WO2022151297A1 - 数据传输方法及装置 - Google Patents

数据传输方法及装置 Download PDF

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Publication number
WO2022151297A1
WO2022151297A1 PCT/CN2021/071956 CN2021071956W WO2022151297A1 WO 2022151297 A1 WO2022151297 A1 WO 2022151297A1 CN 2021071956 W CN2021071956 W CN 2021071956W WO 2022151297 A1 WO2022151297 A1 WO 2022151297A1
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WIPO (PCT)
Prior art keywords
rlc
entity
information
access network
network device
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PCT/CN2021/071956
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English (en)
French (fr)
Inventor
高云龙
罗海燕
曾清海
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华为技术有限公司
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Priority to PCT/CN2021/071956 priority Critical patent/WO2022151297A1/zh
Publication of WO2022151297A1 publication Critical patent/WO2022151297A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W80/00—Wireless network protocols or protocol adaptations to wireless operation
    • H04W80/06—Transport layer protocols, e.g. TCP [Transport Control Protocol] over wireless

Definitions

  • the present application relates to the field of communication technologies, and in particular, to a data transmission method and apparatus.
  • Multicast broadcast service is a service for multiple terminal equipment (user equipment, UE), such as live broadcast service, public safety service, batch software update service, etc.
  • UE user equipment
  • MBS service data is sent from the access network equipment to the terminal equipment, there are two transmission methods: the first is point to multi-point (PTM) transmission; the second is point-to-point ( point to point, PTP) transmission method.
  • PTM point to multi-point
  • PTP point-to-point
  • the existing automatic repeat request (ARQ) technology cannot be directly applied, so that the highly reliable transmission of the MBS service data cannot be guaranteed.
  • Embodiments of the present application provide a data transmission method and apparatus, which are used to ensure highly reliable transmission of MBS service data.
  • a data transmission method is provided, which is applied to an access network device, and the access network device is configured with a packet data convergence protocol (PDCP) entity, a first radio link control (radio link control) entity. , RLC) entity and the second RLC entity, the first RLC entity and the second RLC entity are respectively associated with the PDCP entity, the first RLC entity is used to support the point-to-multipoint PTM transmission mode to send the multicast broadcast service MBS service data, the second The RLC entity is used to support the point-to-point PTP transmission mode to send MBS service data, and the first RLC entity and the second RLC entity are associated with the same multicast radio bearer (MBS radio bearer, MRB).
  • MBS radio bearer MRB
  • At least one terminal device including the terminal device sends at least one RLC service data unit (service data unit, SDU); the second RLC entity receives first information from the first terminal device, and the first information is used to indicate the RLC of the first RLC SDU Serial number (serial number, SN), the first RLC SDU belongs to at least one RLC SDU that has not been successfully received; the second RLC entity submits second information to the first RLC entity or PDCP entity, and the second information is used to indicate The RLC SN of the first RLC SDU; the first entity sends the first RLC SDU to the first terminal device, and the first entity is the first RLC entity or the second RLC entity.
  • RLC service data unit service data unit
  • the access network device transmits the MBS service data in a PTM manner through the first RLC entity, and obtains the receiving state of the terminal device for the MBS service data through the second RLC entity. Further, the access network device may determine the MBS service data that needs to be retransmitted, and retransmit the MBS service data through the first RLC entity or the second RLC entity. It can be seen that the technical solution provided by the present application can make the ARQ mechanism applied to the PTM transmission mode, and ensure the highly reliable transmission of MBS service data.
  • the first entity is the first RLC entity; before the first entity sends the first RLC SDU to the first terminal device, the method further includes: the first RLC entity obtains the first RLC according to the second information SDU.
  • the first entity is the second RLC entity; before the first entity sends the first RLC SDU to the first terminal device, the method further includes: the first RLC entity sends the second RLC entity to the second RLC according to the second information The entity submits the first RLC SDU.
  • the method before the first entity sends the first RLC SDU to the first terminal device, the method further includes: the PDCP entity submits the first RLC SDU to the first entity according to the second information.
  • the second information includes the RLC SN of the first RLC SDU
  • the PDCP entity submits the first RLC SDU to the first entity according to the second information, including: the PDCP entity according to the RLC SN of the first RLC SDU, and
  • the preset mapping relationship is to determine the PDCP SN of the first PDCP protocol data unit (protocol data unit, PDU), and the preset mapping relationship is used to indicate the mapping relationship between the PDCP SN and the RLC SN; the PDCP entity is based on the PDCP of the first PDCP PDU.
  • SN obtains the first PDCP PDU
  • the first PDCP PDU is the first RLC SDU;
  • the PDCP entity submits the first RLC SDU to the first entity.
  • the second information includes the PDCP SN of the first PDCP PDU, and the PDCP entity submits the first RLC SDU to the first entity according to the second information, including: the PDCP entity obtains, according to the PDCP SN of the first PDCP PDU, the first RLC SDU.
  • the first PDCP PDU, the first PDCP PDU is the first RLC SDU; the PDCP entity submits the first RLC SDU to the first entity.
  • the method before the second RLC entity submits the second information to the PDCP entity, the method further includes: the second RLC entity determines the first PDCP PDU according to the RLC SN of the first RLC SDU and the preset mapping relationship.
  • the PDCP SN, the preset mapping relationship is used to indicate the mapping relationship between the PDCP SN and the RLC SN. Based on this design, the first RLC entity and the second RLC entity can perform the same RLC SN number on the RLC SDUs with the same content and submitted by the PDCP.
  • the method further includes: the access network device sends first indication information to the first terminal device, where the first indication information is used to instruct the first terminal device to receive starting data sequence number information of the MBS service data.
  • the starting data sequence number information includes the PDCP SN, the PDCP count value and/or the starting RLC SN.
  • the method further includes: the access network device sends MRB configuration information to the first terminal device, where the MRB configuration information is used to configure an MBS session between the first terminal device and the access network device.
  • the MRB configuration information includes a PTM identifier or MBS session information.
  • the MRB configuration information includes two RLC bearer configuration information, the two RLC bearer configuration information are associated with the same MRB, and at least one RLC bearer configuration information in the two RLC bearer configuration information includes a PTM identifier or MBS session information.
  • a data transmission method is provided, the method is applied to a first terminal device, the first terminal device is configured with a third RLC entity and a fourth RLC entity, and the third RLC entity is used to receive the access network device in a PTM manner
  • the sent MBS service data, the fourth RLC entity is used to receive the MBS service data sent by the access network device in the PTP manner, the third RLC entity and the fourth RLC entity are associated to the same MRB
  • the method includes: the third RLC entity is connected from the The network access device receives at least one RLC SDU; the fourth RLC entity receives third information from the third RLC entity, the third information indicates the RLC SN of the first RLC SDU in the at least one RLC SDU; the fourth RLC entity generates the first RLC SDU according to the third information.
  • the fourth RLC entity sends the first information to the access network device, where the first information is used to indicate the RLC SN of the first RLC SDU, and the first RLC SDU belongs to the RLC SDU that is not successfully received in at least one RLC SDU.
  • the third RLC entity receives at least one RLC SDU, and the third RLC entity sends the third information to the fourth RLC entity to trigger the fourth RLC entity to send the first information to the access network device, so that the access network device can be accessed by the third RLC entity.
  • the network device learns that the first RLC SDU was not successfully received. Therefore, based on the mutual interaction between the third RLC entity and the fourth RLC entity, the ARQ mechanism in the PTM transmission mode can be implemented, and the highly reliable transmission of the MBS service data can be ensured.
  • the method before the fourth RLC entity receives the third information from the third RLC entity, the method further includes: the third RLC entity determines that the first RLC SDU has not been successfully received; the third RLC entity determines that the first RLC SDU is not successfully received; The RLC SN of the SDU generates the third information.
  • the method before the fourth RLC entity receives the third information from the third RLC entity, the method further includes: the third RLC entity determines that the second RLC SDU in the at least one RLC SDU is successfully received; the third RLC The entity generates the third information according to the RLC SN of the second RLC SDU.
  • the method further includes: the fourth RLC entity receives the first RLC SDU from the access network device.
  • the method further includes: the third RLC entity receives the first RLC SDU from the access network device.
  • the method further includes: the third RLC entity indicates to the fourth RLC entity that the first RLC SDU is successfully received. Therefore, the fourth RLC entity may learn that the first RLC SDU is successfully received, and thus the fourth RLC may not need to send the first information again, so as to trigger the access network device to retransmit the first RLC SDU.
  • the method further includes: the first terminal device receives first indication information from the access network device, where the first indication information is used to instruct the first terminal device to receive starting data sequence number information of the MBS service data.
  • the first indication information is specifically used to indicate the starting PDCP SN, the PDCP count value and/or the starting RLC SN.
  • the method further includes: the first terminal device receives MRB configuration information from the access network device, where the MRB configuration information is used to configure an MBS session between the first terminal device and the access network device.
  • the MRB configuration information includes a PTM identifier or MBS session information.
  • the MRB configuration information includes two RLC bearer configuration information, the two RLC bearer configuration information are associated with the same MRB, and at least one RLC bearer configuration information in the two RLC bearer configuration information includes a PTM identifier or MBS session information.
  • a data transmission method comprising: a target access network device receiving a handover request message from a source access network device, where the handover request message is used to request handover of a terminal device from the source access network device to the target access network device Network access device; the target access network device sends fourth information to the source access network device, where the fourth information is used to instruct the source access network device to forward to the target access network device at least one SN corresponding to the first sequence number SN MBS service data of terminal equipment.
  • the target access network device sends fourth information to the source access network device to instruct the source access network device to forward the information of the terminal device corresponding to at least one SN before the first sequence number SN to the target access network device.
  • unnecessary data forwarding between base stations is avoided during MBS service switching.
  • the method before the target access network device sends the fourth information to the source access network device, the method further includes: the target access network device obtains the second SN information from the core network element; the target access network device obtains the second SN information; The device determines the first SN information according to the second SN information.
  • the first SN information is used to indicate the first SN.
  • the target access network device obtains the second SN information from the core network element, including: the target access network device sends a path switch request message to the core network element, where the path switch request message is used to request the core network
  • the network element switches the transmission path of the MBS service data of the terminal device; the target access network device receives a path switching confirmation message from the core network network element, and the path switching confirmation message includes the second SN information.
  • the first SN is PDCP SN, general packet radio service tunneling protocol (general packet radio service tunneling protocol, GTP)-user plane (user, U) SN or quality of service flow ID (quality of service flow ID). , QFI)SN.
  • GTP general packet radio service tunneling protocol
  • U user plane
  • QFI quality of service flow ID
  • a data transmission method comprising: a source access network device sending a handover request message to a target access network device, where the handover request message is used to request handover of a terminal device from the source access network device to the target access network device network access device; the source access network device receives fourth information from the target access network device, where the fourth information is used to instruct the source access network device to forward the terminal device corresponding to at least one SN before the first SN to the target access network device MBS business data.
  • the target access network device sends fourth information to the source access network device to instruct the source access network device to forward the information of the terminal device corresponding to at least one SN before the first sequence number SN to the target access network device.
  • MBS service data reduces unnecessary data forwarding between base stations in handover scenarios.
  • the first SN is a PDCP SN, a GTP-US SN, or a QFI SN.
  • a fifth aspect provides a communication device, the communication device includes a PDCP entity, a first RLC entity and a second RLC entity, the first RLC entity and the second RLC entity are respectively associated with the PDCP entity, and the first RLC entity is used to support PTM
  • the transmission mode sends the MBS service data
  • the second RLC entity is used to support the PTP transmission mode to send the MBS service data
  • the first RLC entity and the second RLC entity are associated to the same MRB.
  • the first RLC entity is configured to send at least one RLC SDU to at least one terminal device including the first terminal device.
  • the second RLC entity is configured to receive first information from the first terminal device, where the first information is used to indicate the RLC sequence number SN of the first RLC SDU, and the first RLC SDU belongs to at least one RLC SDU that is not successfully received in the RLC SDU .
  • the second RLC entity is further configured to submit second information to the first RLC entity or the PDCP entity, where the second information indicates the RLC SN of the first RLC SDU.
  • the first entity is configured to send the first RLC SDU to the first terminal device, where the first entity is the first RLC entity or the second RLC entity.
  • the first entity is the first RLC entity; before the first entity is used to send the first RLC SDU to the first terminal device, the first RLC entity is also used to obtain the first RLC entity according to the second information.
  • One RLC SDU is the first RLC entity
  • the first entity is the second RLC entity; before the first entity is used to send the first RLC SDU to the first terminal device, the first RLC entity is also used to send the second RLC SDU according to the second information.
  • the RLC entity delivers the first RLC SDU.
  • the PDCP entity before the first entity is configured to send the first RLC SDU to the first terminal device, the PDCP entity is configured to deliver the first RLC SDU to the first entity according to the second information.
  • the second information includes the RLC SN of the first RLC SDU.
  • the PDCP entity is specifically used to determine the PDCP SN of the first PDCP PDU according to the RLC SN of the first RLC SDU and the preset mapping relationship, and the preset mapping relationship is used to indicate the mapping relationship between the PDCP SN and the RLC SN;
  • the PDCP SN of a PDCP PDU obtains the first PDCP PDU, which is the first RLC SDU; and submits the first RLC SDU to the first entity.
  • the second information includes the PDCP SN of the first PDCP PDU.
  • the PDCP entity is specifically configured to obtain the first PDCP PDU according to the PDCP SN of the first PDCP PDU, and the first PDCP PDU is the first RLC SDU; and submit the first RLC SDU to the first entity.
  • the second RLC entity is also used to determine the PDCP SN of the first PDCP PDU according to the RLC SN of the first RLC SDU and a preset mapping relationship, and the preset mapping relationship is used to indicate the PDCP SN and the RLC. Mapping relationship between SNs.
  • the communication device further includes a communication module.
  • the communication module is configured to send first indication information to the first terminal device, where the first indication information is used to instruct the first terminal device to receive the starting data sequence number information of the MBS service data.
  • the starting data sequence number information includes the PDCP SN, the PDCP count value and/or the starting RLC SN.
  • the communication module is further configured to send MRB configuration information to the first terminal device, where the MRB configuration information is used to configure the MBS session between the first terminal device and the access network device.
  • the MRB configuration information includes a PTM identifier or MBS session information.
  • the MRB configuration information includes two RLC bearer configuration information, the two RLC bearer configuration information are associated with the same MRB, and at least one RLC bearer configuration information in the two RLC bearer configuration information includes a PTM identifier or MBS session information.
  • a communication apparatus in a sixth aspect, includes a third RLC entity and a fourth RLC entity.
  • the third RLC entity is used to receive the MBS service data sent by the access network device in the PTM mode; the fourth RLC entity is used to receive the MBS service data sent by the access network device in the PTP mode; the third RLC entity and the fourth RLC entity Entities are associated to the same MRB.
  • the third RLC entity is configured to receive at least one RLC SDU from the access network device.
  • the fourth RLC entity is configured to receive third information from the third RLC entity, where the third information indicates the RLC SN of the first RLC SDU in the at least one RLC SDU.
  • the fourth RLC entity is further configured to generate first information according to the third information; send the first information to the access network device, where the first information is used to indicate the RLC SN of the first RLC SDU, and the first RLC SDU belongs to at least one RLC SDU RLC SDUs that were not successfully received in .
  • the third RLC entity is also used to determine that the first RLC SDU is not successfully received; generate the third information according to the RLC SN of the first RLC SDU.
  • the third RLC entity is further configured to determine that the second RLC SDU in the at least one RLC SDU is successfully received; and generate the third information according to the RLC SN of the second RLC SDU.
  • the fourth RLC entity is further configured to receive the first RLC SDU from the access network device after sending the first information to the access network device.
  • the third RLC entity is further configured to receive the first RLC SDU from the access network device.
  • the third RLC entity is further configured to indicate to the fourth RLC entity that the first RLC SDU is successfully received.
  • the communication device further includes a communication module.
  • the communication module is configured to receive first indication information from the access network device, where the first indication information is used to instruct the first terminal device to receive the starting data sequence number information of the MBS service data.
  • the first indication information is specifically used to indicate the starting PDCP SN, the PDCP count value and/or the starting RLC SN.
  • the communication module is further configured to receive MRB configuration information from the access network device, where the MRB configuration information is used to configure the MBS session between the first terminal device and the access network device.
  • the MRB configuration information includes a PTM identifier or MBS session information.
  • the MRB configuration information includes two RLC bearer configuration information, the two RLC bearer configuration information are associated with the same MRB, and at least one RLC bearer configuration information in the two RLC bearer configuration information includes a PTM identifier or MBS session information.
  • a communication device comprising: a processing module and a communication module connected to the processing module.
  • the communication module is configured to receive a handover request message from the source access network device, where the handover request message is used to request the terminal device to be handed over from the source access network device to the target access network device.
  • the processing module is configured to generate fourth information, where the fourth information is used to instruct the source access network device to forward the MBS service data of the terminal device corresponding to at least one SN before the first sequence number SN to the target access network device.
  • the communication module is further configured to send fourth information to the source access network device.
  • the communication module is further configured to obtain the second SN information from the core network element before sending the fourth information to the source access network device; the processing module is further configured to obtain the second SN information according to the second SN information. , and determine the first SN information.
  • the first SN information is used to indicate the first SN.
  • the communication module is further configured to send a path switching request message to the core network element, and the path switching request message is used to request the core network element to switch the transmission path of the MBS service data of the terminal device;
  • the element receives the path switch confirmation message, and the path switch confirmation message includes the second SN information.
  • the first SN is a PDCP SN, a GTP-US SN, or a QFI SN.
  • a communication device comprising: a processing module and a communication module connected to the processing module.
  • the processing module is configured to generate a handover request message, where the handover request message is used to request handover of the terminal device from the source access network device to the target access network device.
  • the communication module is used for sending a handover request message to the target access network device.
  • the communication module is further configured to receive fourth information from the target access network device, where the fourth information is used to instruct the source access network device to forward the information of the terminal device corresponding to at least one SN before the first sequence number SN to the target access network device.
  • MBS business data MBS business data.
  • the first SN is a PDCP SN, a GTP-US SN, or a QFI SN.
  • a communication device in a ninth aspect, includes a processor and a transceiver, and the processor and the transceiver are used to implement the method provided by any one of the above-mentioned first to fourth aspects or any design thereof.
  • the processor is configured to perform processing actions in the corresponding method
  • the transceiver is configured to perform the receiving/transmitting actions in the corresponding method.
  • a computer-readable storage medium stores computer instructions that, when executed on a computer, cause the computer to perform any one of the first to fourth aspects or its Either way the design provides.
  • a computer program product comprising computer instructions, which, when the computer instructions are executed on a computer, cause the computer to perform the method provided by any one of the first aspect to the fourth aspect.
  • a twelfth aspect provides a chip, including: a processing circuit and a transceiver pin, where the processing circuit and the transceiver pin are used to implement the method provided by the first aspect to the fourth aspect or any design thereof.
  • the processing circuit is used for executing the processing actions in the corresponding method
  • the transceiver pins are used for executing the actions of receiving/transmitting in the corresponding method.
  • a thirteenth aspect provides a communication system, comprising: the communication device provided by the fifth aspect or any design thereof, and the communication device provided by the sixth aspect or any design thereof.
  • a fourteenth aspect provides a communication system, comprising: the communication device provided by the seventh aspect or any design thereof, and the communication device provided by the eighth aspect or any design thereof.
  • FIG. 1 is a schematic diagram of an MBS service data transmission process according to an embodiment of the present application
  • FIG. 2(a) is a schematic diagram of an air interface protocol stack provided by an embodiment of the present application.
  • 2(b) is a schematic diagram of transmission of MBS service data through an air interface protocol stack according to an embodiment of the present application
  • FIG. 3 is a schematic diagram of a sending window and a receiving window provided by an embodiment of the present application.
  • FIG. 4 is a schematic diagram of the architecture of a 5G communication system provided by an embodiment of the present application.
  • FIG. 5 is a schematic diagram of a CU-DU architecture provided by an embodiment of the present application.
  • FIG. 6 is a schematic diagram of still another CU-DU architecture provided by an embodiment of the present application.
  • FIG. 7 is a schematic diagram of another CU-DU architecture provided by an embodiment of the present application.
  • FIG. 8 is a schematic structural diagram of a protocol stack of an access network device according to an embodiment of the present application.
  • FIG. 9 is a flowchart of a data transmission method provided by an embodiment of the present application.
  • FIG. 10(a) is a schematic structural diagram of a protocol stack of another access network device according to an embodiment of the present application.
  • FIG. 10(b) is a schematic structural diagram of a protocol stack of another access network device according to an embodiment of the present application.
  • FIG. 11(a) is a schematic diagram of the architecture of a protocol stack of a terminal device according to an embodiment of the present application.
  • FIG. 11(b) is a schematic diagram of transmission of MBS service data through an air interface protocol stack according to an embodiment of the present application
  • FIG. 13(a) is a schematic diagram of the architecture of a protocol stack of a terminal device according to an embodiment of the present application.
  • FIG. 13(b) is a schematic diagram of transmission of MBS service data through an air interface protocol stack according to an embodiment of the present application
  • 16 is a flowchart of another data transmission method provided by an embodiment of the present application.
  • 17 is a flowchart of another data transmission method provided by an embodiment of the present application.
  • FIG. 19 is a flowchart of another data transmission method provided by an embodiment of the present application.
  • 21 is a flowchart of another data transmission method provided by an embodiment of the present application.
  • FIG. 23 is a schematic structural diagram of a communication device according to an embodiment of the present application.
  • FIG. 24 is a schematic structural diagram of another communication apparatus provided by an embodiment of the present application.
  • indication may include direct indication and indirect indication, as well as explicit indication and implicit indication.
  • the information indicated by a certain piece of information is called information to be indicated, and in the specific implementation process, there are many ways to indicate the information to be indicated.
  • the information to be indicated may be directly indicated, wherein the information to be indicated itself or an index of the information to be indicated, etc.
  • the information to be indicated may also be indirectly indicated by indicating other information, wherein there is an association relationship between the other information and the information to be indicated.
  • only a part of the information to be indicated may be indicated, while other parts of the information to be indicated are known or agreed in advance.
  • the indication of specific information can also be implemented by means of the arrangement order of each information pre-agreed (for example, stipulated by the protocol), thereby reducing the indication overhead to a certain extent.
  • the technical solutions provided in the embodiments of the present application can be applied to various communication systems, for example, a long term evolution (LTE) communication system, a new radio (NR) communication system using 5G communication technology, a future evolution system or A variety of communication fusion systems and so on.
  • LTE long term evolution
  • NR new radio
  • the technical solutions provided in this application can be applied to various application scenarios, such as machine to machine (M2M), macro-micro communication, enhanced mobile broadband (eMBB), ultra-reliable and ultra-low latency Communication (ultra-reliable & low latency communication, uRLLC) and massive IoT communication (massive machine type communication, mMTC) and other scenarios.
  • M2M machine to machine
  • eMBB enhanced mobile broadband
  • uRLLC ultra-reliable and ultra-low latency Communication
  • massive IoT communication massive machine type communication
  • These scenarios may include, but are not limited to: a communication scenario between a terminal device and a terminal device, a communication scenario between a network device and a network device, a communication scenario between a network device and a terminal device, and the like.
  • the following description is given by taking an example of application in a communication scenario between a network device and a terminal device.
  • the access network device may be a base station or a base station controller for wireless communication.
  • the base station may include various types of base stations, such as a micro base station (also referred to as a small cell), a macro base station, a relay station, an access point, etc., which are not specifically limited in this embodiment of the present application.
  • the base station can be a global system for mobile communication (GSM), a base station (base transceiver station, BTS) in a code division multiple access (code division multiple access, CDMA), a broadband code division multiple access (WCDMA) in the base station (node B), long term evolution (long term evolution, LTE) in the evolved base station (evolutional node B, eNB or e-NodeB), Internet of things (internet of things, IoT) ) or an eNB in a narrow band-internet of things (NB-IoT), a gNB in a future 5G mobile communication network or a future evolved public land mobile network (PLMN), an embodiment of the present application There are no restrictions on this.
  • GSM global system for mobile communication
  • CDMA code division multiple access
  • WCDMA Wideband code division multiple access
  • WCDMA Wideband code division multiple access
  • LTE long term evolution
  • evolutional node B, eNB or e-NodeB Internet of things
  • the terminal device is a device with a wireless transceiver function.
  • Terminal equipment can be deployed on land, including indoor or outdoor, handheld or vehicle; can also be deployed on water (such as ships, etc.); can also be deployed in the air (such as aircraft, balloons and satellites, etc.).
  • the terminal equipment may be user equipment (user equipment, UE).
  • the UE includes a handheld device, a vehicle, an in-vehicle device, a wearable device or a computing device with a wireless communication function.
