As this method, each cell measures the communication quality of the backhaul link of its own cell, and notifies the neighbor cell of the result together with or in association with the identity (PCI, GCI) of the cell. An X2 interface or an S1 interface may be used as the notification interface.
リレーの場合は、ドナーeNB(DeNB)に上りバックホールリンク(リレーからDeNBへのリンク)を用いて通知してもよい。該DeNBが、傘下のリレーに通知してもよい。こうすることで、リレーが隣接のリレーのバックホールリンクの通信品質を認識することができる。通知方法としては、DeNBから傘下のリレーへ個別に通知してもよいし、DeNBから報知してもよい。また、リレーの場合は、DeNBが上りバックホールリンクの通信品質を測定して、その結果を該リレーのバックホールリンクの通信品質として用いてもよい。これによって、リレーからDeNBへ通知する必要がなくなる。このようにすることで、サービングセルが隣接セルのバックホールリンクの通信品質を認識することが可能となる。
In the case of a relay, the donor eNB (DeNB) may be notified using an uplink backhaul link (link from the relay to the DeNB). The DeNB may notify the relays being served thereby. By doing so, the relay can recognize the communication quality of the backhaul link of the adjacent relay. As a notification method, you may notify separately to a subordinate relay from DeNB, and you may alert | report from DeNB. In the case of a relay, the DeNB may measure the communication quality of the uplink backhaul link and use the result as the communication quality of the backhaul link of the relay. This eliminates the need to notify the DeNB from the relay. In this way, the serving cell can recognize the communication quality of the backhaul link of the adjacent cell.
HeNBGWに接続されるHeNBの場合、HeNBGWが傘下のHeNBのバックホールリンクの通信品質を測定し、HeNBGWが該測定値を傘下のHeNBへ通知するようにしてもよい。
In the case of the HeNB connected to the HeNBGW, the HeNBGW may measure the communication quality of the backhaul link of the HeNB being served, and the HeNBGW may notify the measurement value to the HeNB being served.
サービングセルが、隣接セルのバックホールリンクの通信品質を報知する方法は、実施の形態1の変形例1で開示したサービングセルのバックホールリンクの通信品質の報知方法と同様とすればよい。
The method in which the serving cell reports the communication quality of the backhaul link of the neighboring cell may be the same as the method of reporting the communication quality of the backhaul link of the serving cell disclosed in the first modification of the first embodiment.
バックホールリンクの通信品質の平均値あるいはフィルタリング後の値の導出は、サービングセルが行ってもよいし、UEが行ってもよいし、セル毎に行ってもよい。セル各々が自セルにおいて行うようにしておくのがよい。これによって、平均化後あるいはフィルタリング後の情報を、ある期間毎に通知すればよくなる。該ある期間を報知情報が修正されるタイミングに合わせるようにしてもよい。こうすることで、各セルがサービングセルに通知する情報量や、サービングセルがUEに通知する情報量を削減することが可能となる。
The derivation of the average value of the communication quality of the backhaul link or the value after filtering may be performed by the serving cell, the UE, or may be performed for each cell. Each cell should be performed in its own cell. As a result, the information after averaging or filtering may be notified every certain period. You may make it match this certain period with the timing when alerting | reporting information is corrected. By doing so, it is possible to reduce the amount of information that each cell notifies the serving cell and the amount of information that the serving cell notifies the UE.
サービングセルは、隣接セルのバックホールリンクの通信品質をSIB4に含めて報知するようにしてもよい。SIB4には隣接セルの情報が含まれるので、UEは、他の隣接セルの情報、例えばPCIと関連付けて受信することが可能となる。このため、UEの受信動作を簡略化でき、また、制御誤動作の削減が可能となる。
The serving cell may be notified by including the communication quality of the backhaul link of the adjacent cell in the SIB4. Since SIB4 includes information on neighboring cells, the UE can receive information associated with other neighboring cells, for example, PCI. For this reason, the reception operation of the UE can be simplified, and the control malfunction can be reduced.
バックホールリンクの通信品質に用いる指標とそれを用いた導出方法、セルの受信電力測定値の単位が異なる場合の導出方法は、実施の形態1の変形例1で開示したのと同様の方法を用いればよい。
The index used for the communication quality of the backhaul link, the derivation method using the index, and the derivation method when the units of the received power measurement values of the cells are different are the same as those disclosed in the first modification of the first embodiment. Use it.
本実施の形態で開示した方法とすることで、隣接セルのバックホールリンクの通信品質とともに、サービングセルのバックホールリンクの通信品質を考慮に入れたセルリセレクションが可能となる。たとえサービングセルの受信品質が良好であったとしても、該サービングセルのバックホールリンクの通信品質が悪い場合は、他のセルへのセルリセレクションを行わせることが可能となる。このため、サービングセルのバックホールリンクの通信品質の劣化による通信速度の低下や通信断の発生を抑制することが可能となる。
The method disclosed in the present embodiment enables cell reselection in consideration of the communication quality of the backhaul link of the neighboring cell and the communication quality of the backhaul link of the serving cell. Even if the reception quality of the serving cell is good, if the communication quality of the backhaul link of the serving cell is bad, cell reselection to another cell can be performed. For this reason, it becomes possible to suppress the reduction in communication speed and the occurrence of communication disconnection due to the deterioration of the communication quality of the backhaul link of the serving cell.
また、バックホールリンクの通信品質の悪いセルへは、セルリセレクションすることが無くなるため、リセレクション後に通信速度の低下や通信断の発生を抑制することが可能となる。
In addition, cell reselection is not performed on cells with poor communication quality on the backhaul link, so that it is possible to suppress a decrease in communication speed and occurrence of communication disconnection after reselection.
また、リセレクション後の無線リンク失敗や、さらに通信断などによる再度のセルセレクション、セルリセレクション動作を行なわなくて済むため、UEの消費電力の削減や、システムとしての動作が不安定になることを無くすことが可能となる。
In addition, since it is not necessary to perform cell selection and cell reselection operations again due to a radio link failure after reselection and further communication disconnection, it is possible to reduce UE power consumption and make the system unstable. It can be eliminated.
また、サービングセルのバックホールリンクの通信品質と、隣接セル毎のバックホールリンクの通信品質とを個別に考慮に入れて、トータルのセルの通信品質を導出することで、セル毎に異なって変動するバックホールリンクの通信品質を、個別に入れ込むことが可能となる。バックホールリンクの通信品質に変動の無いセルは、変更した該通信品質を報知する必要が無くなるため、報知あるいはX2インタフェース、S1インタフェースを用いた通知回数を削減することができる。したがって、シグナリング負荷の削減、UEの消費電力の削減が可能となる。
In addition, taking into account the communication quality of the backhaul link of the serving cell and the communication quality of the backhaul link for each neighboring cell individually, and deriving the total cell communication quality, it varies depending on the cell. The communication quality of the backhaul link can be individually entered. A cell having no change in the communication quality of the backhaul link does not need to notify the changed communication quality, so the number of notifications using the X2 interface or the S1 interface can be reduced. Therefore, it is possible to reduce the signaling load and the power consumption of the UE.
バックホールリンクの通信品質を、サービングセルの受信電力の単位で表せるオフセット値としてもよい。例えば、サービングセルのバックホールリンクの通信品質を考慮に入れたオフセット値をQoffset,sとし、隣接セルのバックホールリンクの通信品質を考慮に入れたオフセット値をQoffset,nとしてもよい。サービングセルは、該オフセット値をUEに報知する。ステップST1701で、UEは、以下の式を用いてRs_total、Rn_totalを算出する。
The communication quality of the backhaul link may be an offset value that can be expressed in units of received power of the serving cell. For example, the offset value taking into account the communication quality of the backhaul link of the serving cell may be Qoffset, s, and the offset value taking into account the communication quality of the backhaul link of the neighboring cell may be set to Qoffset, n. The serving cell notifies the UE of the offset value. In Step ST1701, the UE calculates Rs_total and Rn_total using the following equations.
Rs_total=Qmeas,s-Qoffset,s+Qhyst
Rn_total=Qmeas,n-Qoffset,n
UEは、算出したRs_total、Rn_totalを用いて、最も高い受信電力となるセル(ベストセル)を選択する。そして、UEが選択したベストセルにセルリセレクションを行う。 Rs_total = Qmeas, s-Qoffset, s + Qhyst
Rn_total = Qmeas, n-Qoffset, n
The UE uses the calculated Rs_total and Rn_total to select the cell (best cell) with the highest received power. Then, celery selection is performed on the best cell selected by the UE.
Rn_total=Qmeas,n-Qoffset,n
UEは、算出したRs_total、Rn_totalを用いて、最も高い受信電力となるセル(ベストセル)を選択する。そして、UEが選択したベストセルにセルリセレクションを行う。 Rs_total = Qmeas, s-Qoffset, s + Qhyst
Rn_total = Qmeas, n-Qoffset, n
The UE uses the calculated Rs_total and Rn_total to select the cell (best cell) with the highest received power. Then, celery selection is performed on the best cell selected by the UE.
こうすることで、従来のセルリセレクションとほぼ同じ方法で、バックホールリンクの通信品質を考慮に入れることが可能となる。
By doing so, it becomes possible to take into account the communication quality of the backhaul link in almost the same manner as conventional celery selection.
本実施の形態では、サービングセルは、隣接セルのバックホールリンクの通信品質を認識するため、セルは各々、自セルのバックホールリンクの通信品質を測定し、その結果を、X2インタフェースあるいはS1インタフェースなどを用いて隣接セルに通知する。別の方法として、各セルは、複数の周波数キャリア上で、自セルのバックホールリンクの通信品質を報知するようにしてもよい。各セルは、該複数の周波数キャリアの中で、自セルが用いる周波数キャリアと異なる周波数キャリア上の隣接セルの報知情報を受信する。該報知情報を報知する専用の周波数キャリアを予め静的に決めておいてもよい。各セルは、定期的あるいは随時、該報知情報が送信される周波数キャリアについて、隣接セルのメジャメントを行い、受信電力がある閾値より大きいセルの報知情報を受信するようにしておく。こうすることで、各セルは、隣接セルの報知情報を認識することが可能となる。
In this embodiment, since the serving cell recognizes the communication quality of the backhaul link of the neighboring cell, each cell measures the communication quality of the backhaul link of its own cell, and the result is obtained as an X2 interface or an S1 interface. Is used to notify neighboring cells. As another method, each cell may broadcast the communication quality of its own backhaul link on a plurality of frequency carriers. Each cell receives broadcast information of an adjacent cell on a frequency carrier different from the frequency carrier used by the own cell among the plurality of frequency carriers. A dedicated frequency carrier for broadcasting the broadcast information may be statically determined in advance. Each cell measures a neighboring cell with respect to a frequency carrier to which the broadcast information is transmitted periodically or at any time, and receives broadcast information of a cell whose received power is larger than a certain threshold. In this way, each cell can recognize the broadcast information of neighboring cells.
LTE-Aシステムでは、LTEシステムの周波数帯域幅(transmission bandwidths)よりも大きい周波数帯域幅をサポートすることが考えられている。そのため、LTE-A対応の移動端末は、同時に1つあるいは複数のコンポーネントキャリア(Component Carrier:CC)を受信することが考えられている。このコンポーネントキャリアを用いて上述の方法を行うようにしてもよい。各セルは、複数のコンポーネントキャリア上で自セルのバックホールリンクの通信品質を報知し、各セルは、該複数のコンポーネントキャリアの中で、自セルが用いるコンポーネントキャリア上の隣接セルの報知情報を受信するようにすればよい。該報知情報が送信されるコンポーネントキャリアも、UEとの通信に使用することが可能である。
In the LTE-A system, it is considered to support a frequency bandwidth larger than the frequency bandwidth (transmission シ ス テ ム bandwidths) of the LTE system. Therefore, it is considered that an LTE-A compatible mobile terminal receives one or a plurality of component carriers (Component : Carrier: CC) at the same time. You may make it perform the above-mentioned method using this component carrier. Each cell broadcasts the communication quality of its own backhaul link on a plurality of component carriers, and each cell reports broadcast information on neighboring cells on the component carrier used by the own cell among the plurality of component carriers. What is necessary is just to make it receive. The component carrier to which the broadcast information is transmitted can also be used for communication with the UE.
3GPPでは、現在HeNBにはX2インタフェースが設けられていない。したがって、この方法をHeNBが存在するヘテロジーニアスネットワークで用いることで、X2インタフェースが無くても、エアインタフェースにより隣接セルの情報を得ることが可能となる。例えば、HeNBがマクロセル圏内に存在しているような場合に、マクロセルから該HeNBに対して、あるいは、該HeNBからマクロセルに対して、上述の方法を用いて自セルのバックホールリンクの通信品質を通知するようにしてもよい。これにより、S1インタフェースを介して通知するよりも早期に通知することが可能となる。時間的に変動するバックホールリンクの通信品質を、S1インタフェースより小さい遅延時間で隣接セルに通知可能となる。
In 3GPP, the HeNB currently does not have an X2 interface. Therefore, by using this method in a heterogeneous network in which a HeNB is present, it is possible to obtain information on neighboring cells through an air interface without an X2 interface. For example, when the HeNB exists in the macro cell range, the communication quality of the backhaul link of the own cell is increased from the macro cell to the HeNB or from the HeNB to the macro cell using the above-described method. You may make it notify. As a result, notification can be made earlier than notification via the S1 interface. The communication quality of the backhaul link that varies with time can be notified to the neighboring cell with a delay time smaller than that of the S1 interface.
実施の形態2 変形例1.
実施の形態2では、隣接セルのバックホールリンクの通信品質をサービングセルがUEに報知する。しかし、サービングセルが全ての隣接セルについて該通信品質をUEに報知すると、報知情報が膨大になってしまう。さらに、シグナリング負荷も増大し、UEの消費電力も増大してしまう。また、HeNBは、ホームユースにおいて一般利用者が該HeNBを設置することが想定されており、大量のHeNBがそれぞれ任意の場所に設置されることになる。したがって、これらのHeNBを含むネットワークで隣接セル情報を構成するのは、非常に複雑になってしまう。よって、サービングセルが隣接セルのバックホールリンクの通信品質をUEに報知するのは、システムとして複雑になる。このことは、サービングセルが、隣接セルのバックホールリンクの通信品質を考慮に入れたオフセット値を報知する場合や、非特許文献9に開示されるQoffsetを報知する場合にも生じる問題である。Embodiment 2 Modification 1
InEmbodiment 2, the serving cell notifies the UE of the communication quality of the backhaul link of the adjacent cell. However, if the serving cell notifies the UE of the communication quality for all neighboring cells, the notification information becomes enormous. Furthermore, the signaling load increases and the power consumption of the UE also increases. In addition, it is assumed that a general user installs the HeNB in home use, and a large amount of HeNB is installed in an arbitrary place. Therefore, configuring neighboring cell information in a network including these HeNBs becomes very complicated. Therefore, it is complicated as a system for the serving cell to notify the UE of the communication quality of the backhaul link of the adjacent cell. This is a problem that occurs even when the serving cell broadcasts an offset value that takes into account the communication quality of the backhaul link of the neighboring cell, or when it broadcasts Qoffset disclosed in Non-Patent Document 9.
実施の形態2では、隣接セルのバックホールリンクの通信品質をサービングセルがUEに報知する。しかし、サービングセルが全ての隣接セルについて該通信品質をUEに報知すると、報知情報が膨大になってしまう。さらに、シグナリング負荷も増大し、UEの消費電力も増大してしまう。また、HeNBは、ホームユースにおいて一般利用者が該HeNBを設置することが想定されており、大量のHeNBがそれぞれ任意の場所に設置されることになる。したがって、これらのHeNBを含むネットワークで隣接セル情報を構成するのは、非常に複雑になってしまう。よって、サービングセルが隣接セルのバックホールリンクの通信品質をUEに報知するのは、システムとして複雑になる。このことは、サービングセルが、隣接セルのバックホールリンクの通信品質を考慮に入れたオフセット値を報知する場合や、非特許文献9に開示されるQoffsetを報知する場合にも生じる問題である。
In
これらの問題を解消するため、本変形例では、サービングセルが隣接セルのバックホールリンクの通信品質を報知するのではなく、セルが各々自セルのバックホールリンクの通信品質を報知して、UEがセルリセレクションにおいて該通信品質をセルランキングに用いることとする。
In order to solve these problems, in this modified example, the serving cell does not report the communication quality of the backhaul link of the neighboring cell, but the cell notifies the communication quality of the backhaul link of its own cell, and the UE The communication quality is used for cell ranking in celery selection.
セルリセレクションのためのセルの測定を開始するUEは、図17に示すステップST1302において、セルの測定を開始する。この際にUEは、各セルの受信電力を測定するだけでなく、各セルが報知する自セルのバックホールリンクの通信品質を受信する。
UE which starts the measurement of the cell for celery selection starts the measurement of a cell in step ST1302 shown in FIG. At this time, the UE not only measures the reception power of each cell, but also receives the communication quality of the backhaul link of the own cell broadcast by each cell.
