KR20050020058A - Method for changing cell in mobile communication system that support mbms service - Google Patents

Abstract

PURPOSE: A cell changing method in a mobile communication system supporting a broadcasting service is provided to collect MBMS-related information for a target cell when the same MBMS is to be received from the target cell included in the second RNC(Radio Network Controller), and to transmit the collected information to the first RNC, thereby suppressing an unnecessary procedure for cell changing. CONSTITUTION: A UE(501) reports to an SRNC(Serving RNC)(503) that the UE(501) moves to a target cell through a cell update message(510). The SRNC(503) transmits an RL(Radio Link) setup request message to a DRNC(Drift RNC)(502)(511). The DRNC(502) informs the SRNC(503) that an MBMS attach process is successful and an RL is set(513). The SRNC(503) transmits a cell update confirm message to the UE(501) as a response to the cell update message(514). The UE(501) receives MBMS data in accordance with a desired MBMS through the DRNC(502) from the SRNC(503)(516).

Description

Cell change in mobile communication system supporting broadcasting service {METHOD FOR CHANGING CELL IN MOBILE COMMUNICATION SYSTEM THAT SUPPORT MBMS SERVICE}

The present invention relates to a method for providing a broadcast service in a mobile communication system, and more particularly, to a method of managing a dedicated Iur signaling connection corresponding to a cell change during a session according to a broadcast service.

Due to the development of the telecommunications industry, not only voice service data but also packet services for transmitting large data such as packet data and circuit data, that is, services for multicasting multimedia communication are changing. Accordingly, in order to support the multicasting multimedia communication, a broadcast / multicast service providing a service to a plurality of mobile terminals (hereinafter referred to as UEs) from one or several multimedia data sources. ) Is being discussed. The broadcasting / multi-broadcasting service is a multimedia broadcasting / multi-broadcasting service supporting a multimedia service such as a cell broadcast service (hereinafter, referred to as a “CBS service”), a message-oriented service, and real-time video, audio, still images, and text. (Multimedia Broadcast / Multicast Service, hereinafter referred to as "MBMS Service").

The CBS service is a service that broadcasts a plurality of messages to all UEs located in a specific service area. In this case, the specific service area for providing the CBS service may be an entire area for providing the CBS service in one cell.

The MBMS service is a service that simultaneously supports multimedia formats such as real time video, voice, still image, and text, and requires a large amount of transmission resources. Therefore, the MBMS service is serviced through a broadcast channel in that there is a possibility that a large number of services can be simultaneously deployed in one cell. In particular, the MBMS service requires more radio resources than the CBS service. The MBMS service is a "point to point (hereinafter referred to as" PtP "mode) mode" in consideration of the number of UEs to be provided with the MBMS service in one cell or the transmission power used by the MBMS service. And "Point to Multi-point (hereinafter referred to as" PtM ") mode" mode. The PtP mode provides a desired MBMS service by allocating a dedicated channel for each UE when the number of UEs that desire MBMS service in a cell or when there is sufficient surplus transmission power. The PtM mode is a method of providing a desired MBMS service by allocating a common channel to UEs when the number of UEs that desire MBMS service in a cell or when there is insufficient surplus transmission power. Of course, it is also possible to switch the MBMS service provided by the PtP mode for each cell to PtM mode or to provide the MBMS service provided in the PtM mode by switching to PtP mode. However, the mode switching is limited to the case where the environment for providing the MBMS service changes in terms of efficient use of radio resources.

Next, a network structure for providing the MBMS service in the mobile communication system will be described with reference to FIG. 1.

1 is a diagram schematically illustrating a network structure for providing an MBMS service in a mobile communication system.

Referring to FIG. 1, a multicast / broadcast-service center (MB-SC) hereinafter referred to as a "MB-SC" 110 is a source for providing an MBMS stream. (source). The MB-SC 110 schedules a stream for the MBMS service and transmits the stream to the transmission network 120. The transmission network 120 is a network existing between the MB-SC 110 and a service packet radio service support node (Serving 'GPRS (General Packet Radio Service) Support Node' (hereinafter referred to as "SGSN") 130). (network), and serves as a communication path for delivering the stream for the MBMS service received from the MB-SC (110) to the SGSN (130). Although not shown, the transmission network 120 may be connected to an external network through a Gateway GPRS Support Node (hereinafter referred to as a "GGSN"). The SGSN 130 receiving the stream for the MBMS service in the transmission network 120 controls the MBMS-related services of subscribers, that is, UEs, to receive the MBMS service. For example, the service manager manages MBMS service charging related data of each subscriber and selectively transmits MBMS data to a specific Radio Network Controller (hereinafter, referred to as "RNC") 140. To this end, the SGSN 130 needs to know the list of the specific RNCs receiving the MBMS service. The RNC 140 refers to an apparatus for controlling the plurality of cells 160 and 170. The RNC 140 transmits MBMS data to a cell where a UE requesting MBMS service exists among cells managed by the RNC 140, and controls a radio channel configured to transmit the MBMS data. In addition, it manages the information about the MBMS service by the stream for the MBMS service received from the SGSN (130). As described above, the RNC 140 must know the list of cells receiving the MBMS service in order to transmit selective MBMS data to the corresponding cells. Cell 1 (Cell 1) 160 and Cell 2 (Cell 2) 170 refer to a base station apparatus for transmitting MBMS-related data to subscribers. Typically, a base station may have a plurality of cells, but for convenience of description, it is assumed that one base station is composed of one cell. In the cells 160 and 170, a plurality of UEs that wish to receive the MBMS service may be located at any time. In FIG. 1, UE # 1 161, UE # 2 162, and UE # 3 163 are located at a first base station (cell 1) 160, and a UE is located at a second base station (cell 2) 170. An example of # 4 171 and UE # 5 172 is located. The UEs 161, 162, 163, 171, and 172 refer to terminal devices or subscribers that want to receive MBMS service from the RNC 140 through cell 1 160 or cell 2 170. Although not shown in FIG. 1, a Home Location Register (HLR) is connected to the SGSN 130 to perform subscriber authentication for an MBMS service.

1 illustrates a structure in which only one RNC 140 is connected to one SGSN 130 and the SGSN 130 in response to one MBMS service. However, it will be apparent that there may be a plurality of SGSNs corresponding to one MBMS service, and there may be a plurality of RNCs for each SGSN.

2 is a diagram illustrating a signal flow for providing an MBMS service between a UE and a network in a mobile communication system.

Referring to FIG. 2, the UE performs a SUBSCRIPTION process with a core network (CN) to receive a random MBMS service (step 201). Here, the core network includes an MB-SC, a transmission network, and an SGSN as described in FIG. 1. The user registration process is a process of exchanging basic information related to charging or receiving MBMS service in an MBMS service between a service provider and a user. When the user registration is completed, the core network performs an ANNOUNCEMENT process to guide basic information on MBMS services currently available, for example, menu information, to UEs serving the MBMS service. Perform (step 202). Here, the menu information is information indicating time information (START TIME) and duration time for each MBMS service. The core network may broadcast the menu information through predetermined service areas (broadcast service such as CBS) or transmit only to UEs having a MBMS service request. The core network transmits an MBMS service ID for identifying each MBMS service to the UE through the menu information. Here, the MBMS service identifier may be composed of a multicast address (hereinafter referred to as a "multicast IP address") and an access point name (hereinafter referred to as "APN").

Each of the UEs notified of the menu information through the service guide process selects a specific MBMS service to be serviced from the menu information, and performs a service request (JOINING) process for the selected MBMS service to the core network. Step 203). Here, the service request message transmitted by the UE to the core network includes an MBMS service identifier indicating the selected MBMS service and a UE identifier indicating the corresponding UE. According to the service request of the UE, the core network identifies the MBMS service that the UE wants to receive. In this process, the SGSN, the transmission network, etc. constituting the core network may recognize UEs that want to receive a certain MBMS service and a device where the UEs are located. That is, through the JOINNING process, SGSN can grasp the list of UEs and the list of RNCs where the UEs are located, thereby creating an MBMS context for managing the MBMS service.

Thereafter, the core network performs a NOTIFICATION process, which is a kind of paging process indicating that an MBMS service requested by the UE will be started (step 204). In the calling process performed in step 204, an existing calling method may be used or an calling method optimized for MBMS service published in application number P2002-34704 previously filed by the same applicant may be used. Meanwhile, the quality of service (hereinafter referred to as "QoS") information and the multicast region information of the MBMS service are transmitted through the service notification process.

Upon detecting that the requested MBMS service will be started soon through the service notification process, the UE actually allocates radio resources for providing the MBMS service through the RADIO RESOURCE ALLOCATION process (step 205). . Then, the radio resource related information is announced to related devices. Here, the radio resource allocation process, the RNC informs the UEs located in any cell radio bearer information to be transmitted the MBMS service in the cell (hereinafter referred to as "radio bearer setup") &Quot; Step " and the RNC informs transport bearer information and radio bearer information to be configured on the Iub interface to cells where UEs to receive MBMS service are located (hereinafter, " radio link setup " ) "Step). In the RESOURCE ALLOCATION process, the RNC is based on information about the number of UEs belonging to an arbitrary cell and a radio resource management function (PtM) / point-to-point (PtM). / PCE can be determined.

When the radio resource allocation process is completed, all UEs that want to receive a specific MBMS service are aware of radio link related information to be provided with the specific MBMS service and higher layer information to be processed. In addition, the cells to which the UE belongs to complete the radio link and Iub interface configuration. With the preparation for providing the MBMS service between the RNC and the UEs as described above, the core network performs an MBMS data transmission process of transmitting MBMS service data to the UEs through the RNC (step 207). In addition, in the DATA TRANSFER step, a ciphering key may be updated. For example, if a need arises to change the ciphering key for a given MBMS service, the RNC delivers a new ciphering key to all UEs receiving the MBMS service.

Thereafter, when the MBMS service data transmission is completed, a radio resource release process of releasing the set radio resources, that is, the transport bearer and the radio bearer, is performed between the UE and the core network (step 207). The devices configuring the core network delete relevant information of the MBMS service of which the radio resource is released. Otherwise, the UE may voluntarily request to stop receiving a service through a service deleting process in the middle of receiving any MBMS service.

Typically the UE has mobility. Accordingly, the UE may move to a service area by another RNC while establishing an RRC connection to a specific RNC and receiving MBMS service through the specific RNC. In this case, the specific RNC registered by the UE to receive the MBMS service for the first time is called a 'Serving RNC (hereinafter referred to as a' SRNC '), and the RNC currently receiving the MBMS service by moving is referred to as a' drift RNC '. (Drift RNC, hereinafter referred to as "DRNC"). The DRNC and the Control RNC (hereinafter referred to as "CRNC") are distinguished by the control target (UE or base station) but indicate the same RNC.

Meanwhile, signaling between the SRNC and the DRNC should be provided in order to continuously provide an MBMS service to a UE whose SRNC and the DRNC do not match. For this purpose, there is typically an Iur interface between RNCs and a signaling connection control part (hereinafter referred to as "SCCP") signaling connection is used as a signaling bearer on the Iur interface. The RNSAP (Radio Network Subsystem Application Part) message between the two RNCs is transmitted through the SCCP signaling connection.

3 is a diagram illustrating a procedure of attaching to a DRNC through an existing MBMS procedure as the UE moves to a cell controlled by another DRNC. In FIG. 3, the UE 301 represents a mobile terminal receiving an MBMS service, the DRNC 302 represents a DRNC corresponding to the UE 301, and the SRNC 303 corresponds to the UE 301. Represents one SRNC.

Referring to FIG. 3, when the UE 301 detects that the cell has been changed, the UE 301 reports this to the SRNC 303 through an RRC message in step 310. The UE 301 uses the CELL UPDATE message as the RRC message in the CELL_PCH state or the CELL_FACH state, and uses the MEASUREMENT REPORT message as the RRC message in the CELL_DCH state.

The SRNC 303 receives the RRC message from the UE 301 and determines to change the cell based on the RRC message or adds a radio link (hereinafter referred to as "RL") in step 320. To decide. If the cell to be changed is a cell controlled by another RNC (DRNC 302 in FIG. 3) instead of the cell controlled by the SRNC 303, the SRNC 303 provides the MBMS service related information through the Iur interface in step 330. Send to DRNC 302. The MBMS service related information is transmitted through an MBMS Attach REQUEST message, and includes an MBMS service identifier for identifying the MBMS service.