  • the UE may be a mobile phone, a tablet computer, or a computer with a wireless transceiver function.
  • the terminal device may also be a virtual reality (VR) terminal device, an augmented reality (AR) terminal device, a wireless terminal device in industrial control, a wireless terminal device in unmanned driving, and a wireless terminal in telemedicine. equipment, wireless terminal equipment in smart grid, wireless terminal equipment in smart city, wireless terminal equipment in smart home, etc.
  • the apparatus for implementing the function of the terminal device may be the terminal device, or may be an apparatus capable of supporting the terminal device to implement the function, such as a chip system.
  • the chip system may be composed of chips, or may include chips and other discrete devices.
  • the technical solutions provided by the embodiments of the present application are described by taking the device for realizing the function of the terminal device as the terminal device as an example.
  • the network architecture and service scenarios described in the embodiments of the present application are for the purpose of illustrating the technical solutions of the embodiments of the present application more clearly, and do not constitute limitations on the technical solutions provided by the embodiments of the present application.
  • the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.
  • Multicast broadcast service is a service for multiple terminal equipment (user equipment, UE), such as live broadcast service, public safety service, batch software update service, etc.
  • multicast is a specific form of multicast, so multicast may also be called multicast.
  • FIG. 1 shows the transmission process of MBS service data.
  • the data server sends the MBS service data to the core network, then the core network sends the MBS service data to the base station, and finally the base station sends the MBS service data to at least one UE receiving the MBS service.
  • the MBS service data is sent from the core network to the base station, there are two basic transmission modes.
  • One is the 5G core network (5G Core, 5GC) shared MBS service delivery method (5GC shared MBS traffic delivery method), and the other is the 5GC individual MBS service delivery method (5GC individual MBS traffic delivery method).
  • This paper takes the 5GC shared MBS service transmission mode as an example.
  • the MBS service data is transmitted through a common general packet radio service tunneling protocol (GTP)-user plane (user, U) channel between the core network and the base station. transport, and each MBS session uses one GTP-U channel.
  • GTP general packet radio service tunneling protocol
  • an MBS session includes one or more quality of service (quality of service, QoS) flows, and these QoS flows of an MBS are mapped to one or more MBS radio bearers (MBS radio bearers, MRB) over the air interface.
  • QoS quality of service
  • MBS radio bearers MRB
  • different MRBs have different QoS requirements or belong to different MBS sessions.
  • QoS flows of different MBS sessions cannot be mapped to the same MRB.
  • the base station supporting MBS when the MBS service data is sent from the base station to the UE, there are two transmission modes: the first is the PTM (point to multi-point, point-to-multipoint) transmission mode; the second is PTP (point to point, point to point) transmission method.
  • the PTM transmission mode may also be called a group scheduling mode or a multicast transmission mode.
  • the base station supporting MBS can support the above two transmission modes.
  • the PTM transmission mode refers to a transmission mode in which a certain service sends data to multiple terminal devices simultaneously through a network device.
  • a network device e.g, a base station.
  • PTM is mainly divided into two modes: Multicast Broadcast Single Frequency Network (MBSFN) mode and Single Cell Point to Multipoint (SC-PTM) mode .
  • MBSFN Multicast Broadcast Single Frequency Network
  • SC-PTM Single Cell Point to Multipoint
  • the MBSFN mode means that multiple mutually synchronized cells (belonging to different base stations) in the MBSFN area transmit the same information to multiple terminal devices at the same time, so as to improve the strength of the signal received by the terminal device and eliminate the interference between cells.
  • the SC-PTM mode means that the MBS service is transmitted only through one cell (eg, one base station), and one network device performs group scheduling on multiple terminal devices at the same time.
  • PTM in NR is similar to SC-PTM.
  • the sending device using the PTM transmission mode to send means: when the sending device sends the transport block (transport block, TB) corresponding to the protocol data unit (protocol data unit, PDU), the packet wireless network temporary identifier is used.
  • Group radio network temporary identifier G-RNTI
  • receiving by the receiving apparatus in the PTM transmission mode means that the receiving apparatus descrambles and receives the PDCCH and PDSCH according to the G-RNTI to obtain the PDU.
  • the PTP transmission mode refers to the transmission mode in which a certain service sends data to a terminal device through a network device.
  • a terminal device receives at the same time in the process of sending by a network device (eg, a base station).
  • the sending device using PTP transmission means that: when the sending device sends the TB corresponding to the PDU, the PDCCH and PDSCH are scrambled by using a cell network temporary identifier (C-RNTI) respectively.
  • C-RNTI cell network temporary identifier
  • receiving by the receiving apparatus in the PTP transmission mode means that the receiving apparatus descrambles and receives the PDCCH and PDSCH according to the C-RNTI to obtain the PDU.
  • Access network equipment and terminal equipment have a certain protocol stack structure for mutual communication.
  • Figure 2(a) shows a protocol stack structure of an access network device and a terminal device.
  • the protocol stack of the access network device or the terminal device may include a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, Radio link control (radio link control, RLC) layer, media access control (media Access Link control, MAC) and physical layer (physical layer, PHY) and so on.
  • SDAP service data adaptation protocol
  • PDCP packet data convergence protocol
  • RLC Radio link control
  • media access control media Access Link control
  • MAC physical layer
  • PHY physical layer
  • the physical layer is located at the lowest layer (ie, layer 1).
  • the MAC layer, the RLC layer, the PDCP layer, and the SDAP layer belong to the second layer (ie, layer 2).
  • the SDAP layer is responsible for the mapping of QoS flows to radio bearers.
  • the PDCP layer is responsible for functions such as data transmission, encryption, integrity protection, and header compression on the user plane and control plane.
  • the RLC layer is responsible for functions such as segment reassembly and automatic repeat request (ARQ); the MAC layer completes functions such as data scheduling and mapping between logical channels and transport channels.
  • the PHY layer is responsible for functions such as encoding and decoding, modulation, demodulation, and multi-antenna mapping.
  • the access network device and the terminal device will create an SDAP entity for each MBS session and a PDCP entity for each MRB.
  • Each PDCP entity may correspond to one or more RLC entities. It should be understood that each RLC entity corresponds to one logical channel.
  • the MBS service data first arrives at the SDAP layer of the access network device, and the SDAP layer delivers the MBS service data to the corresponding PDCP layer according to the mapping relationship between the QoS flow and the MRB determined by the access network device.
  • the MBS service data is sequentially delivered to the RLC layer and the MAC layer.
  • the RLC layer and the MAC layer After being processed by the RLC layer and the MAC layer, it is sent from the physical layer and transmitted to the terminal device through the air interface.
  • Each protocol layer of the terminal device sequentially processes the data packets according to the processing sequence opposite to that of the access network device, so as to receive the MBS service data.
  • MBS service data needs to be processed by each layer at each layer, and each layer has corresponding functional entities to perform corresponding functions, such as the PDCP entity of the PDCP layer, or the RLC entity of the RLC layer.
  • RLC entity transmission modes include the following three:
  • Transparent Mode The RLC entity does not perform any processing on the data, and only provides the pass through function of the data.
  • the RLC entity that adopts this transmission mode is called TM RLC entity, or TM entity for short.
  • Unacknowledged Mode The RLC entity provides all RLC functions except retransmission and re-segmentation. Even in the case of packet transmission errors, the RLC entity in this transmission mode does not retransmit function, can only provide an unreliable transmission service. An RLC entity that adopts this transmission mode is called a UM RLC entity, or UM entity for short.
  • AM Acknowledged Mode
  • the RLC entity provides all RLC functions, including the ARQ function, and the RLC entity provides a reliable transmission service through error detection and retransmission.
  • An RLC entity that adopts this transmission mode is called an AM RLC entity, or AM entity for short.
  • ARQ is one of the important functions of the RLC acknowledgment mode. ARQ can detect the lost PDU and request retransmission by checking the sequence number of the received PDU.
  • Stop-And-Wait (SAW) ARQ In stop-and-wait ARQ, after the data frame is sent, the sender waits for a status report from the receiver, and if the status report message is successfully sent, the subsequent data is sent frame, otherwise retransmit the data frame.
  • SAW Stop-And-Wait
  • the size of the sending window and the receiving window are both 1.
  • the sender must stop and wait for the acknowledgement from the receiver after sending a frame, and only continue to send the next frame when the receiver confirms the correct reception.
  • the RLC acknowledgement mode in NR is similar to that in LTE, but reordering to ensure in-order delivery is not supported in NR. Removing in-order delivery from RLC helps reduce overall latency because subsequent packets can be forwarded immediately without having to wait for previously lost packets to be retransmitted to higher layers. This also has positive implications for reducing the memory requirements of the buffer.
  • the RLC protocol in LTE supports in-order delivery, and an RLC SDU cannot be forwarded to the upper layer until all previous SDUs have been received correctly. For example, because an SDU is lost due to an instantaneous interference burst, the SDU can only be delivered after a long period of blocking.
  • the RLC entity in acknowledged mode is bidirectional, i.e. data can flow bidirectionally between two peer entities.
  • the entity receiving the SDU needs to feed back an acknowledgment to the entity sending the SDU.
  • the receiver provides the information of the missing SDU to the sender in the form of a status report.
  • the status report can be sent by the receiver actively or requested by the sender.
  • the sequence number is used in the header.
  • the RLC entity maintains two windows, namely the sending window and the receiving window.
  • the sender only the SDUs located in the sending window are allowed to be sent, and the SDUs whose sequence numbers are smaller than the starting point of the window are SDUs that have been confirmed by the RLC entity of the receiver to be successfully received.
  • the receiving end can only receive SDUs whose sequence numbers are within the receiving window. Since the receiving end only needs to submit one SDU to the upper layer for the same data, the receiving end will also discard the duplicate SDU.
  • the sending window and the receiving window are described below with reference to FIG. 3 . It should be understood that only the receiving window of the RLC entity of the receiving end is shown in FIG. 3 , and the sending window is not shown. Only the sending port of the RLC entity of the sending end is shown in FIG. 3, and the receiving window is not shown.
  • the sender has sent SDUs with sequence numbers n and before n, wherein the SDUs before n-1 and n-1 have been acknowledged by the receiver. Therefore, the sending window of the sender starts from n, the first unacknowledged SDU. The receiving window of the receiving end starts from n+1, that is, the next SDU expected to be received.
  • SDU X in this embodiment of the present application represents an SDU with a serial number of X, where X is any positive integer or 0.
  • the receiving end can update the starting point of the receiving window, so that the starting point of the receiving end's receiving window starts from n+3.
  • a communication system generally includes a core network and an access network.
  • FIG. 4 shows a schematic diagram of the architecture of a 5G communication system provided by an embodiment of the present application.
  • the 5G communication system includes a next generation radio access network (NG-RAN) and a 5G core network (5G core network, 5GC).
  • NG-RAN next generation radio access network
  • 5G core network 5G core network
  • 5GC includes various core network equipment, such as access and mobility management function (AMF), user plane function (UPF), session management function (session management function, SMF) etc.
  • AMF access and mobility management function
  • UPF user plane function
  • SMF session management function
  • AMF belongs to the core network entity and is mainly responsible for the mobility management processing part, such as: access control, mobility management, attachment and detachment, and SMF selection and other functions.
  • the AMF provides services for a session in a terminal device, it provides storage resources of the control plane for the session to store the session ID, the SMF ID associated with the session ID, and the like.
  • SMF is mainly used for session management, Internet Protocol (IP) address allocation and management of terminal devices, selection of endpoints that can manage user plane functions, policy control, or charging function interfaces, and downlink data notification.
  • IP Internet Protocol
  • UPF can be used for packet routing and forwarding, or QoS processing of user plane data.
  • User data can be accessed to a data network (DN) through this network element.
  • DN data network
  • AMF, SMF and UPF are only a name, and do not constitute a limitation on the device itself. It can be understood that, in a 5G network and other future networks, AMF, SMF, and UPF may also be other names, which are not specifically limited in this embodiment of the present application.
  • the UPF may also be referred to as a UPF network element or a UPF entity, which will be uniformly described here, and will not be repeated below.
  • the core network device may be implemented by one device, or jointly implemented by multiple devices, or may be a functional module in one device, which is not specifically limited in this embodiment of the present application.
  • the above-mentioned functional modules may be network elements in hardware devices, software functional modules running on dedicated hardware, or virtualized functional modules instantiated on a platform (eg, a cloud platform).
  • the access network includes access network equipment.
  • the access network device in a communication system, there is an interface between two gNBs, which is called an Xn interface in this paper.
  • the NG2 interface is between the gNB and the AMF
  • the NG3 interface is between the gNB and the UPF.
  • CU Centralized unit
  • DU distributed unit
  • the gNB can adopt the CU-DU architecture. That is, the gNB is composed of a CU and at least one DU. In this case, some functions of the gNB are deployed on the CU, and another part of the functions of the gNB are deployed on the DU. Multiple DUs can share the same CU for cost savings and easy expansion.
  • the CU and DU are functionally divided according to the protocol stack.
  • the CU is deployed with a radio resource control (RRC) layer, a PDCP layer, and a service data adaptation protocol (SDAP) layer in the protocol stack; DU is deployed with the protocol stack.
  • RRC radio resource control
  • SDAP service data adaptation protocol
  • RLC layer media access control (media access control, MAC) layer
  • physical layer physical layer, PHY.
  • the CU has the processing capabilities of RRC, PDCP and SDAP.
  • DU has the processing capability of RLC, MAC and PHY. It can be understood that the division of the above functions is only an example, and does not constitute a limitation on the CU and the DU. That is to say, there may also be other functional division manners between the CU and the DU, which are not described in detail in this embodiment of the present application.
  • the CU and DU are connected through the F1 interface.
  • the CU represents the gNB is connected to the core network through the NG interface
  • the CU represents the gNB is connected to other gNBs through the Xn interface
  • the CU can also represent the gNB to connect to other eNBs through the X2 interface to perform dual connectivity operations.
  • the above interfaces are all logical interfaces. In a 5G network and other future networks, the above interface may also have other names, which are not limited in this embodiment of the present application.
  • the CU can also be divided into CU-CP and CU-UP.
  • the CU-CP is responsible for the control plane function, mainly including the RRC and the PDCP (ie PDCP-C) corresponding to the control plane.
  • PDCP-C is mainly responsible for encryption and decryption of control plane data, integrity protection, and data transmission.
  • the CU-UP is responsible for the user plane function, mainly including SDAP and the PDCP (ie PDCP-U) corresponding to the user plane.
  • SDAP is mainly responsible for processing the data of the core network and mapping the flow to the bearer.
  • PDCP-U is mainly responsible for data plane encryption and decryption, integrity protection, header compression, serial number maintenance, data transmission, etc.
  • PDCP-C is also in CU-UP.
  • the CU-CP and CU-UP are connected through the E1 interface.
  • CU-CP represents that the gNB is connected to the core network through the NG interface.
  • the F1-C is connected to the DU through the F1 interface control plane.
  • the CU-UP is connected through the F1 interface user plane, namely the F1-U and the DU.
  • one DU can be connected to one or more CU-UPs.
  • One CU-UP can connect one or more DUs.
  • a DU can only be connected to one CU-CP.
  • One CU-CP can connect one or more DUs. Only one CU-CP can be connected to a CU-UP.
  • One CU-CP can be connected to one or more CU-UPs.
  • FIG. 8 is a schematic structural diagram of a protocol stack of an access network device according to an embodiment of the present application. It can be understood that the access network device may be other communication devices, which is not limited in this application.
  • the access network device is configured with a PDCP entity, a first RLC entity and a second RLC entity.
  • the first RLC entity and the second RLC entity are associated with the PDCP entity, and the first RLC entity and the second RLC entity are associated with related MRBs.
  • the first RLC entity is used to support the PTM transmission mode to send MBS service data. That is, the first RLC entity is used to send MBS service data to at least one terminal device.
  • the second RLC entity is used to support the PTP transmission mode to send MBS service data. That is, the second RLC entity is used to send MBS service data to a terminal device (the first terminal device is taken as an example below). It should be understood that, for one MRB, there may be one or more second RLC entities on the device side of the access network. Each second RLC entity corresponds to one terminal device.
  • the first RLC entity may be referred to as an mRLC entity
  • the second RLC entity may be referred to as a pRLC entity.
  • the access network device may have other protocol layers not shown in FIG. 8 , such as SDAP layer, MAC layer, physical layer, etc., which are not limited.
  • the access network device can flexibly switch to use the PTP transmission mode or the PTM transmission mode to adapt to different application scenarios and obtain better transmission Effect.
  • an RLC entity supporting AM mode may request to retransmit the unsuccessfully transmitted data if it is determined that a piece of data has not been successfully transmitted.
  • the access network device using the architecture shown in FIG. 8 adopts the PTM transmission mode
  • the first RLC entity in the access network device does not support the AM mode
  • the above ARQ cannot obtain retransmission data from the PDCP layer. That is, for the scenario in which the access network equipment adopts the PTM transmission mode to transmit the MBS service data, the above ARQ technology cannot be directly applied, so that the highly reliable transmission of the MBS service data cannot be guaranteed.
  • This paper mainly considers how the first RLC entity and the second RLC entity on the access network device side interact to realize the RLC ARQ function.
  • an embodiment of the present application provides a data transmission method, which can be applied to an access network device using the architecture shown in FIG. 8 .
  • the data transmission method includes the following steps:
  • the first RLC entity sends at least one RLC SDU to at least one terminal device including the first terminal device.
  • At least one RLC SDU belongs to MBS service data.
  • the PDCP entity delivers at least one PDCP PDU (that is, an RLC SDU) to the first RLC entity.
  • the first RLC entity sends at least one RLC SDU to at least one terminal device in a PTM transmission manner.
  • sending the RLC SDU to the at least one terminal device by the first RLC entity may be specifically implemented as: the first RLC entity adds an RLC header to the RLC SDU to generate an RLC PDU; the first RLC entity sends the RLC PDU to the at least one terminal device.
  • the working mode adopted by the first RLC entity is hereinafter referred to as an improved UM mode.
  • the first RLC entity that adopts the improved UM mode may assign an RLC SN to each RLC SDU in sequence.
  • the first RLC entity may set a discard timer (discard timer) for each RLC SDU. Therefore, after the discard timer corresponding to the RLC SDU times out, the first RLC entity discards the RLC SDU.
  • a discard timer discard timer
  • the first RLC entity discards the RLC SDU after confirming that an RLC SDU is successfully transmitted through a mechanism such as an RLC status report, or after receiving a discarding instruction for the RLC SDU from the PDCP entity.
  • the second RLC entity receives the first information from the first terminal device.
  • the first information is used to indicate the reception status of at least one RLC SDU. That is, the first information is used to indicate whether each RLC SDU in the at least one RLC SDU is successfully received.
  • the first information may carry the RLC SN of each successfully received RLC SDU, or only carry the RLC SN of the unsuccessfully received RLC SDU, or other methods, which are not limited in the embodiments of the present application.
  • the first RLC entity After the first RLC entity receives the first information (for example, RLC Status Report), for the "RLC SDUs that have been successfully received by the UE and whose RLC SN is x" indicated by the first information, there is no need to indicate "transmission success" to the PDCP layer.
  • the underlined part is the standard modification content:
  • the transmitting side of an AM RLC entity shall:
  • the AM RLC entity at the receiving end shall:
  • the RLC entity shall indicate to the upper layer that the RLC SDU has been successfully transmitted, set the TX_Next_Ack to the SN of the RLC SDU with the smallest SN whose SN is between TX_Next_Ack and not yet received Acknowledgment between TX_Next of acknowledgment.
  • the second RLC entity may adopt the AM mode.
  • the first information is used to indicate the RLC SN of the first RLC SDU, and the first RLC SDU belongs to an RLC SDU that has not been successfully received in the above at least one RLC SDU.
  • the first information is used to indicate the RLC SN of the first RLC SDU, and any one of the following designs may be adopted:
  • the first information includes the RLC SN of the first RLC SDU.
  • the first information includes the packet loss start RLC SN and the packet loss end RLC SN in the RLC SN set.
  • the RLC SN set includes the RLC SNs of a plurality of consecutively unsuccessfully received RLC SDUs. It should be understood that the plurality of unsuccessfully received RLC SDUs belong to the above at least one RLC SDU.
  • the first RLC SDU is any one of the multiple unsuccessfully received RLC SDUs.
  • the first RLC entity sends RLC SDUs of RLC SN#1-10.
  • the first terminal device none of the RLC SDUs with RLC SNs 5, 6, 7, and 8 are successfully received. Therefore, the RLC SN at the start of the packet loss is RLC SN#5, and the RLC SN at the end of the packet loss is RLC SN#8.
  • the first information may include RLC SN#5 and RLC SN#8.
  • the second RLC entity may determine the RLC SN of the first RLC SDU according to the first information.
  • the second RLC entity may not indicate to the PDCP layer that the RLC SDU is successfully transmitted. where X is a positive integer.
  • the first entity retransmits the first RLC SDU to the first terminal device.
  • the first entity may be the first RLC entity or the second RLC entity.
  • the first entity sends the first RLC SDU to the terminal device, which means that the first entity retransmits the first RLC SDU to the first terminal device.
  • An RLC SDU is to retransmit the first RLC SDU sent by the first RLC entity, in other words, the content of the first RLC SDU retransmitted by the first entity is exactly the same as the first RLC SDU sent by the first entity before.
  • the receiving network device may buffer a backup of the first RLC SDU in a buffer when the first RLC entity sends the first RLC SDU, and when the first entity needs to send (retransmit) the first RLC SDU , and then obtain the first RLC SDU of the backup from the buffer.
  • the embodiments of the present application do not impose any limitations on the above-mentioned backup method and acquisition method from the cache.
  • the second RLC entity obtains the first RLC SDU, and any one of the following methods 1 to 4 can be used:
  • Mode 1 The second RLC entity obtains the first RLC SDU from its own buffer area.
  • the PDCP entity will copy the at least one RLC SDU into multiple copies and submit them to the first RLC entity and the second RLC SDU respectively.
  • RLC entity After acquiring the above at least one RLC SDU, the first RLC entity transmits the at least one RLC SDU according to step S101.
  • the PDCP entity instructs the second RLC entity to buffer the at least one RLC SDU to prevent the second RLC entity from initially transmitting the at least one RLC SDU.
  • the second RLC SDU can find the first RLC SDU from its own buffer area according to the RLC SN of the first RLC SDU.
  • the second RLC entity when the second RLC entity receives the PDCP PDU (that is, the RLC SDU) sent by the PDCP for the first time, it is stored in its own buffer area and not sent. Only after receiving the first information fed back by the terminal device, the second RLC entity acquires the first RLC SDU and retransmits the first RLC SDU to the first terminal device.
  • the PDCP PDU that is, the RLC SDU
  • the second RLC entity Only after receiving the first information fed back by the terminal device, the second RLC entity acquires the first RLC SDU and retransmits the first RLC SDU to the first terminal device.
  • the second RLC entity obtains the first RLC SDU from the shared buffer area.
  • the shared buffer area is a buffer area that can be used by both the first RLC entity and the second RLC entity.
  • the first RLC entity will buffer the at least one RLC SDU in the shared buffer area.
  • the second RLC SDU can find the first RLC SDU from the shared buffer area according to the RLC SN of the first RLC SDU.
  • the second RLC entity may not initially transmit the data stored in the shared buffer area according to its own configuration or an instruction of the PDCP entity.
  • Manner 3 The second RLC entity obtains the first RLC SDU from the first RLC entity.
  • the second RLC entity submits second information to the first RLC entity, where the second information is used to indicate the first RLC SDU.
  • the first RLC entity obtains the first RLC SDU according to the second information.
  • the first RLC entity submits the first RLC SDU to the second RLC entity.
  • the second RLC entity obtains the first RLC SDU from the PDCP entity.
  • the second RLC entity submits second information to the PDCP entity, where the second information is used to indicate the first RLC SDU.
  • the PDCP entity submits the first PDCP PDU (ie, the first RLC SDU) to the second RLC entity according to the second information.
  • PDCP PDU and RLC SDU are different names for the same data by different protocol layers.
  • the first RLC entity Before retransmitting the first RLC SDU, the first RLC entity obtains the first RLC SDU, and any one of the following manners 5 to 6 may be used:
  • the first RLC entity obtains the first RLC SN.
  • the second RLC entity submits second information to the first RLC entity, where the second information is used to indicate the first RLC SN.
  • the first RLC acquires the first RLC SDU according to the second information.
  • the first RLC entity obtains the first RLC SN from the PDCP entity.
  • the second RLC entity submits second information to the PDCP entity, where the second information is used to indicate the first RLC SDU.
  • the PDCP entity submits the first PDCP PDU (ie, the first RLC SDU) to the first RLC entity according to the second information.
  • mode 5 or mode 6 is only an example, and does not constitute a specific limitation.