UEは、このステップST1302で受信した各セルのバックホールリンクの通信品質を用いて、ステップST1701で、該各セルのRs_total、Rn_totalを導出する。バックホールリンクの通信品質の指標と導出方法、セルの受信電力測定値の単位が異なる場合の導出方法は、実施の形態2と同様の方法で行うとよい。
In step ST1701, the UE derives Rs_total and Rn_total of each cell using the communication quality of the backhaul link of each cell received in step ST1302. The backhaul link communication quality index and the derivation method, and the derivation method when the unit of the cell received power measurement value is different may be performed in the same manner as in the second embodiment.
各セルは、自セルのバックホールリンクの通信品質を報知するが、該バックホールリンクの通信品質は変動する。したがって、該バックホールリンクの通信品質を変更して報知する場合は、報知情報の修正により行えばよい。バックホールリンクの通信品質の平均値あるいはフィルタリング後の値の導出は、UEが行ってもよいし、セル毎に行ってもよいが、セル各々が自セルにおいて行うようにしておくのがよい。こうすることで、平均化後あるいはフィルタリング後の情報をある期間毎に通知すればよくなる。したがって、各セルがサービングセルに通知する情報量や、サービングセルがUEに通知する情報量を削減することが可能となる。該ある期間を報知情報が修正されるタイミングに合わせるようにしてもよい。
Each cell reports the communication quality of its own backhaul link, but the communication quality of the backhaul link varies. Therefore, when the communication quality of the backhaul link is changed and notified, the notification information may be corrected. The derivation of the average value of the communication quality of the backhaul link or the value after filtering may be performed by the UE or may be performed for each cell, but each cell is preferably performed in its own cell. By doing so, it is only necessary to notify the information after averaging or after filtering every certain period. Therefore, it is possible to reduce the amount of information that each cell notifies the serving cell and the amount of information that the serving cell notifies the UE. You may make it match this certain period with the timing when alerting | reporting information is corrected.
各セルは、自セルのバックホールリンクの通信品質を報知するが、この際SIB1に含めて報知してもよい。SIB1の場合、予め報知されるタイミングが決められているので、UEはメジャメント時に早期に受信可能となる。このため、UEのメジャメント動作において制御遅延を小さくすることが可能となる。この場合、前述の図12に示したセルサーチの手順において、ステップST1203のベストセル選択を、ステップST1205でSIB1を受信した後で行うようにすればよい。
Each cell reports the communication quality of the backhaul link of its own cell, but at this time, it may be reported in SIB1. In the case of SIB1, since the timing to be notified in advance is determined, the UE can receive early at the time of measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE. In this case, in the above-described cell search procedure shown in FIG. 12, the best cell selection in step ST1203 may be performed after receiving SIB1 in step ST1205.
本変形例の方法とすることで、実施の形態2で記載した効果に加えて、以下の効果を得ることができる。サービングセルが報知する情報から、隣接セルの情報を削減することができる。また、各セルは、自セルのバックホールリンクの通信品質や該セルのアイデンティティ(PCI、GCI)を隣接セルに通知しなくてもよくなる。したがって、エアインタフェースやX2インタフェース、S1インタフェースにおけるシグナリング負荷を削減することが可能となる。また、このため、大量に、そして任意の場所に設置されるHeNBを含むネットワークにおいても、簡易な構成のシステムを構築することが可能となる。
In addition to the effects described in the second embodiment, the following effects can be obtained by adopting the method of the present modification. Neighboring cell information can be reduced from information broadcast by the serving cell. In addition, each cell does not need to notify the neighboring cell of the communication quality of the backhaul link of the own cell and the identity (PCI, GCI) of the cell. Accordingly, it is possible to reduce the signaling load on the air interface, the X2 interface, and the S1 interface. For this reason, it is possible to construct a system with a simple configuration even in a network including a large amount of HeNBs installed in an arbitrary place.
また、セルは、各々自セルのバックホールリンクの通信品質を考慮に入れたオフセット値あるいは非特許文献9に開示されるQoffsetを報知するようにしてもよい。このようにしても、本変形例と同等の効果が得られる。
Also, each cell may broadcast an offset value taking into account the communication quality of the backhaul link of its own cell or Qoffset disclosed in Non-Patent Document 9. Even if it does in this way, the effect equivalent to this modification is acquired.
実施の形態2 変形例2.
本変形例では、セルリセレクション対象となることを許可するかどうかを示すインジケータを設ける。サービングセルが、自セルがセルリセレクション対象となることを許可するかどうかを示すインジケータと、隣接セルがセルリセレクション対象となることを許可するかどうかを示すインジケータとを報知する。隣接セルの該インジケータは、セル毎に設けて報知してもよい。Embodiment 2 Modification 2
In this modification, an indicator is provided that indicates whether or not to be subject to celery selection. The serving cell broadcasts an indicator that indicates whether or not the own cell is allowed to be subject to celery selection, and an indicator that indicates whether or not neighboring cells are allowed to be subject to celery selection. The indicator of the adjacent cell may be provided for each cell and notified.
本変形例では、セルリセレクション対象となることを許可するかどうかを示すインジケータを設ける。サービングセルが、自セルがセルリセレクション対象となることを許可するかどうかを示すインジケータと、隣接セルがセルリセレクション対象となることを許可するかどうかを示すインジケータとを報知する。隣接セルの該インジケータは、セル毎に設けて報知してもよい。
In this modification, an indicator is provided that indicates whether or not to be subject to celery selection. The serving cell broadcasts an indicator that indicates whether or not the own cell is allowed to be subject to celery selection, and an indicator that indicates whether or not neighboring cells are allowed to be subject to celery selection. The indicator of the adjacent cell may be provided for each cell and notified.
セルリセレクションの際のUEの動作は、例えば前述の図17に示すフローチャートの一部を変更することで可能となる。UEは、予めサービングセルから報知された該インジケータを受信しておき、セルリセレクションの際に、図17のステップST1303において、該インジケータによりセルリセレクション対象となることが許可されたセルに対してのみ、Srxlevを算出するようにする。
The operation of the UE at the time of celery selection is made possible by changing a part of the flowchart shown in FIG. The UE receives the indicator broadcast from the serving cell in advance, and at the time of cell reselection, in step ST1303 of FIG. 17, only the cell that is allowed to be subject to cell reselection by the indicator is Srxlev. Is calculated.
そしてUEは、ステップST1303において、該Srxlevを算出したセルのうち、ステップST1304で、Srxlevが0より大きくなったセルの中から、ステップST1701でセルランキングを行い、ベストセルを選択するようにすればよい。こうすることで、セルリセレクション対象となることが許可されたセルの中から、ベストセルを選択することが可能となる。
Then, in step ST1303, the UE performs cell ranking in step ST1701 from the cells in which Srxlev is greater than 0 in step ST1304, and selects the best cell. Good. By doing so, it is possible to select the best cell from the cells that are permitted to be subject to celery selection.
セルランキングおよびベストセルの選択方法としては、図17のステップST1701の処理を行う必要はなく、図13~図16のステップST1306の処理を行うようにしてもよい。この場合、UEは、ステップST1304で、Srxlevが0より大きくなったセルの中から、ステップST1306でセルランキングおよびベストセル選択を行う。こうすることで、セルリセレクション対象となることが許可されたセルの中から、ベストセルを選択することが可能となる。
As the cell ranking and best cell selection method, it is not necessary to perform the process of step ST1701 in FIG. 17, and the process of step ST1306 in FIGS. 13 to 16 may be performed. In this case, the UE performs cell ranking and best cell selection in Step ST1306 from among cells in which Srxlev is greater than 0 in Step ST1304. By doing so, it is possible to select the best cell from the cells that are permitted to be subject to celery selection.
もし該インジケータが、セルリセレクション対象となることが許可されないセルの場合は、ステップST1303でSrxlevを算出する対象から外す。これにより、ベストセルの選択において、セルリセレクション対象となることが許可されないセルが選択されることはなくなる。
If the indicator is a cell that is not permitted to be subject to celery selection, the indicator is excluded from the targets for calculating Srxlev in step ST1303. As a result, in selecting the best cell, a cell that is not permitted to be subject to celery selection is not selected.
本変形例では、ステップST1303において、該インジケータによりセルリセレクション対象となることが許可されたセルに対してのみ、Srxlevを算出するようにしたが、これに限らない。たとえばステップST1302に示すセルリセレクションのためのセルの受信電力の測定の際に、該インジケータによりセルリセレクションの対象となることが許可されたセルのみの測定を行うようにしてもよい。また、たとえばセルランキングおよびベストセルの選択方法として、図13~図16のステップST1306の処理を行う場合は、ステップST1306において、該インジケータによりセルリセレクション対象となることが許可されたセルに対してのみ、Rs,Rnを算出するようにしてもよい。また図17のステップST1701の処理を行う場合は、ステップST1701において、該インジケータによりセルリセレクション対象となることが許可されたセルに対してのみ、Rs_total,Rn_totalを算出するようにしてもよい。該インジケータによりセルリセレクション対象となることが許可されたセルから、ベストセルが選択されればよい。
In this modification, Srxlev is calculated only for the cells permitted to be subject to celery selection by the indicator in step ST1303, but the present invention is not limited to this. For example, when measuring the received power of a cell for celery selection shown in step ST1302, only the cell permitted to be subject to celery selection by the indicator may be measured. Further, for example, when performing the process of step ST1306 in FIG. 13 to FIG. 16 as the cell ranking and best cell selection method, in step ST1306, only the cells that are permitted to be subject to cell reselection by the indicator. , Rs, Rn may be calculated. When performing the processing of step ST1701 in FIG. 17, Rs_total and Rn_total may be calculated only for the cells that are permitted to be subject to cell reselection by the indicator in step ST1701. The best cell may be selected from the cells permitted to be subject to celery selection by the indicator.
サービングセルは、隣接セルの該インジケータを認識する必要がある。この方法は、実施の形態2で開示した、サービングセルが隣接セルのバックホールリンクの通信品質を認識する方法と同様にすればよい。
The serving cell needs to recognize the indicator of the neighboring cell. This method may be the same as the method disclosed in Embodiment 2 in which the serving cell recognizes the communication quality of the backhaul link of the neighboring cell.
また、サービングセルが該インジケータを報知する方法は、実施の形態2で開示した、サービングセルが隣接セルのバックホールリンクの通信品質を報知する方法と同様にすればよい。
Also, the method of notifying the indicator by the serving cell may be the same as the method of notifying the communication quality of the backhaul link of the adjacent cell disclosed by the second embodiment.
各セルは、自セルのバックホールリンクの通信品質を測定し、その測定結果に応じて該インジケータの値を設定するようにしておく。こうすることで、バックホールリンクの通信品質が悪く、バックホールリンクの通信が十分に行なえない状態においては、該インジケータにより、セルリセレクション対象となることを許可しないようにできるので、セルリセレクションの際に、UEが該セルを選択してしまうことを防ぐことができる。
Each cell measures the communication quality of its own backhaul link and sets the value of the indicator according to the measurement result. In this way, when the backhaul link communication quality is poor and the backhaul link communication is not sufficient, the indicator can be used to prevent the cell reselection from being permitted. In addition, it is possible to prevent the UE from selecting the cell.
また、本変形例で開示した方法とすることで、実施の形態2で記載した効果に加えて、以下の効果を得ることができる。バックホールリンクの通信品質が極めて悪いセルが存在する場合などに、セルリセレクション対象から該セルを外すことが可能となるため、セルリセレクション制御を簡易にすることができる。また、UEの消費電力の削減を図ることができる。
In addition to the effects described in the second embodiment, the following effects can be obtained by using the method disclosed in the present modification. When there is a cell with extremely poor communication quality of the backhaul link, the cell can be removed from the cell reselection target, so that the cell reselection control can be simplified. In addition, the power consumption of the UE can be reduced.
また、該インジケータは、実施の形態2で記載した各セルのバックホールリンクの通信品質よりも少ない情報量にできるので、各セルからサービングセルへ通知する情報量やサービングセルから報知する情報量を削減することが可能となる。
In addition, since the indicator can have a smaller amount of information than the communication quality of the backhaul link of each cell described in Embodiment 2, the amount of information notified from each cell to the serving cell and the amount of information broadcast from the serving cell can be reduced. It becomes possible.
該インジケータを1ビットとしてもよい。1(あるいは0)が、セルリセレクション対象となることを許可することを示し、0(あるいは1)がセルリセレクション対象となることを許可しないことを示すようにする。これにより、最小の情報量で実現可能となる。
The indicator may be 1 bit. 1 (or 0) indicates that it is permitted to become a celery selection target, and 0 (or 1) indicates that it is not permitted to be a celery selection target. As a result, it can be realized with a minimum amount of information.
本変形例では、サービングセルが、自セルがセルリセレクション対象となることを許可するかどうかを示すインジケータと、隣接セルがセルリセレクション対象となることを許可するかどうかを示すインジケータとを報知するようにしたが、各セルが、自セルがセルリセレクション対象となることを許可するかどうかを示すインジケータを報知するようにしてもよい。この場合は、実施の形態2の変形例1で開示した方法と同様に、セルリセレクションのためのセルの測定を開始するUEは、図17に示すステップST1302でのセルの測定の際に、各セルが報知する該インジケータを受信するようにしておけばよい。これにより、サービングセルが隣接セルの該インジケータを報知する必要がなくなる。各セルが該インジケータを報知する方法は、実施の形態2の変形例1の方法と同様にすればよい。
In this modification, the serving cell broadcasts an indicator that indicates whether the own cell is permitted to be subject to celery selection, and an indicator that indicates whether neighboring cells are allowed to be subject to celery selection. However, each cell may notify an indicator indicating whether or not each cell is permitted to be subject to celery selection. In this case, as in the method disclosed in the first modification of the second embodiment, the UE that starts measuring the cell for celery selection performs each cell measurement in step ST1302 illustrated in FIG. The indicator broadcast by the cell may be received. This eliminates the need for the serving cell to report the indicator of the neighboring cell. The method for notifying each cell of the indicator may be the same as the method of the first modification of the second embodiment.
各セルが、自セルがセルリセレクション対象となることを許可するかどうかを示すインジケータを報知するようにすることで、さらに以下の効果を得ることができる。サービングセルが報知する情報から、隣接セルの情報を削減することができる。また、各セルは、自セルのバックホールリンクの通信品質や該セルのアイデンティティ(PCI、GCI)を隣接セルに通知しなくてもよくなる。したがって、エアインタフェースやX2インタフェース、S1インタフェースにおけるシグナリング負荷を削減することが可能となる。また、このため、大量に、そして任意の場所に設置されるHeNBを含むネットワークにおいても簡易な構成のシステムを構築することが可能となる。
The following effects can be further obtained by notifying each cell of an indicator indicating whether or not each cell is permitted to be subject to celery selection. Neighboring cell information can be reduced from information broadcast by the serving cell. In addition, each cell does not need to notify the neighboring cell of the communication quality of the backhaul link of the own cell and the identity (PCI, GCI) of the cell. Accordingly, it is possible to reduce the signaling load on the air interface, the X2 interface, and the S1 interface. For this reason, it is possible to construct a system having a simple configuration even in a network including a large amount of HeNBs installed at an arbitrary place.
実施の形態2 変形例3.
本変形例では、セルランキング時にサービングセルおよび隣接セルの少なくともいずれか一方のバックホールリンクの通信品質を入れこむ別の方法を開示する。本変形例では、受信品質が、ある値以上のセルがある場合、バックホールリンクの受信品質を考慮してセルランキングを行うようにする。該ある値として、受信品質閾値(基準値)を設ける。Embodiment 2 Modification 3
In this modified example, another method of incorporating the communication quality of the backhaul link of at least one of the serving cell and the neighboring cell at the time of cell ranking is disclosed. In this modification, when there is a cell whose reception quality exceeds a certain value, cell ranking is performed in consideration of the reception quality of the backhaul link. A reception quality threshold value (reference value) is provided as the certain value.
本変形例では、セルランキング時にサービングセルおよび隣接セルの少なくともいずれか一方のバックホールリンクの通信品質を入れこむ別の方法を開示する。本変形例では、受信品質が、ある値以上のセルがある場合、バックホールリンクの受信品質を考慮してセルランキングを行うようにする。該ある値として、受信品質閾値(基準値)を設ける。
In this modified example, another method of incorporating the communication quality of the backhaul link of at least one of the serving cell and the neighboring cell at the time of cell ranking is disclosed. In this modification, when there is a cell whose reception quality exceeds a certain value, cell ranking is performed in consideration of the reception quality of the backhaul link. A reception quality threshold value (reference value) is provided as the certain value.
