JP6017325B2 - Buffer state report instruction method and radio base station apparatus - Google Patents

Description

  The present invention relates to the field of radio communication technology, and in particular, to a buffer status report instruction method for a user apparatus and a radio base station apparatus.

In LTE (Long Term Evolution), when uplink data to be transmitted occurs, the user equipment (UE) is specified to make a scheduling request to the radio base station (eNB) in the following steps ( For example, refer nonpatent literature 1).
(1) Step 1: Transmission of scheduling request As shown in FIG. 1 (A), if uplink data is generated in the user equipment, the user equipment has an individual uplink resource (PUCCH). Then, a scheduling request is transmitted using this uplink resource (PUCCH-SR). If the user equipment does not have an individual uplink resource, a random access (RA) procedure is activated.
(2) Step 2: Transmission of Buffer Status Report (BSR: Buffer Status Report) A BSR is transmitted using a PUSCH (Physical Uplink Shared Channel) corresponding to the UL grant allocated to the request of Step 1. In the case of a random access procedure, UL grant is instructed by a random access response (RA response).

  As shown in FIG. 1B, the total amount of data is calculated for each logical channel group (LCH # A to LCH # D) in which data exists, and the BSR is reported.

The user equipment (UE) triggers the BSR in the following cases.
(1) When data is generated or when higher priority data is generated
(2) When there is no more data to send
(3) When the number of surplus bits of MAC PDU (Medium Access Control Protocol Data Unit) is larger than the number of bits required for BSR storage (Padding BSR)
(4) When the Periodic BSR timer expires (periodic BSR trigger)

3GPP, TS36.321

  At present, the BSR can only be reported by a trigger in the user apparatus (UE), so the eNB cannot grasp the buffer retention amount in the UE in real time.

  For example, if the BSR is lost wirelessly, the buffer retention amount of the UE cannot be grasped in real time on the eNB side. Although it is conceivable that the UE periodically triggers the BSR, if the frequency is too high, the BSR is reported even when the BSR report is unnecessary, which is not desirable from the viewpoint of resource efficiency.

  Therefore, the present invention provides a buffer state report instruction method and a configuration of a radio base station apparatus that allows the radio base station to grasp the buffer retention amount of the user apparatus in real time.

In a first aspect, a buffer status report instruction method is provided. This method
In the radio base station, set a condition that triggers a buffer status report for the user equipment,
When the condition is satisfied, a buffer status report trigger instruction is transmitted from the radio base station to the user apparatus,
Receiving a buffer status report in response to the buffer status report trigger instruction from the user equipment in the radio base station;
It is characterized by that.

In a second aspect, a radio base station apparatus is provided. The radio base station device
An uplink buffer management unit that sets a condition for instructing a trigger for a buffer status report to a user apparatus, and generates a buffer status report trigger instruction for the user apparatus when the condition is satisfied;
A transmission unit for transmitting the buffer status report trigger instruction to the user apparatus;
A receiver for receiving a buffer status report in response to the buffer status report trigger instruction from the user device;
Have

  The radio base station apparatus can grasp the buffer retention amount of the user apparatus in real time.

It is a figure which shows the outline | summary of BSR control in LTE. It is a figure which shows an example of the BSR report of embodiment. It is a figure which shows another example of the BSR report of embodiment. It is a flowchart which shows the process performed with a user apparatus. It is a figure which shows the structural example of a user apparatus. It is a flowchart which shows the process performed in a network (eNB). It is a figure which shows the structural example of eNB.

Embodiments will be described below with reference to the drawings.
<Operation in user device>
FIG. 2 is a diagram illustrating an example of a BSR transmission operation by a user apparatus (UE). A user apparatus triggers a buffer status report (BSR) according to the instruction | indication from a radio base station (eNB). In the example of FIG. 2, the eNB issues only a BSR trigger instruction and separately allocates UL-SCH (Uplink Shared Channel), which is a radio resource for BSR transmission. In this case, the operation after triggering conforms to the current BSR control.

  Specifically, the user apparatus receives a BSR trigger instruction from the eNB (S1). The BSR trigger instruction is transmitted by, for example, a MAC (Media Access Control) control element (CE), a radio resource control (RRC) signal, or a physical downlink control channel (PDCCH).

  The user apparatus triggers the BSR based on the reception of the BSR trigger instruction (S2). Subsequent to the BSR trigger instruction, the user apparatus receives from the eNB a UL grant instructing a resource for BSR transmission (S3). A user apparatus transmits BSR with PUSCH corresponding to UL-grant (S4).

