CN115802406A

CN115802406A - State report sending method, radio bearer retransmission execution method and user equipment

Info

Publication number: CN115802406A
Application number: CN202111055582.XA
Authority: CN
Inventors: 肖芳英; 刘仁茂
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 2021-09-09
Filing date: 2021-09-09
Publication date: 2023-03-14
Also published as: WO2023036173A1

Abstract

The invention provides a status report transmission method performed by user equipment, a radio bearer retransmission execution method performed by a base station, and user equipment. The method of transmitting a status report performed by a user equipment includes: upon receiving a PDCP PDU via a specific RLC entity of a plurality of RLC entities configured for transmitting a corresponding split radio bearer, determining whether a currently received PDCP PDU is a first PDCP PDU consecutively received via the specific RLC entity; and sending a PDCP status report to the base station in case that the currently received PDCP PDU is the first PDCP PDU, the PDCP status report including information indicating whether the historical PDCP PDU that has been currently sent by the base station was correctly received by the user equipment.

Description

State report sending method, radio bearer retransmission execution method and user equipment

Technical Field

The present disclosure relates to the field of wireless communication technologies, and more particularly, to a method for transmitting a status report performed by a user equipment, a method for performing radio bearer retransmission performed by a base station, and a user equipment.

Background

A research project SI (see SP-190625 in particular) on 5G multicast broadcast service architecture improvement has been approved and is in progress. One of the targets of this SI, called target a, is to support generic MBS services in 5GS, and examples that have been determined to benefit from this feature include, but are not limited to, public safety, V2X applications, transparent IPv4/IPv6 multicast transmission, IPTV, wireless software transmission, group communication, and internet of things applications. Accordingly, approval is obtained for a work item for which NR Multicast and Broadcast Service (NR MBS) is proposed (see non-patent document: RP-193248 New WID. The work item is intended to provide support for target a in the RAN.

The present disclosure discusses relevant issues involved in the RAN achieving the above-mentioned operational goals.

Disclosure of Invention

The invention aims to provide a scheme capable of retransmitting a radio bearer in time so as to reduce data loss.

In order to solve the above problems, an aspect of the present invention provides a method of transmitting a status report, performed by a user equipment, comprising: determining, upon receipt of a PDCP PDU via a particular RLC entity of a plurality of RLC entities configured for transmission of a corresponding split radio bearer, whether a currently received PDCP PDU is a first PDCP PDU consecutively received via the particular RLC entity; and transmitting a PDCP status report to the base station in case that the currently received PDCP PDU is the first PDCP PDU, the PDCP status report including information indicating whether the historical PDCP PDUs transmitted by the base station were correctly received by the user equipment.

Optionally, the separated radio bearer is a separated MBS radio bearer, and the specific RLC is a PTP RLC entity among a plurality of RLC entities configured to transmit the separated MBS radio bearer.

Optionally, the method further comprises: before sending a PDCP status report to a base station, determining whether a separated radio bearer corresponding to a currently received PDCP PDU is configured with report sending indication information, wherein the report sending indication information is used for indicating that the PDCP status report is sent to the base station. In case that the currently received PDCP PDU is the first PDCP PDU, transmitting a PDCP status report to the base station may include: and sending a PDCP status report to the base station under the condition that the currently received PDCP PDU is the first PDCP PDU and a separated radio bearer corresponding to the currently received PDCP PDU is configured with report sending indication information.

Optionally, the report sending indication information is configured for any of the following separate radio bearers: each separate radio bearer; the corresponding plurality of RLC entities are configured with separate radio bearers configured with different response modes indicating whether to respond to the base station (e.g., AM mode and UM mode as described herein); at least one of the corresponding plurality of RLC entities is configured as a split radio bearer of an acknowledgement mode responsive to the base station; PTP RLC entities of the corresponding plurality of RLC entities are configured as separate radio bearers in acknowledged mode.

Optionally, the determining whether the currently received PDCP PDU is a first PDCP PDU consecutively received via the specific RLC entity includes: determining that a currently received PDCP PDU is a first PDCP PDU that is continuously received via the specific RLC entity, in case a timer is not in a running state, the timer being started or restarted when the PDCP PDU is received via the specific RLC entity.