図18は、受信品質が、ある値以上のセルがある場合に、バックホールリンクの受信品質を考慮してセルランキングを行うセルリセレクションの処理手順を示すフローチャートである。図18に示すフローチャートの処理は、図13および図16に示すフローチャートの処理と類似しているので、異なる処理についてのみ説明し、対応する部分については同一のステップ番号を付して、処理の説明を省略する。セルリセレクションのための測定を開始するまでの動作は、実施の形態1の変形例2で開示した方法を用いているが、これに限らない。実施の形態1または実施の形態1の変形例1で開示した方法であってもよい。
FIG. 18 is a flowchart showing a processing procedure of cell reselection in which cell ranking is performed in consideration of the reception quality of the backhaul link when there is a cell whose reception quality is a certain value or more. The process of the flowchart shown in FIG. 18 is similar to the process of the flowcharts shown in FIGS. 13 and 16, so only the different processes will be described, and the corresponding parts will be denoted by the same step numbers and the description of the processes Is omitted. The operation until the measurement for celery selection is started uses the method disclosed in the second modification of the first embodiment, but is not limited thereto. The method disclosed in the first embodiment or the first modification of the first embodiment may be used.
本変形例では、ステップST1304で、Srxlevが0より大きくなったセルについて、UEは、ステップST1801の処理を行う。ステップST1801で、UEは、セルの受信品質が受信品質閾値(基準値)以上か否か、具体的には、セルの受信品質を表す受信電力測定値が受信品質閾値(基準値)以上か否かを判断する。受信電力測定値が受信品質閾値(基準値)以上の場合は、ステップST1803へ移行する。受信電力測定値が受信品質閾値(基準値)より小さい場合は、ステップST1802へ移行する。
In this modification, the UE performs the process of step ST1801 for the cell in which Srxlev is greater than 0 in step ST1304. In Step ST1801, the UE determines whether the reception quality of the cell is equal to or higher than the reception quality threshold (reference value), specifically, whether the received power measurement value indicating the reception quality of the cell is equal to or higher than the reception quality threshold (reference value). Determine whether. When the received power measurement value is greater than or equal to the reception quality threshold (reference value), the mobile terminal makes a transition to step ST1803. When the received power measurement value is smaller than the reception quality threshold value (reference value), the mobile terminal makes a transition to step ST1802.
ステップST1304でSrxlevが0より大きくなったセルのうち、ステップST1801で受信電力測定値が受信品質閾値(基準値)以上となるセルがある場合、ステップST1803で、UEは、該セルの中で、バックホールリンクの通信品質でセルランキングを行い、バックホールリンクの通信品質が最も良好なセルをベストセルとして選択する。そして、UEは、ステップST1803で選択したベストセルにセルリセレクションを行う。受信品質閾値(基準値)を、UEがセルリセレクションを行うのに必要な受信品質に設定することで、受信品質測定値が該必要な受信品質を満足したセルの中から、該セルのバックホールリンクの通信品質に応じてベストセルを選択することができる。
Among the cells in which Srxlev is greater than 0 in step ST1304, if there is a cell whose received power measurement value is equal to or greater than the reception quality threshold (reference value) in step ST1801, in step ST1803, the UE Cell ranking is performed based on the communication quality of the backhaul link, and the cell with the best communication quality of the backhaul link is selected as the best cell. Then, the UE performs celery selection on the best cell selected in step ST1803. By setting the reception quality threshold (reference value) to the reception quality required for the UE to perform cell reselection, the cell backhaul is received from the cells whose reception quality measurement values satisfy the required reception quality. The best cell can be selected according to the communication quality of the link.
ステップST1304でSrxlevが0より大きくなったセルのうち、ステップST1801で受信電力測定値が受信品質閾値(基準値)以上となるセルが無い場合、ステップST1802で、UEは、該セルの中から、受信品質で、具体的には受信電力測定値でセルランキングを行う。このセルランキング方法は、従来のセルランキング方法と同じとすることができる。UEは、ステップST1802で、受信電力測定値が最も良好なセルをベストセルとして選択する。そして、UEは、ステップST1802で選択したベストセルにセルリセレクションを行う。
Among the cells in which Srxlev is greater than 0 in step ST1304, if there is no cell whose received power measurement value is equal to or greater than the reception quality threshold (reference value) in step ST1801, in step ST1802, the UE Cell ranking is performed based on the reception quality, specifically, the received power measurement value. This cell ranking method can be the same as the conventional cell ranking method. In step ST1802, the UE selects the cell with the best received power measurement value as the best cell. Then, the UE performs celery selection on the best cell selected in step ST1802.
該受信品質閾値(基準値)は一つであってもよいし、複数であってもよく、例えばセル毎にあってもよい。例えば受信品質閾値(基準値)がセル毎に設けられる場合、ステップST1801で判断対象とするセル毎に該受信品質閾値(基準値)を用いるようにすればよい。該受信品質閾値(基準値)をセル毎に設ける場合、セルのアイデンティティ(PCI,GCI)と関連付けるようにしておくとよい。こうすることで、セル毎の状況を考慮できるため、より緻密なセルリセレクションが可能となる。
The reception quality threshold value (reference value) may be one or plural, for example, for each cell. For example, when a reception quality threshold (reference value) is provided for each cell, the reception quality threshold (reference value) may be used for each cell to be determined in step ST1801. When the reception quality threshold value (reference value) is provided for each cell, it may be associated with the cell identity (PCI, GCI). By doing so, since the situation for each cell can be taken into consideration, more precise celery selection becomes possible.
該受信品質閾値(基準値)をサービングセルが報知してもよいし、各セルが報知してもよい。サービングセルが報知する場合はSIB3に含めて報知してもよいし、あるいはSIB1に含めて報知してもよいし、SIB4に含めて報知してもよい。SIB3で報知する場合、セルリセレクション用パラメータが含まれるので、他のセルリセレクション用パラメータと一緒に受信することが可能となる。このため、UEの受信動作を簡略化でき、また、制御誤動作の削減が可能となる。SIB1の場合、予め報知されるタイミングが決められているので、UEはメジャメント時に早期に受信可能となる。このため、UEのメジャメント動作において制御遅延を小さくすることが可能となる。SIB4で報知する場合、隣接セルの情報が含まれるので、他の隣接セルの情報、例えばPCIと関連付けて受信することが可能となる。SIB4での報知は、該受信品質閾値(基準値)をセル毎に設ける場合などに適し、UEの受信動作を簡略化でき、また、制御誤動作の削減が可能となるという利点を有する。
The serving cell may notify the reception quality threshold (reference value), or each cell may notify. When the serving cell notifies, it may be included in SIB3, notified in SIB1, or included in SIB4. In the case of broadcasting by SIB3, since the celery selection parameter is included, it can be received together with other celery selection parameters. For this reason, the reception operation of the UE can be simplified, and the control malfunction can be reduced. In the case of SIB1, since the timing to be notified in advance is determined, the UE can receive early at the time of measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE. When broadcasting by SIB4, since information on neighboring cells is included, it is possible to receive information in association with information on other neighboring cells, for example, PCI. Broadcasting by SIB4 is suitable when the reception quality threshold value (reference value) is provided for each cell, and has an advantage that the reception operation of the UE can be simplified and the control malfunction can be reduced.
各セルが受信品質閾値(基準値)を報知する場合は、SIB1に含めて報知してもよい。SIB1の場合、予め報知されるタイミングが決められているので、UEはメジャメント時に早期に受信可能となる。このため、UEのメジャメント動作において制御遅延を小さくすることが可能となる。
When each cell broadcasts the reception quality threshold (reference value), it may be broadcast by including it in SIB1. In the case of SIB1, since the timing to be notified in advance is determined, the UE can receive early at the time of measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE.
該受信品質閾値(基準値)は報知されるのではなく、静的な値として予め決められていてもよい。この場合、UEは、予め決められた値を用いることができる。UEは、該受信品質閾値(基準値)を報知される必要がなくなるので、シグナリング負荷の削減、UEの消費電力の削減が可能となる。
The reception quality threshold (reference value) may be determined in advance as a static value instead of being notified. In this case, the UE can use a predetermined value. Since the UE does not need to be notified of the reception quality threshold (reference value), the signaling load can be reduced and the power consumption of the UE can be reduced.
また、該受信品質閾値(基準値)に、初期値として予め決められた値を用い、該受信品質閾値(基準値)がサービングセルあるいは各セルから報知された場合に、初期値に代えて報知された各々のセルの該受信品質閾値(基準値)を用いるようにしてもよい。この場合、サービングセルあるいは各セルは、必要に応じて該受信品質閾値(基準値)を報知すればよい。
In addition, when a predetermined value is used as the initial value for the reception quality threshold (reference value), and the reception quality threshold (reference value) is reported from the serving cell or each cell, it is notified instead of the initial value. Alternatively, the reception quality threshold value (reference value) of each cell may be used. In this case, the serving cell or each cell may notify the reception quality threshold (reference value) as necessary.
UEは、ステップST1803で、バックホールリンクの通信品質をもとにベストセルを選択する。したがって、UEは、サービングセルおよび各セルのバックホールリンクの通信品質を認識しておく必要がある。この方法については、実施の形態2、実施の形態2の変形例1などを用いるとよい。
In step ST1803, the UE selects the best cell based on the communication quality of the backhaul link. Therefore, the UE needs to recognize the communication quality of the serving cell and the backhaul link of each cell. For this method, Embodiment 2, Modification 1 of Embodiment 2, or the like may be used.
本変形例で開示した方法とすることで、実施の形態2、実施の形態2の変形例1で記載した効果に加えて、以下の効果を得ることができる。通信に十分な受信品質を得られている場合は、バックホールリンクの通信品質によって、ベストセルを選択することが可能となる。受信品質を優先して選択するセルを決定することができるため、セルを見つけやすくできる。また、UEがバックホールリンクの通信品質を用いて、トータルの受信品質を導出する必要が無い。したがって、UEのセルリセレクション制御が容易となり、UEの低消費電力化を図ることができる。
By using the method disclosed in this modification, the following effects can be obtained in addition to the effects described in the second embodiment and the first modification of the second embodiment. When sufficient reception quality is obtained for communication, the best cell can be selected depending on the communication quality of the backhaul link. Since the cell to be selected with priority on the reception quality can be determined, the cell can be easily found. Further, it is not necessary for the UE to derive the total reception quality using the communication quality of the backhaul link. Therefore, the celery selection control of the UE becomes easy, and the power consumption of the UE can be reduced.
本変形例では、図18において、ステップST1304のSrxlevによる判断とは別に、ステップST1801で、受信品質が受信品質閾値(基準値)以上か否かの判断を行っている。この二つの判断を一つにして、ステップST1801およびステップST1802の処理を無くしてもよい。この場合には、以下のようにする。
In this modified example, in FIG. 18, apart from the determination by Srxlev in step ST1304, it is determined in step ST1801 whether or not the reception quality is equal to or higher than the reception quality threshold (reference value). By making these two judgments as one, the processing of step ST1801 and step ST1802 may be eliminated. In this case, the following is performed.
ステップST1304では、セル毎の受信電力測定値に、あるオフセット値を考慮してSrxlevを導出していることを述べた。このオフセットの他に、新たなオフセットを設けて、受信品質閾値(基準値)を考慮した値を該新たなオフセット値とすればよい。該新たなオフセットを、Srxlevを導出する際に用いることで、受信品質閾値(基準値)も考慮に入れることが可能となる。該新たなオフセットを設けるのではなく、既存のオフセットに受信品質閾値(基準値)を考慮した値を入れ込むようにしてもよい。
In step ST1304, it was described that Srxlev was derived in consideration of a certain offset value for the received power measurement value for each cell. In addition to this offset, a new offset may be provided, and a value considering the reception quality threshold (reference value) may be used as the new offset value. By using the new offset when deriving Srxlev, the reception quality threshold value (reference value) can be taken into consideration. Instead of providing the new offset, a value considering the reception quality threshold value (reference value) may be inserted into the existing offset.
このようにして、ステップST1304のSrxlevによる判断と、ステップST1801の受信品質が受信品質閾値(基準値)以上か否かの判断とを一つのステップで行うことによって、UEでの判断を簡易にすることが可能となる。また、従来のセルのランキング方法と同様にすることが可能となる。
In this way, the determination by Srxlev in step ST1304 and the determination of whether the reception quality in step ST1801 is equal to or higher than the reception quality threshold (reference value) are performed in one step, thereby simplifying the determination in the UE. It becomes possible. Further, it can be performed in the same manner as the conventional cell ranking method.
実施の形態2 変形例4.
本変形例では、セルランキング時にサービングセルおよび隣接セルの少なくともいずれか一方のバックホールリンクの通信品質を入れこむ別の方法を開示する。本変形例では、バックホールリンクの通信品質が、ある値以上のセルがある場合、セルの受信品質を考慮してセルランキングを行うようにする。該ある値として、バックホール閾値(基準値)を設ける。Embodiment 2 Modification 4
In this modified example, another method of incorporating the communication quality of the backhaul link of at least one of the serving cell and the neighboring cell at the time of cell ranking is disclosed. In this modification, when there is a cell whose backhaul link communication quality exceeds a certain value, cell ranking is performed in consideration of the reception quality of the cell. As the certain value, a backhaul threshold value (reference value) is provided.
本変形例では、セルランキング時にサービングセルおよび隣接セルの少なくともいずれか一方のバックホールリンクの通信品質を入れこむ別の方法を開示する。本変形例では、バックホールリンクの通信品質が、ある値以上のセルがある場合、セルの受信品質を考慮してセルランキングを行うようにする。該ある値として、バックホール閾値(基準値)を設ける。
In this modified example, another method of incorporating the communication quality of the backhaul link of at least one of the serving cell and the neighboring cell at the time of cell ranking is disclosed. In this modification, when there is a cell whose backhaul link communication quality exceeds a certain value, cell ranking is performed in consideration of the reception quality of the cell. As the certain value, a backhaul threshold value (reference value) is provided.
図19は、バックホールリンクの通信品質が、ある値以上のセルがある場合、セルの受信品質を考慮してセルランキングを行うセルリセレクションの処理手順を示すフローチャートである。図19に示すフローチャートの処理は、図13および図16に示すフローチャートの処理と類似しているので、異なる処理についてのみ説明し、対応する部分については同一のステップ番号を付して、処理の説明を省略する。セルリセレクションのための測定を開始するまでの動作は、実施の形態1の変形例2で開示した方法を用いているが、これに限らない。実施の形態1または実施の形態1の変形例1で開示した方法であってもよい。
FIG. 19 is a flowchart showing a processing procedure of cell reselection in which cell ranking is performed in consideration of the reception quality of a cell when the communication quality of the backhaul link exceeds a certain value. The processing of the flowchart shown in FIG. 19 is similar to the processing of the flowcharts shown in FIGS. 13 and 16, so only the different processing will be described, and the corresponding steps will be denoted by the same step numbers and the description of the processing. Is omitted. The operation until the measurement for celery selection is started uses the method disclosed in the second modification of the first embodiment, but is not limited thereto. The method disclosed in the first embodiment or the first modification of the first embodiment may be used.
本変形例では、ステップST1304で、Srxlevが0より大きくなったセルについて、UEは、ステップST1901の処理を行う。ステップST1901で、UEは、セルのバックホールリンクの通信品質がバックホール閾値(基準値)以上か否かを判断する。バックホールリンクの通信品質がバックホール閾値(基準値)以上の場合は、ステップST1903へ移行する。バックホールリンクの通信品質がバックホール閾値(基準値)より小さい場合は、ステップST1902へ移行する。
In this modification, the UE performs the process of step ST1901 for the cell in which Srxlev is greater than 0 in step ST1304. In Step ST1901, the UE determines whether or not the communication quality of the cell backhaul link is equal to or higher than a backhaul threshold (reference value). When the communication quality of a backhaul link is more than a backhaul threshold value (reference value), it transfers to step ST1903. When the communication quality of a backhaul link is smaller than a backhaul threshold value (reference value), it transfers to step ST1902.
ステップST1304でSrxlevが0より大きくなったセルのうち、ステップST1901でバックホールリンクの通信品質がバックホール閾値(基準値)以上となるセルがある場合、ステップST1903で、UEは、該セルの中で、受信品質、具体的には受信電力測定値によりセルランキングを行い、受信品質、具体的には受信電力測定値が最も良好なセルをベストセルとして選択する。このセルランキング方法は、従来のセルランキング方法と同じとすることができる。そして、UEは、ステップST1903で選択したベストセルにセルリセレクションを行う。バックホール閾値(基準値)を、UEがセルリセレクションを行うのに必要なバックホールリンクの通信品質に設定することで、バックホールリンクの通信品質が、該必要なバックホールリンクの通信品質を満足したセルの中から、該セルの受信品質、具体的には受信電力測定値に応じてベストセルを選択することができる。
If there is a cell in which the communication quality of the backhaul link is greater than or equal to the backhaul threshold (reference value) in step ST1901 among the cells in which Srxlev is greater than 0 in step ST1304, in step ST1903, the UE Then, cell ranking is performed based on the reception quality, specifically, the received power measurement value, and the cell having the best reception quality, specifically, the received power measurement value, is selected as the best cell. This cell ranking method can be the same as the conventional cell ranking method. And UE performs celery selection to the best cell selected by step ST1903. By setting the backhaul threshold (reference value) to the communication quality of the backhaul link necessary for the UE to perform cell reselection, the communication quality of the backhaul link satisfies the required communication quality of the backhaul link. The best cell can be selected from the received cells according to the reception quality of the cell, specifically, the received power measurement value.