  When the BSR is triggered in the user apparatus according to the BSR trigger instruction from the eNB, the user apparatus may not trigger the scheduling request (SR).

  According to this method, the user apparatus can transmit the buffer retention information according to the instruction from the eNB without waiting for the timing of the conventional BSR trigger. In other words, the eNB can acquire the buffer retention information at a desired timing earlier than the timing of the BSR trigger by the user apparatus.

  FIG. 3 is a diagram illustrating another example of the BSR transmission operation by the user apparatus. In the example of FIG. 3, a user apparatus receives UL-grant which designates the resource for BSR transmission simultaneously with the trigger instruction of BSR from eNB (S5). Based on this trigger instruction, the user apparatus triggers the BSR (S6), and always transmits the BSR on the UL-SCH assigned by the trigger instruction. That is, when receiving a trigger instruction together with allocation of uplink resources from the eNB, the user apparatus transmits the BSR to the network (eNB) with the highest priority even when there is data having a higher priority than the BSR. The trigger instruction at this time may be specified in the PDCCH of UL-grant.

  Even in this method, the user apparatus can transmit the buffer retention information according to the instruction from the eNB without waiting for the timing of the BSR trigger. The eNB can acquire the buffer retention information at a desired timing earlier than the timing of the BSR trigger by the user apparatus.

  Next, a case where uplink carrier aggregation (UL CA) is set will be described as an application example of BSR transmission.

  Carrier aggregation is a technique for performing communication by bundling a plurality of component carriers in order to realize broadband communication exceeding 20 MHz (for example, 100 MHz). Carrier aggregation not only bundles component carriers between cells under the same base station (eNB), but also includes inter-site carrier aggregation (Inter-site CA) that bundles cells under different base stations (eNBs). Inter-site CA provides a more flexible network architecture.

  In the case of inter-site uplink carrier aggregation, for example, the cell under the radio base station (for example, macro eNB) where the user equipment is located is set as a highly reliable primary cell (PCell: primary serving cell), etc. A cell (other macro cell or small cell) under the control of the wireless base station can be set as an additional secondary cell (SCell: secondary serving cell).

  The connection between the user apparatus and the eNB of the secondary cell can be managed on the eNB of the primary cell or the network side. As shown in FIG. 2 and FIG. 3, when the user apparatus triggers the BSR in response to the BSR trigger instruction, the BSR may be transmitted using the PUSCH of the primary cell. Or you may transmit to eNB of the secondary cell which has the largest or the smallest index number (SCell-Index) in a secondary cell. In this case, the secondary cell that has received the BSR performs scheduling for the user equipment according to the buffer retention amount of the user equipment.

  Or you may transmit BSR to eNB of the secondary cell estimated that quality is good in a secondary cell. A cell with good quality is, for example, a cell with good CQI or a cell with a small number of UL HARQ (Uplink Hybrid Automatic Repeat reQuest) retransmissions.

  Or a user apparatus may recognize the cell which should transmit BSR according to designation | designated of eNB, and may transmit BSR to the designated eNB. The cell of the BSR transmission destination may be dynamically specified by a MAC control element or PDCCH (physical downlink control channel), or may be specified semi-static by an RRC signal.

  Furthermore, when the user apparatus is connected to a plurality of eNBs, an instruction as to which eNB should transmit the BSR may be received from the network. For example, the user equipment is connected to the eNB of the primary cell for transmission / reception of control plane (C-plane) data, and is connected to the eNB of the secondary cell for data transmission of user plane (U-plane) When it exists, it is good also as a structure which a user apparatus receives the instruction | indication of eNB used as the transmission destination of BSR from eNB of a primary cell.

  As yet another application example, when the user apparatus transmits a BSR in accordance with a BSR trigger instruction from the eNB, the BSR-related timer may not be restarted. Currently, when a user equipment reports a BSR, the Periodic BSR timer of the user equipment is restarted from the beginning. However, in the application example of the embodiment, the activated current state may be maintained as it is without newly restarting the periodic BSR timer. By maintaining the current state of the BSR timer, it is possible to prevent a new period from being counted from the BSR transmission, and to transmit the next BSR earlier at the timing when the BSR timer expires.