  • the second information may include the RLC SN of the first RLC SDU.
  • the second information may include the RLC SN of the first RLC SDU.
  • the second information may include the PDCP SN of the first PDCP PDU.
  • the second RLC entity may determine the PDCP SN of the first PDCP PDU according to the RLC SN of the first RLC SDU and the first preset mapping relationship.
  • the first preset mapping relationship is used to indicate the mapping relationship between the PDCP SN and the RLC SN.
  • the second RLC entity may encapsulate the PDCP SN of the PDCP PDU corresponding to the first RLC SDU in the second information.
  • the PDCP entity submits the first RLC SDU to the first entity according to the second information, which may be specifically implemented as: the PDCP entity submits the first RLC SDU according to the RLC SN of the first RLC SDU. , and the first preset mapping relationship to determine the PDCP SN of the first PDCP PDU corresponding to the first RLC SDU. After that, the PDCP entity obtains the first PDCP PDU according to the PDCP SN of the first PDCP PDU; the PDCP entity submits the first PDCP PDU (ie, the first RLC SDU) to the first entity.
  • the second information includes the RLC SN of the first RLC SDU
  • the PDCP entity submits the first RLC SDU to the first entity according to the second information, which may be specifically implemented as: the PDCP entity submits the first RLC SDU according to the RLC SN of the first RLC SDU. , and the first preset mapping relationship to determine the PDCP SN of the
  • the PDCP entity submits the first RLC SDU to the first entity according to the second information, which may be specifically implemented as: the PDCP entity according to the PDCP SN of the first PDCP PDU , obtain the first PDCP PDU; the PDCP entity submits the first PDCP PDU (ie, the first RLC SDU) to the first entity.
  • the second information may be specifically implemented as: the PDCP entity according to the PDCP SN of the first PDCP PDU , obtain the first PDCP PDU; the PDCP entity submits the first PDCP PDU (ie, the first RLC SDU) to the first entity.
  • the first preset mapping relationship may be agreed in a protocol, or configured by a core network (or a network management) to an access network device.
  • the size (size) of the RLC SN should be less than or equal to the size of the PDCP SN to ensure that a PDCP SN can only derive a unique RLC SN.
  • the above size may also be referred to as the length, that is, the number of bits occupied by the sequence number.
  • max RLC SN represents the maximum value that RLC SN can take.
  • the first RLC entity and the second RLC entity perform the same RLC SN number on the PDCP PDU with the same content and submitted by the PDCP entity according to the first preset mapping relationship, thereby ensuring that the first RLC entity and the second RLC entity have the same RLC SN number.
  • the RLC entity can obtain the same RLC SDU according to the same RLC SN, thereby ensuring accurate retransmission of the RLC SDU.
  • the RLC SN size in this embodiment of the present application is Support 12bit.
  • the size of the RLC SN in the embodiments of the present application is not fixed. In the case where the size of the RLC SN in AM mode and/or UM mode is changed in the protocol, or the size of the PDCP SN is changed, the size of the RLC SN in this embodiment of the present application can also be changed.
  • the first RLC entity may decide to adopt the multicast PTM method according to the preset retransmission rule.
  • the unicast PTP method is used to retransmit the data.
  • the first RLC entity decides to retransmit data in a multicast PTM manner, that is, the first RLC entity (or PDCP entity) decides to retransmit data by the first RLC entity.
  • the first RLC entity decides to use the unicast PTP mode to retransmit data, that is, the first RLC entity (or PDCP entity) decides to use the second RLC entity to retransmit data.
  • the retransmission rule may be: if the first RLC entity (or PDCP entity) receives more than a preset number of second information within a preset time period, the first RLC entity (or PDCP entity) decides that the first The RLC entity retransmits the first RLC SDU; otherwise, the first RLC entity (or the PDCP entity) decides to retransmit the first RLC SDU by the second RLC entity.
  • the retransmission rule may be: the first RLC entity (or PDCP entity) receives more than a preset number of information for triggering retransmission of data within a preset time period, then the first RLC entity (or PDCP entity) ) decides to retransmit the data by the first RLC entity; otherwise, the first RLC entity (or PDCP entity) decides to retransmit the data by the second RLC entity.
  • the retransmitted data may be the RLC SDU sent by the first RLC entity in the previous period of time.
  • the information for triggering data retransmission submitted by the second RLC entity corresponding to different terminal devices to the first RLC entity or the PDCP entity may indicate that different RLC SDUs are not successfully received.
  • the access network device transmits the MBS service data in the PTM manner through the first RLC entity, and obtains the receiving state of the terminal device for the MBS service data through the second RLC entity. Further, the access network device may determine the MBS service data that needs to be retransmitted, and retransmit the MBS service data through the first RLC entity or the second RLC entity. It can be seen that the technical solution provided by the present application can make the ARQ mechanism applied to the PTM transmission mode, and ensure the highly reliable transmission of MBS service data.
  • the access network device may send a MAC CE to the terminal device to instruct the terminal device to switch between the PTM transmission mode and the PTP transmission mode.
  • the access network device may send the MAC CE for activating the PTM to at least one terminal device.
  • the terminal device monitors the PDCCH and PDSCH scrambled by the G-RNTI, and performs corresponding steps according to the method shown in FIG. 9 .
  • the access network device may send a MAC CE for deactivating the PTM to one or more terminals.
  • the terminal device stops monitoring the PDCCH and PDSCH scrambled by the G-RNTI, uses the PTP mode to monitor the PDCCH and PDSCH scrambled by the C-RNTI, and transmits the corresponding MBS service data. with retransmission.
  • the access network device can use C-RNTI to scramble and schedule the PDCCH and PDSCH corresponding to the MAC CE.
  • the access network device may use G-RNTI to scramble and schedule the PDCCH and PDSCH of the MAC CE.
  • the protocol stack architecture shown in FIG. 8 may be specifically implemented as the protocol stack architecture shown in FIG. 10(a) or FIG. 10(b).
  • the gNB-CU is configured with a PDCP entity
  • the gNB-DU is configured with a first RLC entity and a second RLC entity.
  • the first RLC entity and the second RLC entity use the same F1-U tunnel to communicate with the PDCP entity, that is, the first RLC entity and at least one second RLC entity share the F1-U tunnel. That is, the F1-U tunnel corresponds to the MBS service/MRB, the MBS service/MRB corresponds to the PDCP entity, the first RLC entity and the second RLC entity, so the F1-U tunnel corresponds to the first RLC entity.
  • the gNB-DU can deliver the data packet to the second RLC entity corresponding to the terminal device according to the F1-U UE identifier of the terminal device carried in the F1-U header of the data packet. If the F1-U header does not carry any identification of the terminal device, the gNB-DU delivers the data packet to the first RLC entity corresponding to the F1-U tunnel.
  • the gNB-CU is configured with a PDCP entity
  • the gNB-DU is configured with a first RLC entity and a second RLC entity.
  • the first RLC entity and the second RLC entity use different F1-U tunnels respectively to communicate with the PDCP entity. That is, the first RLC entity and each second RLC entity correspond to respective F1-U tunnels, and the first RLC entity or the second RLC entity associated with the terminal device can be determined according to the F1-U tunnel.
  • the method for example, the data transmission method shown in FIG. 9
  • the method in the embodiments of the present application applicable to the access network device using the architecture shown in FIG. 8 is also applicable to the method using FIG. 10( a ) or FIG. 10( b ) Access network equipment of the architecture shown.
  • the access network device adopts the CU-DU architecture
  • the PDCP entity of the gNB-CU-UP submits the PDCP PDU to the first RLC entity and/or the second RLC entity in the gNB-DU
  • the gNB - The CU-UP uses the PDCP SN contained in the PDCP PDU carried in the GTP-U message of the F1-U tunnel to indicate to the first RLC entity and/or the second RLC entity the PDCP of the PDCP PDU transmitted by the F1-U tunnel SN. Therefore, the first RLC entity and/or the second RLC entity in the gNB-DU can map data of the same content (same PDCP SN) to the same RLC SN according to the PDCP SN and the first preset mapping relationship.
  • the CU when configuring the logical channel corresponding to the MRB, can indicate to the DU the type of each radio bearer or logical channel on the DU side through the F1-C tunnel, so as to determine whether the data in the radio bearer or logical channel adopts the PTP mode. Or PTM mode for transmission.
  • the CU when configuring the logical channel corresponding to the MRB, the CU indicates to the DU the binding relationship between the logical channel on the DU side and the RNTI. For example, if a logical channel is bound to a C-RNTI, the PDSCH or PDCCH corresponding to the data of the logical channel is scrambled by the C-RNTI and sent in a unicast manner. For another example, if a certain logical channel is bound with G-RNTI, the PDSCH or PDCCH corresponding to the data of the logical channel is scrambled by G-RNTI, and sent by multicast or broadcast.
  • the CU determines the PTP/PTM type corresponding to each radio bearer or logical channel.
  • the CU may include in the F1AP message (eg UE context setup/modification request) the MRB ID/data radio bearer (DRB) identity (identity, ID)/logical channel identity (LCID) and the corresponding PTP/PTM indication.
  • DRB/DRB ID#1 corresponds to PTP or C-RNTI
  • MRB/DRB ID#2 corresponds to PTM or G-RNTI
  • LCID#1 corresponds to PTP or C-RNTI
  • LCID#2 corresponds to PTM or G-RNTI.
  • the CU determines the PTP/PTM type corresponding to each radio bearer, and the DU determines the PTP/PTM type corresponding to each logical channel based on this.
  • the CU may include the MRB/DRB ID and the corresponding PTP/PTM indication in the F1AP message.
  • MRB/DRB ID#1 corresponds to PTP+PTM mode or C-RNTI+G-RNTI mode
  • MRB/DRB ID#2 corresponds to PTP or C-RNTI mode
  • DU can be configured with associated MRB/DRB ID#1
  • Two LCIDs for example, LCID#1 corresponds to PTP or C-RNTI, and LCID#2 corresponds to PTM or G-RNTI.
  • LCID#2 corresponds to PTP or C-RNTI. That is, for the PTP mode, the subsequent PDCCH and PDSCH are scrambled and descrambled with the C-RNTI. For the PTM method, the subsequent PDCCH and PDSCH are scrambled and descrambled with G-RNTI.
  • the PTP/PTM type can define a PTP/PTM type information element, and the value of the information element can be ⁇ 0, 1, 2 ⁇ , for example, 0 corresponds to the PTP mode or C-RNTI mode, and 1 corresponds to the PTM mode or G-RNTI mode Mode, 2 corresponds to PTP+PTM or C-RNTI+G-RNTI mode. Other similar representation methods are not repeated here.
  • the following describes the data transmission method provided by the embodiments of the present application from the perspective of a terminal device.
  • FIG. 11( a ) shows a schematic diagram of the architecture of a protocol stack of a terminal device.
  • the terminal device may be other communication devices, which is not limited in this application.
  • the terminal device may configure the third RLC entity and the fourth RLC entity.
  • the third RLC entity and the fourth RLC entity are associated with the same MRB.
  • the third RLC entity is used for receiving MBS service data sent by the access network device in a PTM manner.
  • the fourth RLC entity is configured to receive MBS service data sent by the access network device in a PTP manner.
  • the terminal device is further configured with a PDCP entity.
  • the third RLC entity and the fourth RLC entity are respectively associated with the PDCP entity.
  • the PDCP entity corresponds to one MBS service or MRB, and correspondingly, the third RLC entity and the fourth RLC entity correspond to one MBS service or MRB.
  • the third RLC entity uses the For communicating with the first RLC entity of the access network device
  • the fourth RLC entity is used for communicating with the second RLC entity corresponding to the terminal device on the access network device side.
  • a data transmission method provided by an embodiment of the present application is applied to the first terminal device adopting the architecture shown in FIG. 11( a ).
  • the method includes the following steps:
  • a third RLC entity receives at least one RLC SDU from an access network device.
  • step S201 may be specifically implemented as: the third RLC entity receives at least one RLC SDU from the first RLC entity of the access network device.
  • the working mode adopted by the third RLC entity is referred to as an improved UM mode or an improved AM mode below.
  • the third RLC entity that adopts the improved UM mode will feed back the reception status of the RLC SDU to the fourth RLC entity.
  • the third RLC entity may submit third information to the fourth RLC entity, where the third information is used to indicate the RLC SN of the first RLC SDU.
  • the third RLC entity submits the third information to the fourth RLC entity.
  • the fourth RLC entity obtains the third information from the third RLC entity.
  • the third information is used to indicate the RLC SN of the first RLC SDU.
  • the third RLC entity may generate the third information in the following implementation manner.
  • the third RLC entity determines that the first RLC SDU is not successfully received.
  • the third RLC entity generates third information according to the RLC SN of the first RLC SDU.
  • the third information may include the RLC SN of the first RLC SDU.
  • the third RLC entity maintains the receiving window according to the RLC SN (similar to the UM window pulling mechanism). Based on the receive window, the third RLC entity may acknowledge unsuccessfully received RLC SDUs (eg, the first RLC SDU).
  • the fourth RLC entity may not need to maintain the receiving window.
  • Implementation mode 2 The third RLC entity determines that the second RLC SDU in the at least one RLC SDU is successfully received.
  • the third RLC entity generates third information according to the RLC SN of the second RLC SDU.
  • the third information may include the RLC SN of the second RLC SDU.
  • the third RLC entity may not need to maintain the receiving window, that is, the third RLC entity may not need to confirm the unsuccessfully received RLC SDUs.
  • the third RLC entity submits the third information to the fourth RLC entity, so that the fourth RLC entity knows each RLC SDU successfully received by the third RLC entity.
  • the fourth RLC entity needs to maintain the receive window according to the RLC SN (similar to the AM window push mechanism).
  • the fourth RLC entity may determine the RLC SN of the unsuccessfully received RLC SDU (eg, the first RLC SDU) according to the third information.
  • the first terminal device receives an RRC reconfiguration message sent by the access network device, where the RRC reconfiguration message includes MRB configuration information.
  • the two logical channels (logical channel, LCH) configured in the MRB configuration information are associated with the same DRB or MRB, and one of the LCHs is associated with an MBS session, the first terminal device can determine that the DRB/MRB is actually an MRB .
  • the RRC module of the first terminal device determines that the fourth RLC entity configured by the MRB configuration information is in the AM mode, the RRC module will notify the third RLC entity to send the fourth RLC entity to the fourth RLC entity according to implementation 1 or implementation 2 subsequently.
  • Three information are associated with the same DRB or MRB, and one of the LCHs is associated with an MBS session.
  • the fourth RLC entity acquires the first information according to the third information.
  • the first information is used to indicate the RLC SN of the first RLC SDU.
  • the fourth RLC entity may determine the RLC SN of the first RLC SDU according to the third information, and then generate the first information.
  • the fourth RLC entity may directly use the third information as the first information.
  • the fourth RLC entity determines the RLC SN of the second RLC SDU according to the third information. After that, the fourth RLC entity determines the RLC SN of the first RLC SDU according to the RLC SN of the second RLC SDU. The fourth RLC entity generates the first information according to the RLC SN of the first RLC SDU.
  • the first information reference may be made to the content in the foregoing embodiment, which is not repeated here.
  • the fourth RLC entity sends the first information to the access network device.
  • step S204 may be specifically implemented as: the fourth RLC entity sends the first information to the second RLC entity of the access network device.
  • the fourth RLC entity may set a corresponding timer for the RLC SDU to be retransmitted. Before the timer expires, if the first terminal device receives the RLC SDU, the timer is cleared. Or, when the timer expires, if the first terminal device has not received the RLC SDU, the fourth RLC entity may trigger the access network device to retransmit the RLC SDU again, for example, the fourth RLC entity may send the first RLC SDU again information.
  • the fourth RLC entity may set the maximum number of retransmissions for the RLC SDU to be retransmitted. After the number of triggered retransmissions is greater than the maximum number of retransmissions, the fourth RLC entity may notify a higher layer (eg, the RRC layer) that a radio link failure occurs.
  • a higher layer eg, the RRC layer
  • the first RLC entity of the access network device may retransmit the first RLC SDU.
  • the third RLC entity of the first terminal device receives the retransmitted first RLC SDU from the first RLC entity of the access network device.
  • the third RLC entity may indicate to the fourth RLC entity that the first RLC SDU is successfully received.
  • the fourth RLC entity learns that the first RLC SDU is successfully received, it can clear the timer corresponding to the first RLC SDU, or push the receiving window, or delete the RLC SN of the first RLC SDU, so as not to trigger the The access network device sends the first information.
  • the second RLC entity of the access network device may retransmit the first RLC SDU.
  • the fourth RLC entity of the first terminal device receives the retransmitted first RLC SDU from the second RLC entity of the access network device.
  • the fourth RLC entity can clear the corresponding data of the first RLC SDU. timer, or push the receiving window, or delete the RLC SN of the first RLC SDU, so as not to trigger the transmission of the first information to the access network device again.
  • the first terminal device receives, through the third RLC entity, the MBS service data transmitted by the access network device in the PTM manner; the third RLC entity triggers the third RLC entity by sending third information to the fourth RLC entity.
  • the fourth RLC entity sends the first information to the access network device, so that the access network device knows that the first RLC SDU has not been successfully received.
  • FIG. 13(a) shows a schematic diagram of the architecture of a protocol stack of another terminal device.
  • the terminal device may configure a PDCP entity and a fifth RLC entity, the fifth RLC entity is associated with the PDCP entity of the terminal device, and the fifth RLC entity is associated with the MBS service or MRB. That is, the MRB service or MRB corresponds to the PDCP entity and the fifth RLC entity.
  • the fifth RLC entity is used to communicate with the access network equipment.
  • the first RLC entity of the network device communicates with the fifth RLC entity for communicating with the second RLC entity of the access network device.
  • the terminal device only configures one RLC entity to support the PTM transmission mode and the PTP transmission mode with the access network device, which is beneficial to simplify the RLC configuration of the terminal device.
  • a data transmission method provided by an embodiment of the present application is applied to the first terminal device adopting the architecture shown in FIG. 13( a ).
  • the method includes the following steps:
  • the fifth RLC entity receives at least one RLC SDU from the access network device.
  • step S301 may be specifically implemented as: the fifth RLC entity receives at least one RLC SDU from the first RLC entity of the access network device.
  • the fifth RLC entity generates first information.
  • the fifth RLC entity maintains the receiving window, and determines the RLC SN of the unsuccessfully received RLC SDU (for example, the first RLC SDU) according to the receiving window.
  • the fifth RLC entity may generate the first information according to the RLC SN of the unsuccessfully received RLC SDU.
  • the fifth RLC entity sends the first information to the access network device.
  • step S303 may be specifically implemented as: the fifth RLC entity sends the first information to the second RLC entity of the access network device.
  • the fifth RLC entity submits the first information to the lower layer (eg, the physical layer).
  • the bottom layer scrambles the first information by using the C-RNTI, and sends the scrambled first information to the access network device.
  • the bottom layer of the access network device After receiving the scrambled first information, the bottom layer of the access network device performs descrambling according to the C-RNTI used for scrambling the first information, and delivers the first information to the corresponding second RLC entity.
  • the first RLC entity or the second RLC entity of the access network device may retransmit the first RLC. SDU.
  • the fifth RLC entity of the first terminal device may receive the retransmitted first RLC SDU from the first RLC entity or the second RLC entity of the access network device.
  • the fifth RLC entity of the first terminal device receives the MBS service data transmitted by the access network device in the PTM manner, and the fifth RLC entity may send the first information to the access network device to The access network device is made aware that the first RLC SDU has not been successfully received. It can be seen that the technical solutions provided by the embodiments of the present application can enable the ARQ mechanism to be applied to the MBS service data transmission scenario, so as to ensure highly reliable transmission of the MBS service data.
  • a data transmission method provided by this embodiment of the present application includes the following steps:
  • An access network device generates first indication information.
  • the first indication information is used to instruct the first terminal device to receive the starting data sequence number information of the MBS service data.
  • the starting data sequence number information includes the starting PDCP SN, the PDCP count value (count) and/or the starting RLC SN.
  • the PDCP SN, PDCP count value (count) and/or RLC SN corresponding to the next received RX_NEXT and the next received RX_DELIV.
  • the initial PDCP SN, PDCP count value or initial RLC SN is not 0.
  • the first indication information may be carried in the PTM activation signaling, or included in the RRC reconfiguration message, which is not limited in this embodiment of the present application.
  • the access network device sends first indication information to the first terminal device.
  • the first terminal device receives the first indication information from the access network device.
  • the access network device may send the first indication information to the first terminal device.
  • the access network device sends the first indication information to the first terminal device, so that the RLC entity in the first terminal device can set the start point of the corresponding receiving window according to the first indication information, Instead of having to set the start point of the receive window to 0.
  • FIG. 15 may be used in combination with the embodiment shown in FIG. 8 , FIG. 12 or FIG. 14 .
  • a data transmission method provided by this embodiment of the present application includes the following steps:
  • An access network device generates MRB configuration information.
  • the MRB configuration information is used to configure an MRB session between the first terminal device and the access network device.
  • the protocol may predefine an MRB-specific radio bearer identifier. Therefore, the radio bearer identifier included in the MRB configuration information belongs to the radio bearer identifier dedicated to the MRB.
  • the MRB configuration information includes PTM identity and/or MBS session information.
  • the MBS session information may include a temporary mobile group identity (TMGI).
  • TMGI temporary mobile group identity
  • the MBS session information may contain TMGI and session identification.
  • the following describes the MRB configuration information in detail with respect to the first terminal device using the protocol stack architecture shown in FIG. 11( a ) or FIG. 13 ( a ) respectively.
  • the first terminal device adopts the protocol stack architecture shown in FIG. 11( a ), the MRB configuration information includes two RLC bearer configuration information, the two RLC bearer configuration information is associated with the same MRB, and the two RLC bearer configuration information At least one of the RLC bearer configuration information includes PTM identification and/or MBS session information.
  • the MRB configuration information may include RLC bearer configuration information, and the RLC bearer configuration information is used to configure the fifth terminal device that processes the MBS service for the first terminal device.
  • RLC entity The RLC bearer configuration information includes a first LCID and a second LCID, and the first LCID is associated with a PTM identifier or MBS session information.
  • the PTM identification may be implemented in the form of an MBSPTIndication information element.
  • MBS session information may exist in the form of associatedMBSSession cells. That is, the RLC bearer information includes the MBSPT Mendication information element, which is equivalent to the RLC bearer information including the PTM identifier.
  • the RLC bearer information includes the associatedMBSSession information element, which is equivalent to the RLC bearer information including the MBS session information.
  • the RLC bearer configuration information may include a PTM identifier and/or MBS session information.
  • the RLC bearer configuration information may be in the following format, where the underlined part is the standard new content:
  • the associatedMBSSession information element is also added to the RLC bearer configuration information, and the associatedMBSSession information element is used to bear the MBS session information.
  • the condition for the existence of the associatedMBSSession information element is the PTM-leg. That is, when the LCID in the RLC bearer configuration information corresponds to the PTM-leg, the RLC bearer configuration information includes the associatedMBSSession information element.
  • the RLC bearer configuration information may be in the following format, where the underlined part is the standard new content:
  • the MBSPTMIndicationd information element is also added to the RLC bearer configuration information, and the MBSPTMIndicationd information element is used to indicate whether the LCH is associated with a PTM identifier.
  • the existence condition of the MBSPTMIndicationd cell is the PTM-leg. That is, when the LCID in the RLC bearer configuration information corresponds to the PTM-leg, the RLC bearer configuration information includes the MBSPTMIndicationd information element, and the value of the MBSPTMIndicationd information element is "true".
  • the RLC bearer configuration information may be in the following format, where the underlined part is the standard new content:
  • the RLC bearer configuration information provided by the embodiment of the present application adds an optional mrb-Identity to the servedRadioBearer information element.
  • the associatedMBSSession information element is also added to the RLC bearer configuration information, and the associatedMBSSession information element is used to carry the MBS session information.
  • the condition for the existence of the associatedMBSSession information element is the PTM-leg. That is, when the LCID in the RLC bearer configuration information corresponds to the PTM-leg, the RLC bearer configuration information includes the associatedMBSSession information element.
  • the RLC bearer configuration information may be in the following format, where the underlined part is the standard addition:
  • the RLC bearer configuration information may be in the following format, where the underlined part is the standard addition:
  • the "mrb-ToAddModList" information element may be added to the RLC bearer configuration information, or the LCID included in the RLC bearer configuration information belongs to the range of the logical channel identifier dedicated to the MBS service, or the RLC bearer configuration information includes MBS related indication information, Therefore, the first terminal device can be made to know that the RLC entity configured by the RLC bearer configuration information is used for processing the MBS service.