Optionally, the timer is stopped when any one of the following conditions is met: receiving a PDCP PDU via another RLC entity of the plurality of RLC entities that is a different type from the particular RLC entity; receiving PDCP PDUs via the other RLC entity and not receiving PDCP PDUs via the specific RLC entity for a predetermined period from when the PDCP PDUs are received via the other RLC entity; receiving PDCP PDUs via the other RLC entity and not receiving PDCP PDUs via the specific RLC entity from a period until the PDCP PDUs received via the other RLC entity reach a predetermined number; receiving handover information from the base station, the handover information indicating a handover from a first transmission mode corresponding to the certain RLC entity to a second transmission mode corresponding to the other RLC entity.

Optionally, the report sending indication information includes timer configuration information for the timer.

According to another aspect of the present invention, there is also provided a method performed by a base station of performing radio bearer retransmission, including: determining whether there is a PDCP PDU which is not successfully received by the user equipment according to a PDCP status report received from the user equipment, the PDCP status report being transmitted to the base station by the user equipment through the method of transmitting a status report as described above; and if there is a PDCP PDU that is not successfully received by the user equipment, retransmitting the PDCP PDU to the user equipment via a corresponding PTP PLC entity.

Optionally, the method further comprises: and sending timer configuration information to the user equipment, wherein the timer configuration information is used for configuring a timer for determining the first PDCP PDU.

According to another aspect of the present invention, there is also provided user equipment comprising: a processor; and a memory storing instructions, wherein the instructions, when executed by the processor, perform the method of sending a status report as described above.

Effects of the invention

According to the invention, the wireless bearer can be retransmitted in time so as to reduce data loss.

Drawings

The above and other features of the present disclosure will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which:

fig. 1 is a diagram illustrating an example of a PDCP status report format according to an embodiment of the present invention.

Fig. 2 is a flow chart of a transmission method performed by a user equipment.

Fig. 3 is a block diagram for explaining a user equipment according to an embodiment of the present invention.

Fig. 4 is a flowchart of one example of a method of transmitting a status report according to an embodiment of the present invention.

Fig. 5 is a flowchart of another example of a method of transmitting a status report according to an embodiment of the present invention.

Fig. 6 is a diagram for explaining one example of a switching procedure from the PTM transmission mode to the PTP transmission mode.

Fig. 7 is a block diagram of a user equipment according to an embodiment of the present invention.

Fig. 8 is a schematic diagram for explaining parameters involved in the description.

Detailed Description

The present disclosure is described in detail below with reference to the attached drawings and detailed description. It should be noted that the present disclosure should not be limited to the specific embodiments described below. In addition, for the sake of brevity, detailed descriptions of well-known technologies not directly related to the present disclosure are omitted to prevent confusion of understanding of the present disclosure.

Some of the terms referred to in this disclosure are described below, and the specific meaning of the terms can be found in 3GPP latest relevant documents, such as TS38.300, TS38.321, TS38.323, TS38.331, and the like. In addition, the embodiment of the present disclosure is not limited to broadcast/multicast services, and may also be applied to other application scenarios.

UE: user Equipment, user Equipment.

RRC: radio Resource Control, radio Resource Control.

RRC _ CONNECTED: RRC connected state.

RRC _ INACTIVE: RRC inactive state.

RRC _ IDLE: RRC idle state.

RAN: radio Access Network, radio Access Network.

NR: new RAT, new radio access technology.

MBMS: multimedia Broadcast/Multicast Service, multimedia Broadcast Multicast Service.

MBS: multicast Broadcast Services.

PDCP, packet Data Convergence Protocol.

Fig. 1 illustrates an example of a PDCP Status Report (PDCP Status Report) format. As shown in fig. 1, the D/C occupies 1 bit for indicating whether the corresponding PDCP PDU is a PDCP data PDU or a PDCP control PDU; a PDU Type (PDU Type) occupies 3 bits for indicating a Type of control information contained in a corresponding PDCP control PDU; FMC (F)irst Missing COUNT) takes 32 bits and indicates the first Missing COUNT (COUNT represents the number of PDU, which consists of HFN and PDCP sequence number PDCP SN, as shown in fig. 8), which indicates the COUNT value (i.e., RX _ DELIV) of the first Missing PDCP SDU in the reordering window; the Bitmap (Bitmap) is variable in length to indicate which SDUs are missing and which SDUs have been received correctly in the receiving PDCP entity (indications of which value meaning each bit is given in table 1), where the bit position of the nth bit in the Bitmap is (bit position of N) ^th bit in the Bitmap is N); r occupies 1 bit and is a reserved bit, which will be ignored by the receiving end.