The DRNC 302 adds a UE attached through the MBMS Attach REQUEST message to an MBMS Service Context. The MBMS service context exists for each MBMS service. In addition, after the number of UEs receiving the MBMS service is increased by one in the corresponding cell, it is checked whether the number of UEs exceeds a threshold for determining a PtP / PtM channel type. If the channel type needs to be changed through this, the procedure for changing the channel type is performed.

After the DRNC 302 successfully adds the UE 301 to the MBMS service context, the DRNC 302 transmits an MBMS ATTACH RESPONSE message in response to the MBMS Attach REQUEST message to the SRNC 303 in step 331. The MBMS ATTACH RESPONSE message includes a channel type, radio bearer information, service area information, etc. of a cell attached to the UE 301.

In step 340, an Iur signaling bearer is set up between the SRNC 303 and the DRNC 302. The Iur signaling bearer is used when delivering a RANAP message when it is determined to provide MBMS service for UEs in CELL_FACH and CELL_DCH states. In step 340, a procedure of setting a data bearer to be used when carrying an RRC message and user data is performed to the UE 301.

If necessary, the SRNC 303 transmits an RRC message to the UE 301 in step 311. For example, a CELL UPDATE CONFIRM message is used when a CELL UPDATE is received in step 310 as the RRC message, and an ACTIVE SET UPDATE message is used when a MEASUREMENT REPORT is received. In addition, messages such as PHYSICAL CHANNEL, TRANSPORT CHANNEL, and RADIO BEARER RECONFIGURATION may be used for each case requiring reconfiguration on the physical channel, the transport channel, and the radio bearer.

In general, for one MBMS service, the SRNC cannot know the state of a cell managed by the DRNC. As described above with reference to FIG. 3, in order to solve this problem, the state (channel type, radio bearer information, service area information) of a cell managed by the DRNC is transmitted through an MBMS Attach procedure, a PtM TRANSMISSION INITIATION / TERMINATION procedure, and the like. Use the method. Accordingly, the SRNC determines whether to receive MBMS service through the corresponding cell by referring to previously received information and internal UE context. That is, whether to receive the MBMS service through the corresponding cell is determined in consideration of whether the RRC state of the UE and other services other than the MBMS service are simultaneously received.

As can be seen from the above description, the conventional DRNC performs the operation of adding the UE to the internal MBMS service context according to the MBMS Attach procedure before the SRNC finally determines whether to receive the MBMS service through the corresponding cell. This causes a problem that causes unnecessary message exchanges frequently through the Iur interface. An example of causing this problem will be described with reference to FIG. 4.

4 illustrates a problem when a UE in a Cell DCH state attaches to a DRNC through an existing MBMS service procedure when moving to a cell controlled by the DRNC. In FIG. 4, the UE 401 indicates a UE receiving an MBMS service, the DRNC 402 indicates a DRNC for an MBMS service corresponding to the UE 401, and the SRNC 403 indicates the UE 401. Represents an SRNC corresponding to Meanwhile, in FIG. 4, although a specific MBMS service is provided by a PtP mode in a corresponding cell of the DRNC, the number of UEs that want to receive the MBMS service is close to a threshold for selecting a PtM mode, and when a new UE is added, PtM Assume a situation to be changed to the channel type of the mode.

Referring to FIG. 4, the UE 401 indicates that the event has occurred in step 460 when a predefined event occurs, such as when the reception strength of the neighboring cell observed exceeds a preset threshold. Report to SRNC 403 via REPORT message.

In step 490, the SRNC 403 determines to handover to the received neighbor cell based on the received MEASUREMENT REPORT message. In this case, if the received neighbor cell belongs to the DRNC, before adding the radio link to the DRNC, in step 470, the MBMS Attach procedure of transmitting information related to the MBMS service to the DRNC is performed. In this case, the DRNC adds the UE 401 to the internal MBMS service context through the MBMS Attach procedure of step 370, thereby determining to change the channel type to the PtM mode. The DRNC 402 transmits an MBMS ATTACH RESPONSE message to the SRNC 403 indicating that the MBMS service is provided by the PtM mode in the cell due to the change of the channel type.

If the UE 401 has a plurality of radio links to simultaneously receive other services in addition to the MBMS service, the SRNC 403 performs handover to the cell providing the MBMS service in the PtM mode in step 493. Decide to cancel. On the other hand, since the DRNC 402 determines to change the channel type from the PtP mode to the PtM mode, the DRNC 402 performs an operation for changing the channel type for the MBMS service in step 492. The change of the channel type releases all dedicated channels allocated in the PtP mode and prepares to establish a new radio resource for providing the MBMS service by the PtM mode.

The SRNC 403 transmits an MBMS DETACH REQUEST message to the DRNC 402 in step 480 to request the UE 401 to be removed from an internal MBMS service context. In response, the DRNC 402 removes the UE 401 from the MBMS service context through an MBMS Detach procedure. Thus, when the number of UEs to receive the MBMS service is smaller than the threshold, the DRNC 401 determines to change the channel type from PtM mode to PtP mode in step 494. In step 481, the MBMS DETACH RESPONSE message in response to the MBMS DETACH REQUEST message is transmitted to the SRNC 403. The channel type change according to the determination is made in step 495. In addition, by releasing all dedicated channels allocated in the PtM mode, and by setting a new radio resource for providing the MBMS service by the PtP mode.

As described above, there is a problem in that an unnecessary channel type change occurs in a handover situation as well as a load on the Iur interface due to the MBMS ATTACH procedure and the MBMS DETACH procedure. That is, without performing the MBMS information (channel type, radio bearer information, service area information) of the cell to which the SRNC has moved and the RRC state (CELL_FACH, CELL_DCH) of the UE, and performing the MBMS Attach procedure, efficient information transmission and MBMS data It is not possible to efficiently set up the resources required for transmission.

Accordingly, an object of the present invention for solving the above problems is to request MBMS service related information and MBMS service requests between different wireless network controllers when a mobile station receiving MBMS service moves a cell after a session starts in a mobile communication system. The present invention provides a method for efficiently transmitting UE-related information.

Another object of the present invention is to provide a method for efficiently setting up resources required for MBMS data transmission on a network.

It is still another object of the present invention to provide a message used for attaching according to an RRC state of a mobile terminal and a method of applying a message when the radio network controller for managing a target cell is different from an SRNC. have.

Another object of the present invention is to attach a mobile terminal according to the state of the target cell in a situation where the SRNC knows MBMS service related information of the target cell in advance when the radio network controller managing the target cell is different from the SRNC. The present invention provides a method for using a message and a method of applying the message differently.

It is still another object of the present invention to provide a method for efficiently transmitting MBMS-related information in service in a target cell to be moved when the SRNC and the DRNC are different, without additional information exchange on the Iur from the DRNC to the SRNC.

Still another object of the present invention is to provide a method for transferring an MBMS related information being served by a target cell to an SRNC using an RRC procedure when the SRNC and the DRNC are different.

Another object of the present invention is to provide a method for a mobile station to interpret information contained in an MBMS control message after receiving the MCCH of a target cell, and adds it to the RRC message requesting cell change by the mobile station and transmits the information to the SRNC. have.

It is still another object of the present invention to provide a method for efficiently transmitting PTM RB information for an MBMS service from a radio network controller to a mobile terminal.

Another object of the present invention is that the DRNC transmits PTM RB information to the SRNC through the Iur interface, and the SRNC transmits the PtM RB to the mobile terminal through the DCCH in consideration of the PtP / PtM status of the target cell and the RRC status of the mobile terminal. It provides a method for determining whether or not to do so.

Another object of the present invention is to inform that MBMS service is impossible due to a temporary shortage of radio resources in a cell to which a radio link is added for a mobile terminal in a CELL_DCH state, or because the cell is not included in the MBMS service area. In providing a method.

In a first aspect for achieving the above object, the present invention provides a situation in which a broadcast service is provided through a common channel from a first and a second wireless network controller and a source cell belonging to the first wireless network controller. In the mobile communication system including at least one mobile terminal to move to a target cell belonging to the second wireless network controller in the radio communication system, the radio terminal is allocated a radio resource so that the mobile terminal can receive the broadcast service from the second wireless network controller The method of claim 1, wherein the mobile station receives a broadcast service related information from the target cell and requests the cell update by transmitting the broadcast service related information to the first wireless network controller, and the first wireless network controller. Determines whether to allocate radio resources based on the broadcast service related information, and determines the second wireless network agent by the determination. Groups is characterized in that it comprises the step of requesting a radio resource allocation.

Preferably, in the first aspect, when the target cell receives broadcast service related information indicating that there is no mobile terminal to provide a broadcast service or a broadcast service through a dedicated channel, request for allocation of radio resources. It is characterized by.

In the first aspect described above, preferably, when the target cell receives the broadcast service related information indicating that the target cell provides the broadcast service through the common channel, the mobile terminal can receive the broadcast service only through the common channel. Characterized by requesting an assignment

In the first aspect described above, preferably, when the target cell receives the broadcast service related information indicating that the target cell is not providing the broadcast service due to lack of radio resources, the radio resource allocation is reserved.

Preferably, in the first aspect, when receiving broadcast service related information indicating that broadcast service related information is not provided from a target cell, the second wireless network controller is requested to provide a broadcast service to the second wireless network controller. And a procedure for providing the broadcast service between the SGSN and the like.

Preferably, in the first aspect, when a call update request is received from the mobile station without broadcast service related information, the second wireless network controller requests the MBMS ATTACH procedure and the establishment of a common channel at the same time.

In a second aspect for achieving the above object, the present invention provides a situation in which a broadcast service is provided through a dedicated channel from a first and a second wireless network controller and a source cell belonging to the first wireless network controller. In the mobile communication system including at least one mobile terminal to move to a target cell belonging to the second wireless network controller in the radio communication system, the radio terminal is allocated a radio resource so that the mobile terminal can receive the broadcast service from the second wireless network controller The method of claim 1, wherein the mobile station measures the signal strength of a neighboring cell, and reports the measurement result to the first wireless network controller when the target cell is detected through the measurement; The network controller determines whether to handover to the target cell, and by the determination, wirelessly transmits to the second wireless network controller to which the target cell belongs. Requesting resource allocation, transmitting, by the second wireless network controller, broadcast service related information about the target cell to the first wireless network controller in response to the radio resource allocation request, and the first wireless network And a controller determines whether to allocate the radio resource based on the broadcast service related information.

Preferably, in the second aspect, when the target cell receives broadcast service related information indicating that there is no mobile terminal to provide a broadcast service or a broadcast service through a dedicated channel, the radio resource allocation is determined. It is characterized by.

Preferably, in the second aspect, when the target cell receives the broadcast service related information indicating that the target cell provides the broadcast service through the common channel, the mobile station may receive the broadcast service only through the common channel. Determine the assignment.

Preferably, in the second aspect, when the target cell receives the broadcast service related information indicating that the target cell is not providing the broadcast service due to the lack of radio resources, the radio resource allocation is reserved to the second wireless network controller. It is done.

Preferably, in the second aspect, when the target cell receives the broadcast service related information indicating that the target cell is not a broadcast serviceable area, the target cell notifies the mobile station that the target cell is not a broadcast service area.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

DETAILED DESCRIPTION In the following detailed description, one representative embodiment of the present invention is set forth in order to achieve the above technical problem. And other embodiments that can be presented with the present invention are replaced by the description in the configuration of the present invention.

In general, in a mobile communication system providing an MBMS service, mobility between cells is supported by UE mobility. To this end, a UE requires a measurement function for detecting a cell having better signal strength (hereinafter referred to as a "target cell") than a cell currently receiving MBMS service (hereinafter referred to as a "source cell"). When the target cell is detected through the measurement function, the mobile communication system performs a "cell-to-cell mobility procedure" for providing the MBMS service from the target cell at the request of the UE. In an embodiment of the present invention to be described below, it is assumed that the source cell and the target cell are supported by MBMS service by different wireless network controllers. In this case, the inter-cell moving procedure is an "MBMS Attach procedure" between a radio network controller supporting the source cell (hereinafter referred to as "SRNC") and a radio network controller supporting the target cell (hereinafter referred to as "DRNC"). It includes.

In the embodiments of the present invention to be described below, the MBMS service in the PtP mode refers to a situation in which a dedicated transport channel (hereinafter referred to as "DCH") is allocated as a logical channel (hereinafter referred to as "MTCH") for transmitting MBMS data. . On the other hand, the MBMS service in the PtM mode refers to a situation in which a common transport channel (hereinafter referred to as "FACH") is allocated as an MTCH for transmitting MBMS data.