  • the protocol may predefine the range of logical channel identifiers dedicated to the MBS service. That is, when the UE receives the configuration information that includes the logical channel identifier within the range of the logical channel identifier, it considers that the logical channel corresponds to the MBS service.
  • the RLC bearer configuration information may be in the following format, where the underlined part is standard new content:
  • the content of mrb-identity is added to the serving radio bearer (servedRadioBearer) information element of the RLC bearer configuration information.
  • the protocol does not define the range of the logical channel identifier dedicated to the MBS service
  • the first terminal device sends the MBS service.
  • the device can notify the network side to reconfigure the LCID related to the MBS service to avoid the conflict between the transmission of the MBS service and the transmission of the unicast service.
  • the first terminal device may notify the access network device of the LCID corresponding to the MBS service it is interested in, to It is ensured that the access network device does not configure the first terminal device with these LCIDs for the logical channel of the unicast radio bearer.
  • the LCID corresponding to the unicast radio bearer and the LCID corresponding to the MRB are set to different values, the purpose of which is to prevent the MAC layer from demultiplexing according to the MAC subheader when it receives the MAC PDU submitted by the physical layer. LCID to determine whether the corresponding MAC sub-SDU is DRB or MRB.
  • the access network device sends MRB configuration information to the first terminal device.
  • the first terminal device receives the MRB configuration information from the access network device.
  • the first terminal device can learn the MRB configuration information for configuring the MRB.
  • the MRB configuration information may be carried in an RRC reconfiguration message.
  • the access network device sends the MRB configuration information to the first terminal device, so that the first terminal device knows the relevant configuration of its own RLC layer.
  • FIG. 16 may be used in combination with the embodiment shown in FIG. 8 , FIG. 12 , FIG. 14 or FIG. 15 .
  • the method includes the following steps:
  • the first terminal device sends a PDU session establishment request (PDU session establishment request) message to a mobility management network element.
  • PDU session establishment request PDU session establishment request
  • the PDU session establishment request message is used to request the establishment of a PDU session.
  • the first terminal device sends a PDU session establishment request to the mobility management network element through the access network device.
  • the PDU session establishment request message includes MBS session indication information, where the MBS session indication information is used to indicate that the PDU session requested to be established by the PDU session establishment request message is an MBS session.
  • the MBS session indication information may be a session identifier dedicated to the MBS service.
  • the MBS session indication information may be a session type set as a preset value, for example, the MBS session indication information may be a session type with a value of "MBS". It should be understood that the MBS session indication information may also adopt other implementation manners, which are not limited thereto.
  • the mobility management network element may select a session management network element that provides services for the first terminal device.
  • the session management network element may acquire the subscription information of the first terminal device to determine whether the first terminal device has the right to establish the MBS session indicated by the MBS session indication information. If the first terminal device has the corresponding authority, the session management network element may further perform the process of establishing a PDU session. Therefore, the mobility management network element can perform the following step S602.
  • the mobility management network element sends a PDU session resource setup request (PDU session resource setup request) message to the gNB-CU.
  • PDU session resource setup request PDU session resource setup request
  • the PDU session resource establishment request message includes N2 session management information and a PDU session establishment accept (PDU session establishment accept) message in which the destination node is the first terminal device.
  • the N2 session management information includes the shared N3 GTP-U Tunnel information corresponding to the requested MBS session.
  • the shared N3 GTP-U Tunnel information may include one or more of the following parameters: : MBS session identifier, TMGI, tunnel endpoint identifier (TEID), or QoS flow information of the MBS session.
  • the QoS information of the MBS session may include a QoS flow identifier and a QoS parameter.
  • the shared N3 GTP-U Tunnel information may only include the MBS session identifier or the TEID corresponding to the MBS session. .
  • the gNB-CU sends a PDU session resource setup response (PDU session resource setup response) message to the mobility management network element.
  • the gNB-CU After receiving the PDU session resource establishment request, the gNB-CU can perform session admission control according to the N2 session management information and its own current network load. Afterwards, the gNB-CU may send a PDU session resource establishment response message to the mobility management network element according to the admission result.
  • the PDU session resource establishment response message may include information on whether the MBS session requested by the first terminal device is accepted by the gNB-CU.
  • the gNB-CU sends an MBS context setup request (MBS context setup request) message to the gNB-DU.
  • MBS context setup request MBS context setup request
  • the MBS context establishment request message includes the TMGI corresponding to the MBS session and one or more MRB configuration information.
  • TMGI is usually used to scramble the PDCCH when used in the PTM transmission mode.
  • the terminal equipment interested in the MBS service corresponding to the TMGI uses the TMGI to descramble the PDCCH to determine whether there is data of the MBS service scheduled by the PDCCH.
  • the access network device may also use the G-RNTI corresponding to the TMGI to scramble the PDCCH and the PDSCH.
  • the terminal device can use the G-RNTI corresponding to the TMGI to descramble the PDCCH and PDSCH.
  • the MRB configuration information includes QoS parameters for one or more QoS flows.
  • the MRB configuration information may also include shared F1 GTP-U Tunnel information, such as the TEID on the CU side.
  • the MBS context establishment request message may also include one or more of the following information: TMGI, MBS session identifier, MBS local area (local area) information, MBS service pattern (traffic pattern) information, service PLMN ID, Service network identifier (network ID, NID).
  • TMGI MBS session identifier
  • MBS local area (local area) information MBS service pattern (traffic pattern) information
  • service PLMN ID service PLMN ID
  • Service network identifier network ID, NID
  • the MBS local area information is used to indicate a geographic area suitable for transmitting MBS service data.
  • the MBS local area information may include a cell list or a service area identification list.
  • the MBS traffic pattern information is used to indicate the generation rule of the MBS service data, such as the generation period, quantity, and generation start time of the MBS service data.
  • the serving PLMN ID is used to indicate the operator to which the MBS service belongs.
  • the service NID is used to indicate the private network to which the MBS service belongs in the private network scenario.
  • the gNB-DU can configure a shared RLC entity (that is, the first RLC entity in FIG. 8 ) for each MRB of the MBS service, and submit the data of the shared RLC entity.
  • the bottom layer is transmitted over the air interface in PTM mode.
  • the gNB-DU sends an MBS context setup response (MBS context setup response) message to the gNB-CU.
  • MBS context setup response MBS context setup response
  • the MBS context establishment response information may include the shared F1 GTP-U Tunnel information corresponding to the MRB, such as the TEID on the DU side.
  • steps S604-S605 are to configure the MRB corresponding to the MBS session between the gNB-DU and the gNB-CU, such as configuring the shared F1 GTP-U Tunnel corresponding to the MRB.
  • the shared F1 GTP-U Tunnel corresponding to the MBS session already exists, you can choose not to perform the above steps S604-S605.
  • the gNB-DU can receive data from the shared F1 GTP-U Tunnel and remove the GTP-U header.
  • the shared RLC entity the first RLC entity
  • the second RLC entity please refer to the foregoing for the specific method of which RLC entity to submit to.
  • the gNB-CU sends a UE context modification request (UE context modification request) message to the gNB-DU.
  • UE context modification request UE context modification request
  • the UE context modification request message includes one or more MRB configuration information corresponding to the MBS service requested by the first terminal device.
  • the MRB configuration information includes at least the MRB ID.
  • the UE context modification request message includes the "MRB to be setup list” information element, and the "MRB to Be Setup List” IE further contains the MRB ID of each MRB.
  • the gNB-DU after receiving the UE context modification request message, the gNB-DU generates a separate RLC entity (that is, the second RLC entity in FIG. 8 ) for each MRB of the MBS service.
  • the gNB-DU can be configured with one first RLC entity.
  • the gNB-DU may be configured with a second RLC entity respectively. Therefore, for the same MRB, the gNB-DU may have one first RLC entity and at least one second RLC entity.
  • the logical channels corresponding to these RLC entities may have different LCIDs or the same LCID.
  • the gNB-DU may configure only one RLC entity in AM mode for one MRB. Based on this design, the MRB configuration information sent by the gNB-CU to the gNB-DU needs to carry the C-RNTIs of all terminal devices corresponding to the MRB.
  • the first RLC entity transmits the MBS service data over the air interface in the PTM manner
  • the second RLC entity transmits the MBS service data over the air interface in the PTP manner.
  • the physical layer of the gNB-DU scrambles the PDCCH containing the scheduling grant with the C-RNTI.
  • the physical layer of the gNB-DU scrambles the PDCCH containing the scheduling grant with the G-RNTI.
  • each terminal device has its own C-RNTI, that is, different terminal devices are configured with different C-RNTIs.
  • the G-RNTI is in a one-to-one correspondence with an MBS service identifier (eg, TMGI).
  • MBS service identifier eg, TMGI
  • the G-RNTI can also correspond to multiple MBS services.
  • the MAC layer of the gNB-DU when the MAC layer of the gNB-DU receives the uplink data of the LCID corresponding to the MRB, it can submit the uplink data to the terminal equipment that provides services for the terminal equipment corresponding to the C-RNTI according to the C-RNTI scrambled by the uplink data.
  • the second RLC entity performs processing.
  • the uplink data of the LCID corresponding to the MRB may be the first information in the embodiment shown in FIG. 9 .
  • the first RLC entity when the first RLC entity receives the indication information sent by the corresponding PDCP entity to indicate that the RLC SDU is discarded, if the RLC SDU instructed to be discarded has been handed over to the second RLC entity, the first RLC entity needs to send the RLC SDU to the second RLC entity.
  • the second RLC entity sends indication information for indicating discarding of the RLC SDU.
  • the gNB-DU sends a UE context modification response (UE context modification response) message to the gNB-CU.
  • UE context modification response UE context modification response
  • the gNB-CU sends MBS control information (MBS control info) to the UE.
  • MBS control info MBS control info
  • the MBS control information includes the TMGI of the MBS service requested by the UE.
  • the MBS control information may further include MBS scheduling pattern information corresponding to the MBS service.
  • the MBS scheduling pattern information is used to indicate the time domain resource location and/or the frequency domain resource location for transmitting MBS service data.
  • the MBS scheduling pattern information includes one or more of the following parameters: scheduling/transmission period, time offset, starting position, and frequency domain resource position.
  • the frequency domain resource location may be a bandwidth part (bandwidth part, BWP), etc., which is not limited.
  • the MBS control information may be sent through system information and/or an MBS control channel.
  • the gNB-DU or gNB-CU may send a paging message or other types of notification messages, so that the first terminal device knows that the MBS control information is updated. In this way, the first terminal device can accurately receive the MBS control information to know the start of a new MBS service.
  • the gNB-CU sends an RRC reconfiguration (RRC reconfiguration) message to the first terminal device.
  • RRC reconfiguration RRC reconfiguration
  • the RRC reconfiguration message includes one or more MRB configuration information corresponding to the MBS service.
  • the MRB configuration information is used to configure the PDCP layer and the RLC layer.
  • the RRC reconfiguration message may include a PDU session establishment accept message.
  • the gNB-CU may send a PDU session establishment accept message to the first terminal device through another RRC message.
  • the first terminal device sends an RRC reconfiguration complete (RRC reconfiguration complete) message to the gNB-CU.
  • RRC reconfiguration complete RRC reconfiguration complete
  • both the gNB and the first terminal device can configure the corresponding RLC layer, so that the gNB and the first terminal device can perform the data transmission shown in FIG. 9 . method.
  • FIG. 17 only introduces a part of the steps of the PDU session establishment process.
  • the PDU session establishment process may further include other steps, which will not be repeated here.
  • the embodiment shown in FIG. 17 is mainly described from the perspective that the access network device adopts the CU-DU architecture. In fact, it is also applicable to other architectures of the access network device, such as the gNB integrated architecture or the gNB-CU. The architecture of CP/UP separation, etc. Wherein, when the embodiment shown in FIG. 17 is applied to the gNB integrated architecture, the information exchange between the gNB-CU and the gNB-DU is the internal operation of the gNB.
  • the terminal device can be switched from the source access network device to the target access network device through the handover process to ensure the communication continuity and service quality of the terminal device.
  • the handover process provided by the related art includes the following steps:
  • the terminal device sends a measurement report (measurement report) to the source access network device.
  • the terminal device in the RRC connected state may send the measurement report according to the measurement report triggering criterion configured by the source access network device.
  • the source access network device determines the target access network device according to the measurement report.
  • the source access network device determines whether the terminal device satisfies the handover condition according to the measurement report and a radio resource management (radio resource management, RRM) algorithm. In the case that the terminal device satisfies the handover condition, the source access network device determines the target access network device.
  • RRM radio resource management
  • the source access network device sends a handover request message to the target access network device.
  • the handover request message may include the context of the terminal device.
  • the target access network device sends a handover request confirmation message to the source access network device.
  • the handover request confirmation message may include the C-RNTI and other parameters allocated by the target access network device to the terminal device.
  • the source access network device may prepare to forward the packet data to the target access network device.
  • the source access network device sends a handover command (handover command) to the terminal device.
  • the handover command may include: C-RNTI allocated by the target access network device to the terminal device, random access channel (random access channel, RACH) parameters, and protocol layer configuration information of the terminal device.
  • the protocol layer configuration information of the terminal device may be used to configure protocol layers such as PHY, MAC, RLC, PDCP, and SDAP.
  • the terminal device stops uplink data or downlink data transmission with the source access network device, and prepares to synchronize with the target access network device.
  • the terminal device does not stop data transmission with the source access network device until the terminal device and the target access network device complete synchronization.
  • the source access network device may send the uplink data from the terminal device and/or the downlink data from the user plane network element to the target access network device.
  • the source access network device sends SN status information (SN status transfer) to the target access network device.
  • the terminal device and the target access network device perform synchronization and random access procedures.
  • the terminal device can learn the uplink timing and uplink resource allocation.
  • S708 The terminal device sends a handover confirmation message to the target access network device.
  • the handover confirmation message is used to indicate that the handover is completed.
  • the target access network device sends a handover complete message to the source access network device.
  • the handover complete message is used to trigger the source access network device to release the context information of the terminal device.
  • the target access network device may notify the core network network element to update the target access network device for data forwarding of the terminal device, so that the core network can forward the data of the terminal device to the target access network device.
  • the source base station supports MBS, and the target base station supports MBS; 2) the source base station supports MBS, but the target base station does not support MBS; 3) the source base station supports MBS The base station does not support MBS, and the target base station supports MBS; 4) The source base station does not support MBS, and the target base station does not support MBS.
  • the source base station does not support MBS, after the core network receives the path switch of the target base station, it will not continue to send the MBS data to the terminal device from the source base station, but the source base station can forward the buffered data packets to the target base station.
  • the source base station supports MBS
  • the target station does not support MBS
  • this article does not expand.
  • the source station supports MBS and the target station also supports MBS. Since the source base station will not stop receiving MBS service data from the core network due to the departure of the UE, that is, after the UE moves, the source station will continue to receive MBS service data from the MBS UPF. Therefore, the source base station does not know which MBS service data data is forwarded to the target base station.
  • the target base station needs to clearly inform the source station whether it needs to do data forwarding. If necessary, to which SN number the data is forwarded to. Otherwise, more unnecessary data forwarding may occur in the handover process between the source access network device and the target access network device, resulting in a waste of system resources.
  • an embodiment of the present application provides a data transmission method. As shown in Figure 19, the data transmission method includes the following steps:
  • the source access network device sends handover request information to the target access network device.
  • the target access network device receives the handover request message from the source access network device.
  • the handover request message is used to request to handover the terminal device from the source access network device to the target access network device.
  • the handover request message contains relevant information of the MBS session, such as the TMGI corresponding to the MBS session, the MBS session identifier, the MRB ID, the QoS flow identifier corresponding to the MRB ID, and the QoS parameters. Therefore, the target access network device learns which service of the MBS session the terminal device currently includes.
  • the target access network device sends fourth information to the source access network device.
  • the source access network device receives the fourth information from the target access network device.
  • the fourth information is used to instruct the source access network device to forward the MBS service data corresponding to at least one SN before the first SN to the terminal device to the target access network device.
  • forwarding the MBS service data corresponding to at least one SN before the first SN of the terminal device may include forwarding the MBS service data corresponding to the first SN; or, does not include forwarding the MBS service data corresponding to the first SN.
  • first SN may have other names, such as last forwarding SN (last forwarding SN), which is not limited.
  • the fourth information may include first SN information.
  • the first SN may be a PDCP SN, a COUNT value, a GTP-US SN, or a QFI and a corresponding QFI SN.
  • the COUNT value contains the PDCP SN and the hyper frame number (HFN).
  • the fourth information may be of the following types: 1) MBS session information (TMGI and/or MBS session identifier) and corresponding PDCP SN (or COUNT value); 2) MBS session information, MRB ID and corresponding PDCP SN (or COUNT value); 3) MBS session information, QFI and corresponding QFI SN; 3) MBS session information and GTP-US SN number.
  • the fourth information may be included in the handover request confirmation message sent by the target access network device to the source access network device.
  • Scenario 1 The user plane tunnel corresponding to the MBS session has not been established between the target access network device and the core network element.
  • the user plane tunnel corresponding to the MBS session is simply referred to as the MBS tunnel.
  • the MBS tunnel is a user plane tunnel used for transmitting MBS service data of the terminal device.
  • the above MBS tunnel may be a Shared N3 GTP-U Tunnel.
  • the core network element may be a user plane network element, which is not limited.
  • the target access network device may obtain the second SN information from the core network element; the target access network device determines the first SN information according to the second SN information.
  • the second SN information is used to indicate the second SN
  • the first SN information is used to indicate the first SN.
  • the second SN is the next SN to the first SN, or the second SN is equal to the first SN.
  • the target access network device sends a path switching request message to the core network element, where the path switching request message is used to request the core network element to switch the transmission path of the MBS service data of the terminal device.
  • the target access network device receives a path switching confirmation message from the core network element, where the path switching confirmation message includes the second SN information.
  • the second SN information contained in the path switch confirmation message may be 1) MBS session information and corresponding GTP-U SN number; or 2) MBS session information, QFI and QFI SN number.
  • the second SN, or the second SN and other information may be included in interface messages between other target access network devices and core network elements.
  • the target access network device determines that the first SN information is the MBS session information and the GTP-US SN. Or the target access network device determines the PDCP SN (or COUNT value) corresponding to the GTP-USN, thereby determining that the first SN information is MBS session information and PDCP SN (or COUNT value), or MBS session information, MRB ID and corresponding PDCP SN (or COUNT value).
  • the target access network device When the target access network device obtains the MBS session information, the QFI and the corresponding QFI SN number from the core network element, the target access network device determines that the first SN information is the MBS session information, the QFI and the corresponding QFI SN number.
  • the second SN is the SN corresponding to the MBS service data of the first terminal device sent by the core network element to the target access network device.
  • the second SN may have other names, such as the first forwarded SN (first SN), which is not limited.
  • Scenario 2 An MBS tunnel has been established between the target access network device and the core network element.
  • the target access network device can obtain and cache the MBS service data of the terminal device from the core network element through the MBS tunnel.
  • the target access network device may send the fourth information to the source access network device after receiving the handover request message.
  • the fourth information includes the first SN, where the first SN is the SN corresponding to the first MBS service data of the terminal device buffered by the target access network device.
  • the target access network device after receiving the handover request message, receives the SN status report information sent by the source access network device, the SN status report information indicates the third SN, and the third SN is the SN status report
  • the target access network device sends fourth information to the source access network device.
  • the fourth information includes the first SN, where the first SN is the SN corresponding to the first MBS service data of the terminal device buffered by the target access network device.
  • a second preset mapping relationship may be specified in the protocol, or the core network or network management Configure the second preset mapping relationship.
  • the second preset mapping relationship is a preset mapping relationship between the PDCP SN (or the COUNT value) and the GTP-US SN.
  • the second preset mapping relationship is a preset mapping relationship between the combination of QFI and QFI SN and the PDCP SN (or COUNT value).
  • the introduction is made by taking the second preset mapping relationship as the preset mapping relationship between the PDCP SN (or the COUNT value) and the GTP-US SN as an example.
  • the size of the PDCP SN (or COUNT value) is less than or equal to the size of the GTP-US SN to ensure that a GTP-US SN can only derive a unique PDCP SN.
  • the PDCP SN size in the current protocol is 12 bits or 18 bits, and the GTP-US SN size is 16 bits, in order to ensure that the size of the PDCP SN is less than or equal to the size of the GTP-US SN, the PDCP SN in this embodiment of the present application size can only support 12bit.
  • the size of the PDCP SN in the embodiments of the present application is not fixed.
  • the size of the PDCP SN in the embodiment of the present application can also be changed.
  • maxPDCP SN is the maximum value that PDCP SN can take.
  • the target access network device sends the fourth information to the source access network device, so that the source access network device forwards the information before the first SN to the target access network device.
  • the MBS service data of the terminal equipment corresponding to at least one SN reduces the number of data to be forwarded, which is beneficial to saving system overhead.
  • the source access network device forwards the MBS service data of the terminal device corresponding to at least one SN before the first SN to the target access network device, which can realize lossless or minimal packet loss transmission during the handover process.
  • the target access network device may have established a user plane tunnel corresponding to the MBS session with the core network element, and the target access network device can obtain the MBS service data of the terminal device from the core network element.
  • the source access network device cannot perceive the information that the target access network device has established the user plane tunnel corresponding to the MBS session with the core network element. Therefore, during the handover process, the source access network device follows the steps shown in FIG. When the handover process is executed, the source access network device will forward unnecessary MBS data to the target access network device, thereby causing waste of system resources.
  • an embodiment of the present application provides a data transmission method. As shown in Figure 20, the data transmission method includes the following steps:
  • the source access network device sends handover request information to the target access network device.
  • the target access network device receives the handover request message from the source access network device.
  • the handover request message is used to request to handover the terminal device from the source access network device to the target access network device.
  • the handover request message contains relevant information of the MBS session, such as the TMGI corresponding to the MBS session, the MBS session identifier, the MRB ID, the QoS flow identifier corresponding to the MRB ID, and the QoS parameters. Therefore, the target access network device learns which service of the MBS session the terminal device currently includes.
  • the target access network device sends fifth information to the source access network device.
  • the source access network device receives the fifth information from the target access network device.
  • the fifth information is used to instruct the source access network device not to forward the MBS service data of the terminal device to the target access network device.
  • step S901 an MBS tunnel has been established between the target access network device and the core network element.
  • the target access network device has buffered the MBS service data received from the MBS tunnel for a long enough time. Therefore, the target access network device can obtain the terminal device's status in the source connection from its own cache after receiving the terminal device handover.
  • the network access device receives the MBS service data at the breakpoint, and sends the MBS service data to the terminal device, so as to ensure the continuity of the terminal device's reception of the MBS service data.
  • the target access network device does not need to acquire the MBS service data from the source access network device, so the target access network device can send the fifth information to the source access network device.
  • an MBS tunnel has been established between the target access network device and the core network element.
  • the target access network device receives and buffers some MBS service data of the terminal device from the MBS tunnel.
  • the target access network device receives the handover request message, it receives the SN status report information sent by the source access network device, the SN status report information indicates the third SN, and the third SN is the first unidentified SN indicated by the SN status report information.
  • the SN corresponding to the successfully received MBS service data.
  • the target access network device sends fifth information to the source access network device.
  • the above-mentioned MBS tunnel is used to transmit the MBS service data that the terminal device is receiving.
  • the above MBS tunnel may be a Shared N3 GTP-U Tunnel.
  • a second preset mapping relationship can be specified in the protocol, or the core network or the network management can configure the second Default mapping relationship.
  • the second preset mapping relationship reference may be made to the description in the embodiment shown in FIG. 19 , which will not be repeated here.
  • the fifth information may be carried in the handover request confirmation message.
  • the fifth information may be an indication of "do not forward", or an indication of "MBS already exists". It should be understood that the "MBS already exists" indication is used to indicate that the target access network device has buffered the MBS service data.
  • the handover request confirmation message does not carry the Xn forwarding tunnel information of the MBS session to implicitly indicate that the handover request confirmation message contains the fifth information.
  • the 3rd generation partnership project (3GPP) 38.423 protocol defines the handover request confirmation message to include: "Data forwarding info from target NG-RAN node" "Cell.
  • the handover request confirmation message does not include the "data forwarding info from target NG-RAN node” information element, it is implicitly indicated that the handover request confirmation message includes the fifth information.
  • the target access network device sends fifth information to the source access network device, so that the source access network device does not need to forward the MBS of the terminal device to the target access network device business data, thereby reducing the number of data to be forwarded, which is beneficial to saving system overhead.
  • FIG. 19 or FIG. 20 only describes a part of the steps in the handover process. Other parts in the handover process will not be repeated here.
  • the same gNB-CU may be simultaneously connected to a gNB-DU that supports MBS services and a gNB-DU that does not support MBS services.
  • MBS data is transmitted in a shared transmission mode between the UPF and the gNB-CU.