TABLE 1

Bits	Means of
		0	COUNT = (FMC + bits) modulo 2 ³² PDCP SDU loss
1	COUNT = (FMC + bits) modulo 2 ³² Correct reception of PDCP SDU

RLC, radio Link Control.

As an example, the RLC may be an Acknowledged Mode (AM) RLC, an Unacknowledged Mode (UM) RLC, an UM RLC, and a Transparent Mode (TM) RLC. The UM RLC entity is configured to transmit the UM RLC entity or receive the UM RLC entity, and submit or receive RLC data PDUs. The AM RLC entity includes a transmission end and a reception end, and submits or receives RLC data PDUs and RLC control PDUs. In AM mode, the RLC entity submits or receives RLC data PDUs and RLC control PDUs (i.e., status PDUs), and the receiving end of the AM RLC entity uses the status PDUs to inform a peer RLC entity (i.e., the transmitting end of another AM RLC entity) about RLC data PDUs that it successfully received and RLC data PDUs that are detected as missing.

Service Data Unit, SDU. The data packets received or delivered from or to the upper layer by this layer are called SDUs.

PDU is Protocol Data Unit and Protocol Data Unit. The data packets that the layer receives from or delivers to the lower layer are called PDUs. For example, the PDCP data PDU is a packet obtained by adding a PDCP header to a PDCP SDU.

RB: radio Bearer, radio Bearer.

MRB: an MBS radio bearer, i.e. a radio bearer configured for MBS multicast/broadcast transmission (Aradio bearer that is configured for MBS multicast/broadcast delivery).

MCCH: multicast Control Channel, multicast Control Channel. The MBS-MCCH is used for transmitting control information related to receiving the MBS service.

SC-MCCH: single Cell Multicast Control Channel, single Cell Multicast Control Channel.

TMGI: temporal Mobile Group Identity, temporary Mobile Group Identity.

PLMN: public Land Mobile Network, public Land Mobile Network.

RNTI: radio Network Temporary Identifier.

And PTM: point to Multipoint, a delivery (sender) mode of MBS service. In the PTM delivery mode, the RAN node delivers a copy of MBS data packets to a set of UEs (a RAN node a single copy of MBS data packets over radio to a set of UEs) by radio.

PTP: point to Point, a delivery method of MBS service. In the PTP delivery mode, the RAN node delivers copies of a plurality of MBS data packets to each UE (a RAN node partial copies of MBS data packet over radio to individual UE) by radio.

LTE SC-PTM: LTE Single Cell Point to Multipoint, long term evolution Single Cell Point to Multipoint.

MTCH: multicast Traffic Channel, multicast Traffic Channel. MBS multicast (or multicast communication service) means that the same service and the same specific content are simultaneously provided to a specific group of UEs. A multicast communication service is delivered to the UE using a multicast session.

A UE in RRC _ CONNECTED may receive a multicast communication service using PTP and/or PTM.

G-RNTI: group RNTI, used to scramble the scheduling and transmission of MTCH. The NR MBS supports a 1-1 mapping relation between G-RNTI and MBS conversation (One-to-One mapping between G-RNTI and MBS conversation is supported in NR MBS).

In the present disclosure, the network, the base station, and the RAN may be used interchangeably, and the network may be a long term evolution LTE network, an NR network, an enhanced long term evolution LTE network, or other networks defined in subsequent evolution releases of 3 GPP.

In LTE SC-PTM, a base station broadcasts a Multimedia Broadcast Multicast Service (MBMS) service supported by the base station and scheduling information thereof through system information and information transmitted on an SC-MCCH channel, and radio bearer configuration information for transmitting the MBMS service is predefined. The UE can know the MBMS service supported or ongoing by the current cell or base station by receiving the corresponding system information and the message transmitted on the SC-MCCH. When UE needs to receive a certain MBMS service, a radio bearer is established according to predefined parameters and data is received. In this case, the UE can receive the MBMS service without establishing an RRC connection.