FIG. 4 is a diagram illustrating a processing flow performed by the user device. First, it is determined whether or not a BSR trigger condition in the user apparatus is satisfied (S101). For example, when the condition of the BSR trigger is satisfied,
(a) When data is generated in the user device (including a case where data is newly generated from a state where there is no data to be transmitted and a case where another data is generated while there is transmission data)
(b) If there is no more data to send,
(c) If the number of surplus bits in the MAC PDU is larger than the number of bits required for BSR storage,
(d) If the Periodic BSR timer expires,
Etc.

  If the BSR trigger condition is satisfied (YES in S101), the user apparatus triggers the BSR (S103).

  If the BSR trigger condition is not satisfied (NO in S101), it is determined whether a BSR trigger instruction is received from the eNB (S102). If a BSR trigger instruction has been received (YES in S102), the user apparatus triggers a BSR (S103). If a BSR trigger instruction has not been received (NO in S102), the process returns to step S101 to determine whether or not the BSR trigger condition is satisfied.

  With this process, the user apparatus can report a BSR according to a BSR trigger instruction from the eNB in addition to the normal BSR control in LTE.

  FIG. 5 is a block diagram illustrating a configuration example of the user device 10. The user apparatus includes a downlink (DL) signal reception unit 11, an uplink (UL) signal transmission unit 12, a MAC management unit 13, and an uplink (UL) buffer management unit 15. The MAC management unit 13 includes a BSR management unit 14.

  The DL signal receiving unit 11 receives a downlink radio signal via an antenna (not shown). The UL signal transmission unit 12 transmits an uplink radio signal via an antenna (not shown). The antenna, the baseband processing unit, etc. are not shown because they are not directly related to the present invention, but the RF side of the DL signal receiving unit 11 and the UL signal transmitting unit 12 is connected to one or more antenna elements, The baseband side is connected to a baseband processing unit (including a digital signal processing unit).

  The MAC management unit 13 performs MAC PDU (Protocol Date Unit) generation / processing, HARQ (Hybrid Automatic Repeat Request) management, RACH management, and the like. The BSR management unit 14 generates and processes a BSR. The UL buffer management unit 15 monitors the uplink buffer retention amount and notifies the BSR management unit 14 of the uplink buffer retention amount.

  When the DL signal receiving unit 11 receives the BSR trigger instruction, the BSR management unit 14 generates a BSR based on information from the UL buffer management unit 15 and transmits the BSR via the UL signal transmission unit 12 .

With such a configuration, flexible BSR reporting is realized.
<Operation in eNB>
FIG. 6 is a flowchart showing processing by the eNB. The eNB determines whether or not the condition of the BSR trigger instruction (report instruction) in the network is satisfied (S201). If the condition is satisfied, a BSR trigger instruction (report instruction) is transmitted to the user apparatus (S202).

The case where the BSR trigger instruction condition is satisfied (YES in S201) and the BSR trigger instruction is issued is, for example, as follows.
(1) A BSR trigger instruction is issued when a predetermined period has elapsed after receiving a BSR indicating that there is no buffer retention amount (data).

For example, even after the user equipment runs out of data, the BSR can be allocated immediately in anticipation of the possibility of occurrence of severe delay demand data such as TCP (Transport Control Protocol) ACK. In order to be able to grasp the presence or absence of data with severe delay requirements as soon as possible.
(2) A BSR trigger instruction is issued if a subsequent BSR cannot be received after a predetermined period of time has elapsed since the last BSR was received.

For example, when further data is generated in the user apparatus during data communication, the eNB can grasp this data generation as early as possible and use it for scheduling.
(3) Regardless of reception of BSR, a BSR trigger instruction is issued when a period comes (periodic trigger). The period of the trigger can be determined based on traffic statistics, for example. Depending on the type of user device, some background data is generated every certain period, so it may be adjusted to the cycle.
(4) A BSR trigger instruction is issued when performing carrier aggregation (CA) or deconfiguring a secondary cell.

  For example, if the latest BSR is received when adding or activating a secondary cell (SCell), or when performing uplink timing alignment in the case of uplink carrier aggregation (UL CA), scheduling in SCell Can begin early.

Moreover, it is good also as a structure which ensures that there is little or almost no data by confirming the uplink data retention amount just before deactivate / deconfigure a secondary cell. At this time, if there is a large amount of uplink data retention, the SCell deactivate / deconfigure may be stopped.
(5) A BSR trigger instruction is issued when the user apparatus is caused to make an IDLE transition.