  • the F1-U interface between the gNB-CU and the gNB-DU should establish a separate transmission channel; if the gNB-DU supports the MBS service, the gNB-CU to the gNB-DU
  • the F1-U interface establishes a shared transmission channel.
  • the gNB-CU cannot accurately know whether the gNB-DU supports the MBS service, so the gNB-CU cannot accurately determine the type of transmission channel that should be established with the gNB-DU.
  • the data transmission method includes the following steps:
  • the gNB-DU generates first capability indication information.
  • the first capability indication information is used to indicate the air interface support capability of the gNB-DU for the MBS. That is, the first capability indication information may be used to indicate whether the gNB-DU supports MBS. In other words, the first capability indication information is used to indicate whether the gNB-DU can support air interface broadcast and multicast MBS services.
  • the gNB-DU sends first capability indication information to the gNB-CU.
  • the gNB-CU acquires the first capability indication information from the gNB-DU.
  • the first capability indication information is carried in the F1AP message, or the F1-U setup request message, or the gNB-DU Configuration Update message, which is not limited.
  • the gNB-CU may determine whether the gNB-DU supports the MBS service according to the first capability indication information, and then select the type of transmission channel established with the gNB-DU. For example, when the UE applies to the core network for establishing an MBS session, and the core network determines that the base station where the gNB-CU is located supports MBS, it notifies the gNB-CU to establish a shared user plane tunnel corresponding to the MBS service. The gNB-CU further judges whether the gNB-DU where the UE is located supports MBS according to the first capability indication information reported by the gNB-DU accessed by the UE.
  • the F1-U interface between the gNB-CU and the gNB-DU establishes a shared transmission channel. If the gNB-DU does not support MBS, the F1-U interface between the gNB-CU and the gNB-DU shall establish a separate transmission channel.
  • the air interface support capability of the gNB-DU for MBS may change, for example, the gNB-DU may change from supporting MBS to not supporting MBS; or, the gNB-DU may change from not supporting MBS to supporting MBS.
  • the gNB-DU may send a configuration update (configuration update) message to the gNB-CU to indicate the latest air interface support capability of the gNB-DU for MBS.
  • the gNB-CU may send a gNB-DU Configuration Update Acknowledge message to the gNB-DU to indicate the gNB-DU. Change the type of transmission channel established by the F1-U interface.
  • an embodiment of the present application provides a data transmission method, and the method includes the following steps:
  • the gNB-CU-UP generates second capability indication information.
  • the second capability indication information is used to indicate the air interface support capability of the gNB-CU-UP for the MBS. That is, the second capability indication information is used to indicate whether the gNB-CU-UP supports MBS.
  • the gNB-CU-UP sends the second capability indication information to the gNB-CU-CP.
  • the second capability indication information may be carried in a gNB-CU-UP E1 setup message or a gNB-CU-UP configuration update message, which is not limited.
  • the gNB-CU-CP can report the capability information of whether to support MBS to the core network according to the second capability indication information.
  • the core network further determines the type of the transmission channel established by the NG-U interface between the UPF and the gNB-CU-UP according to the capability information on whether or not the MBS is supported reported by the gNB-CU-CP.
  • the NG-U interface between the UPF and the gNB-CU-UP establishes a shared transmission channel; or, in the case that the gNB-CU-UP does not support the MBS service , the NG-U interface between UPF and gNB-CU-UP establishes a separate transmission channel.
  • the above-mentioned separate transmission channel may also have other names, such as a dedicated transmission channel, which is not limited.
  • a communication apparatus eg, an access network device and a terminal device
  • a communication apparatus includes corresponding hardware structures and/or software modules for executing each function.
  • the embodiments of this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is performed by hardware or computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods for each specific application to implement the described functions, but such implementation should not be considered beyond the scope of the technical solutions of the embodiments of the present application.
  • the communication device may be divided into functional modules according to the foregoing method examples.
  • each functional module may be divided corresponding to each function, or two or more functions may be integrated into one processing unit.
  • the above-mentioned integrated units can be implemented in the form of hardware, or can be implemented in the form of software function modules. It should be noted that the division of units in the embodiments of the present application is illustrative, and is only a logical function division, and other division methods may be used in actual implementation.
  • a communication apparatus provided by an embodiment of the present application includes a processing module 101 and a communication module 102 .
  • the processing module 101 is configured to support the access network device to perform step S401 in FIG. 15 , step S501 in FIG. 16 , and/or the embodiments of the present application. Other processing operations that need to be performed by the access network device.
  • the communication module 102 is configured to support the access network device to perform steps S101 to S103 in FIG. 9 , step S402 in FIG. 15 , step S502 in FIG. 16 , and/or other needs to be performed by the access network device in the embodiment of the present application communication operations.
  • the processing module 101 is configured to support the terminal device to parse information (for example, MRB configuration information), and/or other processing operations that the terminal device needs to perform in this embodiment of the present application
  • the processing module 101 is configured to execute steps S202 and S203 in FIG. 12 and step S302 in FIG. 14 .
  • the communication module 102 is configured to support the terminal device to perform steps S201 and S204 in FIG. 12 , step S402 in FIG. 15 , step S502 in FIG. 16 , and/or other communication operations that the terminal device needs to perform in this embodiment of the present application.
  • the processing module 101 is configured to support the target access network device to generate information (for example, the fourth information or the fifth information), and/or the implementation of this application. Other processing operations that need to be performed by the target access network device in the example.
  • the communication module 102 is configured to support the target access network device to perform steps S801-S802 in FIG. 19 , steps S901 and S902 in FIG. 20 , and/or other communication operations that the target access network device needs to perform in this embodiment of the present application.
  • the processing module 101 is configured to support the source access network device to parse information (for example, the fourth information or the fifth information), and/or implement the In the example, the source access network device needs to perform other processing operations.
  • the communication module 102 is configured to support the source access network device to perform steps S801-S802 in FIG. 19 , steps S901 and S902 in FIG. 20 , and/or other communication operations that the source access network device needs to perform in this embodiment of the present application.
  • the processing module 101 is configured to support the gNB-DU to perform step S1001 in FIG. 21 .
  • the communication module is used to support the gNB-DU to perform step S1002 in FIG. 21 .
  • the processing module 101 is configured to support the gNB-CU to parse the first capability indication information.
  • the communication module is used to support the gNB-CU to perform step S1002 in FIG. 21 .
  • the processing module 101 is configured to support the gNB-CU-UP to execute step S1101 in FIG. 22
  • the communication module is configured to support the gNB-CU-UP to execute Step S1102 in FIG. 22 .
  • the processing module 101 is used to support the gNB-CU-CP to parse the second capability indication information, and the communication module is used to support the gNB-CU-CP execution map Step S1102 in 22.
  • the communication device may further include a storage module 103 for storing program codes and data of the communication device, and the data may include but not limited to original data or intermediate data.
  • the processing module 101 may be a processor or a controller, such as a CPU, a general-purpose processor, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other Programmable logic devices, transistor logic devices, hardware components, or any combination thereof. It may implement or execute the various exemplary logical blocks, modules and circuits described in connection with this disclosure.
  • a processor may also be a combination that implements computing functions, such as a combination of one or more microprocessors, a combination of a DSP and a microprocessor, and the like.
  • the communication module 102 may be a communication interface, a transceiver or a transceiver circuit, etc., where the communication interface is a general term, and in a specific implementation, the communication interface may include multiple interfaces, for example, may include: an interface between a base station and a terminal and/or or other interfaces.
  • the storage module 103 may be a memory.
  • the processing module 101 is a processor
  • the communication module 102 is a communication interface
  • the storage module 103 is a memory
  • the communication device involved in the embodiment of the present application may be as shown in FIG. 24 .
  • the communication device includes: a processor 201 , a communication interface 202 , and a memory 203 .
  • the communication device may further include a bus 204 .
  • the communication interface 202, the processor 201 and the memory 203 can be connected to each other through a bus 204; the bus 204 can be a peripheral component interconnect (PCI) bus or an extended industry standard architecture (EISA) bus etc.
  • the bus 204 can be divided into an address bus, a data bus, a control bus, and the like. For ease of presentation, only one thick line is shown in FIG. 24, but it does not mean that there is only one bus or one type of bus.
  • the embodiment of the present application further provides a computer program product carrying computer instructions, when the computer instructions are executed on the computer, the computer is made to execute the method described in the foregoing embodiments.
  • the embodiments of the present application further provide a computer-readable storage medium, where the computer-readable storage medium stores computer instructions, and when the computer instructions are executed on the computer, the computer executes the methods described in the foregoing embodiments.
  • an embodiment of the present application further provides a chip, including: a processing circuit and a transceiver pin, where the processing circuit and the transceiver pin are used to implement the method introduced in the foregoing embodiment.
  • the processing circuit is used for executing the processing actions in the corresponding method
  • the transceiver pins are used for executing the actions of receiving/transmitting in the corresponding method.
  • the computer instructions may be stored in or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be downloaded from a website site, computer, server, or data center Transmission to another website site, computer, server or data center via wired (eg coaxial cable, optical fiber, Digital Subscriber Line, DSL) or wireless (eg infrared, wireless, microwave, etc.) means.
  • the computer-readable storage medium may be any available medium that a computer can access, or a data storage device such as a server, a data center, or the like that includes an integration of one or more available media.
  • the available media may be magnetic media (eg, floppy disks, hard disks, magnetic tapes), optical media (eg, Digital Video Disc (DVD)), or semiconductor media (eg, Solid State Disk (SSD)) Wait.
  • the disclosed system, apparatus and method may be implemented in other manners.
  • the apparatus embodiments described above are only illustrative.
  • the division of the modules is only a logical function division. In actual implementation, there may be other division methods.
  • multiple modules or components may be combined or Can be integrated into another system, or some features can be ignored, or not implemented.
  • the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or modules, and may be in electrical or other forms.
  • the units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple devices. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.
  • the present application can be implemented by means of software plus necessary general-purpose hardware, and of course hardware can also be used, but in many cases the former is a better implementation manner .
  • the technical solutions of the present application can be embodied in the form of software products in essence or contributed parts, and the computer software products are stored in a readable storage medium, such as a floppy disk, a hard disk or an optical disk of a computer etc., including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute the methods described in the various embodiments of the present application.

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Abstract

一种数据传输方法及装置，涉及通信技术领域，用于保证MBS业务数据的高可靠传输。该方法包括：接入网设备侧的第一RLC实体向包括第一终端设备在内的至少一个终端设备发送至少一个RLC SDU；接入网设备侧的第二RLC实体从第一终端设备接收第一信息，第一信息用于指示至少一个RLC SDU中未成功接收到的第一RLC SDU的RLC SN；接入网设备侧的第二RLC实体向第一RLC实体递交第二信息，第二信息用于指示未成功接收到的RLC SDU；第一RLC实体或第二RLC实体向第一终端设备发送第一RLC SDU。

Description

数据传输方法及装置 技术领域
本申请涉及通信技术领域，尤其涉及一种数据传输方法及装置。
背景技术
多播广播业务(multicast and broadcast service，MBS)是面向多个终端设备(user equipment，UE)的业务，例如直播业务、公共安全业务、批量软件更新业务等。在MBS业务数据从接入网设备向终端设备发送的时候，有两种传输方式：第一种是点到多点(point to multi-point，PTM)传输方式；第二种是点到点(point to point，PTP)传输方式。
当前，针对接入网设备采用PTM传输方式来传输MBS业务数据的场景，现有的自动重发请求(automatic repeat request，ARQ)技术无法直接应用，从而无法保证MBS业务数据的高可靠传输。
发明内容
本申请实施例提供一种数据传输方法及装置，用于保证MBS业务数据的高可靠传输。
第一方面，提供一种数据传输方法，该方法应用于接入网设备，接入网设备配置有分组数据汇聚协议(packet data convergence protocol，PDCP)实体、第一无线链路控制(radio link control，RLC)实体和第二RLC实体，第一RLC实体和第二RLC实体分别和PDCP实体关联，第一RLC实体用于支持点对多点PTM传输方式发送多播广播业务MBS业务数据，第二RLC实体用于支持点对点PTP传输方式发送MBS业务数据，第一RLC实体和第二RLC实体关联到相同的多播无线承载(MBS radio bearer，MRB)，方法包括：第一RLC实体向包括第一终端设备在内的至少一个终端设备发送至少一个RLC服务数据单元(service data unit，SDU)；第二RLC实体从第一终端设备接收第一信息，第一信息用于指示第一RLC SDU的RLC序列号(serial number，SN)，第一RLC SDU属于至少一个RLC SDU中未成功接收到的RLC SDU；第二RLC实体向第一RLC实体或者PDCP实体递交第二信息，第二信息用于指示第一RLC SDU的RLC SN；第一实体向第一终端设备发送第一RLC SDU，第一实体为第一RLC实体或者第二RLC实体。
基于上述技术方案，接入网设备通过第一RLC实体以PTM方式传输MBS业务数据，以第二RLC实体来获取终端设备针对MBS业务数据的接收状态。进而，接入网设备可以确定需要重传的MBS业务数据，并通过第一RLC实体或第二RLC实体重传MBS业务数据。可见，本申请所提供的技术方案能够使得ARQ机制应用于PTM传输方式，保证MBS业务数据的高可靠传输。
一种可能的设计中，第一实体为第一RLC实体；在第一实体向第一终端设备发送第一RLC SDU之前，该方法还包括：第一RLC实体根据第二信息，获取第一RLC SDU。
一种可能的设计中，第一实体为第二RLC实体；在第一实体向第一终端设备发送 第一RLC SDU之前，该方法还包括：第一RLC实体根据第二信息，向第二RLC实体递交第一RLC SDU。
一种可能的设计中，在第一实体向第一终端设备发送第一RLC SDU之前，该方法还包括：PDCP实体根据第二信息，向第一实体递交第一RLC SDU。
一种可能的设计中，第二信息包括第一RLC SDU的RLC SN，PDCP实体根据第二信息，向第一实体递交第一RLC SDU，包括：PDCP实体根据第一RLC SDU的RLC SN，以及预设映射关系，确定第一PDCP协议数据单元(protocol data unit，PDU)的PDCP SN，预设映射关系用于指示PDCP SN与RLC SN之间的映射关系；PDCP实体根据第一PDCP PDU的PDCP SN，获取第一PDCP PDU，第一PDCP PDU为第一RLC SDU；PDCP实体向第一实体递交第一RLC SDU。
一种可能的设计中，第二信息包括第一PDCP PDU的PDCP SN，PDCP实体根据第二信息，向第一实体递交第一RLC SDU，包括：PDCP实体根据第一PDCP PDU的PDCP SN，获取第一PDCP PDU，第一PDCP PDU为第一RLC SDU；PDCP实体向第一实体递交第一RLC SDU。
一种可能的设计中，在第二RLC实体向PDCP实体递交第二信息之前，该方法还包括：第二RLC实体根据第一RLC SDU的RLC SN，以及预设映射关系，确定第一PDCP PDU的PDCP SN，预设映射关系用于指示PDCP SN与RLC SN之间的映射关系。基于该设计，可以使得第一RLC实体和第二RLC实体对PDCP递交过来的、相同内容的RLC SDU进行相同的RLC SN编号。
一种可能的设计中，该方法还包括：接入网设备向第一终端设备发送第一指示信息，第一指示信息用于指示第一终端设备接收MBS业务数据的起始数据序列号信息。
一种可能的设计中，起始数据序列号信息包括PDCP SN、PDCP计数值和/或起始的RLC SN。
一种可能的设计中，该方法还包括：接入网设备向第一终端设备发送MRB配置信息，MRB配置信息用于配置第一终端设备与接入网设备之间的MBS会话。
一种可能的设计中，MRB配置信息包括PTM标识或者MBS会话信息。
一种可能的设计中，MRB配置信息包括两个RLC承载配置信息，两个RLC承载配置信息关联相同的MRB，两个RLC承载配置信息中至少一个RLC承载配置信息包括PTM标识或者MBS会话信息。
第二方面，提供一种数据传输方法，该方法应用于第一终端设备，第一终端设备配置有第三RLC实体和第四RLC实体，第三RLC实体用于接收接入网设备以PTM方式发送的MBS业务数据，第四RLC实体用于接收接入网设备以PTP方式发送的MBS业务数据，第三RLC实体和第四RLC实体关联到相同的MRB，方法包括：第三RLC实体从接入网设备接收至少一个RLC SDU；第四RLC实体从第三RLC实体接收第三信息，第三信息指示至少一个RLC SDU中第一RLC SDU的RLC SN；第四RLC实体根据第三信息生成第一信息；第四RLC实体向接入网设备发送第一信息，第一信息用于指示第一RLC SDU的RLC SN，第一RLC SDU属于至少一个RLC SDU中未成功接收到的RLC SDU。
基于上述技术方案，第三RLC实体接收至少一个RLC SDU，第三RLC实体通过 向第四RLC实体发送第三信息，以触发第四RLC实体向接入网设备发送第一信息，以使得接入网设备获知第一RLC SDU未成功接收到。从而，基于第三RLC实体和第四RLC实体之间的相互交互，能够实现PTM传输模式下的ARQ机制，保证MBS业务数据的高可靠传输。
一种可能的设计中，在第四RLC实体从第三RLC实体接收第三信息之前，该方法还包括：第三RLC实体确定第一RLC SDU未成功接收到；第三RLC实体根据第一RLC SDU的RLC SN生成第三信息。
一种可能的设计中，在第四RLC实体从第三RLC实体接收第三信息之前，该方法还包括：第三RLC实体确定至少一个RLC SDU中的第二RLC SDU成功接收到；第三RLC实体根据第二RLC SDU的RLC SN生成第三信息。