In NR MBS, a part of MBS services (services) may also be scheduled in a similar manner as SC-PTM, so that UEs in RRC idle state and RRC inactive state may also receive the MBS services. However, there is another part of MBS service that requires the UE to establish RRC connection with the base station, and then the base station configures the UE through dedicated RRC signaling (also called dedicated RRC message), and the radio bearer receiving these MBS services can also be configured for the UE by the base station through dedicated RRC signaling. Fig. 2 is a block diagram illustrating a transmission method performed by such a user equipment. S101 establishes RRC connection between the UE and the base station, and S102 configures the base station for the UE to receive the radio bearer of the MBS service through the RRC message. The radio bearer may be an MRB configured with PTM transmission only (as shown in (a) of fig. 3), or a split MRB configured with both PTM and PTP (split MRB) (as shown in (b) of fig. 3) or an MRB configured with PTP transmission only (as shown in (c) of fig. 3). It should be noted that (a) - (c) of fig. 3 only show the corresponding PDCP entity and RLC entity and the relationship therebetween. In the downlink direction, the PDCP PDUs encapsulated by the PDCP entity (i.e., with the addition of a PDCP header) are delivered to the RLC entity. For split MRBs, the base station may dynamically decide whether to transmit an MBS session (or PDCP PDU) using PTM or PTP. For example, when the link quality corresponding to the PTM is degraded or the quality of service (QoS) of the MBS session cannot be satisfied, the base station may transmit in a PTP manner (i.e., the base station delivers the PDCP PDU to the PTP RLC entity). For MRBs with only PTM transmission configured, the base station reconfigures the MRBs to MRBs with PTP transmission through RRC signaling. For a separate MRB in which PTM transmission and PTP transmission are configured simultaneously, the base station dynamically decides to employ PTM transmission or PTP transmission and does not explicitly indicate to the UE, i.e. when the base station enables PTP or PTM transmission, the data is transmitted directly without sending an indication to the UE. In this case, the base station employs PTP transmission when the link quality corresponding to the PTM deteriorates. However, in order to meet the QoS requirements for the MBS service, the base station will retransmit part of the PDCP PDUs, which have been delivered to the PTM (or PTM RLC entity), through the PTP (or PTP RLC entity) to reduce data loss. How the UE triggers the PDCP status report so that the base station determines which PDCP PDUs should be retransmitted on the PTP is a problem to be solved.

The present disclosure provides the following embodiments to solve the above problems.

The present invention will be described in detail below with reference to the accompanying drawings.

As shown in fig. 4, the user equipment receives PDCP PDUs via a plurality of RLC entities at S202. The plurality of RLC entities may be, for example, the RLC entities for the separate MRBs in (b) of fig. 3, i.e., the PTM RLC entity and the PTP RLC entity. The split radio bearer may be a split MBS radio bearer. At this time, among the plurality of RLC entities, for example, a PTM RLC entity and a PTP RLC entity may be included. In other examples, the number of PTM RLC entities and PTP RLC entities may be arbitrary.

Upon receiving the PDCP PDU, the user equipment determines whether the received PDCP PDU is a PDCP PDU received via a specific RLC entity at S204.

In one example, where the split radio bearer is a split MBS radio bearer, the particular RLC entity may be a PTP RLC entity of a plurality of RLC entities configured for transmission of the split MBS radio bearer.

If the PDCP PDU is received via the specific RLC entity, i.e., if the PDCP PDU is received via the specific RLC entity, it is determined whether the currently received PDCP PDU is the first PDCP PDU continuously received via the specific RLC entity at S206.

If the currently received PDCP PDU is the first PDCP PDU that is continuously received via the specific RLC entity, the user equipment transmits a PDCP status report to the base station S208. The PDCP status report includes information indicating whether the historical PDCP PDUs transmitted by the base station were correctly received by the user equipment. The base station, upon receiving the PDCP status report, may determine whether there is a PDCP PDU that was not correctly received by the user equipment according to the PDCP status report. If there is a PDCP PDU that is not correctly received by the user equipment, retransmission can be initiated for the PDCP PDU. That is, the PDCP PDU is retransmitted to the user equipment.