This may be classified according to the case where the UE is in the state of receiving the desired MBMS service in the PtM mode (CELL_FACH state) and in the state in the state of receiving the desired MBMS service in the PtP mode (CELL_DCH state). Can be. In the following description, embodiments corresponding to each of the two cases described above will be described.

1. First embodiment (in case of CELL_FACH state)

In the first embodiment of the present invention to be described later, the UE in the CELL_FACH state collects the relevant information about the MBMS service (hereinafter referred to as "MBMS service related information") from the target cell, and reports it to the SRNC. The SRNC posts performing the MBMS Attach procedure to the DRNC to which the target cell belongs by the MBMS service related information reported from the UE.

Briefly referring to the operation of the UE collecting the MBMS service related information, the UE receives a broadcast control channel (BCCH) transmitted from the target cell. When the session of the MBMS service is in progress, the target cell transmits configuration information (hereinafter referred to as "MCCH configuration information") of the MBMS service control channel (MCCH) corresponding to the MBMS service through the BCCH. Accordingly, the UE can receive MCCH from the target cell by acquiring MCCH configuration information through the BCCH. The target cell transmits the MBMS service related information which is basic information for receiving the MBMS service through the MCCH. The MBMS service related information includes the following elements.

MBMS Service ID: An identifier of the MBMS service that can be received by the cell.

Channel Type Indicator (PtP / PtM Indicator): an indicator indicating whether a type of a transmission channel for transmitting MBMS data in a cell is PtP mode or PtM mode.

No UE: An indicator indicating that a cell is included in the MBMS service area and a session for the MBMS service is started and MBMS data is being transmitted, but is not currently provided because there is no UE to receive the MBMS service in the cell.

-Lack of Resource: Indicator that indicates that the cell is included in the MBMS service area, the session for the MBMS service is started and MBMS data is being transmitted, but the MBMS service is temporarily unavailable due to the lack of radio resources of the cell.

However, the MBMS service related information that the UE intends to receive may not be transmitted through the MCCH. In this case, when there is a UE in the PMM-IDLE state, since the location of the UE is not recognized, MBMS service related information is transmitted in a routing area (RA) unit, but the UE is located in a cell that does not belong to the RA. For example, the cell where the UE is located may be an example that is not a service area for the MBMS service.

The UE, which has acquired MBMS service related information through the MCCH, transmits the MBMS service related information to the SRNC through a Cell Update message as a start of a cell update procedure. The Cell Update message according to the present invention includes the MBMS service identifier and the MBMS cause information element in the existing Cell Update message. Table 1 below shows an example of the Cell Update message.

Information Element / Group name Need MBMS information elements MBMS Service ID OP MBMS cause OP

In Table 1, the MBMS Service ID is an identifier for identifying an MBMS service allocated by a core network, such as TMGI, and the MBMS cause is information on an environment for providing an MBMS service in a target cell. The MBMSS causes are defined in Table 2 below.

Information Element / Group name Need Multi Type and reference Semantics description MBMS cause MP Enumerated (PtM data transmission, PtP data transmission, no UE, radio resources not available, service information not available)

In Table 2, 'PtM data transmission' means that an MBMS service is provided by a PtM mode in a corresponding cell. 'PtP data transmission' means that the MBMS service is served by the PtP mode in the cell. 'No UE' means that the MBMS service is not currently provided because there is no UE to receive the MBMS service in the cell. 'Radio Resource not available' means that the MBMS service cannot be temporarily provided due to lack of radio resources in the cell. 'Service information not available' indicates that there is no information on the MBMS service that the UE intends to receive in the MCCH. Among these, the 'PtM data transmission' may be explicitly signaled as shown in <Table 2>, or may be implicitly signaled when the MBMS cause is not included in the Cell update message of <Table 1>. In addition, the PtP data transmission and the no UE may be replaced with one cause value.

Hereinafter, with reference to the accompanying drawings according to the first embodiment of the present invention will be described in detail the attach procedure in the case that the UE in the CELL_FACH state provides the MBNC service-related information of the target cell to be moved using the Cell Update message to the SRNC Do it.

1.1 Signaling procedure when MBMS cause is PtP data transmission or No UE

5A to 5C illustrate an attach procedure performed by a request of a UE in a CELL_FACH state when a target cell provides a corresponding MBMS service by a PtP mode or there is no UE to receive the MBMS service. A diagram showing signaling. If the target cell is providing the MBMS service in the PtP mode or there is no UE to be provided with the MBMS service, the UE is likely to be provided the MBMS service in the PtP mode from the target cell. have. Therefore, the RL (Radio Link) SETUP procedure for allocating a dedicated channel will be accompanied after the MBMS Attach procedure is made. In the present invention to be described later, in performing the attach procedure, the SRNC attempts to attach the RL with respect to the DRNC through the RL SETUP procedure. Meanwhile, in FIGS. 5A to 5C, the UE 501 indicates a UE that wants to receive a specific MBMS service from a newly moving target cell, and the DRNC 502 indicates an RNC that provides the specific MBMS service to the target cell. SRNC 503 represents an RNC currently providing the specific MBMS service to the UE 501.

Referring to FIG. 5A, the UE 501 in the CELL_FACH state reports to the SRNC 503 that the UE 501 has moved to the target cell through a CELL UPDATE message in step 510. The CELL UPDATE message further includes an MBMS service identifier and an MBMS Cause IE. In this case, "PtP data transmission" or "no UE" is set in the MBMS Cause IE. When the SRNC 503 determines that the MBMS Cause IE is set to "PtP data transmission" or "no UE" through the CELL UPDATE message, the SRNC 503 determines to provide a corresponding MBMS service through a dedicated channel. Thereafter, in step 511, the SRNC 503 transmits an RL SETUP REQUEST message requesting to establish a radio link to the DRNC 502 managing the target cell. In this case, the SRNC 503 attempts an MBMS Attach together by including an MBMS service identifier in the RL SETUP REQUEST message. The DRNC 502 adds the UE 501 to the MBMS service context corresponding to the MBMS service by receiving the RL SETUP REQUEST message. Before that, the DRNC 502 adds the UE 501 to the MBMS service context to determine whether a change to PtM mode is required. The determination can be made by checking whether the number of UEs that wish to receive the MBMS service exceeds a predetermined threshold. That is, the DRNC 502 adds the UE 501 to the MBMS service context only when it is not necessary to change the channel type to the PtM mode. Adding the UE 501 to the MBMS service context implies a decision to add an RL with the SRNC 503. Thereafter, the DRNC 502 informs the SRNC 503 that MBMS Attach has been successfully performed through the RL SETUP RESPONSE message in response to the RL SETUP REQUEST message in step 513.

After receiving the RL SETUP RESPONSE message, the SRNC 503 transmits a CELL UPDATE CONFIRM message in response to the CELL UPDATE message to the UE 501 in step 514. The CELL UPDATE CONFIRM message includes modified radio bearer (RB), transport channel, physical channel information, and the like.

The UE 501 receives the CELL UPDATE CONFIRM message and transitions the RRC state to CELL_DCH. Accordingly, the UE 501 receives MBMS data according to a desired MBMS service from the SRNC 503 through the DRNC 502 in step 516.

Referring to FIG. 5B, the UE 501 in the CELL_FACH state reports to the SRNC 503 that the UE 501 moves to the target cell through a CELL UPDATE message in step 520. The CELL UPDATE message further includes an MBMS service identifier and an MBMS Cause IE. In this case, "PtP data transmission" or "no UE" is set in the MBMS Cause IE. When the SRNC 503 determines that the MBMS Cause IE is set to "PtP data transmission" or "no UE" through the CELL UPDATE message, the SRNC 503 determines to provide a corresponding MBMS service through a dedicated channel. Thereafter, in step 521, the SRNC 503 transmits an RL SETUP REQUEST message requesting radio link establishment to the DRNC 502 managing the target cell. In this case, the SRNC 503 attempts an MBMS Attach together by including an MBMS service identifier in the RL SETUP REQUEST message. The DRNC 502 determines whether to add the UE 501 to the MBMS service context corresponding to the MBMS service by receiving the RL SETUP REQUEST message. Determining whether to add the UE 510 to the MBMS service context is as described with reference to FIG. 5A. In operation 522, the channel type is changed to the PtM mode. In this case, the DRNC 502 not only adds the UE 501 to the MBMS service context, but also decides not to add an RL with the SRNC 503 as well. Thereafter, the DRNC 502 transmits an RL SETUP FAILURE message to the SRNC 503 indicating that the MBMS Attach to the UE 501 has failed in step 523. When the SRNC 503 receives the RL SETUP FAILURE message, the UE 501 refers to a UE context corresponding to the UE 501, and the UE 501 determines a CS (Circuit Service) or PS (Packet Service) excluding the current MBMS service. The RRC state of the UE 501 is determined by comprehensively considering the reception or the like. If the RRC state of the UE 501 is to be maintained as CELL_FACH, the SRNC 503 performs a Common Transport Channel Resource Initiation process in steps 524 and 525. The Common Transport Channel Resource Initiation procedure attaches the UE 501 to the DRNC 502 and creates a bearer for data on the Iur. To this end, the SRNC 503 transmits a COMMON Tr CH RESOURCE REQUEST message to the DRNC 502 in step 524, and the DRNC 502 sends a COMMON Tr CH RESOURCE RESPONSE message to the SRNC 503 in step 525. do. If the common transport channel resource initialization procedure (Common Transport Channel Resource Initiation) together with the MBMS Attach, the COMMON Tr CH RESOURCE REQUEST message includes the MBMS service identifier, the COMMON Tr CH RESOURCE RESPONSE message PtM RB information May be included.

Meanwhile, the SRNC 503 may determine that the channel type is changed from the PtP mode to the PtM mode by the above-described procedure. In this case, the UE 501 may read the MCCH and obtain PtM RB information, but more efficiently deliver the PtM RB information to the UE 501 through a DCCH RRC message. To this end, the SRNC 503 notifies the changed RB, transport channel, and physical channel information through a CELL UPDATE CONFIRM message transmitted to the UE 501 in response to the CELL UPDATE message in step 526.

The UE 501 receives the CELL UPDATE CONFIRM message and maintains the RRC state as CELL_FACH. Accordingly, the UE 501 receives MBMS data according to a desired MBMS service from the DRNC 502 in step 527.

FIG. 5C illustrates a signaling procedure when the SRNC 503 receives the RL SETUP FAILURE message from the DRNC 502 and then transitions the RRC state of the UE 501 to CELL_PCH. If the SRNC 503 wants to change the RRC state of the UE 501 to CELL_PCH, the SRNC 503 performs the MBMS Attach procedure in steps 534 and 535. To this end, the SRNC 503 transmits an MBMS Attach Request message to the DRNC 502 in step 534, and the DRNC 502 sends an MBMS Attach Response message to the SRNC 503 in step 535. In this case, the MBMS Attach Request message may include a UE ID, and the MBMS Attach Response message may include PtM RB information.

By the above-described procedure, the SRNC 503 determines that the channel type is changed from the PtP mode to the PtM mode, and then transmits a CELL UPDATE CONFIRM message to the UE 501 in response to the CELL UPDATE message in step 536. . The CELL UPDATE message includes PtM RB information.

The UE 501 receives the CELL UPDATE CONFIRM message and changes the RRC state to CELL_PCH in step 537. Thereafter, the UE 501 receives MBMS data according to a desired MBMS service from the DRNC 502 in step 538.

As described above, according to FIG. 5A, if the target cell to be moved is providing the MBMS service in the PtP mode, the RL SETUP procedure is successfully completed and the attachment is also performed. On the contrary, in FIG. 5B and FIG. 5C, if the target cell to be moved provides the MBMS service in the PtM mode, the common transport channel resource initialization procedure or the MBMS Attach according to the RRC state of the UE. Attempt to attach to DRNC through the procedure. The RRC state of the UE is maintained as CELL_FACH by the Common Transport Channel Resource Initiation procedure, but is switched to the CELL_PCH state by the MBMS Attach procedure.

1.2 Signaling procedure when MBMS cause is PtM data transmission

FIG. 6 is a diagram illustrating signaling in an attach procedure performed by a request of a UE in a CELL_FACH state when a target cell provides a corresponding MBMS service in a PtM mode. When the target cell provides the MBMS service in the PtM mode, it may be said that the UE is unlikely to receive the MBMS service in the PtP mode from the target cell. Meanwhile, in FIG. 6, the UE 601 indicates a UE that wants to receive a specific MBMS service from a newly moving target cell, and the DRNC 602 indicates an RNC that provides the specific MBMS service to the target cell. ) Represents an RNC currently providing the specific MBMS service to the UE 601.