一种可能的设计中，在第四RLC实体向接入网设备发送第一信息之后，该方法还包括：第四RLC实体从接入网设备接收第一RLC SDU。
一种可能的设计中，在第四RLC实体向接入网设备发送第一信息之后，该方法还包括：第三RLC实体从接入网设备接收第一RLC SDU。
一种可能的设计中，该方法还包括：第三RLC实体向第四RLC实体指示成功接收到第一RLC SDU。从而，第四RLC实体可以获知第一RLC SDU成功接收到，进而第四RLC可以不用再次发送第一信息，以触发接入网设备重传第一RLC SDU。
一种可能的设计中，该方法还包括：第一终端设备从接入网设备接收第一指示信息，第一指示信息用于指示第一终端设备接收MBS业务数据的起始数据序列号信息。
一种可能的设计中，第一指示信息具体用于指示起始的PDCP SN、PDCP计数值和/或起始的RLC SN。
一种可能的设计中，该方法还包括：第一终端设备从接入网设备接收MRB配置信息，MRB配置信息用于配置第一终端设备与接入网设备之间的MBS会话。
一种可能的设计中，MRB配置信息包括PTM标识或者MBS会话信息。
一种可能的设计中，MRB配置信息包含两个RLC承载配置信息，两个RLC承载配置信息关联相同的MRB，两个RLC承载配置信息中至少一个RLC承载配置信息包括PTM标识或者MBS会话信息。
第三方面，提供一种数据传输方法，该方法包括：目标接入网设备从源接入网设备接收切换请求消息，切换请求消息用于请求将终端设备从源接入网设备切换到目标接入网设备；目标接入网设备向源接入网设备发送第四信息，第四信息用于指示源接入网设备向目标接入网设备转发第一序列号SN之前的至少一个SN对应的终端设备的MBS业务数据。
基于上述技术方案，通过目标接入网设备向源接入网设备发送第四信息以指示源接入网设备向目标接入网设备转发第一序列号SN之前的至少一个SN对应的终端设备的MBS业务数据，实现了在MBS业务切换时，避免了不必要的基站之间的数据转发。
一种可能的设计中，在目标接入网设备向源接入网设备发送第四信息之前，该方法还包括：目标接入网设备从核心网网元获取第二SN信息；目标接入网设备根据第二SN信息，确定第一SN信息。其中，第一SN信息用于指示第一SN。
一种可能的设计中，目标接入网设备从核心网网元获取第二SN信息，包括：目标接入网设备向核心网网元发送路径切换请求消息，路径切换请求消息用于请求核心网网元切换终端设备的MBS业务数据的传输路径；目标接入网设备从核心网网元接收路径切换确认消息，路径切换确认消息包括第二SN信息。
一种可能的设计中，第一SN为PDCP SN、通用分组无线业务隧道协议(general packet radio service tunneling protocol，GTP)-用户面(user，U)SN或者服务质量流标识(quality of service flow ID，QFI)SN。
一种可能的设计中，PDCP SN和GTP-U SN之间存在预设的映射关系；或者，QFI与QFI SN的组合和PDCP SN之间存在预设的映射关系。基于该设计，保证了核心网给源接入网设备和目标接入网设备发送相同内容的数据具有相同的PDCP SN，避免终端设备在切换过程中出现数据包丢失，保证无损或者最小丢包切换。
第四方面，提供一种数据传输方法，该方法包括：源接入网设备向目标接入网设备发送切换请求消息，切换请求消息用于请求将终端设备从源接入网设备切换到目标接入网设备；源接入网设备从目标接入网设备接收第四信息，第四信息用于指示源接入网设备向目标接入网设备转发第一SN之前的至少一个SN对应的终端设备的MBS业务数据。
基于上述技术方案，通过目标接入网设备向源接入网设备发送第四信息以指示源接入网设备向目标接入网设备转发第一序列号SN之前的至少一个SN对应的终端设备的MBS业务数据，在切换场景下减少不必要的基站之间的数据转发。
一种可能的设计中，第一SN为PDCP SN、GTP-U SN或者QFI SN。
一种可能的设计中，PDCP SN和GTP-U SN之间存在预设的映射关系；或者，QFI与QFI SN的组合和PDCP SN之间存在预设的映射关系。基于该设计，保证了核心网给源接入网设备和目标接入网设备发送相同内容的数据具有相同的PDCP SN，避免终端设备在切换过程中出现数据包丢失，保证无损或者最小丢包切换。
第五方面，提供一种通信装置，该通信装置包括PDCP实体、第一RLC实体和第二RLC实体，第一RLC实体和第二RLC实体分别和PDCP实体关联，第一RLC实体用于支持PTM传输方式发送MBS业务数据，第二RLC实体用于支持PTP传输方式发送MBS业务数据，第一RLC实体和第二RLC实体关联到相同的MRB。第一RLC实体，用于向包括第一终端设备在内的至少一个终端设备发送至少一个RLC SDU。第二RLC实体，用于从第一终端设备接收第一信息，第一信息用于指示第一RLC SDU的RLC序列号SN，第一RLC SDU属于至少一个RLC SDU中未成功接收到的RLC SDU。第二RLC实体，还用于向第一RLC实体或者PDCP实体递交第二信息，第二信息指示第一RLC SDU的RLC SN。第一实体，用于向第一终端设备发送第一RLC SDU，第一实体为第一RLC实体或者第二RLC实体。
一种可能的设计中，第一实体为第一RLC实体；在第一实体，用于向第一终端设备发送第一RLC SDU之前，第一RLC实体，还用于根据第二信息，获取第一RLC SDU。
一种可能的设计中，第一实体为第二RLC实体；在第一实体，用于向第一终端设备发送第一RLC SDU之前，第一RLC实体还用于根据第二信息，向第二RLC实体递 交第一RLC SDU。
一种可能的设计中，在第一实体，用于向第一终端设备发送第一RLC SDU之前，PDCP实体，用于根据第二信息，向第一实体递交第一RLC SDU。
一种可能的设计中，第二信息包括第一RLC SDU的RLC SN。PDCP实体，具体用于根据第一RLC SDU的RLC SN，以及预设映射关系，确定第一PDCP PDU的PDCP SN，预设映射关系用于指示PDCP SN与RLC SN之间的映射关系；根据第一PDCP PDU的PDCP SN，获取第一PDCP PDU，第一PDCP PDU为第一RLC SDU；向第一实体递交第一RLC SDU。
一种可能的设计中，第二信息包括第一PDCP PDU的PDCP SN。PDCP实体，具体用于根据第一PDCP PDU的PDCP SN，获取第一PDCP PDU，第一PDCP PDU为第一RLC SDU；向第一实体递交第一RLC SDU。
一种可能的设计中，第二RLC实体，还用于根据第一RLC SDU的RLC SN，以及预设映射关系，确定第一PDCP PDU的PDCP SN，预设映射关系用于指示PDCP SN与RLC SN之间的映射关系。
一种可能的设计中，该通信装置还包括通信模块。通信模块，用于向第一终端设备发送第一指示信息，第一指示信息用于指示第一终端设备接收MBS业务数据的起始数据序列号信息。
一种可能的设计中，起始数据序列号信息包括PDCP SN、PDCP计数值和/或起始的RLC SN。
一种可能的设计中，通信模块，还用于向第一终端设备发送MRB配置信息，MRB配置信息用于配置第一终端设备与接入网设备之间的MBS会话。
一种可能的设计中，MRB配置信息包括PTM标识或者MBS会话信息。
一种可能的设计中，MRB配置信息包括两个RLC承载配置信息，两个RLC承载配置信息关联相同的MRB，两个RLC承载配置信息中至少一个RLC承载配置信息包括PTM标识或者MBS会话信息。
第六方面，提供一种通信装置，该通信装置包括第三RLC实体和第四RLC实体。第三RLC实体，用于接收接入网设备以PTM方式发送的MBS业务数据；第四RLC实体，用于接收接入网设备以PTP方式发送的MBS业务数据；第三RLC实体和第四RLC实体关联到相同的MRB。第三RLC实体，用于从接入网设备接收至少一个RLC SDU。第四RLC实体，用于从第三RLC实体接收第三信息，第三信息指示至少一个RLC SDU中第一RLC SDU的RLC SN。第四RLC实体，还用于根据第三信息生成第一信息；向接入网设备发送第一信息，第一信息用于指示第一RLC SDU的RLC SN，第一RLC SDU属于至少一个RLC SDU中未成功接收到的RLC SDU。
一种可能的设计中，第三RLC实体，还用于确定第一RLC SDU未成功接收到；根据第一RLC SDU的RLC SN生成第三信息。
一种可能的设计中，第三RLC实体，还用于确定至少一个RLC SDU中的第二RLC SDU成功接收到；根据第二RLC SDU的RLC SN生成第三信息。
一种可能的设计中，第四RLC实体，还用于在向接入网设备发送第一信息之后，从接入网设备接收第一RLC SDU。
一种可能的设计中，第三RLC实体，还用于从接入网设备接收第一RLC SDU。
一种可能的设计中，第三RLC实体，还用于向第四RLC实体指示成功接收到第一RLC SDU。
一种可能的设计中，该通信装置还包括通信模块。通信模块，用于从接入网设备接收第一指示信息，第一指示信息用于指示第一终端设备接收MBS业务数据的起始数据序列号信息。
一种可能的设计中，第一指示信息具体用于指示起始的PDCP SN、PDCP计数值和/或起始的RLC SN。
一种可能的设计中，通信模块，还用于从接入网设备接收MRB配置信息，MRB配置信息用于配置第一终端设备与接入网设备之间的MBS会话。
一种可能的设计中，MRB配置信息包括PTM标识或者MBS会话信息。
一种可能的设计中，MRB配置信息包含两个RLC承载配置信息，两个RLC承载配置信息关联相同的MRB，两个RLC承载配置信息中至少一个RLC承载配置信息包括PTM标识或者MBS会话信息。
第七方面，提供一种通信装置，包括：处理模块和与处理模块连接的通信模块。通信模块，用于从源接入网设备接收切换请求消息，切换请求消息用于请求将终端设备从源接入网设备切换到目标接入网设备。处理模块，用于生成第四信息，第四信息用于指示源接入网设备向目标接入网设备转发第一序列号SN之前的至少一个SN对应的终端设备的MBS业务数据。通信模块，还用于向源接入网设备发送第四信息。
一种可能的设计中，通信模块，还用于在向所述源接入网设备发送第四信息之前，从核心网网元获取第二SN信息；处理模块，还用于根据第二SN信息，确定第一SN信息。其中，第一SN信息用于指示第一SN。
一种可能的设计中，通信模块，还用于向核心网网元发送路径切换请求消息，路径切换请求消息用于请求核心网网元切换终端设备的MBS业务数据的传输路径；从核心网网元接收路径切换确认消息，路径切换确认消息包括第二SN信息。
一种可能的设计中，第一SN为PDCP SN、GTP-U SN或者QFI SN。
一种可能的设计中，PDCP SN和GTP-U SN之间存在预设的映射关系；或者，QFI与QFI SN的组合和PDCP SN之间存在预设的映射关系。
第八方面，提供一种通信装置，包括：处理模块和与处理模块连接的通信模块。处理模块，用于生成切换请求消息，切换请求消息用于请求将终端设备从源接入网设备切换到目标接入网设备。通信模块，用于向目标接入网设备发送切换请求消息。通信模块，还用于从目标接入网设备接收第四信息，第四信息用于指示源接入网设备向目标接入网设备转发第一序列号SN之前的至少一个SN对应的终端设备的MBS业务数据。
一种可能的设计中，第一SN为PDCP SN、GTP-U SN或者QFI SN。
一种可能的设计中，PDCP SN和GTP-U SN之间存在预设的映射关系；或者，QFI与QFI SN的组合和PDCP SN之间存在预设的映射关系。
第九方面，提供一种通信装置，所述通信装置包括处理器和收发器，处理器和收发器用于实现上述第一方面至第四方面中任一方面或其任一设计提供的方法。其中， 处理器用于执行相应方法中的处理动作，收发器用于执行相应方法中的接收/发送的动作。
第十方面，提供一种计算机可读存储介质，所述计算机可读存储介质存储计算机指令，当该计算机指令在计算机上运行时，使得计算机执行第一方面至第四方面的任一方面或其任一设计提供的方法。
第十一方面，提供一种包含计算机指令的计算机程序产品，当该计算机指令在计算机上运行时，使得计算机执行第一方面至第四方面中任一方面的任一设计提供的方法。
第十二方面，提供一种芯片，包括：处理电路和收发管脚，处理电路和收发管脚用于实现上述第一方面至第四方面或其任一设计提供的方法。其中，处理电路用于执行相应方法中的处理动作，收发管脚用于执行相应方法中的接收/发送的动作。
第十三方面，提供一种通信***，包括：上述第五方面或其任一设计提供的通信装置，以及上述第六方面或其任一设计提供的通信装置。
第十四方面，提供一种通信***，包括：上述第七方面或其任一设计提供的通信装置，以及上述第八方面或其任一设计提供的通信装置。
需要说明的是，上述第五方面至第十四方面中任一种设计所带来的技术效果可以参见第一方面至第四方面中任一方面中对应设计所带来的技术效果，此处不再赘述。
附图说明
图1为本申请实施例提供的一种MBS业务数据传输过程的示意图；
图2(a)为本申请实施例提供的一种空口协议栈的示意图；
图2(b)为本申请实施例提供的一种MBS业务数据经过空口协议栈传输的示意图；
图3为本申请实施例提供的一种发送窗口和接收窗口的示意图；
图4为本申请实施例提供的一种5G通信***的架构示意图；
图5为本申请实施例提供的一种CU-DU架构的示意图；
图6为本申请实施例提供的又一种CU-DU架构的示意图；
图7为本申请实施例提供的另一种CU-DU架构的示意图；
图8为本申请实施例提供的一种接入网设备的协议栈的架构示意图；
图9为本申请实施例提供的一种数据传输方法的流程图；
图10(a)为本申请实施例提供的另一种接入网设备的协议栈的架构示意图；
图10(b)为本申请实施例提供的另一种接入网设备的协议栈的架构示意图；
图11(a)为本申请实施例提供的一种终端设备的协议栈的架构示意图；
图11(b)为本申请实施例提供的一种MBS业务数据经过空口协议栈传输的示意图；
图12为本申请实施例提供的另一种数据传输方法的流程图；
图13(a)为本申请实施例提供的一种终端设备的协议栈的架构示意图；
图13(b)为本申请实施例提供的一种MBS业务数据经过空口协议栈传输的示意图；
图14为本申请实施例提供的另一种数据传输方法的流程图；
图15为本申请实施例提供的另一种数据传输方法的流程图；
图16为本申请实施例提供的另一种数据传输方法的流程图；
图17为本申请实施例提供的另一种数据传输方法的流程图；
图18为相关技术提供的一种切换流程的示意图；
图19为本申请实施例提供的另一种数据传输方法的流程图；
图20为本申请实施例提供的另一种数据传输方法的流程图；
图21为本申请实施例提供的另一种数据传输方法的流程图；
图22为本申请实施例提供的另一种数据传输方法的流程图；
图23为本申请实施例提供的一种通信装置的结构示意图；
图24为本申请实施例提供的另一种通信装置的结构示意图。
具体实施方式
在本申请的描述中，除非另有说明，“/”表示“或”的意思，例如，A/B可以表示A或B。本文中的“和/或”仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。此外，“至少一个”是指一个或多个，“多个”是指两个或两个以上。“第一”、“第二”等字样并不对数量和执行次序进行限定，并且“第一”、“第二”等字样也并不限定一定不同。
需要说明的是，本申请中，“示例性的”或者“例如”等词用于表示作例子、例证或说明。本申请中被描述为“示例性的”或者“例如”的任何实施例或设计方案不应被解释为比其他实施例或设计方案更优选或更具优势。确切而言，使用“示例性的”或者“例如”等词旨在以具体方式呈现相关概念。
在本申请的描述中，“指示”可以包括直接指示和间接指示，也可以包括显式指示和隐式指示。将某一信息所指示的信息称为待指示信息，则具体实现过程中，对所述待指示信息进行指示的方式有很多种。例如，可以直接指示所述待指示信息，其中所述待指示信息本身或者所述待指示信息的索引等。又例如，也可以通过指示其他信息来间接指示所述待指示信息，其中该其他信息与所述待指示信息之间存在关联关系。又例如，还可以仅仅指示所述待指示信息的一部分，而所述待指示信息的其他部分则是已知的或者提前约定的。另外，还可以借助预先约定(例如协议规定)的各个信息的排列顺序来实现对特定信息的指示，从而在一定程度上降低指示开销。
本申请实施例提供的技术方案可以应用于各种通信***，例如，长期演进(long term evolution，LTE)通信***，采用5G通信技术的新空口(new radio，NR)通信***，未来演进***或者多种通信融合***等等。本申请提供的技术方案可以应用于多种应用场景，例如，机器对机器(machine to machine，M2M)、宏微通信、增强型移动互联网(enhanced mobile broadband，eMBB)、超高可靠超低时延通信(ultra-reliable&low latency communication，uRLLC)以及海量物联网通信(massive machine type communication，mMTC)等场景。这些场景可以包括但不限于：终端设备与终端设备之间的通信场景，网络设备与网络设备之间的通信场景，网络设备与终端设备之间的通信场景等。下文中均是以应用于网络设备和终端设备之间的通信场景中为例进行说明的。
在本申请实施例中，接入网设备可以是无线通信的基站或基站控制器等。例如，所述基站可以包括各种类型的基站，例如：微基站(也称为小站)，宏基站，中继站，接入点等，本申请实施例对此不作具体限定。其中，所述基站可以是全球移动通信***(global system for mobile communication，GSM)，码分多址(code division multiple access，CDMA)中的基站(base transceiver station，BTS)，宽带码分多址(wideband code division multiple access，WCDMA)中的基站(node B)，长期演进(long term evolution，LTE)中的演进型基站(evolutional node B，eNB或e-NodeB)，物联网(internet of things，IoT)或者窄带物联网(narrow band-internet of things，NB-IoT)中的eNB，未来5G移动通信网络或者未来演进的公共陆地移动网络(public land mobile network，PLMN)中的gNB，本申请实施例对此不作任何限制。
在本申请实施例中，终端设备是一种具有无线收发功能的设备。终端设备可以被部署在陆地上，包括室内或室外、手持或车载；也可以被部署在水面上(如轮船等)；还可以被部署在空中(例如飞机、气球和卫星上等)。终端设备可以是用户设备(user equipment，UE)。其中，UE包括具有无线通信功能的手持式设备、车辆、车载设备、可穿戴设备或计算设备。示例性地，UE可以是手机(mobile phone)、平板电脑或带无线收发功能的电脑。终端设备还可以是虚拟现实(virtual reality，VR)终端设备、增强现实(augmented reality，AR)终端设备、工业控制中的无线终端设备、无人驾驶中的无线终端设备、远程医疗中的无线终端设备、智能电网中的无线终端设备、智慧城市(smart city)中的无线终端设备、智慧家庭(smart home)中的无线终端设备等等。本申请实施例中，用于实现终端设备的功能的装置可以是终端设备，也可以是能够支持终端设备实现该功能的装置，例如芯片***。本申请实施例中，芯片***可以由芯片构成，也可以包括芯片和其他分立器件。本申请实施例中，以用于实现终端设备的功能的装置是终端设备为例，描述本申请实施例提供的技术方案。
此外，本申请实施例描述的网络架构以及业务场景是为了更加清楚的说明本申请实施例的技术方案，并不构成对于本申请实施例提供的技术方案的限定，本领域普通技术人员可知，随着网络架构的演变和新业务场景的出现，本申请实施例提供的技术方案对于类似的技术问题，同样适用。
为了便于本领域技术人员的理解，下面先对一些技术术语进行介绍。
1、MBS业务传输架构
多播广播业务(multicast and broadcast service，MBS)是面向多个终端设备(user equipment，UE)的业务，例如直播业务、公共安全业务、批量软件更新业务等。
在本申请实施例中，组播为多播的一种具体方式，因此多播也可以称为组播。
示例性的，图1示出MBS业务数据的传输过程。如图1所示，数据服务器将MBS业务数据发送给核心网，然后核心网将MBS业务数据发送给基站，最后基站将MBS业务数据发送给接收MBS业务的至少一个UE。
其中，在MBS业务数据从核心网向基站发送的时候，有两种基本的传输方式。一种是5G核心网(5G Core,5GC)共享MBS业务传输模式(5GC shared MBS traffic  delivery method)，另一种是5GC单独MBS业务传输模式(5GC individual MBS traffic delivery method)。本文以5GC共享MBS业务传输模式为例，MBS业务数据通过核心网和基站之间一个公共的通用无线分组业务隧道协议(general packet radio service tunneling protocol，GTP)-用户面(user，U)通道进行传输，并且每一个MBS会话使用一个GTP-U通道。需要说明的是，一个MBS会话包含一个或多个服务质量(quality of service，QoS)流，一个MBS的这些QoS流在空口映射到一个或多个MBS无线承载(MBS radio bearer，MRB)。通常，不同的MRB具有不同的QoS需求或属于不同的MBS会话。不同MBS会话的QoS流不能映射到同一个MRB。
对于支持MBS的基站而言，在MBS业务数据从基站向UE发送的时候，有两种传输方式：第一种是PTM(point to multi-point，点到多点)传输方式；第二种是PTP(point to point，点到点)传输方式。其中，PTM传输方式也可以被称为组调度方式或者多播传输方式。此处支持MBS的基站即可以支持上述两种传输模式。
(1)PTM传输方式
PTM传输方式是指某种业务通过网络设备同时向多个终端设备发送数据的传输方式。在采用PTM传输时，针对同一数据，网络设备(例如基站)发送的过程中有多个终端设备同时进行接收。
LTE***中中PTM主要分为两种方式：多媒体广播多播单频网络业务(multicast broadcast single frequency network，MBSFN)方式和单小区点到多点业务(single cell point to multipoint，SC-PTM)方式。其中，MBSFN方式是指在MBSFN区域内多个互相同步的小区(属于不同的基站)同时向多个终端设备传输相同的信息，以提高终端设备接收信号的强度，同时消除了小区间的干扰。SC-PTM方式是指MBS业务只通过一个小区(例如一个基站)传输，一个网络设备同时对多个终端设备进行组调度。NR中的PTM和SC-PTM方式类似。
可选的，发送装置(不限于基站)采用PTM传输方式发送是指：发送装置发送协议数据单元(protocol data unit，PDU)对应的传输块(transport block，TB)时，采用分组无线网络临时标识(group radio network temporary identifier，G-RNTI)对物理下行控制信道(physical downlink control channel，PDCCH)和物理下行共享信道(physical downlink shared channel，PDSCH)分别进行加扰。
可选的，接收装置采用PTM传输方式接收是指：接收装置根据G-RNTI对PDCCH和PDSCH进行解扰接收，以获得PDU。
(2)PTP传输方式
PTP传输方式是指某种业务通过网络设备向一个终端设备发送数据的传输方式。在采用PTP传输时，针对同一数据，网络设备(例如基站)发送的过程中有一个终端设备同时进行接收。
可选的，发送装置采用PTP传输方式发送是指：发送装置发送PDU对应的TB时，采用小区无线网络临时标识(cell network temporary identifier，C-RNTI)对PDCCH和PDSCH分别进行加扰。
可选的，接收装置采用PTP传输方式接收是指：接收装置根据C-RNTI对PDCCH和PDSCH进行解扰接收，以获得PDU。
2、无线接入网的协议栈
接入网设备和终端设备具有一定的协议栈结构，以用于相互通信。
图2(a)示出一种接入网设备和终端设备的协议栈结构。如图2(a)所示，接入网设备或者终端设备的协议栈可以包括业务数据适配(service data adaptation protocol,SDAP)层、分组数据汇聚层协议(packet data convergence protocol，PDCP)层、无线链路控制(radio link control，RLC)层、媒体接入控制(media Access Link control，MAC)和物理层(physical layer，PHY)等。
其中，物理层位于最低层(也即层1)。MAC层、RLC层、PDCP层以及SDAP层属于第二层(也即层2)。
SDAP层，用于负责QoS流到无线承载的映射。PDCP层，用于负责用户面和控制面的数据传输、加密、完整性保护和头压缩等功能。RLC层，用于负责分段重组、自动请求重发(automatic repeat request，ARQ)等功能；MAC层完成数据调度以及逻辑信道与传输信道之间的映射等功能。PHY层，用于负责编解码、调制、解调、多天线映射等功能。
基于图2(a)所示的协议栈结构下，接入网设备和终端设备会为每个MBS会话创建一个SDAP实体，为每个MRB创建一个PDCP实体。每个PDCP实体可以对应一个或多个RLC实体。应理解，每个RLC实体对应一个逻辑信道。
示例性的，结合图2(b)来说明MBS业务数据经过无线接入网的协议栈传输的流程。MBS业务数据首先到达接入网设备的SDAP层，SDAP层根据接入网设备确定的QoS流到MRB的映射关系将MBS业务数据递交到对应的PDCP层。MBS业务数据经过接入网设备的PDCP层处理后依次递交到RLC层和MAC层，经过RLC层和MAC层处理之后，从物理层发送出去，通过空口传输给终端设备。终端设备的各个协议层按照与接入网设备相反的处理顺序对数据包依次进行对应的处理，从而接收到MBS业务数据。
应理解，MBS业务数据在每个层的时候都需要经过各个层的处理，每个层都有相应的功能实体来执行相应的功能，比如PDCP层的PDCP实体，或者RLC层的RLC实体。
3、RLC实体传输模式
RLC实体传输模式包括以下三种：
(1)透明模式(Transparent Mode，TM)：RLC实体对数据不作任何处理，只提供数据的透传(pass through)功能。采用该传输模式的RLC实体称为TM RLC实体，简称TM实体。
(2)非确认模式(Unacknowledged Mode，UM)：RLC实体提供除重传和重分段外的所有RLC功能，即使在数据包传输出错的情况下，该传输模式下的RLC实体也没有重传功能，只能提供一种不可靠的传输服务。采用该传输模式的RLC实体称为UM RLC实体，简称UM实体。
(3)确认模式(Acknowledged Mode，AM)：RLC实体提供所有RLC功能，包括ARQ功能，RLC实体通过出错检测和重传，提供了一种可靠的传输服务。采用该传输模式的RLC实体称为AM RLC实体，简称AM实体。
4、自动请求重发ARQ
ARQ是RLC确认模式的重要功能之一，ARQ通过检查接收到的PDU的序列号，可以检测出丢失的PDU并请求重传。
传统ARQ有三种基本类型：
(1)停等式(Stop-And-Wait，SAW)ARQ：在停等式ARQ中，数据帧发送完成之后，发送端等待接收端的状态报告，如果状态报告报文发送成功，发送后续的数据帧，否则重传该数据帧。
停等式ARQ，发送窗口和接收窗口大小均为1，发送方每发送一帧之后就必须停下来等待接收方的确认返回，仅当接收方确认正确接收后再继续发送下一帧。
(2)回退n帧(Go-Back-N，GBN)ARQ：发送端不用等待接收端的应答，持续的发送多个帧，假如发现已发送的帧中有错误发生，那么从那个发生错误的帧开始及其之后所有的帧全部再重新发送。
(3)选择性重传(selective repeat)ARQ：发送端不用等待接收端的应答，持续的发送多个帧，假如发现已发送的帧中有错误发生，那么发送端将只重新发送那个发生错误的帧。
NR中RLC确认模式与LTE中类似，但是NR中不支持确保按序递交的重排序。把按序递交从RLC中去除有助于减少总时延，因为后面的数据包可以立即转发，而不必等到先前丢失的数据包重传后再递交给高层。这对于减小缓冲区的内存需求也有积极意义。LTE中的RLC协议支持按序递交，一个RLC SDU要等到之前所有的SDU都正确接收到才能转发给高层。举个例子，由于瞬时的干扰突发丢失了一个SDU，会在相当长一段时间的阻塞后才可以进行SDU的递交。
确认模式的RLC实体是双向的，即数据可以在两个对等实体之间双向流动。接收SDU的实体需要给发送SDU的实体反馈确认。接收端以状态报告(status report)的形式将丢失的SDU的信息提供给发送端。状态报告可以由接收端主动发送或者发送端请求发送，为了跟踪传输中的SDU，报头里采用了序列号。
5、发送窗口和接收窗口
在确认模式下，RLC实体维护两个窗口，分别为发送窗口和接收窗口。对于发送端来说，位于发送窗口内的SDU才被允许发送，序列号小于窗口起始点的SDU是已经被接收端的RLC实体确认成功接收的SDU。对于接收端来说，接收端只能接收序列号在接收窗口内的SDU。由于接收端对于同一数据只需递交一份SDU给高层，因此接收端还会丢弃重复的SDU。
下面结合图3对发送窗口和接收窗口进行介绍。应理解，图3中仅显示了接收端的RLC实体的接收窗口，未显示发送窗口。图3中仅显示了发送端的RLC实体的发送端口，未显示接收窗口。
在t0时刻，发送端已经发送序列号为n和n之前的SDU，其中n-1和n-1之前的SDU已经被接收机确认。因此，发送端的发送窗口从n开始，即第一个未被确认的SDU。接收端的接收窗口从n+1开始，即下一个期望接收的SDU。
在t1时刻，发送端继续传输SDU。示例性的，由于发送窗口从n开始，因此发送端可以向接收端发送SDU n+1和SDU n+2。应理解，本申请实施例中SDU X，表示序 列号为X的SDU，X为任意正整数或者为0。
假设接收端成功接收到SDU n+2，而未成功接收到SDU n+1，则接收端不会更新接收窗口。接收端口可以启动t-Reassembly定时器，在t-Reassembly定时器超时之后丢失的SDU n＝1仍未成功接收到，则接收端可以请求发送端重传SDU n＝1。
在t2时刻，假设接收端成功接收到SDU n+1和SDU n+2，则接收端可以更新接收窗口的起始点，从而接收端的接收窗口的起始点从n+3开始。
6、通信***
通信***一般包括核心网和接入网。示例性的，图4示出本申请实施例提供的一种5G通信***的架构示意图。如图4所示，5G通信***包括下一代无线接入网络(next generation radio access network，NG-RAN)以及5G核心网(5G core network，5GC)。
5GC包括各种核心网设备，例如接入与移动管理功能网元(access and mobility management function，AMF)、用户面功能网元(user plane function，UPF)、会话管理功能网元(session management function，SMF)等。
AMF属于核心网实体，主要负责移动性管理处理部分，例如：接入控制、移动性管理、附着与去附着以及SMF选择等功能。AMF为终端设备中的会话提供服务的情况下，会为该会话提供控制面的存储资源，以存储会话标识、与会话标识关联的SMF标识等。
SMF主要用于会话管理、终端设备的互联网协议(internet protocol，IP)地址分配和管理、选择可管理用户平面功能、策略控制、或收费功能接口的终结点以及下行数据通知等。
UPF可用于分组路由和转发、或用户面数据的QoS处理等。用户数据可通过该网元接入到数据网络(data network，DN)。
上述AMF、SMF以及UPF仅是一个名称，对设备本身不构成限定。可以理解的是，在5G网络以及未来其它的网络中，AMF、SMF以及UPF也可以是其他的名称，本申请实施例对此不作具体限定。例如，UPF还可以被称为UPF网元或者UPF实体，在此进行统一说明，以下不再赘述。
可选的，核心网设备可以由一个设备实现，也可以由多个设备共同实现，还可以是一个设备内的一个功能模块，本申请实施例对此不作具体限定。可以理解的是，上述功能模块既可以是硬件设备中的网络元件，也可以是在专用硬件上运行的软件功能模块，或者是平台(例如，云平台)上实例化的虚拟化功能模块。
接入网包括接入网设备。以接入网设备为gNB为例，在通信***中，两个gNB之间存在接口，本文称之为Xn接口。gNB与5GC之间存在接口，本文称之为Ng接口。例如gNB和AMF之间为NG2接口，gNB和UPF之间为NG3接口。
7、集中式单元(centralized unit，CU)-分布式单元(distributed unit，DU)架构
如图5所示，gNB可以采用CU-DU架构。也即，gNB由CU和至少一个DU构成。这种情况下，gNB的部分功能部署在CU上，gNB的另一部分功能部署在DU上。多个DU可以共用同一个CU，以节省成本，以及易于扩展。
CU和DU是按照协议栈进行功能切分。作为一种实现方式，CU部署有协议栈中 的无线资源控制(radio Resource Control，RRC)层，PDCP层，以及业务数据适应协议(service data adaptation protocol，SDAP)层；DU部署有协议栈中的RLC层，媒体介入控制(media access control，MAC)层，以及物理层(physical layer，PHY)。从而，CU具有RRC、PDCP和SDAP的处理能力。DU具有RLC、MAC和PHY的处理能力。可以理解的是，上述功能的切分仅为一个示例，不构成对CU和DU的限定。也就是说，CU和DU之间还可以有其他功能切分的方式，本申请实施例在此不予赘述。
CU和DU之间通过F1接口连接。CU代表gNB通过NG接口和核心网连接，CU代表gNB通过Xn接口和其他gNB连接，CU还可以代表gNB通过X2接口和其他eNB连接执行双连接操作。可以理解的是，上述接口均为逻辑接口。在5G网络以及未来其他的网络中，上述接口还可以具有其他名称，本申请实施例对此不作限定。
更进一步的，如图6所示，CU还可以分为CU-CP以及CU-UP。其中CU-CP负责控制面功能，主要包含RRC和控制面对应的PDCP(即PDCP-C)。PDCP-C主要负责控制面数据的加解密，完整性保护，数据传输等。CU-UP负责用户面功能，主要包含SDAP和用户面对应的PDCP(即PDCP-U)。其中SDAP主要负责将核心网的数据进行处理并将flow映射到承载。PDCP-U主要负责数据面的加解密，完整性保护，头压缩，序列号维护，数据传输等。当然还有一种可能的实现是PDCP-C也在CU-UP。
其中CU-CP和CU-UP通过E1接口连接。CU-CP代表gNB通过NG接口和核心网连接。通过F1接口控制面即F1-C和DU连接。CU-UP通过F1接口用户面即F1-U和DU连接。
可选的，如图7所示，一个DU可以连接一个或多个CU-UP。一个CU-UP可以连接一个或多个DU。一个DU只能连接一个CU-CP。一个CU-CP可以连接一个或多个DU。一个CU-UP只能连接一个CU-CP。一个CU-CP可以连接一个或多个CU-UP。
以上是对本申请实施例所涉及的技术术语的介绍，以下不再赘述。
图8为本申请实施例提供的一种接入网设备的协议栈的架构示意图。可以理解的，接入网设备可以为其它通信装置，本申请不作限制。
如图8所示，接入网设备配置有PDCP实体、第一RLC实体和第二RLC实体。其中，第一RLC实体和第二RLC实体关联该PDCP实体，并且第一RLC实体和第二RLC实体关联到相关的MRB。
第一RLC实体用于支持PTM传输方式发送MBS业务数据。也即，第一RLC实体用于向至少一个终端设备发送MBS业务数据。
第二RLC实体用于支持PTP传输方式发送MBS业务数据。也即，第二RLC实体用于向一个终端设备(下面以第一终端设备为例)发送MBS业务数据。应理解，针对一个MRB，接入网设备侧的第二RLC实体可以是一个或多个。每个第二RLC实体对应一个终端设备。
示例性的，针对接入网设备，第一RLC实体可以称为mRLC实体，第二RLC实体可以称为pRLC实体。
应理解，接入网设备可以有图8中未示出的其他协议层，例如SDAP层、MAC层、物理层等，对此不作限定。
在接入网设备采用图8所示的架构的情况下，对于同一MBS业务，接入网设备可以灵活地切换使用PTP传输方式或PTM传输方式，以适应不同的应用场景，获得更好的传输效果。
一种ARQ技术中，支持AM模式的RLC实体在确定一个数据未成功传输的情况下，可以请求重传该未成功传输的数据。但是，在采用图8所示架构的接入网设备在采用PTM传输方式时，接入网设备中的第一RLC实体不支持AM模式，并且上述ARQ并不能从PDCP层获取请求重传数据。也即，针对接入网设备采用PTM传输方式来传输MBS业务数据的场景，上述ARQ技术无法直接应用，从而无法保证MBS业务数据的高可靠传输。本文主要考虑接入网设备侧的第一RLC实体和第二RLC实体如何交互实现RLC ARQ功能。
为了解决上述技术问题，本申请实施例提供一种数据传输方法，该方法可以应用于采用图8所示架构的接入网设备。如图9所示，该数据传输方法包括以下步骤：
S101、第一RLC实体向包括第一终端设备在内的至少一个终端设备发送至少一个RLC SDU。
其中，至少一个RLC SDU属于MBS业务数据。
作为一种可能的实现方式，PDCP实体将至少一个PDCP PDU(也即RLC SDU)递交给第一RLC实体。第一RLC实体以PTM传输方式向至少一个终端设备发送至少一个RLC SDU。
应理解，第一RLC实体向至少一个终端设备发送RLC SDU，可以具体实现为：第一RLC实体为RLC SDU添加RLC包头以生成RLC PDU；第一RLC实体向至少一个终端设备发送RLC PDU。
为了便于描述，以下将第一RLC实体所采用的工作模式称为改进的UM模式。
在本申请实施例中，采用改进的UM模式的第一RLC实体可以为每个RLC SDU都按序分配RLC SN。
可选的，第一RLC实体可以为每个RLC SDU均设置丢弃定时器(discard timer)。从而，在RLC SDU对应的丢弃定时器超时之后，第一RLC实体丢弃该RLC SDU。
可选的，第一RLC实体在通过RLC状态报告等机制确认一个RLC SDU被成功传输，或者在接收到PDCP实体针对该RLC SDU的丢弃指示之后，丢弃该RLC SDU。
S102、第二RLC实体从第一终端设备接收第一信息。
其中，第一信息用于指示至少一个RLC SDU的接收状态。也即，第一信息用于指示至少一个RLC SDU中的每一个RLC SDU是否成功接收到。例如，第一信息可以携带每个成功接收到的RLC SDU的RLC SN，或者只携带没有成功接收到的RLC SDU的RLC SN，或者其它方式，本申请各实施例不作限制。
第一RLC实体接收到第一信息(例如RLC Status Report)后，针对第一信息指示的“已经被UE成功接收的、RLC SN为x的RLC SDU”，不需要向PDCP层指示“传输成功”。具体地，以3GPP TS38.322 v16.1.0为例，可以修改如下：其中下划线部分为标准修改内容：
When receiving a positive acknowledgement for an RLC SDU with SN＝x,the  transmitting side of an AM RLC entity shall:
send an indication to the upper layers of successful delivery of the RLC SDU  except for  an AM RLC entity associated to an MRB；
set TX_Next_Ack equal to the SN of the RLC SDU with the smallest SN,whose SN falls within the range TX_Next_Ack<＝SN<＝TX_Next and for which a positive acknowledgment has not been received yet.