For example, whether the currently received PDCP PDU is the first PDCP PDU continuously received via a specific RLC entity may be determined by the operation state of a timer. The timer may be started or restarted when a PDCP PDU is received via a particular RLC entity. If the timer is in a non-running state when the PDCP PDU is received via a specific RLC entity, it may be determined that the currently received PDCP PDU is the first PDCP PDU consecutively received via the specific RLC entity. At this point, a timer is started. Then, when the PDCP PDU is received via the specific RLC entity next time, since the timer is in a running state, it can be determined that the PDCP PDU received this time is not the first PDCP PDU continuously received via the RLC entity. At this point, the timer may be restarted. Thus, if the base station maintains a state of transmitting a radio bearer through a specific RLC entity, the user equipment continuously receives PDCP PDUs through the specific RLC entity, and when the PDCP PDUs are received again through the specific RLC entity after the first PDCP PDU is received through the specific RLC entity, the timer is in a running state, so that it can be determined that the currently received PDCP PDU is not the first PDCP PDU continuously received through the specific RLC entity.

The value of the timer may be set as appropriate according to actual needs, and the present invention is not particularly limited thereto. A configuration message for the timer may be transmitted to the user equipment by the base station through an RRC message, and the base station may set the timer according to the configuration message.

In one example, the timer may be stopped if the user equipment considers that the base station has switched from a first transmission mode corresponding to a particular RLC entity to another transmission mode different from the first transmission mode, where the another transmission mode corresponds to another RLC entity having a different transmission mode from the particular RLC entity. Thus, in case that the base station switches to the first transmission mode again, when the user equipment receives PDCP PDUs via a specific RLC entity corresponding to the first transmission mode, if the timer is not in a running state, it can be determined that the PDCP PDUs received at this time are the first PDCP PDUs continuously received via the specific RLC entity.

The base station switching transmission mode refers to that the base station switches an RLC entity for data transmission. RLC entities exist correspondingly at the base station side and the user equipment side. For example, in the case that the base station side includes a PTP RLC entity and a PTM RLC entity, the user equipment side also correspondingly has a PTP RLC entity and a PTM RLC entity corresponding to the PTP RLC entity and PTM RLC entity of the base station side, respectively. The PTP RLC entity (or PTM RLC entity) on the base station side and the PTP RLC entity (or PTM RLC entity) on the UE side are mutually called peer RLC entities. When the base station determines to perform data transmission in the PTP mode, the number is transmitted to the user equipment side via the PTP RLC entity of the base station side, and the user equipment correspondingly receives data by the PTP RLC entity. When the base station switches the transmission mode, for example, the base station switches from the PTP mode to the PTM mode, the base station switches from the PTP RLC entity to the PTM RLC entity, and the user equipment also switches to receive data through the corresponding PTM RLC entity.

However, which transmission mode is used for transmitting the PDCP PDUs is decided by the base station, not by the user equipment. In this regard, the user equipment may determine whether the base station switches transmission modes according to a certain policy. The user equipment may consider that the base station has switched transmission modes when any one of the following conditions is satisfied, and may stop the timer at this time: receiving a PDCP PDU via another RLC entity of the plurality of RLC entities, which is of a different type from the specific RLC entity; receiving PDCP PDUs via another RLC entity and not receiving the PDCP PDUs via a specific RLC entity within a predetermined period from when the PDCP PDUs are received via another RLC entity (the predetermined period may be configured for the UE by the base station through an RRC message); receiving PDCP PDUs via another RLC entity and not receiving PDCP PDUs via the specific RLC entity from a period until the PDCP PDUs received via another RLC entity reach a predetermined number; handover information is received from a base station, the handover information indicating a handover from a first transmission mode corresponding to a certain RLC entity to a second transmission mode corresponding to another RLC entity.

In fig. 5, the operation of S302 is the same as the operation of S202, and the operation of S304 may be the same as the operation of S304. Further, the operation of S308 is the same as that of S206, and the operation of S310 is the same as that of S208. Thus, a description of these operations will not be repeated.

As shown in fig. 5, the user equipment may determine whether the split radio bearer corresponding to the currently received PDCP PDU is configured with the report transmission indication information in S306. The report transmission indication information is used to indicate transmission of a PDCP status report to the base station, and may be configured by the base station.

The base station may configure the report transmission indication information for each of the separate radio bearers. The report sending indication information may also be configured only for the split radio bearers that meet the requirements. In case that the first PDCP PDU is determined by a timer, the report transmission indication information may include timer configuration information for the timer. Hereinafter, a case where the report transmission instruction information is timer configuration information for the timer will be described as an example, for which split radio bearer the report transmission instruction information is configured.