Referring to FIG. 6, the UE 601 in the CELL_FACH state reports to the SRNC 603 that the UE 601 moves to the target cell through a CELL UPDATE message in step 610. The CELL UPDATE message further includes an MBMS service identifier and an MBMS Cause IE. In this case, "PtM data transmission" is set in the MBMS Cause IE. The SRNC 603 confirms that MBMS Cause IE is set to "PtM data transmission" through the CELL UPDATE message. Thereafter, the SRNC 603 refers to the UE context corresponding to the UE 601 to comprehensively consider whether the UE 601 receives CS or PS service except for the current MBMS service, and the like. Determine the RRC state of. If the RRC state of the UE 601 is to be maintained as CELL_FACH, the SRNC 603 performs a common transport channel resource initialization procedure in steps 611 and 612. The Common Transport Channel Resource Initiation procedure attaches the UE 601 to the DRNC 602 and generates a bearer for data on the Iur. To this end, the SRNC 603 transmits a COMMON Tr CH RESOURCE REQUEST message to the DRNC 602 in step 611, and the DRNC 602 sends a COMMON Tr CH RESOURCE RESPONSE message to the SRNC 603 in step 612. do. If the common transport channel resource initialization procedure (Common Transport Channel Resource Initiation) together with the MBMS Attach, the COMMON Tr CH RESOURCE REQUEST message includes the MBMS service identifier, the COMMON Tr CH RESOURCE RESPONSE message PtM RB information May be included. Although not shown, if the RRC state of the UE 601 is to be changed to CELL_PCH, the SRNC 603 performs an MBMS Attach procedure.

By the above-described procedure, the SRNC 603 can confirm that the target cell provides the corresponding MBMS service in the PtM mode even after the MBMS Attach procedure. In this case, since the UE 601 reads the MCCH from the DRNC 602 and receives the PtM RB information, the PtM RB information is not included in the DCCH RRC message.

The SRNC 603 notifies the changed RB, transport channel, physical channel information, etc. through the CELL UPDATE CONFIRM message transmitted to the UE 601 in response to the CELL UPDATE message in step 613. The UE 601 receives the CELL UPDATE CONFIRM message and transitions the RRC state to CELL_FACH or CELL_PCH. Accordingly, the UE 601 receives MBMS data according to a desired MBMS service from the DRNC 602 in step 614.

1.3 Signaling procedure when MBMS cause is Radio Resource not available

FIG. 7 illustrates signaling in an attach procedure performed by a request of a UE in a CELL_FACH state when a target cell temporarily fails to provide a desired MBMS service due to lack of radio resources. In FIG. 7, the UE 701 indicates a UE that wants to receive a specific MBMS service from a newly moving target cell, and the DRNC 702 indicates an RNC that provides the specific MBMS service to the target cell. Represents an RNC currently providing the specific MBMS service to the UE 701.

Referring to FIG. 7, the UE 701 in the CELL_FACH state reports to the SRNC 703 that the UE 701 moves to the target cell through a CELL UPDATE message in step 710. The CELL UPDATE message further includes an MBMS service identifier and an MBMS Cause IE. In this case, "Radio Resource not available" is set in the MBMS Cause IE. The SRNC 703 confirms by the MBMS Cause IE that the target cell is temporarily not providing the MBMS service due to lack of radio resources. Thereafter, the SRNC 703 may provide the corresponding MBMS service through another cell except for the target cell with reference to the MBMS service context corresponding to the corresponding MBMS service and the UE context corresponding to the UE 701. Check it. If the target cell is the only cell capable of providing the corresponding MBMS service, the SRNC 703 determines to attach to the DRNC 702 through an MBMS Attach procedure. This is to allow the corresponding MBMS service to be provided to the UE 701 when an available radio resource for providing the corresponding MBMS service occurs in the target cell. In other words, the DRNC 702 adds the UE 701 to the MBMS service context corresponding to the corresponding MBMS service so as to be counted.

The SRNC 703 transmits an MBMS Attach Request message requesting the MBMS Attach corresponding to the UE 701 to the DRNC 702 in step 711. In this case, if an Iur signaling bearer uniquely allocated for each MBMS service is used, the MBMS Attach Request message includes a UE ID. Otherwise, if an Iur signaling bearer uniquely allocated to each UE is used, the MBMS Attach Request message includes an MBMS service identifier.

The DRNC 702 transmits an MBMS Attach Response message to the SRNC 703 in step 712 in response to the MBMS Attach Request message. In this case, the MBMS Attach Response message may include accurate MBMS service related information of the target cell. This is because the SRNC 703 receives the MBMS service related information of the target cell from the UE 701, but obtains more accurate and more information.

When the SRNC 703 receives the MBMS Attach Response message, the SRNC 703 transmits a CELL UPDATE CONFIRM message in response to the CELL UPDATE message to the UE 701 in step 713. The UE 701 receives the CELL UPDATE CONFIRM message to confirm that the UE 701 has successfully moved to the target cell. In this case, the corresponding MBMS service may be additionally informed that it is currently impossible to receive.

1.4 Signaling procedure when MBMS cause is Service information not available

8A and 8B illustrate signaling in an attach procedure performed by a request of a UE in a CELL_FACH state when the MBMS service related information is not received from a target cell. In FIG. 8A and FIG. 8B, the UE 801 indicates a UE that wants to receive a specific MBMS service from a newly moving target cell, and the DRNC 802 indicates an RNC that provides the specific MBMS service to the target cell. 803 represents an RNC currently providing the specific MBMS service for the UE 801. SGSN 804 controls the provision of the MBMS service through the DRNC 802. In FIG. 8A, the MBMS service can be provided from the target cell. In FIG. 8B, the MBMS service is not provided from the target cell.

Referring to FIG. 8A, the UE 801 in the CELL_FACH state reports to the SRNC 803 that the UE 801 moves to the target cell through a CELL UPDATE message in step 810. The CELL UPDATE message further includes an MBMS service identifier and an MBMS Cause IE. In this case, "Service information not available" is set in the MBMS Cause IE. When the SRNC 803 confirms that the MBMS Cause IE is set to "Service information not available" through the CELL UPDATE message, since the UE 801 is likely to receive the desired MBMS service in the PTP mode, the RL SETUP Attempts to attach to the DRNC 802 through a procedure. That is, in step 811, the SRNC 803 transmits an RL SETUP REQUEST message requesting radio link establishment to the DRNC 802. In this case, the SRNC 803 attempts an MBMS Attach together by including an MBMS service identifier in the RL SETUP REQUEST message. When the DRNC 802 receives the MBMS service identifier through the RL SETUP REQUEST message, the DRNC 802 checks whether an MBMS service context corresponding to the MBMS service identifier exists. If the desired MBMS service context does not exist, the DRNC 802 SGSN (804) to the MBMS REGISTER REQUEST message requesting to add itself to the list of target RNC (multicast tree for MBMS) to provide the MBMS service in step 812 ). In this case, the MBMS REGISTER REQUEST message includes a service area identifier (SAI) as well as an MBMS service identifier and an RNC ID. The SAI is information for identifying a service area to which the cell to which the UE 801 intends to move belongs.

Upon receiving the MBMS REGISTER REQUEST message, the SGSN 804 checks whether the SAI provided from the DRNC 802 is included in the MBMS service area by referring to the MBMS service context managed by the SGSN 804. If included, the SGSN 804 adds the DRNC 802 to the RNC list of an internal MBMS service context. In step 813, the SGSN 804 transmits an MBMS REGISTER RESPONSE message to the DRNC 802 indicating that the DRNC 802 has been successfully registered.

Thereafter, through the session initiation procedure, the SGSN 804 provides the DRNC 802 with QoS information, MBMS service area information, and the like related to the MBMS service. That is, the SGSN 804 transmits a Session Start Indication message including an MBMS service identifier, QoS information, etc. to the DRNC 802 in step 814, and in response, the DRNC 802 sends a Session Start Response in step 815. Sends a message to the SGSN 804. Meanwhile, an Iu data dedicated bearer for the MBMS service may be established between the SGSN 804 and the DRNC 802 through the aforementioned session start procedure.

In step 812 to step 815, the DRNC 802 creates an MBMS service context corresponding to the MBMS service, and adds the UE 801 to the MBMS service context. At this time, the DRNC 802 determines that the transmission type is the PtP mode since the UE 801 is the first UE for the MBMS service. Thereafter, the DRNC 802 informs the SRNC 803 that MBMS Attach has been successfully performed through the RL SETUP RESPONSE message in response to the RL SETUP REQUEST message in step 816.

After receiving the RL SETUP RESPONSE message, the SRNC 803 transmits a CELL UPDATE CONFIRM message in response to the CELL UPDATE message to the UE 501 in step 817. The CELL UPDATE CONFIRM message includes modified radio bearer (RB), transport channel, physical channel information, and the like.

The UE 801 receives the CELL UPDATE CONFIRM message and transitions the RRC state to CELL_DCH. Accordingly, the UE 801 receives MBMS data according to a desired MBMS service through the DRNC 802 from the SRNC 803 in step 818.

Although not shown in FIG. 8A, it may be assumed that the MBNC service context corresponding to the MBMS service exists in the DRNC 802 and the target cell is included in the MBMS service area. In this case, instead of performing steps 812 to 815, the RL SETUP RESPONSE message may be transmitted to the SRNC 803 in step 816. In this case, the RL SETUP RESPONSE message includes an indicator indicating that the MBMS service will be provided by the PTP mode.

Referring to FIG. 8B, the UE 801 in the CELL_FACH state reports to the SRNC 803 that the UE 801 moves to the target cell through a CELL UPDATE message in step 820. The CELL UPDATE message further includes an MBMS service identifier and an MBMS Cause IE. In this case, "Service information not available" is set in the MBMS Cause IE. When the SRNC 803 confirms that the MBMS Cause IE is set to "Service information not available" through the CELL UPDATE message, since the UE 801 is likely to receive the desired MBMS service in the PTP mode, the RL SETUP Attempts to attach to the DRNC 802 through a procedure. That is, the SRNC 803 transmits an RL SETUP REQUEST message for requesting wireless link establishment to the DRNC 802 in step 821. In this case, the SRNC 803 attempts an MBMS Attach together by including an MBMS service identifier in the RL SETUP REQUEST message. When the DRNC 802 receives the MBMS service identifier through the RL SETUP REQUEST message, the DRNC 802 checks whether an MBMS service context corresponding to the MBMS service identifier exists. If the desired MBMS service context does not exist, the DRNC 802 SGSN (804) to the MBMS REGISTER REQUEST message requesting to add itself to the target RNC list (multicast tree for MBMS) to provide the MBMS service in step 822 ). In this case, the MBMS REGISTER REQUEST message includes a service area identifier (SAI) as well as an MBMS service identifier and an RNC ID. The SAI is information for identifying a service area to which the cell to which the UE 801 intends to move belongs.

Upon receiving the MBMS REGISTER REQUEST message, the SGSN 804 checks whether the SAI provided from the DRNC 802 is included in the MBMS service area by referring to the MBMS service context managed by the SGSN 804. If not included, the SGSN 804 transmits an MBMS REGISTER FAILURE message to the DRNC 802 in step 823 indicating that it is impossible to provide the MBMS service through the DRNC 752. At this time, the MBMS REGISTER FAILURE message may include a Cause value such as a Non Service Area.

Upon receiving the MBMS REGISTER FAILURE message, the DRNC 802 transmits an RL SETUP FAILURE message indicating that the MBMS Attach and RL setup for the UE 801 has failed to the SRNC 803 in step 824. In this case, the RL SETUP FAILURE message may include a cause value for MBMS to inform that the reason why the RL setting fails is that the target cell is not included in the MBMS service area (Non Service Area).

The SRNC 803 transmits a CELL UPDATE CONFIRM message to the UE 801 in step 825 indicating that the desired MBMS service cannot be provided through the target cell to be updated. In this case, the RL SETUP FAILURE message may include a cause value (Non Service Area) for MBMS indicating that the target cell is not included in the MBMS service area.