其译文如下：
当接收到一个SN为X的的RLC SDU的确认反馈之后，接收端的AM RLC实体应该：
除关联到MRB的AM RLC实体之外，该RLC实体应该向上层指示已经成功传输该RLC SDU，将TX_Next_Ack设置为具有最小SN的RLC SDU的SN，该RLC SDU的SN在TX_Next_Ack和还没有收到确认应答的TX_Next之间。
可选的，在本申请实施例中，第二RLC实体可以采用AM模式。
示例性的，第一信息用于指示第一RLC SDU的RLC SN，第一RLC SDU属于上述至少一个RLC SDU中未成功接收到的RLC SDU。
可选的，第一信息用于指示第一RLC SDU的RLC SN，可以采用以下设计中的任意一种：
设计1、第一信息包括第一RLC SDU的RLC SN。
设计2、第一信息包括RLC SN集合中的丢包起始RLC SN和丢包结束RLC SN。其中，RLC SN集合包括连续的多个未成功接收到的RLC SDU的RLC SN。应理解，所述多个未成功接收到的RLC SDU属于上述至少一个RLC SDU。第一RLC SDU为所述多个未成功接收到的RLC SDU中的任意一个。
举例来说，第一RLC实体发送了RLC SN#1～10的RLC SDU。对于第一终端设备来说，RLC SN分别为5,6,7,8的RLC SDU均未成功接收到。因此，丢包起始RLC SN即为RLC SN#5，丢包结束RLC SN即为RLC SN#8。从而，第一信息可以包括RLC SN#5和RLC SN#8。
应理解，第二RLC实体根据第一信息，可以确定第一RLC SDU的RLC SN。
可选的，第一信息还可以指示传输成功的、且RLC SN＝X的RLC SDU。针对传输成功的RLC SDU，第二RLC实体可以不用向PDCP层指示该RLC SDU传输成功。其中，X为正整数。
S103、第一实体向第一终端设备重传第一RLC SDU。
其中，第一实体可以为第一RLC实体或者第二RLC实体。
在本申请各实施例中，如果特殊说明，在接入网设备接收到第一信息之后，第一实体向终端设备发送第一RLC SDU，指的是第一实体向第一终端设备重传第一RLC SDU，即将第一RLC实体发送过的第一RLC SDU进行重传，换言之，第一实体重传的第一RLC SDU和第一实体之前发送的第一RLC SDU的内容完全相同。例如，接收网设备可以在第一RLC实体发送第一RLC SDU时，将该第一RLC SDU的一个备份缓存在一个缓存器中，当第一实体需要发送(重传)该第一RLC SDU时，再从该缓存 器中获取该备份的第一RLC SDU。本申请各实施例对上述备份方式、以及从缓存器中获取方式不作任何限定。
以第一实体为第二RLC实体为例，在重传第一RLC SDU之前，第二RLC实体获取第一RLC SDU，可以采用以下方式1-方式4中的任意一种：
方式1、第二RLC实体从自身缓存区域中获取第一RLC SDU。
可选的，在上述步骤S101之前，也即在所述至少一个RLC SDU的初传过程中，PDCP实体会将所述至少一个RLC SDU复制成多份，分别递交给第一RLC实体和第二RLC实体。第一RLC实体在获取到上述至少一个RLC SDU之后，按照步骤S101来传输所述至少一个RLC SDU。而PDCP实体会指示第二RLC实体缓存所述至少一个RLC SDU，以避免第二RLC实体初传所述至少一个RLC SDU。在需要重传第一RLC SDU的时候，第二RLC SDU可以根据第一RLC SDU的RLC SN，从自身的缓存区域中查找到第一RLC SDU。
也即，第二RLC实体首次收到PDCP发送的PDCP PDU(即RLC SDU)时，保存在自身缓存区不发送。只有当收到终端设备反馈的第一信息后，第二RLC实体才获取第一RLC SDU并向第一终端设备重传第一RLC SDU。
方式2、第二RLC实体从共享缓存区域中获取第一RLC SDU。其中，共享缓存区域即为第一RLC实体和第二RLC实体均能使用的缓存区域。
示例性的，第一RLC实体会将所述至少一个RLC SDU缓存在共享缓存区域。在需要重传第一RLC SDU的时候，第二RLC SDU可以根据第一RLC SDU的RLC SN，从共享缓存区域中查找到第一RLC SDU。
可选的，第二RLC实体可以根据自身的配置或者PDCP实体的指示，不对共享缓存区域中存储的数据进行初传。
方式3、第二RLC实体从第一RLC实体获取第一RLC SDU。
作为一种可能的实现方式，第二RLC实体向第一RLC实体递交第二信息，该第二信息用于指示第一RLC SDU。第一RLC实体根据第二信息，获取第一RLC SDU。第一RLC实体向第二RLC实体递交第一RLC SDU。
方式4、第二RLC实体从PDCP实体获取第一RLC SDU。
作为一种可能的实现方式，第二RLC实体向PDCP实体递交第二信息，该第二信息用于指示第一RLC SDU。PDCP实体根据第二信息，向第二RLC实体递交第一PDCP PDU(即第一RLC SDU)。
应理解，PDCP PDU和RLC SDU即为不同协议层对同一数据的不同称呼。
应理解，上述方式1至方式4仅是示例，不构成具体限定。
以第一实体为第一RLC实体为例，在重传第一RLC SDU之前，第一RLC实体获取第一RLC SDU，可以采用以下方式5-方式6中的任意一种：
方式5、第一RLC实体获取第一RLC SN。
作为一种可能的实现方式，第二RLC实体向第一RLC实体递交第二信息，第二信息用于指示第一RLC SN。第一RLC根据第二信息，获取第一RLC SDU。
方式6、第一RLC实体从PDCP实体获取第一RLC SN。
作为一种可能的实现方式，第二RLC实体向PDCP实体递交第二信息，该第二信 息用于指示第一RLC SDU。PDCP实体根据第二信息，向第一RLC实体递交第一PDCP PDU(即第一RLC SDU)。
应理解，上述方式5或方式6仅是示例，不构成具体限定。
可选的，针对方式3或方式5，第二信息可以包括第一RLC SDU的RLC SN。
可选的，针对方式4或方式6，第二信息可以包括第一RLC SDU的RLC SN。或者，第二信息可以包括第一PDCP PDU的PDCP SN。
示例性的，第二RLC实体可以根据第一RLC SDU的RLC SN，以及第一预设映射关系，确定第一PDCP PDU的PDCP SN。其中，第一预设映射关系用于指示PDCP SN与RLC SN之间的映射关系。进而，第二RLC实体可以将第一RLC SDU对应的PDCP PDU的PDCP SN封装在第二信息中。
示例性的，若第二信息包括第一RLC SDU的RLC SN，则PDCP实体根据第二信息，向第一实体递交第一RLC SDU，可以具体实现为：PDCP实体根据第一RLC SDU的RLC SN，以及第一预设映射关系，确定第一RLC SDU对应的第一PDCP PDU的PDCP SN。之后，PDCP实体根据第一PDCP PDU的PDCP SN，获取第一PDCP PDU；PDCP实体向第一实体递交第一PDCP PDU(即第一RLC SDU)。
示例性的，若第二信息包括第一PDCP PDU的PDCP SN，则PDCP实体根据第二信息，向第一实体递交第一RLC SDU，可以具体实现为：PDCP实体根据第一PDCP PDU的PDCP SN，获取第一PDCP PDU；PDCP实体向第一实体递交第一PDCP PDU(即第一RLC SDU)。
在本申请实施例中，第一预设映射关系可以是协议约定的，或者核心网(或网管)配置给接入网设备的。为了支持第一预设映射关系，RLC SN的尺寸(size)应该小于或等于PDCP SN的尺寸，以保证一个PDCP SN仅能推导出唯一的一个RLC SN。其中，上述尺寸也可以称为长度，也即指序列号占用比特的数目。
示例性的，第一映射关系可以为：RLC SN＝PDPC SN mod(max RLC SN+1)。其中，max RLC SN表示RLC SN所能够取的最大值。
本申请实施例中第一RLC实体和第二RLC实体根据第一预设映射关系，对PDCP实体递交过来的、相同内容的PDCP PDU进行相同的RLC SN编号，从而保证第一RLC实体和第二RLC实体可以根据同一RLC SN，获取到相同的RLC SDU，进而保证RLC SDU准确地进行重传。
可选的，在本申请实施例中，考虑到第一RLC实体和第二RLC实体应采用相同的RLC SN尺寸，以及RLC SN尺寸不大于PDCP SN尺寸，因此本申请实施例中的RLC SN尺寸支持12bit。
应理解，本申请实施例中的RLC SN尺寸并不是固定的。在协议中更改了RLC SN在AM模式和/或UM模式下的尺寸，或者更改了PDCP SN尺寸的情况下，本申请实施例中的RLC SN尺寸也可以更改。
可选的，在第一RLC实体(或者PDCP实体)从第二RLC实体接收到第二信息之后，第一RLC实体(或者PDCP实体)可以根据预设的重传规则，决定采用多播PTM方式重传数据，还是采用单播PTP方式重传数据。
应理解，第一RLC实体(或者PDCP实体)决定采用多播PTM方式重传数据， 也就是说：第一RLC实体(或者PDCP实体)决定由第一RLC实体来重传数据。第一RLC实体(或者PDCP实体)决定采用单播PTP方式重传数据，也就是说：第一RLC实体(或者PDCP实体)决定由第二RLC实体来重传数据。
示例性的，重传规则可以为：第一RLC实体(或者PDCP实体)在预设时间段内接收到超过预设数目的第二信息，则第一RLC实体(或者PDCP实体)决定由第一RLC实体重传第一RLC SDU；否则，第一RLC实体(或者PDCP实体)决定由第二RLC实体重传第一RLC SDU。
示例性的，重传规则可以为：第一RLC实体(或者PDCP实体)在预设时间段内接收到超过预设数目的用于触发重传数据的信息，则第一RLC实体(或者PDCP实体)决定由第一RLC实体重传数据；否则，第一RLC实体(或者PDCP实体)决定由第二RLC实体重传数据。应理解，重传的数据可以为第一RLC实体在之前一段时间内发送的RLC SDU。
应理解，不同终端设备对应的第二RLC实体向第一RLC实体或PDCP实体递交的用于触发重传数据的信息，可以指示不同的RLC SDU未成功接收到。
基于图9所示的实施例，接入网设备通过第一RLC实体以PTM方式传输MBS业务数据，以第二RLC实体来获取终端设备针对MBS业务数据的接收状态。进而，接入网设备可以确定需要重传的MBS业务数据，并通过第一RLC实体或第二RLC实体重传MBS业务数据。可见，本申请所提供的技术方案能够使得ARQ机制应用于PTM传输方式，保证MBS业务数据的高可靠传输。
可选的，接入网设备可以向终端设备发送MAC CE，以指示终端设备PTM传输方式和PTP传输方式之间的切换。
例如，在步骤S101之前，接入网设备可以向至少一个终端设备发送用于激活PTM的MAC CE。终端设备在接收到用于激活PTM的MAC CE之后，监听G-RNTI加扰的PDCCH和PDSCH，并按照图9所示的方法执行相应的步骤。
又例如，接入网设备可以向一个或多个终端发送用于去激活PTM的MAC CE。终端设备在接收到该用于去激活PTM的MAC CE之后，停止监听G-RNTI加扰的PDCCH和PDSCH，使用PTP模式监听C-RNTI加扰的PDCCH和PDSCH并进行对应的MBS业务数据的传输与重传。
可选的，若接入网设备一次仅对一个终端设备发送用于去激活PTM的MAC CE，则接入网设备可以用C-RNTI加扰调度该MAC CE对应的PDCCH和PDSCH。
可选的，若接入网设备针对MRB所涉及的所有终端设备进行PTM去激活，则接入网设备可以采用G-RNTI加扰调度该MAC CE的PDCCH和PDSCH。
可选的，在接入网设备采用CU-DU架构的情况下，图8所示的协议栈架构可以具体实现为图10(a)或者图10(b)所示的协议栈架构。
示例性的，如图10(a)所示，针对同一个MBS业务/MRB，gNB-CU配置有PDCP实体，gNB-DU配置有第一RLC实体和第二RLC实体。第一RLC实体和第二RLC实体使用同一个F1-U隧道来与PDCP实体通信，即第一RLC实体和至少一个第二RLC实体共享F1-U隧道。即F1-U隧道和MBS业务/MRB对应，MBS业务/MRB和PDCP实体,第一RLC实体以及第二RLC实体对应，因此F1-U隧道和第一RLC实体对应。
可选的，基于图10(a)所示架构，当第一RLC实体和第二RLC实体采用同一个FI-U隧道与PDCP实体通信时，对于gNB-DU从F-U隧道从gNB-CU的PDCP实体获取到的数据包，gNB-DU可以根据数据包的F1-U报头上携带的终端设备的F1-U UE的标识，将数据包递交到该终端设备对应的的第二RLC实体。若F1-U报头未携带任何中终端设备的标识，则gNB-DU将数据包递交到F1-U隧道对应的第一RLC实体。
示例性的，如图10(b)所示，gNB-CU配置有PDCP实体，gNB-DU配置有第一RLC实体和第二RLC实体。第一RLC实体和第二RLC实体分别采用不同的F1-U隧道来与PDCP实体通信。即第一RLC实体，以及每个第二RLC实体都对应各自的F1-U隧道，根据F1-U隧道可以确定第一RLC实体或者终端设备关联的第二RLC实体。
应理解，本申请实施例中适用于采用图8所示架构的接入网设备的方法(例如图9所示的数据传输方法)，同样适用于采用图10(a)或图10(b)所示架构的接入网设备。
可选的，在接入网设备采用CU-DU架构的情况下，gNB-CU-UP的PDCP实体在向gNB-DU中的第一RLC实体和/或第二RLC实体递交PDCP PDU时，gNB-CU-UP通过F1-U隧道的GTP-U报文携带的PDCP PDU中包含的PDCP SN，以向第一RLC实体和/或第二RLC实体指示F1-U隧道所传输的PDCP PDU的PDCP SN。从而，gNB-DU中的第一RLC实体和/或第二RLC实体可以根据PDCP SN，以及第一预设映射关系，将相同内容(相同PDCP SN)的数据映射到相同的RLC SN。
可选的，在配置MRB对应的逻辑信道时，CU可以通过F1-C隧道向DU指示DU侧的每个无线承载或逻辑信道的类型，以确定无线承载或逻辑信道中的数据是采用PTP模式或者PTM模式进行传输。
可选的，在配置MRB对应的逻辑信道时，CU向DU指示DU侧逻辑信道与RNTI的绑定关系。例如，某个逻辑信道绑定C-RNTI，则逻辑信道的数据对应的PDSCH或PDCCH采用C-RNTI进行加扰，采用单播方式进行发送。又例如，某个逻辑信道绑定G-RNTI，则该逻辑信道的数据对应的PDSCH或PDCCH采用G-RNTI进行加扰，采用多播或广播方式进行发送。
示例性地，一种可能是CU确定每个无线承载或逻辑信道对应的PTP/PTM类型。例如CU可以在F1AP消息(例如UE context setup/modification request)中包含MRB ID/数据无线承载(data radio bearer，DRB)标识(identity，ID)/逻辑信道标识(logical channel identity,LCID)以及对应的PTP/PTM指示。例如MRB/DRB ID#1对应PTP或C-RNTI，MRB/DRB ID#2对应PTM或G-RNTI，或者LCID#1对应PTP或C-RNTI，LCID#2对应PTM或G-RNTI。
另一种可能是CU确定每个无线承载对应的PTP/PTM类型，DU基于此确定每个逻辑信道对应的PTP/PTM类型。例如CU可以在F1AP消息中包含MRB/DRB ID以及对应的PTP/PTM指示。例如MRB/DRB ID#1对应PTP+PTM方式或者说C-RNTI+G-RNTI方式，MRB/DRB ID#2对应PTP或C-RNTI方式，则DU可以为MRB/DRB ID#1配置关联的两个LCID，例如LCID#1对应PTP或C-RNTI，LCID#2对应PTM或G-RNTI。为MRB/DRB#2配置关联的1个LCID，例如LCID#2对应PTP或C-RNTI。即针对PTP方式，后续PDCCH和PDSCH用C-RNTI进行加扰和解扰。针对PTM方 式，后续PDCCH和PDSCH用G-RNTI进行加扰和解扰。具体地，PTP/PTM类型可以定义PTP/PTM type信元，该信元取值可以为{0,1,2}，例如0对应PTP方式或者C-RNTI方式，1对应PTM方式或者G-RNTI方式，2对应PTP+PTM或者C-RNTI+G-RNTI方式。其他类似的表示方法不再赘述。
下面从终端设备的角度来介绍本申请实施例提供的数据传输方法。
示例性的，图11(a)示出一种终端设备的协议栈的架构示意图。
可以理解的，终端设备可以为其它通信装置，本申请不作限制。
如图11(a)所示，终端设备可以配置第三RLC实体和第四RLC实体。其中，第三RLC实体和第四RLC实体关联到相同的MRB。其中，第三RLC实体用于接收接入网设备以PTM方式发送的MBS业务数据。第四RLC实体用于接收接入网设备以PTP方式发送的MBS业务数据。
如图11(a)所示，终端设备还配置有PDCP实体。第三RLC实体和第四RLC实体分别关联该PDCP实体。PDCP实体和一个MBS业务或者MRB对应，相应地，第三RLC实体和第四RLC实体和一个MBS业务或MRB对应。
可选的，如图11(b)所示，采用图11(a)所示架构的终端设备与采用图8所示架构的接入网设备之间传输MBS业务数据时，第三RLC实体用于与接入网设备的第一RLC实体通信，第四RLC实体用于与接入网设备侧该终端设备对应的第二RLC实体通信。
如图12所示，为本申请实施例提供的一种数据传输方法，该方法应用于采用图11(a)所示的架构的第一终端设备。该方法包括以下步骤：
S201、第三RLC实体从接入网设备接收至少一个RLC SDU。
可选的，在接入网设备采用图8所示的架构的情况下，步骤S201可以具体实现为：第三RLC实体从接入网设备的第一RLC实体接收至少一个RLC SDU。
为了便于描述，以下将第三RLC实体所采用的工作模式称呼为改进的UM模式或者改进的AM模式。
在本申请实施例中，采用改进的UM模式的第三RLC实体会向第四RLC实体反馈RLC SDU的接收状态。示例性的，第三RLC实体可以向第四RLC实体递交第三信息，第三信息用于指示第一RLC SDU的RLC SN。
S202、第三RLC实体向第四RLC实体递交第三信息。相应的，第四RLC实体从第三RLC实体获取第三信息。
其中，第三信息用于指示第一RLC SDU的RLC SN。
可选的，第三RLC实体可以通过以下实现方式来生成第三信息。
实现方式1、第三RLC实体确定第一RLC SDU未成功接收到。第三RLC实体根据第一RLC SDU的RLC SN，生成第三信息。
可选的，基于实现方式1，第三信息可以包括第一RLC SDU的RLC SN。
可选的，基于该实现方式1，第三RLC实体根据RLC SN维持接收窗口(类似UM拉窗机制)。基于接收窗口，第三RLC实体可以确认未成功接收到的RLC SDU(例如第一RLC SDU)。
可选的，基于实现方式1，第四RLC实体可以不用维持接收窗口。
实现方式2、第三RLC实体确定至少一个RLC SDU中的第二RLC SDU成功接收到。第三RLC实体根据第二RLC SDU的RLC SN，生成第三信息。
可选的，基于实现方式2，第三信息可以包括第二RLC SDU的RLC SN。
可选的，基于实现方式2，第三RLC实体可以不用维护接收窗口，也即第三RLC实体可以不用确认未成功接收的RLC SDU。第三RLC实体通过向第四RLC实体递交第三信息，以使得第四RLC实体获知第三RLC实体每一个成功接收到的RLC SDU。相应的，第四RLC实体需要根据RLC SN维持接收窗口(类似AM推窗机制)。从而，第四RLC实体根据第三信息，可以确定未成功接收到的RLC SDU(例如第一RLC SDU)的RLC SN。
可选的，第一终端设备接收接入网设备发送的RRC重配置消息，RRC重配置消息包括MRB配置信息。当MRB配置信息所配置的2个逻辑信道(logical channel，LCH)关联到相同的DRB或者MRB，同时其中一个LCH关联到某个MBS会话，则第一终端设备可以确定该DRB/MRB其实是MRB。并且，当第一终端设备的RRC模块确定MRB配置信息所配置的第四RLC实体是AM模式时，RRC模块会通知第三RLC实体后续根据实现方式1或者实现方式2给第四RLC实体发送第三信息。
S203、第四RLC实体根据第三信息，获取第一信息。
其中，第一信息用于指示第一RLC SDU的RLC SN。
作为一种可能的实现方式，在第三信息基于上述实现方式1来生成的情况下，第四RLC实体可以根据第三信息，确定第一RLC SDU的RLC SN，进而生成第一信息。或者，第四RLC实体可以直接将第三信息作为第一信息。
作为另一种可能的实现方式，在第三信息基于上述实现方式2来生成的情况下，第四RLC实体根据第三信息，确定第二RLC SDU的RLC SN。之后，第四RLC实体根据第二RLC SDU的RLC SN，确定第一RLC SDU的RLC SN。第四RLC实体根据第一RLC SDU的RLC SN，生成第一信息。关于第一信息的描述，可以参考上述实施例中的内容，在此不作赘述。
S204、第四RLC实体向接入网设备发送第一信息。
可选的，在接入网设备采用图8所示的架构的情况下，步骤S204可以具体实现为：第四RLC实体向接入网设备的第二RLC实体发送第一信息。
可选的，在第四RLC实体发送第一信息之后，第四RLC实体可以为待重传的RLC SDU设置相应的定时器。在定时器到时前，如果第一终端设备接收到该RLC SDU，则将定时器清零。或者，在定时器超时的情况下，如果第一终端设备还未接收该RLC SDU，则第四RLC实体可以再次触发接入网设备重传该RLC SDU，例如第四RLC实体可以再次发送第一信息。