If the split radio bearer corresponding to the currently received PDCP PDU is configured with the report transmission indication information, further performing operations of S308 and S310. In another example, the operation of S306 may also be performed after the operation of S308.

It should be noted that, in the embodiment of the present disclosure, the received PDCP PDU may also be replaced by the received PDCP SDU. It can be further defined that the received PDCP PDU is a PDCP data PDU.

The present invention will be further described with reference to the following specific examples.

Examples

The separate radio bearer is configured with a first RLC entity and a second RLC entity. The PDCP entity corresponding to the separated radio bearer receives PDCP PDUs from a lower layer (namely, an RLC entity), and if the PDCP PDUs (or the PDCP SDUs corresponding to the PDCP PDUs) are received from a first RLC entity, the following operations are carried out:

(1) If the timer is not running, a PDCP status report is triggered and/or the timer is started (start).

(2) Restarting (restart) the timer if the timer is running. It should be noted that, in the present disclosure, the restart timer may also be described as a start timer.

Optionally, the value of the timer is configured for the UE by the base station through RRC signaling. If the value of the timer is configured by the base station, it can be further specified that only the split radio bearer configured with the timer can perform this embodiment. Further, it may be further specified whether the corresponding radio bearer or PDCP entity is configured with the status reportrequired, and the embodiment is only executed when the status reportrequired is configured or its value is true. Wherein, the status report required is included in an RRC message (which may be included in an RRC message configuring the first timer) sent by the base station to the UE, and is used to indicate whether a corresponding radio bearer is configured to send a PDCP status report on the uplink.

Optionally, the timer is stopped when the PDCP entity is re-established. When the PDCP entity is re-established, the parameters of the RLC entity corresponding to the PDCP entity are reset, and the timer may be stopped.

Optionally, the timer is stopped when the second RLC entity is enabled.

The base station may configure the timer for each separate radio bearer. The base station may also configure the timer only for the separate radio bearers for which the associated first RLC entity and second RLC entity are configured with different modes, for example, the mode of the first RLC entity is UM, and the mode of the second RLC entity is AM, that is, the first RLC entity is an UM RLC entity, and the second RLC entity is an AM RLC entity. The base station may also configure the timer only for the separate radio bearer associated with at least one AM RLC entity. AM RLC is typically configured for services with high QoS requirements, for which the base station will enable the second RLC entity when the first RLC entity transmission fails to meet the QoS requirements, and in order to avoid data loss, the UE needs to be triggered to send a PDCP status report so that the base station can retransmit PDCP PDUs or SDUs that have been sent but not yet correctly received by the UE.

The above process is described below by taking the example of separating the MRBs.

The base station configures a separation MRB for the UE through RRC signaling, wherein the separation MRB is associated with two RLC entities, one of the two RLC entities is a PTM RLC entity, and the other one is a PTP RLC entity. Optionally, a timer (or a value of the timer) is configured for the corresponding MRB in the RRC signaling.

The PDCP entity of the MRB is separated to receive PDCP PDUs from a lower layer entity (i.e., RLC entity), and when the PDCP PDUs (or the PDCP SDUs corresponding to the PDCP PDUs) are received from a PTP RLC entity, the following operations are performed:

(1) Triggering a PDCP status report if the timer is not running, and/or starting the timer (the value of the timer is set to a configured value).

(2) If the timer is running, the timer is restarted (the value of the timer is set to the configured value).

An example of a scenario of this embodiment is explained with reference to fig. 6. As shown in fig. 6, it is assumed that PDCP PDUs used for transmission of the split MRB include PDCP PDU No. 1 to PDCP PDU No. N, where N is a positive integer. The base station transmits the PDCP PDU No. 1 through PTM transmission, but when the PDCP PDU No. 2 is transmitted, the QoS is detected to be reduced, which can cause data loss, so that the base station can decide to switch to a PTP mode to transmit the PDCP PDU No. 2. Correspondingly, the user equipment receives PDCP PDU No. 2 via the PTP RLC. When the user equipment receives the PDCP PDU No. 2, since the PDCP PDU No. 2 is the first PDCP PDU received via the PTP RLC, the user equipment may perform the operation of the present embodiment to transmit a PDCP status report to the base station. Information indicating whether each PDCP PDU transmitted by the base station so far is successfully received may be included in the status report. For example, if the user equipment does not receive PDCP PDU No. 1, information indicating that PDCP PDU No. 1 is not received may be included in the PDCP status report. After receiving the PDCP status report, the base station may retransmit the PDCP PDU No. 1 through PTP transmission.