1.5 Signaling procedure when MCCH is received after Call Update

9A and 9B show signaling in an attach procedure performed by a request of a UE in CELL_FACH state when receiving a MCCH from the target cell after performing a call update procedure by the BCCH from the target cell. It is a drawing. In this case, since the SRNC cannot receive MBMS service related information of the target cell through a Cell Update message, the SRNC first attempts to attach to the DRNC through a COMMON TRANSPORT CHANNEL RESOURCE REQUEST message. In this way, the MBMS Attach and the common transport channel can be set at the same time. In FIG. 9A and FIG. 9B, the UE 901 indicates a UE that wants to receive a specific MBMS service from a newly moving target cell, and the DRNC 902 indicates an RNC that provides the specific MBMS service to the target cell. 903 indicates an RNC currently providing the specific MBMS service to the UE 901. In FIG. 9A, the MBMS service is provided from the target cell by the PtM mode. In FIG. 9B, the MBMS service is provided from the target cell by the PtP mode.

Referring to FIG. 9A, the UE 901 in the CELL_FACH state reports to the SRNC 903 that the UE 901 moves to the target cell through a CELL UPDATE message in step 910. Since the CELL UPDATE message is transmitted in a situation in which the MBMS service related information is not received through the MCCH from the target cell, the CELL UPDATE message includes only the MBMS service identifier and does not include the MBMS Cause IE. The SRNC 903 confirms that the MBMS Cause IE is not included in the CELL UPDATE message. Thereafter, the SRNC 903 transmits a COMMON Tr CH RESOURCE REQUEST message to the DRNC 902 in step 911. Upon receiving the COMMON Tr CH RESOURCE REQUEST message, the DRNC 902 checks the MBMS service identifier included in the message. The MBMS service context corresponding to the MBMS service identifier is examined and the MBMS service corresponding to the MBMS service identifier is currently provided by the PtM mode. Thereafter, the DRNC 902 transmits a COMMON Tr CH RESOURCE RESPONSE message including the PtM RB information to the SRNC 903 in step 912.

By the above-described procedure, the SRNC 903 can confirm that the target cell provides the MBMS service in PtM mode. In step 913, the SRNC 903 transmits a CELL UPDATE CONFIRM message to the UE 901 in response to the CELL UPDATE message. The changed RB, transport channel, and physical channel information are transmitted through the CELL UPDATE CONFIRM message. As described above, the PtM RB information is transmitted through the DCCH RRC message called the CELL UPDATE CONFIRM message. The UE 901 may acquire the PtM RB information by receiving the MCCH from the target cell, but more efficiently the PtM RB information. To convey RB information. Accordingly, the UE 901 receives MBMS data according to a desired MBMS service from the DRNC 902.

Referring to FIG. 9B, the UE 901 in the CELL_FACH state reports to the SRNC 903 that the UE 901 has moved to the target cell through a CELL UPDATE message in step 920. Since the CELL UPDATE message is transmitted in a situation in which the MBMS service related information is not received through the MCCH from the target cell, the CELL UPDATE message includes only the MBMS service identifier and does not include the MBMS Cause IE. The SRNC 903 confirms that the MBMS Cause IE is not included in the CELL UPDATE message. Thereafter, the SRNC 903 transmits a COMMON Tr CH RESOURCE REQUEST message to the DRNC 902 in step 921. Upon receiving the COMMON Tr CH RESOURCE REQUEST message, the DRNC 902 checks the MBMS service identifier included in the message. The MBMS service context corresponding to the MBMS service identifier is examined and the MBMS service corresponding to the MBMS service identifier is currently provided by the PtP mode. Thereafter, the DRNC 902 transmits a COMMON Tr CH RESOURCE FAILURE message to the SRNC 903 in step 922. Through the COMMON Tr CH RESOURCE FAILURE message, information indicating that the MBMS service desired by the UE 901 is provided by the PtP mode in the target cell is transmitted.

By the above-described procedure, the SRNC 903 can confirm that the target cell provides the corresponding MBMS service in the PtP mode. The SRNC 903 then attempts to attach to the DRNC 902 via an RL SETUP procedure. That is, in step 923, the SRNC 903 transmits an RL SETUP REQUEST message including an MBMS service identifier to the DRNC 902. The DRNC 902 performs the attachment of the UE 901 by the RL SETUP REQUEST message, and in step 924, the SRNC 903 transmits an RL SETUP RESPONSE message including information indicating that the attachment has been successfully performed. To send.

After the successful completion of the RL SETUP procedure, the SRNC 903 transmits a CELL UPDATE CONFIRM message in response to the CELL UPDATE message to the UE 901 in step 925. The changed RB, transport channel, and physical channel information are transmitted through the CELL UPDATE CONFIRM message. Meanwhile, the UE 901 receives the CELL UPDATE CONFIRM message, changes the RRC state to CELL_DCH, and receives MBMS data according to a desired MBMS service from the DRNC 902.

2. Second embodiment (in case of CELL_DCH state)

In the second embodiment of the present invention, which will be described later, a UE in CELL_DCH state performs an MBMS Attach procedure to a DRNC to which a target cell belongs. If there is a UE that cannot read two or more channels according to the capability of the UE, the UE may not read the S-CCPCH and the DPCH at the same time. In this case, the UE may not read the MCCH. Therefore, the SRNC cannot receive the MBMS service related information of the target cell through the RRC message from the UE. In this case, the SRNC attempts to attach to the DRNC using the RL SETUP procedure, and the DRNC adds the cause value for MBMS to the response message (RL SETUP RESPONSE, RL SETUP FAILURE) and transmits the MBMS service state of the target cell.

2.1 Signaling procedure in case the target cell provides MBMS service by PtP mode

FIG. 10 is a diagram illustrating signaling in an attach procedure performed by a request of a UE in a CELL_DCH state when a target cell provides a corresponding MBMS service in a PtP mode. In FIG. 10, the UE 1001 indicates a UE that wants to receive a specific MBMS service from a newly moving target cell, and the DRNC 1002 indicates an RNC that provides the specific MBMS service to the target cell, and the SRNC 1003 indicates the UE. Represents an RNC currently providing the specific MBMS service to the UE 1001.

Referring to FIG. 10, the UE 1001 in the CELL_DCH state checks whether a cell having a better signal strength than a cell currently receiving MBMS service exists through a measurement function. The UE 1001 reports to the SRNC 1003 through a MEASUREMENT REPORT message in step 1010 when a target cell having a higher signal strength than a source cell exists through the measurement function. Upon receiving the MEASUREMENT REPORT message, the SRNC 1003 determines whether to perform a handover to the target cell in step 1011. Upon determining the handover to the target cell, the SRNC 1003 transmits an RL SETUP REQUEST message requesting radio link establishment to the DRNC 1002 managing the target cell in step 1012. In this case, the SRNC 1003 attempts an MBMS Attach together by including an MBMS service identifier in the RL SETUP REQUEST message. The DRNC 1002 receives the RL SETUP REQUEST message to check whether the corresponding MBMS service is provided by the PtP mode by referring to the MBMS service context corresponding to the MBMS service identifier. If it is confirmed that the MBMS service is currently provided by the PtP mode, the DRNC 1002 transmits an RL SETUP RESPONSE message to the SRNC 1003 in response to the RL SETUP REQUEST message in step 1013. In the RL SETUP RESPONSE message, information indicating that the target cell provides the corresponding MBMS service by the PtP mode is transmitted. Therefore, the RL for providing the MBMS service through the target cell is successfully added.

After receiving the RL SETUP RESPONSE message, the SRNC 1003 transmits a CELL UPDATE CONFIRM message in response to the CELL UPDATE message to the UE 1001 in step 1014. The CELL UPDATE CONFIRM message includes information on the RL added through the ACTIVE SET UPDATE procedure.

The UE 1001 receives the CELL UPDATE CONFIRM message and receives MBMS data according to a desired MBMS service from the SRNC 1003 through the DRNC 1002.

2.2 Signaling procedure when target cell provides MBMS service in PtM mode

11 is a diagram illustrating signaling in an attach procedure performed by a request of a UE in a CELL_DCH state when a target cell provides a corresponding MBMS service by a PtM mode. In FIG. 11, the UE 1101 indicates a UE that wants to receive a specific MBMS service from a newly moving target cell, the DRNC 1102 indicates an RNC providing the specific MBMS service to the target cell, and the SRNC 1103 indicates the UE. Represents an RNC currently providing the specific MBMS service to the UE 1101.

Referring to FIG. 11, the UE 1101 in a CELL_DCH state checks whether a cell having a better signal strength is present than a cell currently receiving MBMS service through a measurement function. The UE 1101 reports to the SRNC 1103 through a MEASUREMENT REPORT message in step 1110 when there is a target cell having better signal strength than the source cell through the measurement function. Upon receiving the MEASUREMENT REPORT message, the SRNC 1103 determines whether to perform a handover to the target cell in step 1111. If the handover to the target cell is determined, the SRNC 1103 transmits an RL SETUP REQUEST message requesting radio link establishment to the DRNC 1102 managing the target cell in step 1112. In this case, the SRNC 1103 attempts an MBMS Attach together by including an MBMS service identifier in the RL SETUP REQUEST message. The DRNC 1102 receives the RL SETUP REQUEST message to check whether the corresponding MBMS service is provided by the PtM mode by referring to the MBMS service context corresponding to the MBMS service identifier. If it is confirmed that the MBMS service is currently provided by the PtM mode, the DRNC 1102 transmits the RL SETUP FAILURE message to the SRNC 1103 in response to the RL SETUP REQUEST message in step 1113. In the RL SETUP FAILURE message, information (Cause: PtM transmission) indicating that the target cell provides the corresponding MBMS service by the PtM mode is transmitted.

Receiving the RL SETUP FAILURE message, the SRNC 1103 refers to the UE context corresponding to the UE 1101 to check whether the UE 1101 can receive the MBMS service from the target cell in PtM mode. do. To this end, whether the UE 1101 is currently allocated a dedicated channel for CS and PS services excluding MBMS service, and whether the UE 1101 is capable of receiving DPCH and S-CCPCH at the same time, etc. should be comprehensively considered.

After the SRNC 1103 receives the RL SETUP FAILURE message from the DRNC 1102, if the SRNC 1100 intends to change the RRC state of the UE 1101 to CELL_PCH, the MBMS attach procedure is performed in steps 1114 and 1115. To this end, the SRNC 1103 transmits an MBMS Attach Request message to the DRNC 1102 in step 1114, and the DRNC 1102 transmits an MBMS Attach Response message to the SRNC 1103 in step 1115. In this case, the MBMS Attach Request message may include a UE ID, and the MBMS Attach Response message may include PtM RB information.

By the above-described procedure, the SRNC 1103 determines that the channel type is changed from the PtP mode to the PtM mode in step 1116, and then transmits a physical CH reconfiguration message to the UE 1101 in response to the CELL UPDATE message. . The physical CH reconfiguration message includes PtM RB information. In addition, the PtM RB information may be delivered to the UE 1101 through a TRANSPORT CHANNEL RECONFIGURATION procedure or a RADIO BEARER RECONFIGURATION procedure.

The UE 1101 receives the Physical CH reconfiguration message and changes the RRC state to CELL_PCH in step 1117. Thereafter, the UE 1101 receives MBMS data according to a desired MBMS service from the DRNC 1102 in step 1118.

12 illustrates a signaling procedure in the case where the SRNC 1203 receives the RL SETUP FAILURE message from the DRNC 1202 and then wants to transition the RRC state of the UE 1201 to CELL_FACH. The procedure until the SRNC 1203 receives the RL SETUP FAILURE message from the DRNC 1202 is the same as the procedure of steps 1110 to 1113 of FIG. 11.

Referring to FIG. 12, if the SRNC 1203 wants to change the RRC state of the UE 1201 to CELL_FACH, the SRNC 1203 performs a common transport channel resource initialization procedure in steps 1214 and 1215. The Common Transport Channel Resource Initiation procedure attaches the UE 1201 to the DRNC 1202 and creates a bearer for data on the Iur. To this end, the SRNC 1203 transmits a COMMON Tr CH RESOURCE REQUEST message to the DRNC 1202 in step 1214, and the DRNC 1202 transmits a COMMON Tr CH RESOURCE RESPONSE message to the SRNC 1203 in step 1215. do. If the common transport channel resource initialization procedure (Common Transport Channel Resource Initiation) together with the MBMS Attach, the COMMON Tr CH RESOURCE REQUEST message includes the MBMS service identifier, the COMMON Tr CH RESOURCE RESPONSE message PtM RB information May be included.