When data is generated at the last timing of IDLE transition by checking the buffer retention amount with BSR just to make sure that the user equipment transitions to IDLE, IDLE transition occurs even though there is uplink data. Can be avoided. If an IDLE transition occurs even though there is uplink data, it takes time to resume the uplink data, so it is meaningful to issue a BSR trigger instruction prior to the IDLE transition.
(6) When the BSR trigger instruction is transmitted but the BSR cannot be received for a predetermined period, the BSR trigger instruction is retransmitted.
(7) BSR trigger instruction is issued when Truncate BSR is received.

Since Truncate BSR reports only a part of the buffer retention amount of the user equipment, in order to obtain accurate and sufficient buffer retention information, if Truncate BSR is received, the subsequent BSR should be triggered immediately. desirable.
(8) When an allocation request (Scheduling Request) is allocated, but a BSR cannot be received for a predetermined period, a BSR trigger instruction is issued.

When the allocation for Scheduling Request is performed, the user equipment should store the BSR in response to the first UL grant. However, the fact that the BSR cannot be received means that the PUSCH corresponding to the first UL grant is missing on the radio. There is a possibility. In this case, it is desirable to issue a BSR trigger instruction in order to receive the BSR as early as possible.
(9) DRX command A BSR trigger instruction is issued when the user device is forced to transit to the DRX (intermittent reception) state by MAC CE. Before transitioning to the DRX state, it can be ensured that no uplink data is generated.
(10) After transmitting DL SRB (Signaling Radio Bearer) data to the user apparatus, when a BSR cannot be received from the user apparatus within a predetermined period, a BSR trigger instruction is issued.

Basically, when the user apparatus receives DL SRB data, the user apparatus transmits feedback information of an RRC (Radio Resource Control) level or an RLC (Radio Link Control) level corresponding thereto. Therefore, the BSR should report that such feedback information has occurred. Therefore, a BSR trigger instruction may be issued to confirm whether feedback information has occurred or whether DL SRB data has been received.
(11) A BSR trigger instruction is issued when the remaining amount of uplink data that the eNB recognizes has become small (for example, when it becomes a predetermined byte or less).

  By issuing an instruction at this timing, for example, when a buffer retention amount is received as 500 bytes in the immediately preceding BSR, a resource is allocated to 490 bytes of data, and the remaining 10 bytes are allocated. It is possible to check whether a large amount of data is generated in the user device.

  These are examples of conditions for an eNB-led BSR trigger instruction. By issuing a BSR trigger instruction from the eNB to the user apparatus, the eNB can acquire the buffer retention amount information at a desired timing without waiting for the BSR timing of the user apparatus.

  FIG. 7 is a schematic block diagram of the eNB (radio base station) 20. The eNB 20 includes a downlink (DL) signal transmission unit 21, an uplink (UL) signal reception unit 22, a MAC scheduler unit 23, and an uplink (UL) buffer management unit 24. The UL buffer management unit 24 includes a BSR processing unit 25.

  The DL signal transmission unit 21 transmits a downlink radio signal via an antenna (not shown). The UL signal receiving unit 22 receives an uplink radio signal via an antenna (not shown). The antenna, the baseband processing unit, and the like are not illustrated because they are not directly related to the present invention, but the RF side of the DL signal transmission unit 21 and the UL signal reception unit 22 is connected to one or more antenna elements, The baseband side is connected to a baseband processing unit (including a digital signal processing unit).

  The MAC scheduler unit 23 allocates radio resources on the shared channel to each user apparatus. The UL buffer management unit 24 determines whether or not the condition of the BSR trigger instruction is satisfied for each user apparatus. An example of the condition of the BSR trigger instruction is as described above. When the condition of the BSR trigger instruction is satisfied, the UL buffer management unit 24 generates a BSR trigger instruction and causes the user apparatus to transmit the BSR trigger instruction via the DL signal transmission unit 21.

  As shown in FIG. 2, when the BSR trigger instruction and the UL grant are transmitted separately, the UL buffer management unit 24 transmits the uplink resources allocated by the MAC scheduler 23 to the user equipment following the transmission of the BSR trigger instruction. Notice.

  As shown in FIG. 3, when the UL grant is transmitted simultaneously with the BSR trigger instruction, the UL buffer management unit 24 illustrates that the BSR trigger instruction is included in, for example, a downlink channel (PDCCH or the like) that transmits the UL grant. Control the signal multiplexing section.

  The BSR processing unit 25 processes the BSR reported from the user device. Based on the processing result of the BSR processing unit 25, the UL buffer management unit 24 determines whether the BSR from the user apparatus is received, whether the buffer retention amount indicated in the BSR is near zero, whether the uplink data retention Determine if the amount is running low.