It may be provided that the timer is configured only when the mode of the PTP RLC entity is AM. It may also be provided that the timer is configured only when two RLC entities that separate MRB associations are used for PTM transmission and PTP transmission, respectively.

The separation MRB is configured by an upper layer in an uplink sending PDCP status report (configured by upper layer to send a PDCP status report in the uplink), and the receiving PDCP entity triggers the PDCP status report when the following conditions are satisfied: the PDCP PDU (or PDCP SDU corresponding to the PDCP PDU) from the PTP RLC entity is received and the timer is not running. The PDCP entity may determine whether the PDCP status report is configured by the upper layer by using an information element status report, where the status report is included in an RRC message (which may be included in an RRC message configuring the first timer) sent by the base station to the UE, to indicate whether a corresponding radio bearer is configured to send the PDCP status report on the uplink.

If the PDCP data PDU (the COUNT value of which is RCVD _ COUNT) received from the PTP RLC entity is not discarded, the receiving PDCP entity (receiving PDCP entry) performs the following operations: the timer is started or restarted. Wherein, RCVD _ COUNT is the COUNT of the received PDCP data PDU, i.e., [ RCVD _ HFN, RCVD _ SN ]; wherein, RCVD _ HFN and RCVD _ SN are parameters of two fields of RCVD _ COUNT. RCVD _ SN is the PDCP SN of the received PDCP Data PDU, which is contained in the PDU header of the PDU, and RCVD _ HFN is the HFN of the received PDCP Data PDU, which is calculated by the receiving PDCP entity.

In the embodiment of the disclosure, the PTM RLC entity is also called a PTM associated RLC entity or an RLC entity configured with G-RNTI or an RLC entity associated with G-RNTI or an RLC entity used for PTM transmission; the PTP RLC entity is also referred to as PTP-associated RLC entity or RLC entity for PTP transmission.

It should be noted that an MBS service (or referred to as an MBS session) may be identified by an MBS id, which may be a TMGI and/or a session id sessionId, where the TMGI may include a PLMN id and/or a service id, and the service id uniquely identifies an MBS service in a PLMN.

Fig. 7 is a block diagram of a schematic structure of a user equipment UE according to the present disclosure. As shown in fig. 7, the user equipment 700 comprises a processor 701 and a memory 702. The processor 701 may include, for example, a microprocessor, a microcontroller, an embedded processor, or the like. The memory 702 may include, for example, volatile memory (e.g., random access memory RAM), a Hard Disk Drive (HDD), non-volatile memory (e.g., flash memory), or other memory, among others. The memory 702 has stored thereon program instructions. The instructions, when executed by the processor 701, may perform the above-described methods performed by the user equipment as detailed in the present disclosure.

In addition, the computer-executable instructions or programs running on the apparatus according to the present disclosure may be programs that cause a computer to realize the functions of the embodiments of the present disclosure by controlling a Central Processing Unit (CPU). The program or information processed by the program may be temporarily stored in a volatile memory (such as a random access memory RAM), a Hard Disk Drive (HDD), a nonvolatile memory (such as a flash memory), or other memory system.

Computer-executable instructions or programs for implementing the functions of embodiments of the present disclosure may be recorded on computer-readable storage media. The corresponding functions can be realized by causing a computer system to read the programs recorded on the recording medium and execute the programs. The term "computer system" as used herein may be a computer system embedded in the device and may include an operating system or hardware (e.g., peripheral devices). The "computer-readable storage medium" may be a semiconductor recording medium, an optical recording medium, a magnetic recording medium, a recording medium that stores a program for short-term dynamics, or any other recording medium that is readable by a computer.

Various features or functional blocks of the devices used in the above-described embodiments may be implemented or performed by circuitry (e.g., a single or multiple chip integrated circuits). Circuitry designed to perform the functions described herein may include a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The circuit may be a digital circuit or an analog circuit. Where new integrated circuit technologies have emerged as a replacement for existing integrated circuits due to advances in semiconductor technology, one or more embodiments of the present disclosure may also be implemented using these new integrated circuit technologies.