Meanwhile, the SRNC 1203 may determine that the channel type is changed from the PtP mode to the PtM mode by the above-described procedure. Accordingly, the SRNC 1203 transmits a Physical CH reconfiguration message in response to the CELL UPDATE message to the UE 1201 in step 1216. The physical CH reconfiguration message includes PtM RB information.

In step 1217, the UE 1201 receives the Physical CH reconfiguration message and changes the RRC state to CELL_FACH. Thereafter, the UE 1201 receives MBMS data according to a desired MBMS service from the DRNC 1202 in step 1218.

Although not shown additionally, if the target cell cannot be serviced due to a temporary shortage of radio resources for the MBMS service, the SRNC can refer to the MBMS service context and the UE context to receive the MBMS service through other cells except the target cell. Check it. If the target cell is the only cell that can provide the MBMS service, the SRNC decides to attach to the DRNC through the MBMS Attach procedure. That is, this is to enable counting by adding the UE to the MBMS service context of the DRNC in advance so that the MBMS service can be started when a radio resource becomes available to a target cell later. Thereafter, the SRNC informs the UE that MBMS service is unavailable due to a temporary lack of radio resources in the target cell through a newly defined RRC message, PHYSICAL CHANNEL RECONFIGURATION, TRANSPORT CHANNEL RECONFIGURATION, or RADIO BEARER RECONFIGURATION procedure.

In addition, although not additionally illustrated, there may be a case in which the target cell does not belong to the MBMS service area for the corresponding MBMS service and thus the service is impossible. In this case, the SRNC informs the UE that MBMS service is not possible because the target cell is not included in the MBMS service area through a newly defined RRC message, PHYSICAL CHANNEL RECONFIGURATION, TRANSPORT CHANNEL RECONFIGURATION, or RADIO BEARER RECONFIGURATION procedure.

3. Description of Operation According to First and Second Embodiments

  Hereinafter, detailed operations of the UE, RNC, and SGSN according to embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3.1 UE operation

13 is a diagram illustrating a control flow performed by a UE for embodiments of the present invention.

Referring to FIG. 13, the UE performs a measurement function on neighboring cells in step 1301, and checks whether there is a cell having better signal strength than a source cell currently receiving MBMS service through the measurement function. do. The inspection result determines whether a cell change is necessary. If the cell change is determined, go to step 1303. In step 1303, the UE receives an MCCH from a target cell to which the cell is to be changed and confirms MBMS service related information transmitted through the MCCH. In step 1305, if the UE determines the MBMS service related information transmitted through the MCCH, the UE proceeds to step 1307. However, if there is no MBMS service related information transmitted through the MCCH, the process proceeds to step 1309.

In step 1307, the UE sets an appropriate value to the MBMS Cause IE in the CELL UPDATE message based on the MBMS service-related information received through the MCCH. In step 1309, the UE sets a value indicating that there is no MBMS service related information received through the MCCH to MBMS Cause IE in a CELL UPDATE message, and then proceeds to step 1311. In step 1311, the UE transmits a Cell UPDATE message including the MBMS Cause IE previously set to an appropriate value to the SRNC.

3.2 Operation of SRNC

The operation of the RNC according to the embodiments of the present invention can be distinguished from the operation of the SRNC to control the source cell currently providing a specific MBMS service for the UE and the operation of the DRNC to control the target cell to which the UE is to move. .

Hereinafter, the operation of the SRNC according to embodiments of the present invention will be described in detail. In describing the operation of the SRNC to be described below, it will be described corresponding to the RRC state of the UE. That is, the operation of the SRNC corresponding to the UE in the CELL_FACH state and the operation of the SRNC corresponding to the UE in the CELL_DCH state will be described.

First, the operation of the SRNC according to the first embodiment of the present invention will be described.

14A to 14C illustrate a control flow performed by an SRNC in response to a UE in a CELL_FACH state according to the first embodiment of the present invention. 14A and 14B are control flows according to an operation when a MBMS Cause IE corresponding to a target cell is received from the UE, and FIG. 14C is a failure of receiving an MBMS Cause IE corresponding to a target cell from the UE. Control flow according to the operation of the case.

14A to 14C, the SRNC checks whether a CELL UPDATE message is received from the UE in step 1400. In step 1410 when the CELL UPDATE message is received. The CELL UPDATE message is transmitted by a UE receiving an MBMS service and includes at least an MBMS service identifier.

In step 1410, the SRNC checks whether a value set in MBMS Cause IE of the CELL UPDATE message is PtM data transmission. If it is PtM data transmission, the process proceeds to step 1420 and performs operations (steps 1420 to 1433) corresponding to the PtM data transmission situation. However, if not PtM data transmission proceeds to step 1411. In step 1411, the SRNC checks whether the value set in the MBMS Cause IE of the CELL UPDATE message is PtP data transmission. If it is PtP data transmission, the process proceeds to step 1440 to perform operations (steps 1440 to 1458) corresponding to the PtP data transmission situation. However, if it is not PtM data transmission, it proceeds to step 1412 and checks whether the value set in the MBMS Cause IE of the CELL UPDATE message is No UE. If it is a NO UE, the process proceeds to step 1420 to perform the same operations (steps 1420 to 1433) corresponding to the operation corresponding to the PtM data transmission situation. However, if the No UE is not in step 1413. In step 1413, the SRNC checks whether a value set in MBMS Cause IE of the CELL UPDATE message is Lack of Resource. If it is a Lack of Resource, the process proceeds to step 1470 and performs operations (steps 1470 to 1472) corresponding to the Lack of Resource situation. However, if it is not a Lack of Resource, it proceeds to step 1414 and checks whether the value set in the MBMS Cause IE of the CELL UPDATE message is No Service info. If No Service info, the process proceeds to step 1460 and performs operations (steps 1460 to 1466) corresponding to the No Service info situation. However, if it is not the No Service info, the process proceeds to step 1470 and performs an operation when the MBMS Cause IE is not received from the UE.

Referring to the operation in the case of the PtM data transmission, the SRNC determines whether to maintain the UE in the CELL_FACH state in step 1420 to receive the MBMS service in the PtM mode. If the determination is made to maintain the CELL_FACH state, the process proceeds to step 1421. However, if it is determined by the determination that the RRC state is to be changed, the process proceeds to step 1430.

The SRNC transmits a COMMON TRANSPORT CHANNEL RESOURCE REQUEST message to the DRNC in step 1421 and proceeds to step 1422. At this time, the COMMON TRANSPORT CHANNEL RESOURCE REQUEST message includes an MBMS service identifier to attach the UE to the MBMS service context of the DRNC. In step 1422, the SRNC receives a response message to the COMMON TRANSPORT CHANNEL RESOURCE REQUEST message from the DRNC. The SRNC updates the information managed in the internal MBMS service context after receiving the response message and before proceeding to step 1423 if necessary. In step 1423, the SRNC transmits a CELL UPDATE CONFIRM message to the UE in response to the CELL UPDATE message. The CELL UPDATE CONFIRM message has a successful cell change procedure, and has a purpose to inform that a desired MBMS service can be provided through a target cell.

In step 1430, the SRNC determines whether to change the RRC state of the UE to the CELL_PCH state. If the determination is made to change to the CELL_PCH state, the flow proceeds to step 1431. The SRNC transmits an MBMS ATTACH REQUEST message to the DRNC in step 1431. Thereafter, the SRNC receives a response message corresponding to the MBMS ATTACH REQUEST message from the DRNC in step 1432. The SRNC updates the information managed in the internal MBMS service context if necessary after receiving the response message. The SRNC transmits a CELL UPDATE CONFIRM message to the UE in response to the CELL UPDATE message in step 1433. The CELL UPDATE CONFIRM message has a successful cell change procedure, and has a purpose to inform that a desired MBMS service can be provided through a target cell.

Referring to the operation in the case of the PtP data transmission or the No UE, the SRNC transmits an RL SETUP REQUEST message to the DRNC to provide an MBMS service in the PtP mode in step 1440. At this time, the RL SETUP REQUEST message includes an MBMS service identifier to attach the UE to the MBMS service context of the DRNC. In step 1441, the SRNC receives a response message corresponding to the RL SETUP REQUEST message from the DRNC. If the response message is an RL SETUP FAILURE message (step 1442), the flow proceeds to step 1450. However, if the response message is an RL SETUP RESPONSE message (step 1443), the process proceeds to step 1444.

In step 1450, the SRNC determines whether to maintain the UE in the CELL_FACH state in order to service the MBMS service in the PtM mode. If the determination is made to maintain the CELL FACH state, the process proceeds to step 1451. However, if it is determined by the determination to change the RRC state of the UE proceeds to step 1455.

The SRNC transmits a COMMON TRANSPORT CHANNEL RESOURCE REQUEST message to the DRNC in step 1451 and proceeds to step 1452. At this time, the COMMON TRANSPORT CHANNEL RESOURCE REQUEST message includes an MBMS service identifier to attach the UE to the MBMS service context of the DRNC. In step 1452, the SRNC receives a response message to the COMMON TRANSPORT CHANNEL RESOURCE REQUEST message from the DRNC. The SRNC updates the information managed in the internal MBMS service context after receiving the response message and before proceeding to step 1453 if necessary. In step 1453, the SRNC sends a CELL UPDATE CONFIRM message to the UE in response to the CELL UPDATE message. The CELL UPDATE CONFIRM message has a successful cell change procedure, and has a purpose to inform that a desired MBMS service can be provided through a target cell. The CELL UPDATE CONFIRM message includes PtM RB information so that the UE can change the radio channel from PtP mode to PtM mode more efficiently.

In step 1455, the SRNC determines whether to change the RRC state of the UE to the CELL_PCH state. If the determination is made to change to the CELL_PCH state, the flow proceeds to step 1456. The SRNC transmits an MBMS ATTACH REQUEST message to the DRNC in step 1456. Thereafter, the SRNC receives a response message corresponding to the MBMS ATTACH REQUEST message from the DRNC in step 1457. The SRNC updates the information managed in the internal MBMS service context if necessary after receiving the response message. In step 1458, the SRNC transmits a CELL UPDATE CONFIRM message to the UE in response to the CELL UPDATE message. The CELL UPDATE CONFIRM message has a successful cell change procedure, and has a purpose to inform that a desired MBMS service can be provided through a target cell. The CELL UPDATE CONFIRM message includes PtM RB information so that the UE can change the radio channel from PtP mode to PtM mode more efficiently.

In step 1444, the SRNC decides to transition the UE to CELL_DCH state in order to receive MBMS service in PtP mode. In step 1445, the SRNC transmits a CELL UPDATE CONFIRM message to the UE in response to the CELL UPDATE message. The CELL UPDATE CONFIRM message has a successful cell change procedure, and has a purpose to inform that a desired MBMS service can be provided through a target cell. The CELL UPDATE CONFIRM message includes PtM RB information.

Referring to the operation in the case of the radio resources not available, the SRNC transmits an MBMS ATTACH REQUEST message to the DRNC in step 1470. In step 1470, the SRNC receives a response message from the DRNC in response to the MBMS ATTACH REQUEST message. The SRNC updates the information managed in the internal MBMS service context if necessary after receiving the response message. In step 1472, the SRNC transmits a CELL UPDATE CONFIRM message to the UE in response to the CELL UPDATE message. The CELL UPDATE CONFIRM message has a successful cell change procedure, but has a purpose of informing that the desired MBMS service cannot be provided through the target cell because no valid radio source remains in the target cell. At this time, by including information indicating why the MBMS service is currently unavailable in the CELL UPDATE CONFIRM message, the UE can operate more efficiently.

Referring to the operation in the case of service information not available, the SRNC transmits an RL SETUP REQUEST message to the DRNC to provide MBMS service in the PtP mode in step 1460. At this time, the RL SETUP REQUEST message includes an MBMS service identifier to attach the UE to the MBMS service context of the DRNC. In step 1461, the SRNC receives a response message corresponding to the RL SETUP REQUEST message from the DRNC. If the response message is an RL SETUP FAILURE message (step 1462), the flow proceeds to step 1463. However, if the response message is an RL SETUP RESPONSE message (step 1464), the process proceeds to step 1465.

The SRNC transmits a CELL UPDATE CONFIRM message indicating that the desired MBMS service cannot be provided through the target cell to the UE that has transmitted the CELL UPDATE message in step 1463. At this time, the CELL UPDATE CONFIRM message includes the reason why the MBMS service is currently unavailable (NSA). In step 1465, the SRNC decides to transition the RRC state of the UE to the CELL_DCH state in order to receive the MBMS service in the PtP mode. The SRNC transmits a CELL UPDATE CONFIRM message to the UE in response to the CELL UPDATE message in step 1466. The CELL UPDATE CONFIRM message has a successful cell change procedure, and has a purpose to inform that a desired MBMS service can be provided through a target cell. At this time, the CELL UPDATE CONFIRM message includes PtP RB information.