  With the above configuration, the eNB 20 can cause the user apparatus 10 to execute a BSR trigger at a desired timing, and can grasp the buffer retention amount of the user apparatus in real time.

DESCRIPTION OF SYMBOLS 10 User apparatus 11 DL signal receiving part 12 UL signal transmission part 13 MAC management part 14 BSR management part 15 UL buffer management part 20 eNB (radio base station)
21 DL signal transmission unit 22 UL signal reception unit 23 MAC scheduler unit 24 UL buffer management unit 25 BSR processing unit

Claims (17)

In the radio base station, set a condition that triggers a buffer status report for the user equipment,
When the condition is satisfied, a buffer status report trigger instruction is transmitted from the radio base station to the user apparatus,
The radio base station receives a buffer status report in response to the buffer status report trigger command from the user apparatus, and provides a buffer status report command method.   The buffer status report according to claim 1, wherein the radio base station notifies the user apparatus of uplink resource allocation for the buffer status report simultaneously with the buffer status report trigger instruction. Instruction method.   The buffer status report according to claim 1, wherein the radio base station notifies the user apparatus of uplink resource allocation for the buffer status report separately from the buffer status report trigger instruction. Instruction method.   The radio base station transmits the buffer status report trigger instruction to the user device when a predetermined period has elapsed after receiving a buffer status report indicating that no data stays from the user device. The buffer status report instruction method according to claim 1.   If the radio base station does not receive a subsequent buffer status report even after a predetermined period has elapsed since the last buffer status report was received from the user device, the radio base station gives the buffer status report trigger instruction to the user device. The buffer status report instruction method according to claim 1, wherein the buffer status report is transmitted.   2. The radio base station periodically transmits the buffer status report trigger instruction to the user apparatus regardless of whether or not the buffer status report is received from the user apparatus. Instruction method for buffer status report described in 1.   The method according to claim 6, wherein the period is determined based on traffic statistics or user equipment specifications.   The radio base station transmits the buffer status report trigger instruction to the user apparatus when performing carrier aggregation for the user apparatus or when canceling the setting of a secondary cell during carrier aggregation. The buffer status report instruction method according to claim 1.   The buffer state according to claim 1, wherein the radio base station transmits the buffer status report trigger instruction to the user apparatus when the user apparatus is transitioned to an IDLE state or an intermittent reception state. How to indicate the report.   The radio base station retransmits the buffer status report trigger instruction when it does not receive the buffer status report for a predetermined period after transmitting the buffer status report trigger command to the user apparatus. 2. The buffer status report instruction method according to 1.   The buffer status according to claim 1, wherein the radio base station transmits the buffer status report trigger instruction to the user apparatus when receiving a truncated buffer status report from the user apparatus. How to indicate the report.   When the radio base station does not receive a buffer status report even after a predetermined period of time has elapsed after allocating uplink resources in response to a scheduling request from the user device, the radio base station triggers the buffer status report trigger to the user device. The buffer status report instruction method according to claim 1, wherein the instruction is transmitted.   When the radio base station does not receive a buffer status report from the user apparatus even after a predetermined period has elapsed since data was transmitted to the user apparatus using a signaling radio bearer, 2. The buffer status report instruction method according to claim 1, wherein a status report trigger instruction is transmitted.   The radio base station transmits the buffer status report trigger instruction to the user apparatus when an uplink data retention amount of the user apparatus ascertained by the radio base station becomes a predetermined amount or less. The buffer status report instruction method according to claim 1. An uplink buffer management unit that sets a condition for instructing a trigger for a buffer status report to a user apparatus, and generates a buffer status report trigger instruction for the user apparatus when the condition is satisfied;
A transmission unit for transmitting the buffer status report trigger instruction to the user apparatus;
A receiver for receiving a buffer status report in response to the buffer status report trigger instruction from the user device;
A radio base station apparatus comprising: A scheduler for allocating uplink resources for the user equipment;
Further comprising
The uplink buffer management unit transmits an uplink resource allocation notification for the buffer status report simultaneously with the buffer status report trigger instruction via the transmission unit. Wireless base station equipment. A scheduler for allocating uplink resources for the user equipment;
Further comprising
16. The uplink buffer management unit causes the uplink resource allocation notification for the buffer status report to be transmitted separately from the buffer status report trigger instruction via the transmission unit. The radio base station apparatus described in 1.

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