Further, the present disclosure is not limited to the above-described embodiments. While various examples of the embodiments have been described, the present disclosure is not so limited. Fixed or non-mobile electronic devices installed indoors or outdoors may be used as terminal devices or communication devices, such as AV devices, kitchen devices, cleaning devices, air conditioners, office devices, vending machines, and other home appliances.

As above, the embodiments of the present disclosure have been described in detail with reference to the accompanying drawings. However, the specific configuration is not limited to the above embodiment, and the present disclosure also includes any design modification without departing from the gist of the present disclosure. In addition, various modifications can be made to the present disclosure within the scope of the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. Further, components having the same effects described in the above embodiments may be substituted for each other.

Claims

1. A method performed by a user equipment of sending a status report, comprising:

upon receiving a PDCP PDU via a specific RLC entity of a plurality of RLC entities configured for transmitting a corresponding split radio bearer, determining whether a currently received PDCP PDU is a first PDCP PDU consecutively received via the specific RLC entity; and

and sending a PDCP status report to a base station in the case that the currently received PDCP PDU is the first PDCP PDU, wherein the PDCP status report comprises information indicating whether the historical PDCP PDUs sent by the base station are correctly received by the user equipment.

2. The method of claim 1, wherein the split radio bearer is a split MBS radio bearer, and the particular RLC is a PTP RLC entity of a plurality of RLC entities configured for transmitting the split MBS radio bearer.

3. The method of claim 1, further comprising:

before sending a PDCP status report to a base station, determining whether a separated radio bearer corresponding to a currently received PDCP PDU is configured with report sending indication information, wherein the report sending indication information is used for indicating to send the PDCP status report to the base station;

in case that the currently received PDCP PDU is the first PDCP PDU, transmitting a PDCP status report to the base station includes:

and sending a PDCP status report to the base station under the condition that the currently received PDCP PDU is the first PDCP PDU and a separated radio bearer corresponding to the currently received PDCP PDU is configured with report sending indication information.

4. The method of claim 3, wherein the report transmission indication information is configured for any of the following separate radio bearers:

each separate radio bearer;

the corresponding plurality of RLC entities are configured with separate radio bearers configured with different response modes indicating a mode of whether to respond to the base station;

at least one of the corresponding plurality of RLC entities is configured as a split radio bearer of an acknowledgement mode responsive to the base station;

PTP RLC entities of the corresponding plurality of RLC entities are configured as separate radio bearers in acknowledged mode.

5. The method according to any one of claims 1 to 4, wherein determining whether the currently received PDCP PDU is a first PDCP PDU that is continuously received via the specific RLC entity comprises:

determining that a currently received PDCP PDU is a first PDCP PDU that is continuously received via the specific RLC entity, in case a timer is not in a running state, the timer being started or restarted when the PDCP PDU is received via the specific RLC entity.

6. The method of claim 5, wherein the timer is stopped when any one of the following conditions is met:

receiving a PDCP PDU via another RLC entity of the plurality of RLC entities that is a different type from the particular RLC entity;

receiving PDCP PDUs via the other RLC entity and not receiving PDCP PDUs via the specific RLC entity within a predetermined period from when the PDCP PDUs are received via the other RLC entity;

receiving PDCP PDUs via the other RLC entity and not receiving PDCP PDUs via the specific RLC entity from a period until the PDCP PDUs received via the other RLC entity reach a predetermined number;

receiving handover information from the base station, the handover information indicating a handover from a first transmission mode corresponding to the certain RLC entity to a second transmission mode corresponding to the other RLC entity.

7. The method of claim 5 when dependent on claim 3, wherein the report transmission indication information comprises timer configuration information for the timer.

8. A method performed by a base station of performing radio bearer retransmission, comprising:

determining whether there are PDCP PDUs which have not been successfully received by a user equipment according to a PDCP status report received from the user equipment, the PDCP status report being transmitted by the user equipment to the base station by the method of any of claims 1-7; and

and if the PDCP PDU which is not successfully received by the user equipment exists, retransmitting the PDCP PDU to the user equipment via a corresponding PTP PLC entity.

9. The method of claim 8, further comprising:

and sending timer configuration information to the user equipment, wherein the timer configuration information is used for configuring a timer for determining the first PDCP PDU.

10. A user equipment, comprising:

a processor; and

a memory having stored therein instructions that, when executed,

wherein the instructions, when executed by the processor, perform the method of any of claims 1 to 7.