ステップST1304で、Srxlevが0より大きくなったセルのうち、ステップST1901でバックホールリンクの通信品質がバックホール閾値(基準値)以上となるセルが無い場合、ステップST1902で、UEは、該セルの中からバックホールリンクの通信品質によってセルランキングを行う。UEは、ステップST1902で、バックホールリンクの通信品質が最も良好なセルをベストセルとして選択する。そして、UEは、ステップST1902で選択したベストセルにセルリセレクションを行う。
If there is no cell whose backhaul link communication quality is equal to or higher than the backhaul threshold (reference value) in step ST1901 among the cells in which Srxlev is greater than 0 in step ST1304, in step ST1902, the UE Cell ranking is performed according to the communication quality of the backhaul link. In step ST1902, the UE selects the cell with the best communication quality of the backhaul link as the best cell. And UE performs celery selection to the best cell selected by step ST1902.
該バックホール閾値(基準値)の設定方法やUEへの通知方法などについては、実施の形態2の変形例3で記載した受信品質閾値(基準値)と同様に設定すればよい。サービングセルと各セルとのバックホールリンクの通信品質についても、実施の形態2の変形例3で記載した方法と同様にすればよい。
The setting method of the backhaul threshold value (reference value), the notification method to the UE, and the like may be set similarly to the reception quality threshold value (reference value) described in the third modification of the second embodiment. The communication quality of the backhaul link between the serving cell and each cell may be the same as the method described in the third modification of the second embodiment.
本変形例で開示した方法とすることで、実施の形態2、実施の形態2の変形例1で記載した効果に加えて、以下の効果を得ることができる。通信に十分なバックホールリンクの通信品質が得られている場合は、セルの受信品質、具体的には受信電力測定値によって、ベストセルを選択することが可能となる。バックホールリンクの通信品質を優先して選択するセルを決定することができるため、確実なリンクを設定できるセルを見つけやすくできる。
By using the method disclosed in this modification, the following effects can be obtained in addition to the effects described in the second embodiment and the first modification of the second embodiment. When the communication quality of the backhaul link sufficient for communication is obtained, it is possible to select the best cell according to the reception quality of the cell, specifically, the received power measurement value. Since it is possible to determine a cell to be selected with priority on the communication quality of the backhaul link, it is possible to easily find a cell in which a reliable link can be set.
また、UEがバックホールリンクの通信品質を用いて、トータルの受信品質を導出する必要が無い。したがって、UEのセルリセレクション制御が容易となり、UEの低消費電力化を図ることができる。
Also, it is not necessary for the UE to derive the total reception quality using the communication quality of the backhaul link. Therefore, the celery selection control of the UE becomes easy, and the power consumption of the UE can be reduced.
実施の形態3.
本実施の形態では、セルリセレクションにサービングセルおよび隣接セルの少なくともいずれか一方のバックホールリンクの通信品質を考慮に入れる別の方法を開示する。本実施の形態では、UEの通信速度に応じたバックホールリンクの通信品質を考慮に入れる。 Embodiment 3 FIG.
In the present embodiment, another method is disclosed in which the communication quality of the backhaul link of at least one of the serving cell and the neighboring cell is taken into consideration for cell reselection. In the present embodiment, the communication quality of the backhaul link according to the communication speed of the UE is taken into consideration.
本実施の形態では、セルリセレクションにサービングセルおよび隣接セルの少なくともいずれか一方のバックホールリンクの通信品質を考慮に入れる別の方法を開示する。本実施の形態では、UEの通信速度に応じたバックホールリンクの通信品質を考慮に入れる。 Embodiment 3 FIG.
In the present embodiment, another method is disclosed in which the communication quality of the backhaul link of at least one of the serving cell and the neighboring cell is taken into consideration for cell reselection. In the present embodiment, the communication quality of the backhaul link according to the communication speed of the UE is taken into consideration.
一例として、UEは、自UEの所望通信速度に応じて、必要なバックホールリンクの通信品質を満足するセルの中でセルランキングを行う。通信速度に応じて所望のバックホールリンクの通信品質は異なる。例えば、高速大容量の通信には、高いバックホールリンクの通信品質が要求され、低速小容量の通信には、低いバックホールリンクの通信品質でよい。そこで、UEの所望通信速度に応じて必要なバックホールリンクの通信品質を満足するセルの中でセルランキングを行うようにする。
As an example, the UE performs cell ranking among cells satisfying the required communication quality of the backhaul link according to the desired communication speed of the own UE. The communication quality of the desired backhaul link varies depending on the communication speed. For example, high backhaul communication quality is required for high speed and large capacity communication, and low backhaul link communication quality may be used for low speed and small capacity communication. Therefore, cell ranking is performed among cells satisfying the required communication quality of the backhaul link according to the desired communication speed of the UE.
UEの所望通信速度に応じた所望のバックホールリンクの通信品質を与える方法として、例えば、UEの通信速度に応じて必要なバックホールリンク通信品質の閾値を設けるとよい。UEは、自UEの所望通信速度から、該通信速度に対応するバックホールリンク通信品質の閾値を導出し、該閾値より高いバックホールリンクの通信品質を有するセルの中からセルランキングによってセルを選択する。
As a method of providing desired backhaul link communication quality according to the desired communication speed of the UE, for example, a threshold value of required backhaul link communication quality according to the communication speed of the UE may be provided. The UE derives a threshold value of the backhaul link communication quality corresponding to the communication speed from the desired communication speed of the own UE, and selects a cell by cell ranking from cells having a communication quality of the backhaul link higher than the threshold value. To do.
UEの通信速度とバックホールリンクの通信品質の閾値との対応関係は、静的な値として予め決めておいてもよいし、あるいは、サービングセルあるいは各セルから報知するようにしてもよい。また、初期値として静的な値としておき、その後、サービングセルあるいは各セルから報知するようにして、初期値に代えて報知された値を用いるようにしてもよい。
The correspondence relationship between the UE communication speed and the backhaul link communication quality threshold value may be determined in advance as a static value, or may be reported from the serving cell or each cell. Alternatively, a static value may be set as the initial value, and then notified from the serving cell or each cell, and the notified value may be used instead of the initial value.
UEの通信速度とバックホールリンクの通信品質の閾値との対応関係は、対応表を設けておいてもよいし、適切な関数を用いてUEの通信速度から導出するようにしてもよい。適切な関数を用いる場合は、該関数を予め決めておくようにしてもよい。
The correspondence relationship between the communication speed of the UE and the threshold value of the communication quality of the backhaul link may be provided with a correspondence table, or may be derived from the communication speed of the UE using an appropriate function. When an appropriate function is used, the function may be determined in advance.
UEの所望通信速度について述べたが、これに限らず、UEの送信バッファ状態や、UEがどれだけの通信速度に対応可能であるかを示すUEのケーパビリティを考慮に入れるようにしてもよい。この場合、UEの送信バッファ状態や、UEのケーパビリティに応じて、バックホールリンクの通信品質の閾値と対応付けるようにしておけばよい。
Although the desired communication speed of the UE has been described, the present invention is not limited thereto, and the UE's transmission buffer state and the UE's capability indicating how much communication speed the UE can support may be taken into consideration. . In this case, what is necessary is just to make it match | combine with the threshold value of the communication quality of a backhaul link according to the transmission buffer state of UE, or the capability of UE.
本実施の形態で開示した方法とすることで、実施の形態2、実施の形態2の変形例1で記載した効果に加えて、UEの所望通信速度を考慮したセルリセレクションを可能にすることができる。
By adopting the method disclosed in the present embodiment, in addition to the effects described in the second embodiment and the first modification of the second embodiment, it is possible to enable celery selection in consideration of the desired communication speed of the UE. it can.
実施の形態4.
前述のように、ヘテロジーニアスネットワークスにおける干渉低減方法およびキャパシティ改善方法として、非特許文献8に、弱受信電力のセルの測定とトリガメカニズムとが必要であることが提案されているが、具体的な方法については、何ら記載されていない。 Embodiment 4 FIG.
As described above, as an interference reduction method and capacity improvement method in heterogeneous networks, Non-Patent Document 8 proposes that measurement of a cell with a weak reception power and a trigger mechanism are necessary. There is no mention of a practical method.
前述のように、ヘテロジーニアスネットワークスにおける干渉低減方法およびキャパシティ改善方法として、非特許文献8に、弱受信電力のセルの測定とトリガメカニズムとが必要であることが提案されているが、具体的な方法については、何ら記載されていない。 Embodiment 4 FIG.
As described above, as an interference reduction method and capacity improvement method in heterogeneous networks, Non-Patent Document 8 proposes that measurement of a cell with a weak reception power and a trigger mechanism are necessary. There is no mention of a practical method.
非特許文献10に、ヘテロジーニアスネットワークスにおいては、下りリンクで最適なセルと、上りリンクで最適なセルとは異なるという問題があることが記載されている。
Non-Patent Document 10 describes that in heterogeneous networks, there is a problem that the optimum cell in the downlink is different from the optimum cell in the uplink.
このような問題が生じる状況として、たとえば、マクロセルのカバレッジ内にHeNBが配置されている場合がある。マクロセルのカバレッジは、HeNBのカバレッジと比較して大きい。よってマクロセルの下り送信パワーは、HeNBの下り送信パワーより大きい。マクロセルよりHeNBの近くにUEが位置した場合であっても、下り受信品質としては、マクロセルの方がHeNBより良好となる場合がある。しかし、該UEは、マクロセルよりHeNBの近くに位置するため、上りリンクの通信品質としては、HeNBの方がマクロセルより良好となる。
As a situation where such a problem occurs, for example, there is a case where a HeNB is arranged in the coverage of a macro cell. The macro cell coverage is large compared to the HeNB coverage. Therefore, the downlink transmission power of the macro cell is larger than the downlink transmission power of the HeNB. Even when the UE is located closer to the HeNB than the macro cell, the macro cell may be better than the HeNB as downlink reception quality. However, since the UE is located closer to the HeNB than the macro cell, the HeNB is better than the macro cell as uplink communication quality.
このような問題を解消するために、非特許文献10には、上りリンクと下りリンクとで異なるセルに独立に接続させることが開示されているが、この具体的方法については、何ら記載されていない。また、上りリンクと下りリンクとで異なるセルに接続させることは、UEがサービングセルを複数有することになるため、通信制御が非常に複雑になってしまうと考えられる。
In order to solve such a problem, Non-Patent Document 10 discloses that the uplink and the downlink are independently connected to different cells, but this specific method is not described at all. Absent. In addition, connecting to different cells in the uplink and the downlink is considered to make communication control very complicated because the UE has a plurality of serving cells.
これらの問題を解消するために、本実施の形態では、セルリセレクションにおいて、上りリンクの状態も考慮に入れることで、弱受信電力のセルへのリセレクションを可能にする方法を開示する。上りリンクの状態は選択情報に相当し、上りリンクは上り通信回線に相当する。
In order to solve these problems, the present embodiment discloses a method that enables reselection to a cell with weak received power by taking the uplink state into consideration in cell reselection. The uplink state corresponds to selection information, and the uplink corresponds to an uplink communication line.
下りリンクで最適なセルと、上りリンクで最適なセルとは異なるため、上りリンクで最適なセルが、下りリンクにおいては弱受信電力のセルとなる場合がある。従来のセルリセレクションでは、下りリンクの受信電力によってセルランキングを行っているため、このような場合に、上りリンクで最適なセルへのセルリセレクションは行えない。そこで、本実施の形態では、セルリセレクションにおいて、上りリンクの状態も考慮に入れることとする。
Since the optimal cell in the downlink is different from the optimal cell in the uplink, the optimal cell in the uplink may be a cell with weak received power in the downlink. In conventional cell reselection, cell ranking is performed based on downlink received power, and in such a case, cell reselection to an optimal cell in the uplink cannot be performed. Therefore, in the present embodiment, the uplink state is also taken into consideration in celery selection.
セルリセレクションにおいて、上りリンクの状態も考慮に入れるために、本実施の形態では、セルリセレクションのための測定開始用サービングセルのパスロス閾値(以下「パスロス閾値(開始)」という場合がある)と、セルランキング用のセル毎のパスロス閾値(以下「パスロス閾値(基準値)」という場合がある)とを新たに設ける。
In this embodiment, in order to take the uplink state into consideration in celery selection, the cell loss threshold of the measurement start serving cell for celery selection (hereinafter also referred to as “path loss threshold (start)”), the cell A path loss threshold value for each cell for ranking (hereinafter sometimes referred to as “path loss threshold value (reference value)”) is newly provided.
これは、パスロスが小さいほど、上りリンクで最適なセルと判断できるためである。パスロスが小さいと、小さいUEの送信電力で、セルが上り信号を復調するために必要な受信電力を得ることができるためである。したがって、UEは低消費電力で動作可能となり、システムとしても上り干渉を低減することができる。
This is because the smaller the path loss, the more optimal the cell can be determined on the uplink. This is because if the path loss is small, the cell can obtain reception power necessary for demodulating the uplink signal with a small UE transmission power. Therefore, the UE can operate with low power consumption, and the uplink interference can be reduced as a system.
パスロスとして、上りリンクのパスロスを用いるようにしてもよいが、上りリンクのパスロスをUEが認識するのは複雑になるため、下りリンクのパスロスを用いるようにしてもよい。パスロスの相対値は、主にセルとUEの各々の位置によって生じるリンクの経路(パス)に依存するため、下りリンクのパスロスを用いても判断可能である。したがって、ここでは上りリンクの状態を考慮に入れるために、下りリンクのパスロスを用いるようにする。
As the path loss, an uplink path loss may be used, but since it is complicated for the UE to recognize the uplink path loss, a downlink path loss may be used. Since the relative value of the path loss mainly depends on the route (path) of the link caused by the positions of the cell and the UE, it can also be determined using the downlink path loss. Therefore, in order to take the uplink state into consideration, downlink path loss is used here.
図20は、上りリンクの状態も考慮に入れたセルリセレクションの処理手順を示すフローチャートである。図20に示すフローチャートの処理は、図13に示すフローチャートの処理と類似しているので、異なる処理についてのみ説明し、対応する部分については同一のステップ番号を付して、処理の説明を省略する。
FIG. 20 is a flowchart showing the processing procedure of celery selection taking into account the uplink state. The processing of the flowchart shown in FIG. 20 is similar to the processing of the flowchart shown in FIG. 13, so only the different processing will be described, the corresponding steps will be denoted by the same step numbers, and the description of the processing will be omitted. .
UEは、セルリセレクションのために、サービングセルの受信電力を測定する。ステップST1301で、UEは、SxとS_intrasearchとを比較し、SxがS_intrasearch以下となった場合に、サービングセルの受信電力が低いと判断し、セルリセレクションのための測定を開始する(ステップST1302)。UEは、SxがS_intrasearchよりも大きい場合は、ステップST2001で、サービングセルのパスロスとパスロス閾値(開始)とを比較する。サービングセルのパスロスは、UEが測定する。該パスロスの測定は、セルリセレクションのために行うサービングセルの受信電力の測定の際に行ってもよい。
UE measures the received power of the serving cell for celery selection. In step ST1301, the UE compares Sx and S_intrasearch, and when Sx is equal to or lower than S_intrasearch, the UE determines that the reception power of the serving cell is low and starts measurement for celery selection (step ST1302). When Sx is larger than S_intrasearch, the UE compares the path loss of the serving cell with the path loss threshold (start) in step ST2001. The UE measures the path loss of the serving cell. The path loss may be measured when measuring the received power of the serving cell for cell reselection.
ステップST2001で、UEは、サービングセルのパスロスがパスロス閾値(開始)以上となった場合は、上りリンクの状態が悪いと判断して、セルリセレクションのための測定を開始する(ステップST1302)。UEは、サービングセルのパスロスがパスロス閾値(開始)より小さい場合は、上りリンクの状態が通信に十分であると判断して、セルリセレクションのための測定を開始せず、ステップST1301に戻り、Sxを測定し、SxとS_intrasearchとを比較する。
In step ST2001, when the path loss of the serving cell is equal to or greater than the path loss threshold (start), the UE determines that the uplink state is bad and starts measurement for cell reselection (step ST1302). If the serving cell path loss is smaller than the path loss threshold (start), the UE determines that the uplink state is sufficient for communication, does not start measurement for cell reselection, returns to step ST1301, and sets Sx Measure and compare Sx and S_intrasearch.
ステップST2001のサービングセルのパスロスとパスロス閾値(開始)との比較は、ステップST1301の通常のサービングセルの受信電力測定値(Sx)と受信電力の閾値(S_intrasearch)との比較と、オア(or)条件で行われるようにするとよい。これによって、いずれかの条件が通信に不十分となった場合に、セルリセレクションのための測定を開始するようにできる。
The comparison between the path loss of the serving cell in step ST2001 and the path loss threshold (start) is based on the comparison between the received power measurement value (Sx) of the normal serving cell in step ST1301 and the threshold (S_intrasearch) of the received power, and the OR condition. It should be done. Thereby, when any of the conditions becomes insufficient for communication, measurement for celery selection can be started.