Finally, when the operation is not received from the UE, the SRNC transmits a COMMON TRANSPORT CHANNEL RESOURCE REQUEST message to the DRNC to provide MBMS service in PtM mode in step 1470. At this time, the COMMON TRANSPORT CHANNEL RESOURCE REQUEST message includes an MBMS service identifier to attach the UE to the MBMS service context of the DRNC. In step 1471, the SRNC receives a response message corresponding to the COMMON TRANSPORT CHANNEL RESOURCE REQUEST message from the DRNC. If the response message is a COMMON TRANSPORT CHANNEL RESOURCE FAILURE message (step 1472), the flow proceeds to step 1474. However, if the response message is a COMMON TRANSPORT CHANNEL RESOURCE RESPONSE message (step 1473), the process proceeds to step 1486.

In step 1474, the SRNC checks whether the MBMS Cause IE value set in the COMMON TRANSPORT CHANNEL RESOURCE FAILURE message is PtP data transmission. If it is PtP data transmission, the flow proceeds to step 1478 to perform operations (steps 1478 to 1481) corresponding to the PtP data transmission situation. However, if there is no PtM data transmission, the process proceeds to step 1475 and determines whether the MBMS Cause IE value set in the COMMON TRANSPORT CHANNEL RESOURCE FAILURE message is No UE. If it is a NO UE, the process proceeds to step 1478 so that the same operations (steps 1478 to 1481) can be performed as the operations corresponding to the PtM data transmission situation. However, if the No UE does not proceed to step 1476. In step 1476, the SRNC checks whether the MBMS Cause IE value set in the COMMON TRANSPORT CHANNEL RESOURCE FAILURE message is Lack of Resource. If it is a Lack of Resource, the process proceeds to step 1482 to perform the operations corresponding to the Lack of Resource situation (steps 1482 to 1484). However, if it is not a Lack of Resource, it proceeds to step 1477 and checks whether the MBMS Cause IE value set in the COMMON TRANSPORT CHANNEL RESOURCE FAILURE message is NSA. If the NSA, the process proceeds to step 1485 to perform the operation (1485) corresponding to the NSA situation. However, if not the NSA ends the operation according to the present invention.

If the MBMS Cause IE value is determined to be PtP data transmission or No UE and proceeds to step 1478, the SRNC transmits an RL SETUP REQUEST message to the DRNC to provide MBMS service in PtP mode. At this time, the RL SETUP REQUEST message includes an MBMS service identifier to attach the UE to the MBMS service context of the DRNC. In step 1479, the SRNC receives a response message corresponding to the RL SETUP REQUEST message from the DRNC. Upon receiving the response message, the SRNC determines to transition the RRC state of the UE to the CELL_DCH state in order to receive the MBMS service in the PtP mode in step 1480. Thereafter, the SRNC transmits a CELL UPDATE CONFIRM message to the UE in response to the CELL UPDATE message in step 1481. The CELL UPDATE CONFIRM message has a successful cell change procedure, and has a purpose to inform that a desired MBMS service can be provided through a target cell. At this time, the CELL UPDATE CONFIRM message includes PTP RB information.

If the MBMS Cause IE value is determined to be radio resource not available and proceeds to step 1482, the SRNC transmits an MBMS ATTACH REQUEST message to the DRNC. Thereafter, in step 1483, the SRNC receives a response message corresponding to the MBMS ATTACH REQUEST message from the DRNC. At this time, if necessary, the SRNC updates information managed in the internal MBMS service context. In step 1484, the SRNC transmits a CELL UPDATE CONFIRM message to the UE in response to the CELL UPDATE message. The CELL UPDATE CONFIRM message has a successful cell change procedure, but has a purpose of informing that a desired MBMS service cannot be received through the target cell because no valid radio resource remains in the target cell. In this case, the UE may be operated more efficiently by including information indicating why the MBMS service is currently unavailable in the CELL UPDATE CONFIRM message.

If the MBMS Cause IE value is determined to be NSA and proceeds to step 1485, the SRNC transmits a CELL UPDATE CONFIRM message to the UE in response to the CELL UPDATE message. The CELL UPDATE CONFIRM message has a purpose of informing that a desired MBMS service cannot be provided through a target cell. In this case, the NELL may be included in the CELL UPDATE CONFIRM message.

Upon receiving the COMMON TRANSPORT CHANNEL RESOURCE RESPONSE message from the DRNC, the SRNC transmits a CELL UPDATE CONFIRM message to the UE in response to the CELL UPDATE message in step 1486. The CELL UPDATE CONFIRM message has a successful cell change procedure, and has a purpose to inform that a desired MBMS service can be provided through a target cell. At this time, by including the PTM RB information in the CELL UPDATE CONFIRM message, the UE can more efficiently change the radio channel from PtP mode to PtM mode.

Next, the operation of the SRNC according to the second embodiment of the present invention will be described.

FIG. 15 is a diagram illustrating a control flow performed by an SRNC in response to a UE in a CELL_DCH state according to the second embodiment of the present invention.

Referring to FIG. 15, the SRNC checks whether a MEASUREMENT REPORT message is received from the UE in step 1500. If the MEASUREMENT REPORT message is received by the check, the process proceeds to step 1501. The MEASUREMENT REPORT message is transmitted by a UE receiving an MBMS service and includes an MBMS service identifier. The SRNC transmits an RL SETUP REQUEST message to the DRNC in order to provide the MBMS service in the PtP mode in step 1501. At this time, the RL SETUP REQUEST message includes an MBMS service identifier to attach the UE to the MBMS service context of the DRNC. Thereafter, the SRNC receives a response message corresponding to the RL SETUP REQUEST message from the DRNC in step 1502. If the response message is an RL SETUP FAILURE message (step 1503), the process proceeds to step 1510. However, if the RL SETUP RESPONSE message (step 1504) proceeds to step 1505.

In step 1510, the SRNC checks whether a value set in MBMS Cause IE of the RL SETUP FAILURE message is PtM data transmission. If it is PtM data transmission, the flow proceeds to step 1511 to perform operations (steps 1511 to 1522) corresponding to the PtM data transmission situation. However, if not PtM data transmission proceeds to step 1530. In step 1530, the SRNC checks whether a value set in MBMS Cause IE of the RL SETUP FAILURE message is Lack of Resource. If it is a Lack of Resource, the process proceeds to step 1531 and performs operations (steps 1531 to 1533) corresponding to the Lack of Resource situation. However, if it is not a Lack of Resource, it proceeds to step 1540 and checks whether the value set in the MBMS Cause IE of the RL SETUP FAILURE message is NSA. If the NSA, the process proceeds to step 1541 to perform the operation (1541) corresponding to the NSA situation. However, if not the NSA ends the operation according to the present invention.

Referring to the operation in the case of the PtM data transmission, the SRNC determines in step 1511 whether it is necessary to change the RRC state of the UE to the CELL_FACH state in order to receive the MBMS service in the PtM mode. If the determination is made to change to the CELL FACH state, the process proceeds to step 1520. However, if it is determined by the determination not to change the RRC state to the CELL FACH state, the process proceeds to step 1512.

The SRNC transmits a COMMON TRANSPORT CHANNEL RESOURCE REQUEST message to the DRNC in step 1520 and proceeds to step 1521. At this time, the COMMON TRANSPORT CHANNEL RESOURCE REQUEST message includes an MBMS service identifier to attach the UE to the MBMS service context of the DRNC. In step 1521, the SRNC receives a response message to the COMMON TRANSPORT CHANNEL RESOURCE REQUEST message from the DRNC. The SRNC updates the information managed in the internal MBMS service context after receiving the response message and before proceeding to step 1522 if necessary. In step 1522, the SRNC transmits a PHYSICAL CHANNEL RECONFIGURATION message to the UE in response to the MEASUREMENT REPORT message. The PHYSICAL CHANNEL RECONFIGURATION message has a successful Active Set change procedure, and has a purpose to inform that the desired MBMS service can be provided by the PtM mode through the target cell. At this time, by including the PtM RB information in the PHYSICAL CHANNEL RECONFIGURATION message, the UE can change the radio channel from PtP mode to PtM mode. Instead of the PHYSICAL CHANNEL RECONFIGURATION message, a TRANSPORT CHANNEL RECONFIGURATION message or a RADIO BEARER RECONFIGURATION message may be used.

In step 1512, the SRNC determines whether to change the RRC state of the UE to the CELL_PCH state. If the determination is made to change to the CELL_PCH state, the process proceeds to step 1513. The SRNC transmits an MBMS ATTACH REQUEST message to the DRNC in step 1513. The SRNC then receives a response message corresponding to the MBMS ATTACH REQUEST message from the DRNC in step 1514. The SRNC updates the information managed in the internal MBMS service context if necessary after receiving the response message. In step 1515, the SRNC transmits a PHYSICAL CHANNEL RECONFIGURATION message to the UE in response to the MEASUREMENT REPORT message. The PHYSICAL CHANNEL RECONFIGURATION message has a successful Active Set change procedure, and has a purpose to inform that the desired MBMS service can be provided by the PtM mode through the target cell. At this time, by including the PtM RB information in the PHYSICAL CHANNEL RECONFIGURATION message, the UE can change the radio channel from PtP mode to PtM mode. Instead of the PHYSICAL CHANNEL RECONFIGURATION message, a TRANSPORT CHANNEL RECONFIGURATION message or a RADIO BEARER RECONFIGURATION message may be used.

In operation 1531, the SRNC transmits an MBMS ATTACH REQUEST message to the DRNC. In step 1532, the SRNC receives a response message from the DRNC in response to the MBMS ATTACH REQUEST message. The MBMS ATTACH procedure in steps 1531 and 1532 is a procedure to ATTACH the corresponding cell (target cell) in advance in case a valid radio resource occurs in the DRNC. In response to the MEASUREMENT REPORT message, the SRNC informs the UE that the MBMS service requested by the UE cannot be provided due to a temporary reason such as lack of radio resources of a target cell.

If it is determined that the MBMS Cause IE value is NSA and proceeds to step 1541, the SRNC informs the UE that the MBMS Cause IE value is not included in the service area for providing the MBMS service requested by the target cell in response to the MEASUREMENT REPORT message.

If the SRNC proceeds to step 1505 by receiving the RL SETUP RESPONSE message, the SRNC transmits an ACTIVE SET UPDATE message to the UE in response to the MEASUREMENT REPORT message. The ACTIVE SET UPDATE message has a successful Active Set change procedure, and has a purpose of informing that a desired MBMS service can be provided through a target cell. At this time, PtP RB information is included in the ACTIVE SET UPDATE message and transmitted.

3.3 DRNC Operation

Hereinafter, the operation of the DRNC corresponding to the operation of the SRNC described above will be described in detail.

16A and 16B illustrate a control flow performed by a DRNC according to an embodiment of the present invention.

16A and 16B, the DRNC checks whether a message related to the MBMS service has been received from the SRNC in step 1600. When the DRNC receives the MBMS service related message, the DRNC checks the MBMS service identifier included in the MBMS related message in step 1601. Thereafter, it is checked whether an MBMS service context corresponding to the MBMS service identifier exists. If the MBMS service context exists by the check, the process proceeds to one of steps 1610, 1620, and 1630 according to the type of the MBMS service related message. However, if the corresponding MBMS service context does not exist by the check, the process proceeds to step 1602.

In step 1602, the DRNC adds itself to the MBMS multicast tree to SGSN and transmits an MBMS REGISTER REQUEST message requesting MBMS service related information. In this case, the MBMS REGISTER REQUEST message may include an SAI for identifying a service area in which a current UE is located or all SAIs managed by a DRNC. When the DRNC receives the MBMS REGISTER RESPONSE message corresponding to the MBMS REGISTER REQUEST message from the SGSN in step 1603, the DRNC proceeds to one of steps 1610, 1620, and 1630 according to the type of the MBMS service related message. . However, if it is determined in step 1604 that the MBMS REGISTER FAILURE message has been received in response to the MBMS REGISTER REQUEST message, the method corresponds to any one of steps 1650, 1660 and 1670 of FIG. Proceed.