このように、サービングセルのパスロス閾値を設けて、セルリセレクションのための測定を開始するか否かの判断に用い、また、該判断をセルリセレクションのための測定開始条件に入れ込むことで、サービングセルの上りリンクの状態を考慮に入れることができる。
Thus, by setting a path loss threshold for the serving cell, it is used to determine whether or not to start measurement for celery selection, and by inserting this determination into the measurement start condition for celery selection, Uplink conditions can be taken into account.
ステップST1302で、セルリセレクションのための測定を開始したUEは、ステップST1303で、各セルの受信電力測定値よりSrxlevを算出し、ステップST1304でSrxlevが0より大きくなったセルについて、UEはステップST2002の処理を行う。ステップST1304でSrxlevが0より大きくなるセルが無い場合、UEはステップST1305に移行して、圏外状態になる。
The UE that has started measurement for cell reselection in step ST1302 calculates Srxlev from the received power measurement value of each cell in step ST1303. For the cell in which Srxlev is greater than 0 in step ST1304, the UE performs step ST2002. Perform the process. When there is no cell in which Srxlev is greater than 0 in Step ST1304, the UE moves to Step ST1305 and enters an out-of-service state.
ステップST2002で、UEは、セルのパスロス測定値がパスロス閾値(基準値)以下か否かを判断する。各セルのパスロスは、UEが測定する。パスロスの測定は、UEがステップST1302におけるセルリセレクションのための測定の際に行ってもよい。セルのパスロス測定値がパスロス閾値(基準値)以下の場合、ステップST2004へ移行する。セルのパスロス測定値がパスロス閾値(基準値)より大きい場合、ステップST2003へ移行する。
In step ST2002, the UE determines whether or not the cell path loss measurement value is equal to or less than the path loss threshold (reference value). The UE measures the path loss of each cell. The path loss may be measured when the UE performs measurement for celery selection in step ST1302. When the path loss measurement value of the cell is equal to or less than the path loss threshold value (reference value), the process proceeds to step ST2004. When the path loss measurement value of the cell is larger than the path loss threshold value (reference value), the process proceeds to step ST2003.
ステップST1304でSrxlevが0より大きくなったセルのうち、ステップST2002でパスロス測定値がパスロス閾値(基準値)以下となるセルがある場合、ステップST2004で、UEは、該セルの中で受信品質をもとにセルランキングを行い、受信品質が最も良好なセルをベストセルとして選択する。このセルランキング方法は、従来のセルランキング方法と同じとすることができる。そして、UEは、ステップST2004で選択したベストセルにセルリセレクションを行う。パスロス閾値(基準値)を、UEがセルリセレクションを行うのに必要なセルの上りリンクの状態に設定することで、必要な上りリンクの状態を満足したセルの中から、該セルの受信品質に応じてベストセルを選択することができる。
Among the cells in which Srxlev is greater than 0 in Step ST1304, if there is a cell whose path loss measurement value is equal to or less than the path loss threshold (reference value) in Step ST2002, in Step ST2004, the UE determines reception quality among the cells. Based on cell ranking, the cell with the best reception quality is selected as the best cell. This cell ranking method can be the same as the conventional cell ranking method. And UE performs celery selection to the best cell selected by step ST2004. By setting the path loss threshold (reference value) to the uplink state of the cell necessary for the UE to perform cell reselection, the reception quality of the cell can be selected from the cells that satisfy the required uplink state. The best cell can be selected accordingly.
ステップST1304でSrxlevが0より大きくなったセルのうち、ステップST2002でパスロス測定値がパスロス閾値(基準値)以下となるセルが無い場合、ステップST2003で、UEは、該セルの中からパスロス測定値でセルランキングを行う。UEは、ステップST2003で、パスロス測定値が最小のセルをベストセルとして選択する。そして、UEは、ステップST2003で選択したベストセルにセルリセレクションを行う。
If there is no cell whose path loss measurement value is equal to or smaller than the path loss threshold value (reference value) in step ST2002 among the cells in which Srxlev is greater than 0 in step ST1304, in step ST2003, the UE determines the path loss measurement value from the cells. Perform cell ranking with. In step ST2003, the UE selects the cell with the smallest path loss measurement value as the best cell. Then, the UE performs celery selection on the best cell selected in step ST2003.
パスロスは変動するので、UEはパスロスの測定結果を、ある期間平均する、あるいはフィルタリングするなどしてもよい。該平均値あるいはフィルタリング後の値を、ステップST2002においてパスロス閾値(基準値)と比較するようにしてもよい。
Since the path loss fluctuates, the UE may average or filter the path loss measurement result for a certain period. The average value or the value after filtering may be compared with a path loss threshold value (reference value) in step ST2002.
サービングセルは、パスロス閾値(開始)を報知する。SIB3に含めて報知してもよいし、あるいはSIB1に含めて報知してもよい。SIB3の場合、セルリセレクション用パラメータが含まれるので、UEは、他のセルリセレクション用パラメータと一緒に受信することが可能となる。このため、UEの受信動作を簡略化でき、また、制御誤動作の削減が可能となる。SIB1の場合、予め報知されるタイミングが決められているので、UEは、メジャメント時に早期に受信可能となる。このため、UEのメジャメント動作において制御遅延を小さくすることが可能となる。
The serving cell notifies the path loss threshold (start). The notification may be included in SIB3 or may be notified in SIB1. In the case of SIB3, since the cell reselection parameter is included, the UE can receive it together with other cell reselection parameters. For this reason, the reception operation of the UE can be simplified, and the control malfunction can be reduced. In the case of SIB1, since the timing to be notified in advance is determined, the UE can receive at an early stage during measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE.
パスロス閾値(開始)は報知されるのではなく、静的な値として予め決められていてもよい。この場合、UEは、予め決められた値を用いることができる。これにより、報知情報を削減でき、シグナリング負荷を低減できる。
The path loss threshold (start) may not be notified but may be determined in advance as a static value. In this case, the UE can use a predetermined value. Thereby, broadcast information can be reduced and signaling load can be reduced.
また、パスロス閾値(開始)に、初期値として予め決められた値を用い、パスロス閾値(開始)が報知された場合に、初期値に代えて報知された該パスロス閾値(開始)を用いるようにしてもよい。この場合、該パスロス閾値(開始)を、サービングセルが必要に応じて報知すればよい。
In addition, when a predetermined value is used as an initial value for the path loss threshold (start) and the path loss threshold (start) is notified, the notified path loss threshold (start) is used instead of the initial value. May be. In this case, the serving cell may notify the path loss threshold (start) as necessary.
パスロス閾値(基準値)は一つであってもよいし、複数であってもよく、例えばセル毎にあってもよい。例えばパスロス閾値(基準値)がセル毎に設けられる場合、ステップST2002で判断対象とするセル毎に該パスロス閾値(基準値)を用いるようにすればよい。該パスロス閾値(基準値)をセル毎に設ける場合、セルのアイデンティティ(PCI,GCI)と関連付けるようにしておくとよい。こうすることで、セル毎の上りリンクの状況を考慮できるため、より緻密なセルリセレクションが可能となる。
The path loss threshold value (reference value) may be one or plural, for example, for each cell. For example, when a path loss threshold value (reference value) is provided for each cell, the path loss threshold value (reference value) may be used for each cell to be determined in step ST2002. When the path loss threshold value (reference value) is provided for each cell, it may be associated with the cell identity (PCI, GCI). By doing so, since the uplink situation for each cell can be taken into account, more precise cell reselection is possible.
該パスロス閾値(基準値)をサービングセルが報知してもよいし、各セルが報知してもよい。サービングセルが報知する場合は、SIB3に含めて報知してもよいし、あるいはSIB1に含めて報知してもよいし、SIB4に含めて報知してもよい。SIB3で報知する場合、セルリセレクション用パラメータが含まれるので、UEは、他のセルリセレクション用パラメータと一緒に受信することが可能となる。このためUEの受信動作を簡略化でき、また、制御誤動作の削減が可能となる。
The serving cell may notify the path loss threshold (reference value), or each cell may notify. When the serving cell notifies, it may be notified by being included in SIB3, may be notified by being included in SIB1, or may be notified by being included in SIB4. When broadcasting with SIB3, since the celery selection parameter is included, the UE can receive it together with other celery selection parameters. For this reason, the reception operation of the UE can be simplified, and the control malfunction can be reduced.
SIB1の場合、予め報知されるタイミングが決められているので、UEはメジャメント時に早期に受信可能となる。このため、UEのメジャメント動作において制御遅延を小さくすることが可能となる。SIB4の場合、隣接セルの情報が含まれるので他の隣接セルの情報、例えばPCIと関連付けて受信することが可能となる。SIB4での報知は、該パスロス閾値(基準値)をセル毎に設ける場合などに適し、UEの受信動作を簡略化でき、また、制御誤動作の削減が可能となる。
In the case of SIB1, since the timing to be notified in advance is determined, the UE can receive early at the time of measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE. In the case of SIB4, since information on neighboring cells is included, it is possible to receive information in association with information on other neighboring cells, for example, PCI. Broadcasting with SIB4 is suitable when the path loss threshold value (reference value) is provided for each cell, and can simplify the reception operation of the UE and reduce control malfunctions.
各セルがパスロス閾値(基準値)を報知する場合は、SIB1に含めて報知してもよい。SIB1の場合、予め報知されるタイミングが決められているので、UEはメジャメント時に早期に受信可能となる。このため、UEのメジャメント動作において制御遅延を小さくすることが可能となる。
When each cell notifies the path loss threshold (reference value), it may be included in SIB1 and notified. In the case of SIB1, since the timing to be notified in advance is determined, the UE can receive early at the time of measurement. For this reason, it becomes possible to reduce the control delay in the measurement operation of the UE.
該パスロス閾値(基準値)は報知されるのではなく、静的な値として予め決められていてもよい。この場合、UEは、予め決められた値を用いることができる。UEは、該パスロス閾値(基準値)を報知される必要がなくなるので、シグナリング負荷の削減、UEの消費電力の削減が可能となる。
The path loss threshold (reference value) may not be notified but may be determined in advance as a static value. In this case, the UE can use a predetermined value. Since the UE does not need to be notified of the path loss threshold (reference value), the signaling load can be reduced and the power consumption of the UE can be reduced.
また、該パスロス閾値(基準値)に、初期値として予め決められた値を用い、該パスロス閾値(基準値)がサービングセルあるいは各セルから報知された場合に、初期値に代えて報知された各々のセルの該パスロス閾値(基準値)を用いるようにしてもよい。この場合、サービングセルあるいは各セルは、必要に応じて該パスロス閾値(基準値)を報知すればよい。
In addition, when a predetermined value is used as the initial value for the path loss threshold (reference value), and the path loss threshold (reference value) is notified from the serving cell or each cell, The path loss threshold value (reference value) of the cell may be used. In this case, the serving cell or each cell may notify the path loss threshold (reference value) as necessary.
また、本実施の形態では、パスロス閾値(開始)とパスロス閾値(基準値)とを設けることとしたが、どちらか一方でもよい。ステップST2001あるいはステップST2002の判断のどちらか一方を行うようにしてもよい。
In this embodiment, the path loss threshold (start) and the path loss threshold (reference value) are provided, but either one may be used. Either the determination in step ST2001 or step ST2002 may be performed.
本実施の形態では、セルとUEとの間の上りリンクの状態を表す指標として、パスロスを用いることを開示したが、上りリンクの状態を表す指標としては、実際の距離を用いてもよい。これらに限らず、上りリンクの状態を表す指標であればよい。距離を用いる場合、セルとUEとの間の距離が小さいほど、上りリンクの状態が良好であると判断する。実際の距離の導出は、例えば以下の方法としてもよい。セルが自セルの位置をGPS(Global Positioning System)等により測定し、該位置情報を報知する。UEは、自セルの位置をGPS等により測定する。また、UEは、サービングセルあるいは各セルから報知されるセルの位置情報を受信する。UEは、測定した自UEの位置情報と、受信した各セルの位置情報とによって、各セルとUEとの間の距離を導出する。これにより、上りリンクの状態を表す指標として、各セルとUEとの間の実際の距離を用いることが可能となる。
In the present embodiment, it is disclosed that a path loss is used as an index indicating the uplink state between the cell and the UE, but an actual distance may be used as an index indicating the uplink state. However, the present invention is not limited to these, and any index that represents the uplink state may be used. When using the distance, it is determined that the uplink state is better as the distance between the cell and the UE is smaller. The actual distance may be derived by, for example, the following method. The cell measures the position of its own cell by GPS (Global Positioning System) or the like, and notifies the position information. The UE measures the position of its own cell by GPS or the like. Moreover, UE receives the positional information on the cell alert | reported from a serving cell or each cell. The UE derives the distance between each cell and the UE based on the measured location information of the own UE and the received location information of each cell. This makes it possible to use the actual distance between each cell and the UE as an index representing the uplink state.
本実施の形態に開示した方法とすることで、各セルの受信品質に加えて、上りリンクの通信品質を考慮に入れて、セルリセレクションを行うことができる。これによって、たとえサービングセルの受信品質が良好であったとしても、サービングセルのパスロスによっては、セルリセレクションを開始することになるため、サービングセルのパスロスの増大による通信速度の低下、通信断の発生、UEの消費電力の増大を抑制することが可能となる。さらに、UEの上り送信電力を抑制することができるので、システムとして上り干渉回避が可能となる。したがって、ヘテロジーニアスネットワークスにおける干渉問題およびキャパシティ問題を改善することが可能となるので、膨大な数のローカルエリアレンジノードの運用およびそれらの柔軟な配置が可能となる。
By using the method disclosed in this embodiment, cell reselection can be performed in consideration of uplink communication quality in addition to reception quality of each cell. Thereby, even if the reception quality of the serving cell is good, depending on the path loss of the serving cell, cell reselection is started, so the communication speed decreases due to the increase of the serving cell path loss, the occurrence of communication disconnection, the UE An increase in power consumption can be suppressed. Furthermore, since the uplink transmission power of the UE can be suppressed, uplink interference can be avoided as a system. Therefore, since it is possible to improve the interference problem and capacity problem in heterogeneous networks, it is possible to operate a large number of local area range nodes and to arrange them flexibly.
また、本実施の形態で開示した方法とすることで、セルランキングの際に、サービングセルのパスロスと隣接セルのパスロスを考慮に入れることが可能となる。これによって、たとえサービングセルの受信品質が良好であったとしても、該サービングセルのパスロスが大きい場合は、他のセルへセルリセレクションさせることが可能となる。このため、サービングセルのパスロスの増大による通信速度の低下、通信断の発生、UEの消費電力の増大を抑制することが可能となる。
Also, by using the method disclosed in the present embodiment, it is possible to take into account the path loss of the serving cell and the path loss of the neighboring cell in cell ranking. As a result, even if the reception quality of the serving cell is good, if the path loss of the serving cell is large, it is possible to perform cell reselection to another cell. For this reason, it becomes possible to suppress a decrease in communication speed due to an increase in path loss of the serving cell, occurrence of communication disconnection, and an increase in power consumption of the UE.
また、パスロスの大きいセルへは、セルリセレクションすることが無くなるため、リセレクション後の通信速度の低下、通信断の発生、UEの消費電力の増大を抑制することが可能となる。
In addition, since cell reselection is not performed on a cell with a large path loss, it is possible to suppress a decrease in communication speed after reselection, occurrence of communication disconnection, and an increase in power consumption of the UE.
また、UEの上り送信電力を抑制することができるので、システムとして上り干渉回避が可能となる。
In addition, since the uplink transmission power of the UE can be suppressed, uplink interference can be avoided as a system.
また、本実施の形態で開示した方法とすることで、上り通信に十分なパスロスを得られている場合は、セルの受信品質によってベストセルを選択することが可能となる。パスロスを優先して選択するセルを決定することができるため、確実な上りリンクを設定できるセルを見つけやすくできる。
In addition, by using the method disclosed in the present embodiment, it is possible to select the best cell according to the reception quality of the cell when a sufficient path loss for uplink communication is obtained. Since a cell to be selected with priority given to path loss can be determined, it is easy to find a cell that can set a reliable uplink.
実施の形態4 変形例1.
本変形例では、セルリセレクションにおいて、上りリンクの状態も考慮に入れる別の方法を開示する。受信品質が、ある値以上のセルがある場合、上りリンクの状態を考慮してセルランキングを行うようにする。該ある値として、受信品質閾値(基準値)を設ける。該受信品質閾値(基準値)は、実施の形態2の変形例3で開示した受信品質閾値(基準値)と異なっていてもよいが、セルの受信品質が、通信に十分な受信品質を得られているかどうかの指標となる閾値であるため、同じにしてもよい。同じ場合は、該受信品質閾値(基準値)を表すパラメータを一つにすることができる。 Embodiment 4Modification 1
In this modification, another method that takes the uplink state into consideration in celery selection is disclosed. When there is a cell whose reception quality is a certain value or higher, cell ranking is performed in consideration of the uplink state. A reception quality threshold value (reference value) is provided as the certain value. The reception quality threshold (reference value) may be different from the reception quality threshold (reference value) disclosed in the third modification of the second embodiment, but the reception quality of the cell obtains reception quality sufficient for communication. Since it is a threshold value that is an index of whether or not it is set, it may be the same. In the case of the same, the parameter indicating the reception quality threshold value (reference value) can be made one.
本変形例では、セルリセレクションにおいて、上りリンクの状態も考慮に入れる別の方法を開示する。受信品質が、ある値以上のセルがある場合、上りリンクの状態を考慮してセルランキングを行うようにする。該ある値として、受信品質閾値(基準値)を設ける。該受信品質閾値(基準値)は、実施の形態2の変形例3で開示した受信品質閾値(基準値)と異なっていてもよいが、セルの受信品質が、通信に十分な受信品質を得られているかどうかの指標となる閾値であるため、同じにしてもよい。同じ場合は、該受信品質閾値(基準値)を表すパラメータを一つにすることができる。 Embodiment 4
In this modification, another method that takes the uplink state into consideration in celery selection is disclosed. When there is a cell whose reception quality is a certain value or higher, cell ranking is performed in consideration of the uplink state. A reception quality threshold value (reference value) is provided as the certain value. The reception quality threshold (reference value) may be different from the reception quality threshold (reference value) disclosed in the third modification of the second embodiment, but the reception quality of the cell obtains reception quality sufficient for communication. Since it is a threshold value that is an index of whether or not it is set, it may be the same. In the case of the same, the parameter indicating the reception quality threshold value (reference value) can be made one.
図21は、受信品質が、ある値以上のセルがある場合に、パスロスを考慮してセルランキングを行うセルリセレクションの処理手順を示すフローチャートである。図21に示すフローチャートの処理は、図13および図20に示すフローチャートの処理と類似しているので、異なる処理についてのみ説明し、対応する部分については同一のステップ番号を付して、処理の説明を省略する。セルリセレクションのための測定を開始するまでの動作は、実施の形態4に開示した方法とする。
FIG. 21 is a flowchart showing a processing procedure of cell reselection in which cell ranking is performed in consideration of path loss when there is a cell whose reception quality exceeds a certain value. The process of the flowchart shown in FIG. 21 is similar to the process of the flowcharts shown in FIGS. 13 and 20, so only the different processes will be described, and the corresponding parts will be denoted by the same step numbers and the description of the processes Is omitted. The operation until the measurement for celery selection is started is the method disclosed in the fourth embodiment.
ステップST1304でSrxlevが0より大きくなったセルについて、UEは、ステップST2101の処理を行う。ステップST2101で、UEは、セルの受信品質、具体的には受信電力測定値が、受信品質閾値(基準値)以上か否かを判断する。受信電力測定値が受信品質閾値(基準値)以上の場合、ステップST2103へ移行する。受信電力測定値が受信品質閾値(基準値)より小さい場合、ステップST2102へ移行する。
The UE performs the process of step ST2101 for the cell where Srxlev is greater than 0 in step ST1304. In Step ST2101, the UE determines whether or not the reception quality of the cell, specifically, the received power measurement value is equal to or higher than the reception quality threshold (reference value). When the received power measurement value is greater than or equal to the reception quality threshold (reference value), the mobile terminal makes a transition to step ST2103. When the received power measurement value is smaller than the reception quality threshold value (reference value), the mobile terminal makes a transition to step ST2102.
ステップST1304でSrxlevが0より大きくなったセルのうち、ステップST2101で受信電力測定値が受信品質閾値(基準値)以上となるセルがある場合、ステップST2103で、UEは、該セルの中で、パスロスでセルランキングを行い、パスロスが最小のセルをベストセルとして選択する。そして、UEは、ステップST2103で選択したベストセルにセルリセレクションを行う。受信品質閾値(基準値)を、UEがセルリセレクションを行うのに必要な受信品質に設定することで、受信品質測定値が該必要な受信品質を満足したセルの中から、該セルのパスロスに応じてベストセルを選択することができる。
Among the cells in which Srxlev is greater than 0 in step ST1304, if there is a cell whose received power measurement value is equal to or higher than the reception quality threshold (reference value) in step ST2101, the UE in step ST2103 Cell ranking is performed by path loss, and the cell with the smallest path loss is selected as the best cell. Then, the UE performs celery selection on the best cell selected in step ST2103. By setting the reception quality threshold (reference value) to the reception quality necessary for the UE to perform cell reselection, the reception quality measurement value is changed from the cell that satisfies the required reception quality to the path loss of the cell. The best cell can be selected accordingly.
ステップST1304でSrxlevが0より大きくなったセルのうち、ステップST2101で受信電力測定値が受信品質閾値(基準値)以上となるセルが無い場合、ステップST2102で、UEは、該セルの中から受信電力測定値でセルランキングを行う。このセルランキング方法は、従来のセルランキング方法と同じとすることができる。ステップST2102で、受信電力測定値が最も良好なセルをベストセルとして選択する。そして、UEは、ステップST2102で選択したベストセルにセルリセレクションを行う。受信品質閾値(基準値)に関しては、実施の形態2の変形例3で開示した方法と同様とすればよい。
If there is no cell whose received power measurement value is equal to or greater than the reception quality threshold value (reference value) in step ST2101 among the cells whose Srxlev is greater than 0 in step ST1304, the UE receives the received cell from the cell in step ST2102. Cell ranking is performed using the measured power value. This cell ranking method can be the same as the conventional cell ranking method. In step ST2102, the cell with the best received power measurement value is selected as the best cell. Then, the UE performs celery selection on the best cell selected in Step ST2102. The reception quality threshold (reference value) may be the same as the method disclosed in the third modification of the second embodiment.
ステップST1304のSrxlevによる判断と、ステップST2101の受信品質が受信品質閾値(基準値)以上か否かの判断とを一つにしてもよい。この方法は、実施の形態2の変形例3で開示した方法と同様とすればよい。これによって、UEでの判断を簡易にすることが可能となる。
The determination by Srxlev in step ST1304 and the determination in step ST2101 whether or not the reception quality is equal to or higher than the reception quality threshold (reference value) may be combined. This method may be the same as the method disclosed in the third modification of the second embodiment. This makes it possible to simplify the determination at the UE.
UEは、ステップST2103でパスロスをもとにベストセルを選択する。したがって、UEは、サービングセルおよび各セルのパスロスを認識しておく必要がある。この方法については、実施の形態4で開示した方法を用いるとよい。
UE selects the best cell based on the path loss in step ST2103. Therefore, the UE needs to recognize the serving cell and the path loss of each cell. For this method, the method disclosed in Embodiment 4 may be used.
本変形例で開示した方法とすることで、実施の形態4で記載した効果に加えて、以下の効果を得ることができる。通信に十分な受信品質を得られている場合は、パスロスによってベストセルを選択することが可能となる。受信品質を優先して選択するセルを決定することができるため、セルを見つけやすくできる。
In addition to the effects described in the fourth embodiment, the following effects can be obtained by using the method disclosed in the present modification. If reception quality sufficient for communication is obtained, the best cell can be selected by path loss. Since the cell to be selected with priority on the reception quality can be determined, the cell can be easily found.
実施の形態5.
ヘテロジーニアスネットワークスにおける問題点を解消するために、実施の形態1から実施の形態4の変形例1で開示した方法を組合せてもよい。 Embodiment 5 FIG.
In order to solve the problem in the heterogeneous networks, the methods disclosed in the first modification of the first to fourth embodiments may be combined.
ヘテロジーニアスネットワークスにおける問題点を解消するために、実施の形態1から実施の形態4の変形例1で開示した方法を組合せてもよい。 Embodiment 5 FIG.
In order to solve the problem in the heterogeneous networks, the methods disclosed in the first modification of the first to fourth embodiments may be combined.
図22は、本発明の実施の形態1から実施の形態4の変形例1で開示した方法を組合せたセルリセレクションの処理手順を示すフローチャートの一例である。図22に示すフローチャートの処理は、図13、図16、図18、図19および図20に示すフローチャートの処理と類似しているので、異なる処理についてのみ説明し、対応する部分については同一のステップ番号を付して、処理の説明を省略する。
FIG. 22 is an example of a flowchart showing a processing procedure of celery selection combining the methods disclosed in the first modification of the first to fourth embodiments of the present invention. The processing of the flowchart shown in FIG. 22 is similar to the processing of the flowcharts shown in FIGS. 13, 16, 18, 19, and 20, so only the different processing will be described, and the corresponding steps will be the same step. A number is attached and explanation of processing is omitted.
UEは、セルリセレクションのための測定を開始するか否かの判断として、ステップST1601、ステップST2001に示すように、サービングセルのバックホールリンクの通信品質とサービングセルのパスロスとを考慮に入れる。ステップST1301に示すサービングセルの受信電力と共に、これらの判断をオア(or)条件とすることにより、いずれかの条件が通信に不十分となった場合に、セルリセレクションのための測定を開始するようにできる。
The UE takes into consideration the communication quality of the backhaul link of the serving cell and the path loss of the serving cell, as shown in Step ST1601 and Step ST2001, as a determination of whether to start measurement for celery selection. Together with the serving cell reception power shown in step ST1301, these determinations are set to an OR condition so that measurement for cell reselection is started when any of the conditions becomes insufficient for communication. it can.
UEは、セルランキングにおいて、ステップST1801に示すように、セルの受信品質を考慮に入れ、ステップST2002でセルのパスロスを考慮に入れ、ステップST1901でセルのバックホールリンクの通信品質を考慮に入れ、ステップST2201でUEの所望通信速度を考慮に入れる。
In cell ranking, as shown in step ST1801, the UE takes into account the reception quality of the cell, takes into account the cell path loss in step ST2002, takes into account the communication quality of the cell backhaul link in step ST1901, In step ST2201, the desired communication speed of the UE is taken into consideration.
ステップST2201で、UEの所望通信速度に対応するバックホールリンクの通信品質閾値を満足するセルが得られない場合は、ステップST2202へ移行し、セルの受信品質でセルランキングを行い、最も良好な受信品質のセル(ベストセル)の選択を行う。あるいは、セルのパスロスでセルランキングを行い、最小のパスロスのセル(ベストセル)の選択を行うようにしてもよい。
If a cell that satisfies the communication quality threshold of the backhaul link corresponding to the desired communication speed of the UE cannot be obtained in step ST2201, the mobile station moves to step ST2202, performs cell ranking based on the reception quality of the cell, and performs the best reception. Select the quality cell (best cell). Alternatively, cell ranking may be performed based on the cell path loss, and the cell with the smallest path loss (best cell) may be selected.
また、ステップST2201では、実施の形態3で開示したUEの所望通信速度とバックホールリンクの通信品質とを対応させる方法としたが、バックホールの通信品質に限らず、上りリンクの状態と対応させるようにしてもよい。また両方行うようにしてもよい。上りリンクの状態を表す指標としては、たとえば実施の形態4で開示したパスロスあるいは距離を用いればよい。パスロスを用いる場合、UEの所望通信速度に対応するパスロスの閾値を設けておき、ステップST2201でUEの所望通信速度に対応するパスロス閾値を満足するか否かを判断する。UEの通信速度と上りパスロスの閾値との対応関係は、実施の形態3で開示した方法と同様にすればよい。これにより、上りリンクの状態を考慮に入れる際にも、UEの所望通信速度を考慮することが可能となる。
Also, in step ST2201, the method of associating the desired communication speed of the UE and the communication quality of the backhaul link disclosed in Embodiment 3 is not limited to the communication quality of the backhaul, but is associated with the uplink state. You may do it. Both may be performed. As an index indicating the uplink state, for example, the path loss or distance disclosed in the fourth embodiment may be used. When path loss is used, a path loss threshold value corresponding to the desired communication speed of the UE is provided, and it is determined in step ST2201 whether the path loss threshold value corresponding to the desired communication speed of the UE is satisfied. The correspondence between the UE communication speed and the uplink path loss threshold may be the same as the method disclosed in the third embodiment. This makes it possible to consider the desired communication speed of the UE when taking the uplink state into consideration.
ステップST2201で、UEの所望通信速度に対応するバックホールリンクの通信品質閾値を満足するセルが得られた場合は、ステップST2203に移行して、セルのバックホールリンクの通信品質でセルランキングを行い、バックホールリンクの通信品質が最も良好なセル(ベストセル)を選択する。UEは、ステップST1802、ステップST2003、ステップST1902、ステップST2202またはステップST2203で選択したベストセルにセルリセレクションを行う。
If a cell that satisfies the communication quality threshold of the backhaul link corresponding to the desired communication speed of the UE is obtained in step ST2201, the mobile terminal moves to step ST2203 and performs cell ranking based on the communication quality of the cell backhaul link. The cell with the best communication quality of the backhaul link (best cell) is selected. The UE performs celery selection on the best cell selected in step ST1802, step ST2003, step ST1902, step ST2202 or step ST2203.
このようにすることで、セルランキングにおいて、実施の形態1から実施の形態4の変形例1で記載した効果を併せ持つことが可能となる。
By doing in this way, it becomes possible to have the effects described in the first modification of the first to fourth embodiments in the cell ranking.
本実施の形態で開示したように、実施の形態1から実施の形態4の変形例1で開示した方法を組合せることによって、サービングセルおよび隣接セルの少なくともいずれか一方のバックホールリンクの品質を考慮したセルリセレクションや、弱受信電力のセルへのセルリセレクションを可能とし、ヘテロジーニアスネットワークスにおける干渉問題やキャパシティ問題を改善することが可能となる。
As disclosed in the present embodiment, the quality of the backhaul link of at least one of the serving cell and the neighboring cell is considered by combining the methods disclosed in the first modification of the first to fourth embodiments. Cell reselection and cell reselection to a cell with weak received power are possible, and it is possible to improve interference problems and capacity problems in heterogeneous networks.
さらに、マクロセルとローカルノードとの配置状況に応じて必要となる方法を組合せることで、より膨大で複雑な状況のヘテロジーニアスネットワークスにおいても、干渉やキャパシティを最適にすることが可能となる。
Furthermore, by combining the necessary methods according to the arrangement status of the macro cell and the local node, it becomes possible to optimize interference and capacity even in a heterogeneous network of a vast and complicated situation. .
実施の形態6.
前述のように、ヘテロジーニアスネットワークスにおいて、干渉の低減、キャパシティの改善が要求される。その方法として、非特許文献8に、弱受信電力のセルの測定とトリガメカニズムとが必要であることが提案されているが、具体的な方法については、何ら記載されていない。また非特許文献9には、リレーノードのバックホールリンクを考慮したセルセレクション方法が開示されているが、どのようなメカニズムで該バックホールリンクの品質を考慮に入れるのか、具体的な方法については、何ら開示されていない。また非特許文献10に示される方法では、通信制御が非常に複雑になってしまう。 Embodiment 6 FIG.
As described above, heterogeneous networks are required to reduce interference and improve capacity. As the method, Non-Patent Document 8 proposes that measurement of a cell with weak received power and a trigger mechanism are necessary, but no specific method is described. Non-Patent Document 9 discloses a cell selection method that considers the backhaul link of the relay node, but what kind of mechanism is taken into consideration the quality of the backhaul link, for a specific method, Nothing is disclosed. Further, in the method disclosed in Non-Patent Document 10, communication control becomes very complicated.
前述のように、ヘテロジーニアスネットワークスにおいて、干渉の低減、キャパシティの改善が要求される。その方法として、非特許文献8に、弱受信電力のセルの測定とトリガメカニズムとが必要であることが提案されているが、具体的な方法については、何ら記載されていない。また非特許文献9には、リレーノードのバックホールリンクを考慮したセルセレクション方法が開示されているが、どのようなメカニズムで該バックホールリンクの品質を考慮に入れるのか、具体的な方法については、何ら開示されていない。また非特許文献10に示される方法では、通信制御が非常に複雑になってしまう。 Embodiment 6 FIG.
As described above, heterogeneous networks are required to reduce interference and improve capacity. As the method, Non-Patent Document 8 proposes that measurement of a cell with weak received power and a trigger mechanism are necessary, but no specific method is described. Non-Patent Document 9 discloses a cell selection method that considers the backhaul link of the relay node, but what kind of mechanism is taken into consideration the quality of the backhaul link, for a specific method, Nothing is disclosed. Further, in the method disclosed in Non-Patent Document 10, communication control becomes very complicated.
これらの問題を解消するために、本実施の形態では、セルセレクションにおいて、セルのバックホールリンクの通信品質および上りリンクの状態の少なくともいずれか一方を考慮に入れるための具体的方法を開示する。本実施の形態では、セルのバックホールリンクの通信品質および上りリンクの状態の両方を考慮に入れる場合を説明する。
In order to solve these problems, this embodiment discloses a specific method for taking into account at least one of the communication quality of the cell backhaul link and the uplink state in the cell selection. In this embodiment, a case will be described in which both the communication quality of the cell backhaul link and the uplink state are taken into consideration.