Referring to the case where the DRNC proceeds to step 1610, the DRNC checks the MBMS service identifier in the RL SETUP REQUEST message received from the SRNC in step 1610. Thereafter, in step 1611, the DRNC checks whether the target cell to which the RL is to be configured is providing the MBMS service corresponding to the MBMS service identifier by the PtP mode. If the corresponding MBMS service is provided in the PtP mode by the check, step 1612 is performed. However, if the corresponding MBMS service is not provided by the PtP mode by the check, the process proceeds to step 1613 to check whether the MBMS service is provided by the PtM mode. If the MBMS service is provided in the PtM mode by the check, the process proceeds to step 1614. If the MBMS service is not provided in the PtM mode, the operation ends.

In step 1612, the DRNC transmits an RL SETUP RESPONSE message to the SRNC to provide the MBMS service in the PtP mode. The UE then terminates after adding the UE to the internal MBMS service context. Otherwise, in step 1614, the DRNC transmits an RL SETUP FAILURE message to the SRNC to provide the MBMS service in the PtM mode.

Referring to the case where the DRNC proceeds to step 1620, the DRNC checks the MBMS service identifier in the COMMON TRANSPORT CHANNEL RESOURCE REQUEST message received from the SRNC in step 1620. Thereafter, in step 1621, the DRNC checks whether the target cell to which the RL is to be configured is providing the MBMS service corresponding to the MBMS service identifier by the PtP mode. If the corresponding MBMS service is provided in the PtP mode by the check, step 1622 is performed. However, if the corresponding MBMS service is not provided by the PtP mode by the check, the process proceeds to step 1623 to check whether the MBMS service is provided by the PtM mode. If the MBMS service is provided by the PtM mode by the check, the process proceeds to step 1624. If the MBMS service is not provided by the PtM mode, the operation ends.

In step 1622, the DRNC ends after transmitting a COMMON TRANSPORT CHANNEL RESOURCE FAILURE message to the SRNC to provide the MBMS service in the PtP mode. At this time, by including the PtP identifier in the COMMON TRANSPORT CHANNEL RESOURCE FAILURE message, it can inform the SRNC that the target cell provides the MBMS service in the PtP mode. Otherwise, in step 1624, the DRNC transmits a COMMON TRANSPORT CHANNEL RESOURCE RESPONSE message to the SRNC to provide the MBMS service in the PtM mode. PtM RB information is transmitted through the COMMON TRANSPORT CHANNEL RESOURCE RESPONSE message. The DRNC then adds the UE to the internal MBMS service context and terminates.

Referring to the case where the DRNC proceeds to step 1630, the DRNC confirms that an MBMS ATTACH REQUEST message has been received from the SRNC in step 1630. Thereafter, in step 1631, the DRNC checks whether the target cell to which the RL is to be configured is providing the corresponding MBMS service by the PtP mode. If the corresponding MBMS service is provided in the PtP mode by the check, the process proceeds to step 1632. However, if the corresponding MBMS service is not provided by the PtP mode by the check, it proceeds to step 1633 to check whether the MBMS service is provided by the PtM mode. If the MBMS service is provided in the PtM mode by the check, the process proceeds to step 1634. If the MBMS service is not provided in the PtM mode, the operation ends.

In step 1632, the DRNC terminates after transmitting an MBMS ATTACH FAILURE message to the SRNC to provide the MBMS service in the PtP mode. At this time, by including the PtP identifier in the MBMS ATTACH FAILURE message, it can inform the SRNC that the MBMS service is currently provided in the PtP mode in the DRNC. Otherwise, in step 1634, the DRNC transmits an MBMS ATTACH RESPONSE message to the SRNC to provide the MBMS service in PtM mode, and then adds the UE to an internal MBMS service context and terminates.

Referring to the case where the DRNC proceeds to step 1650 through step 1604, the DRNC checks the MBMS service identifier in the RL SETUP REQUEST message received from the SRNC in step 1650. Thereafter, in step 1651, the DRNC transmits an RL SETUP FAILURE message corresponding to the RL SETUP REQUEST message to the SRNC. In this case, the RL SETUP FAILURE message includes information indicating that the target cell does not belong to the service area and thus it is impossible to provide a desired MBMS service.

Referring to the case where the DRNC proceeds to step 1660 through step 1604, the DRNC checks the MBMS service identifier in the COMMON TRANSPORT CHANNEL RESOURCE REQUEST message received from the SRNC in step 1660. Thereafter, the DRNC transmits a COMMON TRANSPORT CHANNEL RESOURCE FAILURE message corresponding to the COMMON TRANSPORT CHANNEL RESOURCE REQUEST message to the SRNC in step 1661. In this case, the COMMON TRANSPORT CHANNEL RESOURCE FAILURE message includes information indicating that the target cell does not belong to a service area and thus it is impossible to provide a desired MBMS service.

Referring to the case where the DRNC proceeds to step 1670 through step 1604, the DRNC confirms reception of an MBMS ATTACH REQUEST message in step 1670. Thereafter, the DRNC transmits an MBMS ATTACH FAILURE message corresponding to the MBMS ATTACH REQUEST message to the SRNC in step 1671. In this case, the MBMS ATTACH FAILURE message includes information indicating that it is impossible to provide a desired MBMS service because the corresponding target cell does not belong to a service area.

3.4 operation of SGSN

Hereinafter, the operation of the SGSN corresponding to the above-described DRNC operation will be described in detail.

17 is a diagram illustrating a control flow performed by SGSN according to an embodiment of the present invention.

Referring to FIG. 17, in step 1700, the SGSN checks whether an MBMS REGISTER REQUEST message is received from the DRNC. If the SGSN receives the MBMS REGISTER REQUEST message, the SGSN proceeds to step 1701. In step 1701, the SGSN checks whether an MBMS service context corresponding to the MBMS service identifier included in the MBMS REGISTER REQUEST message exists. If the MBMS service context exists, the flow proceeds to step 1703. However, if the MBMS service context does not exist, the flow proceeds to step 1702. In step 1702, the SGSN generates an MBMS service context corresponding to the MBMS service identifier and then proceeds to step 1703.

In step 1703, the SGSN checks a service area identifier (SAI) included in the MBMS REGISTER REQUEST message. Thereafter, the SAI checks whether an MBMS service corresponding to the MBMS service identifier is included in a possible MBMS service area. If the SAI is included in the MBMS service area, the SGSN proceeds to step 1704. However, if the SAI is not included in the MBMS service area, the flow proceeds to step 1707 and ends after transmitting an MBMS REGISTER FAILURE message to the DRNC. The MBMS REGISTER FAILURE message fails to add the corresponding RNC to the multicast tree for MBMS, and has a purpose to inform that MBMS data transmission through the RNC is impossible. At this time, the MBMS REGISTER FAILURE message may include a Cause IE value such as a non service area.

On the other hand, the SGSN proceeds to step 1704 adds the DRNC sending the MBMS REGISTER REQUEST message to the List of Downstream Node in the MBMS service context to add the RNC to the multicast tree for MBMS. Thereafter, the SGSN sends an MBMS REGISTER RESPONSE message to the DRNC in step 1705 to inform that the RNC has been successfully added to the MBMS multicast tree. That is, transmitting an MBMS REGISTER RESPONSE message means that MBMS data transmission according to the MBMS service is possible through the DRNC. The SGSN terminates after transmitting a SESSION START message to the DRNC in step 1706. The SGSN provides the DRNC with the SESSION START message, QoS information related to MBMS service, MBMS service area information, and the like. At this time, the SESSION START message may also serve as a procedure for establishing a lu data bearer for MBMS service between the SGSN and the RNC.

As described above, the present invention has an advantage of preventing unnecessary MBMS ATTACH procedure by performing the ATTACH procedure according to the cell change in consideration of the MBMS information of the target cell and the RRC state of the mobile terminal. This reduces the load on the Iur interface between the wireless network controllers, thereby enabling efficient use of radio resources.

1 is a diagram showing a network configuration for a multicast multimedia broadcasting service.

2 is a diagram illustrating a procedure for a multicast multimedia broadcasting service.

3 is a diagram illustrating a procedure of attaching through an existing MBMS procedure as a mobile terminal moves to a cell controlled by another radio network controller.

4 is a diagram illustrating a problem when a UE in a Cell DCH state attaches to a DRNC through an existing MBMS service procedure when moving to a cell controlled by the DRNC.

5A to 5C, 6, 7, 8A, 8B, 9A, and 9B illustrate an attach procedure performed by a request of a mobile terminal in a CELL_FACH state in a mobile communication system according to a first embodiment of the present invention. A diagram showing signaling for the.

10, 11, and 12 illustrate signaling for an attach procedure performed by a request of a mobile terminal in a CELL_DCH state in a mobile communication system according to a second embodiment of the present invention.

13 is a view showing a control flow performed in a mobile terminal for the first embodiment of the present invention.

14A to 14C illustrate a control flow performed by an SRNC for a first embodiment of the present invention.

15 is a diagram illustrating a control flow performed by an SRNC for a second embodiment of the present invention.

16A and 16B illustrate a control flow performed by a DRNC for an embodiment of the present invention.

17 illustrates a control flow performed in SGSN for an embodiment of the present invention.

Claims (11)

At least one movement to move to a target cell belonging to the second wireless network controller in a situation where a broadcast service is provided through a common channel from a first and a second wireless network controller and a source cell belonging to the first wireless network controller. In a mobile communication system comprising a terminal, a method for allocating radio resources so that the mobile terminal can receive the broadcast service from the second wireless network controller, Receiving, by the mobile terminal, broadcast service related information from the target cell and requesting cell update by transmitting the broadcast service related information to the first wireless network controller; And determining, by the first radio network controller, whether to allocate radio resources based on the broadcast service related information, and requesting radio resource allocation to the second radio network controller according to the determination. The method of claim 1, wherein the target cell requests the allocation of radio resources when the target cell receives broadcast service related information indicating that there is no mobile terminal to provide the broadcast service or to receive the broadcast service through a dedicated channel. Characterized in that the method. The radio resource allocation according to claim 1, wherein when the target cell receives the broadcast service related information indicating that the target cell provides the broadcast service through the common channel, the mobile station can receive the broadcast service only through the common channel. The method characterized in that for requesting. The method as claimed in claim 1, wherein the allocation of radio resources is reserved when the target cell receives broadcast service related information indicating that the target cell is not providing the broadcast service due to lack of radio resources. The second wireless network controller of claim 1, wherein when receiving the broadcast service related information indicating that the broadcast service related information is not provided from the target cell, the second wireless network controller is requested to provide the broadcast service to the second wireless network controller. And a procedure for providing the broadcast service between the SGSN and the SGSN. The method as claimed in claim 1, wherein when a call update request is received from the mobile terminal without the broadcast service related information, a request for an MBMS ATTACH procedure and establishment of a common channel is simultaneously requested to the second wireless network controller. At least one movement to move to a target cell belonging to the second wireless network controller when a broadcast service is provided through a dedicated channel from a first and a second wireless network controller and a source cell belonging to the first wireless network controller. In a mobile communication system comprising a terminal, a method for allocating radio resources so that the mobile terminal can receive the broadcast service from the second wireless network controller, Measuring, by the mobile terminal, signal strength of a neighboring cell, and reporting the measurement result to the first wireless network controller when the target cell is detected through the measurement; Determining, by the first wireless network controller, whether to handover to the target cell, and requesting radio resource allocation to the second wireless network controller to which the target cell belongs by the determination; Transmitting, by the second wireless network controller, broadcast service related information about the target cell to the first wireless network controller in response to the radio resource allocation request; And determining, by the first wireless network controller, whether to allocate the radio resource based on the broadcast service related information. 8. The method of claim 7, wherein when the target cell receives broadcast service related information indicating that there is no mobile terminal to provide the broadcast service or to receive the broadcast service through a dedicated channel, it determines to allocate radio resources. Characterized in that the method. 8. The method of claim 7, wherein, when the target cell receives broadcast service related information indicating that the target cell provides the broadcast service through a common channel, the radio resource is allocated only when the mobile station can receive the broadcast service through the common channel. The method characterized in that it determines. 8. The method of claim 7, wherein when the target cell receives broadcast service related information indicating that the target cell is not providing the broadcast service due to lack of radio resources, the allocation of radio resources to the second radio network controller is reserved. The method. The method as claimed in claim 7, wherein the target cell notifies the mobile station that the target cell is not the broadcast service area when receiving the broadcast service related information indicating that the target cell is not the broadcast serviceable area. .