図23は、非特許文献3の技術によるUEのセルセレクションの処理手順を示すフローチャートである。ステップST2301で、UEは、セルセレクションのために、周辺セルの受信電力を測定する。ステップST2302で、UEは、セル毎の測定値から、受信電力に、ある補正値を入れ込んだ値(Srxlev)を算出する。この補正値およびその算出方法は、非特許文献3に記載されている。
FIG. 23 is a flowchart showing a UE cell selection processing procedure according to the technique of Non-Patent Document 3. In Step ST2301, the UE measures received power of neighboring cells for cell selection. In Step ST2302, the UE calculates a value (Srxlev) obtained by inserting a certain correction value into the received power from the measurement value for each cell. This correction value and its calculation method are described in Non-Patent Document 3.
Srxlevを算出したUEは、ステップST2303で、該Srxlevが0より大きいか否かを判断する。該Srxlevが0より大きい場合、該セルをベストセル選択の候補として、ステップST2305へ移行する。該Srxlevが0以下の場合は、該セルをベストセル選択の候補としない。
The UE that has calculated Srxlev determines whether or not the Srxlev is greater than 0 in step ST2303. If the Srxlev is greater than 0, the cell is determined as a best cell selection candidate, and the process moves to step ST2305. When the Srxlev is 0 or less, the cell is not regarded as a best cell selection candidate.
UEは、セルセレクションのための測定で得られた一つまたは複数のセルに対して、ステップST2302およびステップST2303の各処理を行う。その結果、Srxlevが0より大きくなるセルが全く得られなかった場合は、ステップST2304に移行し、圏外状態となる。Srxlevが0より大きくなるセルが得られた場合は、ステップST2305の処理を行う。ステップST2305で、UEは、Srxlevが0より大きくなったセルの中から、受信電力が最も高いセル(ベストセル)を選択する。そしてUEは、選択したベストセルにキャンプオンする。
UE performs each process of step ST2302 and step ST2303 with respect to the one or some cell obtained by the measurement for cell selection. As a result, when no cell having Srxlev greater than 0 is obtained, the mobile terminal shifts to step ST2304 to enter an out-of-service state. If a cell having Srxlev greater than 0 is obtained, the process of step ST2305 is performed. In Step ST2305, the UE selects a cell (best cell) having the highest received power from the cells having Srxlev greater than 0. Then, the UE camps on the selected best cell.
図24は、本実施の形態で開示する、セルのバックホールリンクの通信品質および上りリンクの状態を考慮に入れたセルセレクションの処理手順を示すフローチャートである。図24に示すフローチャートの処理は、図18、図19、図20、図22および図23に示すフローチャートの処理と類似しているので、異なる処理についてのみ説明し、対応する部分については同一のステップ番号を付して、処理の説明を省略する。
FIG. 24 is a flowchart showing a cell selection processing procedure that takes into consideration the communication quality of the cell backhaul link and the uplink state, disclosed in the present embodiment. The processing of the flowchart shown in FIG. 24 is similar to the processing of the flowchart shown in FIG. 18, FIG. 19, FIG. 20, FIG. 22 and FIG. A number is attached and explanation of processing is omitted.
本実施の形態では、ステップST2303でSrxlevが0より大きくなるセルが得られた場合は、UEは、ベストセルを選択する際に、ステップST1801でセルの受信品質を考慮に入れ、ステップST2002でセルのパスロスを考慮に入れ、ステップST1901でセルのバックホールリンクの通信品質を考慮に入れ、ステップST2201でUEの所望通信速度を考慮に入れる。
In this embodiment, when a cell having Srxlev greater than 0 is obtained in step ST2303, the UE takes into account the reception quality of the cell in step ST1801 when selecting the best cell, and in step ST2002, the cell In step ST1901, the communication quality of the cell backhaul link is taken into consideration, and in step ST2201, the desired communication speed of the UE is taken into consideration.
ステップST2201で、UEの所望通信速度に対応するバックホールリンクの通信品質閾値を満足するセルが得られない場合は、ステップST2202へ移行し、セルの受信品質が最も良好なセル(ベストセル)の選択を行う。あるいは、セルのパスロスが最小のセル(ベストセル)の選択を行うようにしてもよい。
If a cell that satisfies the communication quality threshold of the backhaul link corresponding to the desired communication speed of the UE cannot be obtained in Step ST2201, the process proceeds to Step ST2202, and the cell with the best cell reception quality (best cell) Make a selection. Alternatively, the cell with the smallest cell path loss (best cell) may be selected.
ステップST2201で、UEの所望通信速度に対応するバックホールリンクの通信品質閾値を満足するセルが得られた場合は、ステップST2203に移行して、セルのバックホールリンクの通信品質が最も良好なセル(ベストセル)を選択する。UEは、ステップST1802、ステップST2003、ステップST1902、ステップST2202またはステップST2203で選択したベストセルを、キャンプオンするセルとして選択する。
If a cell satisfying the communication quality threshold of the backhaul link corresponding to the desired communication speed of the UE is obtained in step ST2201, the cell moves to step ST2203 and the cell with the best communication quality of the cell backhaul link is obtained. Select (Best Cell). The UE selects the best cell selected in Step ST1802, Step ST2003, Step ST1902, Step ST2202 or Step ST2203 as a cell to camp on.
図24からわかるように、本実施の形態では、実施の形態2から実施の形態5に開示したセルリセレクションの、セルリセレクションのための測定開始後のセルランキングの方法を適用することができる。
As can be seen from FIG. 24, in the present embodiment, the cell ranking method of the cell reselection disclosed in the second embodiment to the fifth embodiment after the start of measurement for cell reselection can be applied.
本実施の形態で開示した方法とすることで、セルセレクションにおいても、セルのバックホールリンクの通信品質および上りリンクの状態の少なくともいずれか一方を考慮に入れることが可能となる。このため、ヘテロジーニアスネットワークスにおける干渉問題やキャパシティ問題を改善することが可能となる。
By adopting the method disclosed in the present embodiment, it is possible to take into consideration at least one of the communication quality of the cell backhaul link and the uplink state even in the cell selection. For this reason, it becomes possible to improve the interference problem and capacity problem in heterogeneous networks.
さらに、マクロセルとローカルノードとの配置状況に応じて必要となる方法を組合せることで、より膨大で複雑な状況のヘテロジーニアスネットワークスにおいても、干渉やキャパシティを最適にすることが可能となる。
Furthermore, by combining the necessary methods according to the arrangement status of the macro cell and the local node, it becomes possible to optimize interference and capacity even in a heterogeneous network of a vast and complicated situation. .
また、ベストセルの選択において実施の形態2から実施の形態5に開示した方法を適用することで、各々の効果を併せ持つことが可能となる。
Also, by applying the method disclosed in the second to fifth embodiments in selecting the best cell, it is possible to have each effect.
実施の形態7.
実施の形態1から実施の形態6では、セルリセレクション、セルセレクションにおいて、セルのバックホールリンクの通信品質および上りリンクの状態の少なくともいずれか一方を考慮に入れる方法を開示したが、本実施の形態では、ハンドオーバ(HO)において、セルのバックホールリンクの通信品質および上りリンクの状態の少なくともいずれか一方を考慮に入れる方法を開示する。 Embodiment 7 FIG.
In the first to sixth embodiments, the method of taking into account at least one of the communication quality of the cell backhaul link and the uplink state in celery selection and cell selection has been disclosed. Now, a method of taking into account at least one of the communication quality of the cell backhaul link and the uplink state in handover (HO) is disclosed.
実施の形態1から実施の形態6では、セルリセレクション、セルセレクションにおいて、セルのバックホールリンクの通信品質および上りリンクの状態の少なくともいずれか一方を考慮に入れる方法を開示したが、本実施の形態では、ハンドオーバ(HO)において、セルのバックホールリンクの通信品質および上りリンクの状態の少なくともいずれか一方を考慮に入れる方法を開示する。 Embodiment 7 FIG.
In the first to sixth embodiments, the method of taking into account at least one of the communication quality of the cell backhaul link and the uplink state in celery selection and cell selection has been disclosed. Now, a method of taking into account at least one of the communication quality of the cell backhaul link and the uplink state in handover (HO) is disclosed.
ヘテロジーニアスネットワークスにおいて、前述した問題は、セルセレクションやセルリセレクションのみならず、ハンドオーバ(HO)の場合にも生じる。前述の問題は、サービングセルの選択や変更を行う場合に生じるからである。HOにおいては、HO先となるターゲットセルを選択しなければならない。したがって、このターゲットセルの選択が問題となる。
In the heterogeneous networks, the above-described problems occur not only in cell selection and cell reselection, but also in the case of handover (HO). This is because the aforementioned problem occurs when the serving cell is selected or changed. In HO, a target cell to be a HO destination must be selected. Therefore, the selection of the target cell becomes a problem.
図25は、非特許文献1の技術による通常のHOの処理手順を示すシーケンス図である。サービングセルがソースセルとなる。ここでは、ソースセルとターゲットセルとの間の通信をX2インタフェースで行う場合について示している。
FIG. 25 is a sequence diagram showing a normal HO processing procedure according to the technique of Non-Patent Document 1. The serving cell becomes the source cell. Here, a case where communication between the source cell and the target cell is performed using the X2 interface is shown.
ステップST2501で、ソースセルは、メジャメントコントロール(Measurement control)メッセージをUEに通知して、UEにメジャメント、すなわち測定を行わせる。具体的には、受信品質を表す受信電力を測定させる。ステップST2502で、UEは、メジャメント結果、すなわち測定結果を、メジャメントレポート(Measurement report)として、ソースセルに対して通知する。具体的には、受信品質測定結果、より詳細には受信電力測定値を、メジャメントレポートとして通知する。
In step ST2501, the source cell notifies the UE of a measurement control message, and causes the UE to perform measurement, that is, measurement. Specifically, reception power representing reception quality is measured. In Step ST2502, the UE notifies the source cell of the measurement result, that is, the measurement result, as a measurement report (Measurement report). Specifically, the reception quality measurement result, more specifically, the received power measurement value is notified as a measurement report.
ステップST2503で、ソースセルは、該UEからのメジャメントレポートを用いてターゲットセルを決定する。このように、通常のHOでは、各セルが、主としてUEの受信品質測定結果に基づいて、該UEがHOが必要かどうか、およびどのセルへHOさせるかどうかを判断する。つまり、ソースセルは、ステップST2502においてUEから受信したメジャメントレポートをトリガとして、HO手順を起動する。
In step ST2503, the source cell determines a target cell using a measurement report from the UE. In this way, in normal HO, each cell determines whether the UE needs HO and to which cell to make HO mainly based on the reception quality measurement result of the UE. That is, the source cell activates the HO procedure using the measurement report received from the UE in step ST2502 as a trigger.
ターゲットセルを決定したソースセルは、ステップST2504で、該ターゲットセルにHOリクエスト(HO request)メッセージを通知する。該HOリクエストメッセージには、HOさせるUEに関する情報である、UEコンテキスト(UE context)情報が含まれる。ターゲットセルは、ステップST2505で、自セルの状態および該UEに関する情報を考慮して、該UEへのHOを許可するかどうかを決定する。図25では、ターゲットセルがUEへのHOを許可する場合を示している。
In step ST2504, the source cell that has determined the target cell notifies the target cell of a HO request message. The HO request message includes UE context (UE context) information, which is information related to the UE to be HOed. In Step ST2505, the target cell determines whether to permit HO to the UE in consideration of the state of the own cell and information on the UE. FIG. 25 shows a case where the target cell permits HO to the UE.
HO許可の場合、ターゲットセルは、ステップST2506で、HOリクエストに対する許可メッセージ(HO request Ack)をソースセルに通知する。該許可メッセージを受信したソースセルは、ステップST2507で、UEに対して、Mobility(HO)制御情報を通知する。またソースセルは、ステップST2509で、ターゲットセルに対して、HOで通信を継続させるために必要なデータと、それに関するPDCPのSNステータス(SN status)情報を通知する。
In the case of HO permission, the target cell notifies the source cell of a permission message (HO request Ack) for the HO request in step ST2506. In Step ST2507, the source cell that has received the permission message notifies the UE of Mobility (HO) control information. In step ST2509, the source cell notifies the target cell of data necessary for continuing communication with HO and PDCP SN status (SN (status) information related thereto.
ステップST2507でHO制御情報を受信したUEは、ステップST2508で、ソースセルからデタッチを行い、該HO制御情報に含まれるターゲットセル情報に基づいて、ステップST2510で、ターゲットセルに対して同期(Synchronization)処理を行う。同期確立後、ターゲットセルは、ステップST2511で、上りリソースのアロケーション情報と、送信タイミング情報であるTA(Timing Advance)情報とをUEに通知する。
The UE that has received the HO control information in step ST2507 performs detachment from the source cell in step ST2508, and synchronizes with the target cell in step ST2510 based on the target cell information included in the HO control information. Process. In step ST2511, the target cell notifies the UE of uplink resource allocation information and TA (Timing Advance) information that is transmission timing information.
上りリソースのアロケーション情報とTA情報とを受信したUEは、ステップST2512で、ターゲットセルに対して、RRC接続再構成完了(RRC connection reconfiguration complete)メッセージを通知する。これにより、UEとターゲットセルとの間でのデータ通信が開始される。ステップST2512でRRC接続再構成完了メッセージを受信したターゲットセルは、ステップST2513で、上位装置であるMMEおよびサービングGW(S-GW)を介して、ソースセルとの間で、HO完遂(HO completion)のための処理を行う。ステップST2513におけるHO完遂のための処理に伴って、ソースセルは、ステップST2514で、該UEに関する情報に付随する制御に用いていたリソースを開放する。
In Step ST2512, the UE that has received the uplink resource allocation information and TA information notifies the target cell of an RRC connection reconfiguration complete (RRC connection reconfiguration complete) message. Thereby, data communication between the UE and the target cell is started. In Step ST2513, the target cell that has received the RRC connection reconfiguration completion message in Step ST2512 completes HO (HO ソ ー ス completion) with the source cell via the MME and serving GW (S-GW) that are higher-level devices. Process for. Along with the process for completing HO in step ST2513, the source cell releases the resources used for the control associated with the information on the UE in step ST2514.
セルリセレクション、セルセレクションにおいては、UEがベストセルの選択を行う。しかし、HOにおいては、図25のステップST2503に示すように、ソースセルであるサービングセルが、ターゲットセルの選択を行う。図26は、サービングセルによるターゲットセルの選択手順の一例を示すフローチャートである。ステップST2601で、サービングセルは、UEから通知されたメジャメントリポート(Measurement Report)を受信する。
In celery selection and cell selection, the UE selects the best cell. However, in HO, as shown in step ST2503 in FIG. 25, the serving cell that is the source cell selects the target cell. FIG. 26 is a flowchart illustrating an example of a target cell selection procedure by the serving cell. In Step ST2601, the serving cell receives the measurement report (Measurement Report) notified from the UE.
ステップST2601でUEから通知されたメジャメントリポートを受信したサービングセルは、ステップST2602で、該メジャメントリポートの結果から、UEの受信品質に基づいて、受信品質が最も良いセルをターゲットセルとして選択する。
In step ST2602, the serving cell that has received the measurement report notified from the UE in step ST2601 selects a cell having the best reception quality as a target cell based on the reception quality of the UE from the result of the measurement report.
そこで、本実施の形態では、HOにおいて、サービングセルによるターゲットセルの選択の際に、セルのバックホールリンクの通信品質および上りリンクの状態の少なくともいずれか一方を考慮に入れる。本実施の形態では、セルのバックホールリンクの通信品質および上りリンクの状態の両方を考慮に入れる場合を説明する。
Therefore, in the present embodiment, at the time of selection of a target cell by the serving cell, at least one of the communication quality of the cell backhaul link and the uplink state is taken into account in the HO. In this embodiment, a case will be described in which both the communication quality of the cell backhaul link and the uplink state are taken into consideration.
図27は、本実施の形態で開示する、セルのバックホールリンクの通信品質および上りリンクの状態を考慮に入れたHOの処理手順を示すフローチャートである。図27に示すフローチャートの処理は、図18、図19、図20、図22および図26に示すフローチャートの処理と類似しているので、異なる処理についてのみ説明し、対応する部分については同一のステップ番号を付して、処理の説明を省略する。
FIG. 27 is a flowchart showing the processing procedure of HO taking into consideration the communication quality of the cell backhaul link and the uplink state, disclosed in the present embodiment. The processing of the flowchart shown in FIG. 27 is similar to the processing of the flowcharts shown in FIGS. 18, 19, 20, 22, and 26, so only the different processing will be described, and the corresponding steps will be the same step. A number is attached and explanation of processing is omitted.
ステップST2601で、UEから通知されたメジャメントリポートを受信したサービングセルは、ターゲットセルを選択する際に、ステップST1801でセルの受信品質を考慮に入れ、ステップST2002でセルのパスロスを考慮に入れ、ステップST1901でセルのバックホールリンクの通信品質を考慮に入れ、ステップST2201でUEの所望通信速度を考慮に入れる。
In step ST2601, the serving cell that has received the measurement report notified from the UE takes the cell reception quality into consideration in step ST1801 and the cell path loss in step ST2002 when selecting the target cell. In step ST2201, the desired communication speed of the UE is taken into consideration in step ST2201.
ステップST2201で、UEの所望通信速度に対応するバックホールリンクの通信品質閾値を満足するセルが得られない場合は、ステップST2704へ移行し、セルの受信品質が最も良好なセルをターゲットセルとして選択する。あるいは、セルのパスロスが最小のセルをターゲットセルとして選択するようにしてもよい。
If a cell that satisfies the communication quality threshold of the backhaul link corresponding to the desired communication speed of the UE cannot be obtained in step ST2201, the process proceeds to step ST2704, and the cell with the best cell reception quality is selected as the target cell. To do. Alternatively, the cell with the smallest cell path loss may be selected as the target cell.
ステップST2201で、UEの所望通信速度に対応するバックホールリンクの通信品質閾値を満足するセルが得られた場合は、ステップST2705に移行して、セルのバックホールリンクの通信品質が最も良好なセルをターゲットセルとして選択する。サービングセルは、ステップST2701、ステップST2702、ステップST2703、ステップST2704およびステップST2705で選択したセルをターゲットセルとして選択する。
When a cell that satisfies the communication quality threshold of the backhaul link corresponding to the desired communication speed of the UE is obtained in step ST2201, the cell moves to step ST2705, and the cell having the best communication quality of the cell backhaul link As the target cell. The serving cell selects, as a target cell, the cell selected in step ST2701, step ST2702, step ST2703, step ST2704, and step ST2705.
図27からわかるように、本実施の形態では、実施の形態2から実施の形態5に開示したセルリセレクションにおける、セルリセレクションのための測定開始後のセルランキングの方法を、HOにおけるサービングセルによるターゲットセルの選択に適用することができる。
As can be seen from FIG. 27, in the present embodiment, the cell ranking method after the start of measurement for celery selection in the celery selection disclosed in the second to fifth embodiments is the target cell by the serving cell in HO. Can be applied to the choice of.
本実施の形態で開示したターゲットセルの選択において、サービングセルは、周辺セルのバックホールリンクの通信品質を認識する必要がある。この方法としては、実施の形態2で開示した方法を用いればよい。
In the selection of the target cell disclosed in the present embodiment, the serving cell needs to recognize the communication quality of the backhaul link of the neighboring cell. As this method, the method disclosed in the second embodiment may be used.
本実施の形態で開示したターゲットセルの選択において、サービングセルは、UEとセルとの間のパスロスを認識する必要がある。サービングセルのパスロスだけでなく、隣接セルのパスロスについても認識する必要がある。この方法として、パスロス用のメジャメントコンフィグレーションを設ける。サービングセルは、図25のステップST2501に示すメジャメントコントロールとして、パスロス用のメジャメントコンフィグレーションを用いて、UEに、隣接セルのパスロスの測定を行うことを通知する。UEは、測定したパスロスが、ある条件を満たしたセルについて、該セルのアイデンティティ(PCI,GCI)とともにパスロス値を、該メジャメントコンフィグレーションに対応するメジャメントリポートでサービングセルに通知する。
In the selection of the target cell disclosed in the present embodiment, the serving cell needs to recognize a path loss between the UE and the cell. It is necessary to recognize not only the serving cell path loss but also the neighboring cell path loss. As this method, a measurement configuration for path loss is provided. The serving cell notifies the UE to measure the path loss of the adjacent cell using the measurement configuration for path loss as the measurement control shown in Step ST2501 of FIG. For a cell whose measured path loss satisfies a certain condition, the UE notifies the serving cell of the path loss value together with the identity (PCI, GCI) of the cell in the measurement report corresponding to the measurement configuration.
ある条件としては、例えば、サービングセルが、メジャメントコンフィグレーションでUEにパスロスの閾値を通知しておく。該メジャメントコンフィグレーションを受信したUEは、サービングセルおよび隣接セルの少なくともいずれか一方のパスロスを測定し、該パスロスの測定結果が該閾値より大きくなったセルについて、メジャメントリポートをサービングセルに通知する。また、別の例として、UEはサービングセルおよび隣接セルの少なくともいずれか一方のパスロスを測定し、最も小さいパスロスのセルについて、メジャメントリポートをサービングセルに通知する。これらの方法を、サービングセルは、メジャメントコンフィグレーションで別々にあるいは同時に設定する。これにより、サービングセルは、サービングセルとUEとの間あるいは隣接セルとUEとの間のパスロスを認識することが可能となる。
As a certain condition, for example, the serving cell notifies the UE of the threshold for path loss in the measurement configuration. The UE that has received the measurement configuration measures the path loss of at least one of the serving cell and the neighboring cell, and notifies the serving cell of the measurement report for the cell whose path loss measurement result is greater than the threshold. As another example, the UE measures the path loss of at least one of the serving cell and the neighboring cell, and notifies the serving cell of the measurement report for the cell with the smallest path loss. These methods are set by the serving cell separately or simultaneously in the measurement configuration. Thereby, the serving cell can recognize a path loss between the serving cell and the UE or between the neighboring cell and the UE.
サービングセルとUEとの間のパスロスについては、サービングセルが、UEからの上りリンクの受信電力を測定し、該UEの送信電力と該受信電力測定値とを用いて導出してもよい。該UEの送信電力をサービングセルが設定する場合は、サービングセルは、該UEの送信電力を認識していることになる。UEが送信電力を設定する場合は、該UEが送信データとともに、該送信電力情報をサービングセルに通知するようにしておけばよい。これにより、サービングセルは、該送信電力情報を認識することが可能となる。
As for the path loss between the serving cell and the UE, the serving cell may measure the uplink received power from the UE and derive it using the transmission power of the UE and the received power measurement value. When the serving cell sets the transmission power of the UE, the serving cell recognizes the transmission power of the UE. When the UE sets transmission power, the UE may notify the serving cell of the transmission power information together with the transmission data. Thereby, the serving cell can recognize the transmission power information.
実施の形態4で述べたように、上りリンクの状態としては、パスロスではなく、実際の距離を用いてもよい。この場合、位置測定用のメジャメントコンフィグレーションを設ける。該メジャメントコンフィグレーションを受信したUEは、GPS等により自UEの位置を測定する。UEは、測定した位置を、該メジャメントコンフィグレーションに対応するメジャメントリポートでサービングセルに通知する。
As described in the fourth embodiment, an actual distance may be used as the uplink state instead of a path loss. In this case, a measurement configuration for position measurement is provided. The UE that has received the measurement configuration measures the position of the own UE by GPS or the like. The UE notifies the serving cell of the measured position through a measurement report corresponding to the measurement configuration.
サービングセルは、UEだけでなく、自セルや隣接セルの位置も認識しておく必要がある。各セルは、自セルの位置をGPS等により測定し、予め該位置情報を隣接セルに通知しておくとよい。該通知は、各セルの設置時やinitialize、すなわち初期化時に行われるようにしておくとよい。これにより、サービングセルは、隣接セルの位置を認識することが可能となるため、上記で述べたUEの位置を用いて、各セルとUEとの間の実際の距離を導出することが可能となる。
The serving cell needs to recognize not only the UE but also the location of its own cell and neighboring cells. Each cell may measure the position of its own cell by GPS or the like, and notify the neighboring cell of the position information in advance. The notification may be performed when each cell is installed or initialized, that is, at initialization. As a result, the serving cell can recognize the position of the neighboring cell, and therefore, the actual distance between each cell and the UE can be derived using the position of the UE described above. .
本実施の形態で開示したターゲットセルの選択において、サービングセルは、UEの所望通信速度を認識する必要がある。UEの所望通信速度に限らず、UEの所望通信速度、UEの送信データ量やUEのケーパビリティを用いる場合は、これらの情報をサービングセルが認識する必要がある。ここでは、予めUEは、これらの情報をサービングセルに通知しておくようにする。UEは、RRC接続を要求する際、あるいは、RRC_connected状態にいる際に、これらの情報をサービングセルに通知しておけばよい。あるいは、図25のステップST2502に示すメジャメントリポートとともに、あるいは該メジャメントリポートメッセージに含めてサービングセルに通知するようにすればよい。RRCシグナリングを用いてもよいし、MACシグナリングを用いてもよい。これらの情報を個別に通知してもよいし、必要に応じて複数の情報を組合せて通知するようにしてもよい。
In the selection of the target cell disclosed in the present embodiment, the serving cell needs to recognize the desired communication speed of the UE. When using the desired communication speed of the UE, the amount of transmission data of the UE, and the capability of the UE, not only the desired communication speed of the UE, it is necessary for the serving cell to recognize these pieces of information. Here, the UE notifies the serving cell of such information in advance. The UE may notify the serving cell of these pieces of information when requesting the RRC connection or when in the RRC_connected state. Alternatively, the serving cell may be notified together with the measurement report shown in step ST2502 of FIG. 25 or included in the measurement report message. RRC signaling may be used, or MAC signaling may be used. These pieces of information may be notified individually, or a plurality of pieces of information may be combined and notified as necessary.
本実施の形態で開示した方法とすることで、HOにおいても、セルのバックホールリンクの通信品質および上りリンクの状態の少なくともいずれか一方を考慮に入れることが可能となる。このため、ヘテロジーニアスネットワークスにおける干渉問題やキャパシティ問題を改善することが可能となる。
By adopting the method disclosed in the present embodiment, even in HO, it becomes possible to take into consideration at least one of the communication quality of the cell backhaul link and the uplink state. For this reason, it becomes possible to improve the interference problem and capacity problem in heterogeneous networks.
また、実施の形態1から本実施の形態に開示した方法を組合せてもよく、この場合、UEの状態(RRC_Idle状態およびRRC_Connected状態)にかかわらず、サービングセルを選択あるいは変更する場合に、セルのバックホールリンクの通信品質および上りリンクの状態の少なくともいずれか一方を考慮に入れることが可能となり、ヘテロジーニアスネットワークスにおける干渉問題やキャパシティ問題を改善することが可能となる。
Further, the methods disclosed in the first embodiment to the present embodiment may be combined, and in this case, when the serving cell is selected or changed regardless of the UE state (RRC_Idle state and RRC_Connected state), the cell back It becomes possible to take into consideration at least one of the communication quality of the hall link and the uplink state, and it becomes possible to improve the interference problem and the capacity problem in the heterogeneous network.
また、マクロセルとローカルノードとの配置状況に応じて必要となる方法を組合せることで、より膨大で複雑な状況のヘテロジーニアスネットワークスにおいても、干渉やキャパシティを最適にすることが可能となる。
In addition, by combining the required methods according to the arrangement status of the macro cell and the local node, it becomes possible to optimize interference and capacity even in a heterogeneous network in a vast and complicated situation. .
本発明で開示した方法は、通常のeNB(マクロセル)にローカルノード一つ以上を組み入れたネットワークのみに限らず、マクロセルのみのネットワーク、あるいはローカルノードのみのネットワークにおいても、干渉低減、キャパシティ改善のために適用することが可能である。例えば、マクロセルにおいて、バックホールリンクの多くは専用回線が用いられるが、セル毎に該専用回線の通信品質は異なる。あるセル内でイベントが行われているような場合、該セルの通信負荷が増大し、それに伴い該セルのバックホール専用回線の通信品質も劣化することがある。このような場合にもバックホールリンクの通信品質を考慮してサービングセルの選択を行うことで、該セルを避けて異なるセルを選択可能とすることができる。したがって、セル間でキャパシティの分散を行うことが可能となり、通信速度の低下や、最悪の場合に生じる通信断を防ぐことが可能となる。
The method disclosed in the present invention is not limited to a network in which one or more local nodes are incorporated in a normal eNB (macro cell), but also in a macro cell only network or a local node only network. It is possible to apply for For example, in a macro cell, a dedicated line is used for many of the backhaul links, but the communication quality of the dedicated line varies from cell to cell. When an event is being performed in a certain cell, the communication load of the cell increases, and the communication quality of the backhaul dedicated line of the cell may deteriorate accordingly. Even in such a case, by selecting the serving cell in consideration of the communication quality of the backhaul link, it is possible to select a different cell while avoiding the cell. Therefore, it is possible to distribute the capacity among the cells, and it is possible to prevent the communication speed from being lowered and the communication interruption that occurs in the worst case.
以上の実施の形態では、LTEシステム(E-UTRAN)を中心に記載したが、本発明の移動体通信システムは、一つまたは複数の種類のノードが用いられる通信システムであれば適用可能である。たとえば、W-CDMAシステム(UTRAN、UMTS)またはLTEアドバンスド(LTE-Advanced)に適用可能である。
In the above embodiment, the LTE system (E-UTRAN) has been mainly described. However, the mobile communication system of the present invention can be applied to any communication system using one or a plurality of types of nodes. . For example, the present invention can be applied to a W-CDMA system (UTRAN, UMTS) or LTE-Advanced.
この発明は詳細に説明されたが、上記した説明は、すべての局面において、例示であって、この発明がそれに限定されるものではない。例示されていない無数の変形例が、この発明の範囲から外れることなく想定され得るものと解される。
Although the present invention has been described in detail, the above description is illustrative in all aspects, and the present invention is not limited thereto. It is understood that countless variations that are not illustrated can be envisaged without departing from the scope of the present invention.
71 移動端末、72 基地局、72-1 eNB、72-2 Home-eNB、73 MME/S-GW部、74 HeNBGW。
71 mobile terminals, 72 base stations, 72-1 eNB, 72-2 Home-eNB, 73 MME / S-GW unit, 74 HeNBGW.
Claims (4)
- コアネットワークに接続される複数の基地局装置と、各前記基地局装置と無線通信可能な移動端末装置とを含み、前記複数の基地局装置の通信可能な範囲である複数のセルの少なくとも一部分が重複する移動体通信システムであって、
前記移動端末装置は、
各セルにおける基地局装置からの信号の受信品質と、前記基地局装置と前記コアネットワークとの間の通信回線の通信品質とを含む選択情報に基づいて、前記複数のセルの中から、通信対象となる基地局装置のセルを選択することを特徴とする移動体通信システム。 A plurality of base station devices connected to a core network; and mobile terminal devices capable of wireless communication with each of the base station devices, wherein at least a part of a plurality of cells that are communicable ranges of the plurality of base station devices An overlapping mobile communication system,
The mobile terminal device
Based on selection information including reception quality of a signal from a base station apparatus in each cell and communication quality of a communication line between the base station apparatus and the core network, a communication target is selected from the plurality of cells. A mobile communication system, wherein a cell of a base station device to be selected is selected. - 複数の基地局装置と、各前記基地局装置と無線通信可能な移動端末装置と、前記複数の基地局装置のうちの少なくとも1つの基地局装置と前記移動端末装置との間の無線通信を中継する中継装置とを含み、前記複数の基地局装置の通信可能な範囲である複数のセルの少なくとも一部分が重複する移動体通信システムであって、
前記移動端末装置は、
各セルにおける基地局装置からの信号の受信品質と、前記基地局装置と前記中継装置との間の通信回線の通信品質とを含む選択情報に基づいて、前記複数のセルの中から、通信対象となる基地局装置のセルを選択することを特徴とする移動体通信システム。 Relaying wireless communication between a plurality of base station devices, a mobile terminal device capable of wireless communication with each of the base station devices, and at least one of the plurality of base station devices and the mobile terminal device A mobile communication system in which at least a part of a plurality of cells that are communicable ranges of the plurality of base station devices overlap each other,
The mobile terminal device
Based on selection information including the reception quality of the signal from the base station apparatus in each cell and the communication quality of the communication line between the base station apparatus and the relay apparatus, a communication target is selected from the plurality of cells. A mobile communication system, wherein a cell of a base station device to be selected is selected. - 前記選択情報は、各セルにおける移動端末装置から基地局装置への上り通信回線の状態を含むことを特徴とする請求項1または2に記載の移動体通信システム。 The mobile communication system according to claim 1 or 2, wherein the selection information includes a state of an uplink communication line from the mobile terminal apparatus to the base station apparatus in each cell.
- 複数の基地局装置と、各前記基地局装置と無線通信可能な移動端末装置とを含み、前記複数の基地局装置の通信可能な範囲である複数のセルの少なくとも一部分が重複する移動体通信システムであって、
前記移動端末装置は、
各セルにおける基地局装置からの信号の受信品質と、各セルにおける移動端末装置から基地局装置への上り通信回線の状態とを含む選択情報に基づいて、前記複数のセルの中から、通信対象となる基地局装置のセルを選択することを特徴とする移動体通信システム。 A mobile communication system including a plurality of base station devices and mobile terminal devices capable of wireless communication with each of the base station devices, wherein at least a part of a plurality of cells that are communicable ranges of the plurality of base station devices overlap Because
The mobile terminal device
Based on selection information including the reception quality of the signal from the base station apparatus in each cell and the state of the uplink communication line from the mobile terminal apparatus to the base station apparatus in each cell, the communication target is selected from the plurality of cells. A mobile communication system, wherein a cell of a base station device to be selected is selected.
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