可选的，第四RLC实体可以为待重传的RLC SDU设置最大重传次数。在触发重传的次数大于最大重传次数之后，第四RLC实体可以通知高层(例如RRC层)发生无线链路失败。
一种可能的设计中，在接入网设备接收到第一信息之后，接入网设备的第一RLC实体可以重传第一RLC SDU。相应的，第一终端设备的第三RLC实体从接入网设备的第一RLC实体接收重传的第一RLC SDU。
可选的，在第三RLC实体接收到重传的第一RLC SDU之后，第三RLC实体可以向第四RLC实体指示成功接收到第一RLC SDU。从而，第四RLC实体在获知第一RLC SDU成功接收到的情况下，可以清理第一RLC SDU对应的定时器，或者推动接收窗口，或者删除第一RLC SDU的RLC SN，以便不再次触发给接入网设备发送第一信息。
另一种可能的设计中，在接入网设备接收到第一信息之后，接入网设备的第二RLC实体可以重传第一RLC SDU。相应的，第一终端设备的第四RLC实体从接入网设备的第二RLC实体接收重传的第一RLC SDU。
可选的，若第四RLC实体从第三RLC实体获知第一RLC SDU成功接收到，或者，第四RLC实体成功接收到第一RLC SDU，则第四RLC实体可以清理第一RLC SDU对应的定时器，或者推动接收窗口，或者删除第一RLC SDU的RLC SN，以便不再次触发给接入网设备发送第一信息。
基于图12所示的实施例，第一终端设备通过第三RLC实体接收接入网设备以PTM方式传输的MBS业务数据；第三RLC实体通过向第四RLC实体发送第三信息，以触发第四RLC实体向接入网设备发送第一信息，以使得接入网设备获知第一RLC SDU未成功接收到。可见，本申请实施例所提供的技术方案能够使得ARQ机制可以应用于MBS业务数据传输场景中，保证MBS业务数据的高可靠传输。
示例性的，图13(a)示出另一种终端设备的协议栈的架构示意图。如图13(a)所示，终端设备可以配置PDCP实体和第五RLC实体，第五RLC实体关联终端设备的PDCP实体，并且第五RLC实体关联MBS业务或MRB。即MRB业务或MRB和PDCP实体以及第五RLC实体对应。
如图13(b)所示，采用图13(a)所示架构的终端设备与采用图8所示架构的接入网设备之间传输MBS业务数据时，第五RLC实体用于与接入网设备的第一RLC实体通信，第五RLC实体用于与接入网设备的第二RLC实体通信。
应理解，终端设备仅配置一个RLC实体来支持与接入网设备进行PTM传输方式和PTP传输方式，有利于简化终端设备的RLC配置。
如图14所示，为本申请实施例提供的一种数据传输方法，该方法应用于采用图13(a)所示架构的第一终端设备。该方法包括以下步骤：
S301、第五RLC实体从接入网设备接收至少一个RLC SDU。
可选的，在接入网设备采用图8所示的架构的情况下，步骤S301可以具体实现为：第五RLC实体从接入网设备的第一RLC实体接收至少一个RLC SDU。
应理解，第五RLC实体采用AM模式。
S302、第五RLC实体生成第一信息。
作为一种可能的实现方式，第五RLC实体维持接收窗口，并根据接收窗口确定未成功接收的RLC SDU(例如第一RLC SDU)的RLC SN。从而，第五RLC实体可以根据未成功接收的RLC SDU的RLC SN，生成第一信息。
S303、第五RLC实体向接入网设备发送第一信息。
可选的，在接入网设备采用图8所示的架构的情况下，步骤S303可以具体实现为：第五RLC实体向接入网设备的第二RLC实体发送第一信息。
示例性的，第五RLC实体向底层(例如物理层)递交第一信息。底层使用C-RNTI对第一信息进行加扰，并将加扰后的第一信息发送给接入网设备。接入网设备的底层在接收到加扰后的第一信息之后，根据第一信息加扰所使用的C-RNTI进行解扰，将第一信息递交给相应的第二RLC实体。
可选的，针对采用图8所示的架构的接入网设备，接入网设备在接收到第一信息之后，接入网设备的第一RLC实体或第二RLC实体可以重传第一RLC SDU。相应的，第一终端设备的第五RLC实体可以从接入网设备的第一RLC实体或第二RLC实体接收重传的第一RLC SDU。
基于图14所示的实施例，第一终端设备的第五RLC实体来接收接入网设备以PTM方式传输的MBS业务数据，并且第五RLC实体可以向接入网设备发送第一信息，以使得接入网设备获知第一RLC SDU未成功接收到。可见，本申请实施例所提供的技术方案能够使得ARQ机制可以应用于MBS业务数据传输场景中，保证MBS业务数据的高可靠传输。
可选的，如图15所示，为本申请实施例提供的一种数据传输方法，该方法包括以下步骤：
S401、接入网设备生成第一指示信息。
其中，第一指示信息用于指示第一终端设备接收MBS业务数据的起始数据序列号信息。
示例性的，起始数据序列号信息包括起始的PDCP SN、PDCP计数值(count)和/或起始的RLC SN。例如下一个接收RX_NEXT和递交接收RX_DELIV所对应的PDCP SN，PDCP计数值(count)和/或RLC SN。
可选的，起始的PDCP SN、PDCP计数值或者起始的RLC SN不为0。
示例性的，第一指示信息可以承载于PTM激活信令中，或者包含在RRC重配置消息中，本申请实施例对此不作限制。
S402、接入网设备向第一终端设备发送第一指示信息。相应的，第一终端设备从接入网设备接收第一指示信息。
作为一种可能的实现方式，在初始接入MBS会话或者切换到PTM模式等情况下，接入网设备可以向第一终端设备发送第一指示信息。
基于图15所示的实施例，接入网设备通过向第一终端设备发送第一指示信息，使得第一终端设备中的RLC实体可以按照第一指示信息来设置相应的接收窗口的起始点，而不必将接收窗口的起始点设置为0。
应理解，图15所示的实施例可以和前述图8、图12或图14所示的实施例相互结合使用。
可选的，如图16所示，为本申请实施例提供的一种数据传输方法，该方法包括以下步骤：
S501、接入网设备生成MRB配置信息。
其中，MRB配置信息用于配置第一终端设备和接入网设备之间的MRB会话。
可选的，为了避免混淆MRB与DRB或者信令无线承载(signal radio bearer，SRB)，因此协议可以预先定义MRB专用的无线承载标识。从而，MRB配置信息所包括的无 线承载标识属于MRB专用的无线承载标识。
MRB配置信息包括PTM标识和/或MBS会话信息。示例性的，MBS会话信息可以包括临时移动组标识(temporary mobile group identity，TMGI)。或者，MBS会话信息可以包含TMGI和会话标识。
下面分别针对第一终端设备采用图11(a)或图13(a)所示的协议栈的架构，对MRB配置信息进行具体说明。
(1)针对第一终端设备采用图11(a)所示的协议栈的架构，MRB配置信息包括两个RLC承载配置信息，两个RLC承载配置信息关联相同的MRB，两个RLC承载配置信息中至少一个RLC承载配置信息包括PTM标识和/或MBS会话信息。
(2)针对第一终端设备采用图13(a)所示的协议栈的架构，MRB配置信息可以包括RLC承载配置信息，RLC承载配置信息用于为第一终端设备配置处理MBS业务的第五RLC实体。RLC承载配置信息包括第一LCID和第二LCID，第一LCID关联PTM标识或者MBS会话信息。
示例性的，PTM标识可以以MBSPTMindication信元的形式来实现。MBS会话信息可以以associatedMBSSession信元的形式存在。也即，RLC承载信息包括MBSPTMindication信元，相当于RLC承载信息包含PTM标识。RLC承载信息包括associatedMBSSession信元，相当于RLC承载信息包含MBS会话信息。
示例性的，在RLC承载配置信息包含的LCID采用PTM方式时，RLC承载配置信息可以包括PTM标识和/或MBS会话信息。
举例进行说明，RLC承载配置信息包括LCID＝1和LCID＝2，假设LCID＝1绑定到DRB＝1或MRB＝1，同时绑定MBS会话MBSSessionInfo＝TMGI#1，或者对应MBSPTMindication。LCID＝2也绑定到DRB＝1或MRB＝1。从而，可以说明LCID＝1和LCID＝2对于的DRB＝1其实是MRB。其中，LCID＝1对应PTM方式，对应第一终端设备的第三RLC实体。LCID＝2对应PTP方式，连接到第一终端设备的第四RLC实体。
一种可能的设计中，RLC承载配置信息可以为如下格式，其中下划线部分为标准新增内容：
Figure PCTCN2021071956-appb-000001
Figure PCTCN2021071956-appb-000002
其中，在RLC承载配置信息还增加了associatedMBSSession信元，associatedMBSSession信元用于承载MBS会话信息。associatedMBSSession信元存在的条件是PTM-leg。也即，当RLC承载配置信息中的LCID对应PTM-leg时，RLC承载配置信息包括associatedMBSSession信元。
一种可能的设计中，RLC承载配置信息可以为如下格式，其中下划线部分为标准新增内容：
Figure PCTCN2021071956-appb-000003
其中，在RLC承载配置信息还增加了MBSPTMIndicationd信元，MBSPTMIndicationd信元用于指示该LCH是否关联PTM标识。MBSPTMIndicationd信元的存在条件是PTM-leg。也即，当RLC承载配置信息中的LCID对应PTM-leg时，RLC承载配置信息包括MBSPTMIndicationd信元，并且MBSPTMIndicationd信元的取值为“是(true)”。
一种可能的设计中，RLC承载配置信息可以为如下格式，其中下划线部分为标准新增内容：
Figure PCTCN2021071956-appb-000004
Figure PCTCN2021071956-appb-000005
其中，本申请实施例提供的RLC承载配置信息在servedRadioBearer信元中增加了可选的mrb-Identity。另外，在RLC承载配置信息还增加了associatedMBSSession信元，associatedMBSSession信元用于承载MBS会话信息。associatedMBSSession信元存在的条件是PTM-leg。也即，当RLC承载配置信息中的LCID对应PTM-leg时，RLC承载配置信息包括associatedMBSSession信元。
针对图13(a)所示的终端设备的协议栈的架构示意图，一种可能的设计中，RLC承载配置信息可以为如下格式，其中下划线部分为标准新增内容：
Figure PCTCN2021071956-appb-000006
针对图13(a)所示的终端设备的协议栈的架构示意图，一种可能的设计中，RLC承载配置信息可以为如下格式，其中下划线部分为标准新增内容：
Figure PCTCN2021071956-appb-000007
Figure PCTCN2021071956-appb-000008
示例性的，RLC承载配置信息可以增加“mrb-ToAddModList”信元，或者RLC承载配置信息所包含的LCID属于MBS业务专用的逻辑信道标识范围内，又或者RLC承载配置信息包括MBS相关指示信息，从而可以使得第一终端设备获知该RLC承载配置信息所配置的RLC实体用于处理MBS业务。
可选的，协议可以预先定义MBS业务专用的逻辑信道标识范围。即UE收到配置信息中包含属于逻辑信道标识范围内的逻辑信道标识，则认为该逻辑信道对应MBS业务。
示例性的，RLC承载配置信息可以为如下格式，其中下划线部分为标准新增内容：
Figure PCTCN2021071956-appb-000009
其中，本申请实施例在RLC承载配置信息的服务无线承载(servedRadioBearer)信元中增加了mrb-标识(Identity)这一内容。
可选的，在协议没有定义MBS业务专用的逻辑信道标识范围的情况下，如果第一终端设备在接收MBS业务时发送MBS业务相关的LCID与自身正在使用的单播LCID相同时，第一终端设备可以通知网络侧重新配置MBS业务相关的LCID，以避免MBS业务传输与单播业务传输发生冲突。
可选的，在第一终端设备从空闲态(IDLE)/非激活态(INACTIVE)切换为RRC连接态时，第一终端设备可以通知接入网设备其感兴趣的MBS业务对应的LCID，以保证接入网设备在后续流程中不向第一终端设备配置这些LCID用于单播无线承载的逻辑信道。
应理解，将单播无线承载对应的LCID和MRB对应的LCID设置为不同的值，其目的在于，避免MAC层在接收到物理层递交上来的MAC PDU进行解复用时无法根据MAC子头中的LCID来判断对应的MAC sub-SDU是DRB还是MRB的。
S502、接入网设备向第一终端设备发送MRB配置信息。相应的，第一终端设备从接入网设备接收MRB配置信息。
应理解，由于MRB配置信息包括PTM标识或者MBS会话信息，因此第一终端设备可以获知该MRB配置信息用于配置MRB。
示例性的，该MRB配置信息可以承载于RRC重配置消息中。
基于图16所示的实施例，接入网设备通过向第一终端设备发送MRB配置信息，以使得第一终端设备获知自身的RLC层的相关配置。
应理解，图16所示实施例可以和前述图8、图12、图14或图15所示实施例相互结合使用。
可选的，以下结合图17进行举例说明图16所示的数据传输方法应用在MBS会话建立的场景。如图17所示，该方法包括以下步骤：
S601、第一终端设备向移动管理网元发送PDU会话建立请求(PDU session establishment request)消息。
其中，PDU会话建立请求消息用于请求建立PDU会话。第一终端设备通过接入网设备向移动管理网元发送PDU会话建立请求。
在本申请实施例中，该PDU会话建立请求消息包括MBS会话指示信息，该MBS会话指示信息用于表示PDU会话建立请求消息所请求建立的PDU会话为MBS会话。
可选的，MBS会话指示信息可以为MBS业务专用的会话标识。或者，MBS会话指示信息可以为设置为预设值的会话类型，例如，MBS会话指示信息可以为取值为“MBS”的会话类型。应理解，MBS会话指示信息还可以采用其他实现方式，对此不作限定。
移动管理网元在接收到PDU会话建立请求消息之后，可以选择为第一终端设备提供服务的会话管理网元。会话管理网元可以获取第一终端设备的签约信息，以判断第一终端设备是否有权限建立MBS会话指示信息所指示的MBS会话。如果第一终端设备具有相应的权限，会话管理网元可以进一步执行PDU会话建立的流程。从而，移动管理网元可以执行下述步骤S602。
S602、移动管理网元向gNB-CU发送PDU会话资源建立请求(PDU session resource setup request)消息。
其中，PDU会话资源建立请求消息包括N2会话管理信息和目的节点为第一终端设备的PDU会话建立接受(PDU session establishment accept)消息。
N2会话管理信息包括与所请求建立的MBS会话对应的shared N3 GTP-U Tunnel信息。
可选的，若在步骤S601之前，第一终端设备所请求的MBS会话对应的shared N3 GTP-U Tunnel还未建立，则shared N3 GTP-U Tunnel信息可以包括以下参数中的一项或多项：MBS会话标识、TMGI、隧道端点标识(tunnel endpoint identifier，TEID)或MBS会话的QoS流信息。其中，MBS会话的QoS信息可以包括QoS流标识和QoS参数。
可选的，若在步骤S601之前，第一终端设备所请求的MBS会话对应的shared N3 GTP-U Tunnel已建立，则shared N3 GTP-U Tunnel信息可以仅包括MBS会话标识或者MBS会话对应的TEID。
S603、gNB-CU向移动管理网元发送PDU会话资源建立响应(PDU session resource setup response)消息。
gNB-CU在接收到PDU会话资源建立请求之后，可以根据N2会话管理信息和自身当前的网络负载等情况进行会话接纳控制。之后，gNB-CU可以根据接纳结果向移动管理网元发送PDU会话资源建立响应消息。其中，PDU会话资源建立响应消息可以包含第一终端设备所请求的MBS会话是否被gNB-CU接纳的信息。
S604、gNB-CU向gNB-DU发送MBS上下文建立请求(MBS context setup request)消息。
其中，MBS上下文建立请求消息包括MBS会话对应的TMGI，以及一个或多个MRB配置信息。
TMGI通常用于PTM传输模式时对PDCCH进行加扰。对该TMGI对应的MBS业务感兴趣的终端设备利用该TMGI去解扰PDCCH以判断是否有该MBS业务的数据被PDCCH调度。
可选的，接入网设备还可以使用TMGI对应的G-RNTI对PDCCH和PDSCH进行加扰。相应的，终端设备可以使用TMGI对应的G-RNTI对PDCCH和PDSCH进行解扰。
MRB配置信息包括一个或多个QoS流的QoS参数。可选的，MRB配置信息还可以包括shared F1 GTP-U Tunnel信息，比如CU侧的TEID等。
可选的，MBS上下文建立请求消息还可以包括以下信息中的一项或多项：TMGI、MBS会话标识、MBS本地区域(local area)信息、MBS业务模式(traffic pattern)信息、服务PLMN ID、服务网络标识(network ID，NID)。
其中，MBS local area信息用于指示适用于传输MBS业务数据的地理区域。示例性的，MBS local area信息可以包括小区列表或者业务区域标识列表。
MBS traffic pattern信息用于指示MBS业务数据的生成规律，例如MBS业务数据生成的周期、数量、生成起始时刻等。
服务PLMN ID用于指示MBS业务所属的运营商。
服务NID用于指示私网场景下MBS业务所属的私网。
可选的，gNB-DU在接收到MBS上下文建立请求消息之后，可以为MBS业务的每个MRB分别配置一个共享RLC实体(也即图8中的第一RLC实体)，共享RLC实体的数据递交给底层以PTM方式在空口进行传输。
S605、gNB-DU向gNB-CU发送MBS上下文建立响应(MBS context setup response) 消息。
其中，MBS上下文建立响应信息可以包括MRB对应的shared F1 GTP-U Tunnel信息，比如DU侧的TEID等。
应理解，步骤S604-S605的主要目的在于在gNB-DU和gNB-CU之间配置MBS会话对应的MRB，例如配置MRB对应的shared F1 GTP-U Tunnel。可选的，若MBS session对应的shared F1 GTP-U Tunnel已经存在时，可以选择不执行上述步骤S604-S605。
在gNB-DU和gNB-CU之间建立了MRB对应的shared F1 GTP-U Tunnel之后，gNB-DU可以从shared F1 GTP-U Tunnel接收到数据并去除GTP-U报头后交给该隧道对应的共享RLC实体(第一RLC实体)或第二RLC实体处理，具体往哪个RLC实体递交的方法参见前文。
S606、gNB-CU向gNB-DU发送UE上下文修改请求(UE context modification request)消息。
其中，UE上下文修改请求消息包括第一终端设备所请求的MBS业务对应的一个或多个MRB配置信息。其中，MRB配置信息至少包括MRB ID。
例如，UE上下文修改请求消息包括“MRB建立列表(MRB to be setup list)”信元，该“MRB to Be Setup List”IE进一步包含每个MRB的MRB ID。
一种可能的设计中，gNB-DU在接收到UE上下文修改请求消息之后，为MBS业务的每个MRB生成一个单独RLC实体(也即图8中的第二RLC实体)。这样一来，针对MRB所涉及的所有终端设备，gNB-DU可以配置一个第一RLC实体。针对MRB所涉及的所有终端设备中的每一个终端设备，gNB-DU可以分别配置一个第二RLC实体。从而，对于同一个MRB来说，gNB-DU可以有一个第一RLC实体和至少一个第二RLC实体。可选的，这些RLC实体对应的逻辑信道可以具有不同的LCID或者相同的LCID。
另一种可能的设计中，针对MRB所涉及的所有终端设备，gNB-DU可以仅为一个MRB配置一个AM模式的RLC实体。基于该设计，gNB-CU向gNB-DU发送的MRB配置信息需要携带该MRB对应的所有终端设备的C-RNTI。
可选的，当gNB-DU仅为一个MRB配置一个AM模式的RLC实体时，只有在MRB所涉及的所有终端设备反馈的RLC状态报告信息均确认RLC SN＝X的RLC SDU成功接收的情况下，该RLC实体才确认RLC SN＝X的RLC SDU已成功传输，从而可以进行相应的RLC AM模式操作，例如发送窗口移动和数据丢弃等。
应理解，第一RLC实体以PTM方式在空口传输MBS业务数据，第二RLC实体以PTP方式在空口传输MBS业务数据。针对PTP方式，gNB-DU的物理层以C-RNTI加扰包含调度授权的PDCCH。针对PTM方式，gNB-DU的物理层以G-RNTI加扰包含调度授权的PDCCH。
其中，每个终端设备具有自身的C-RNTI，也即不同终端设备配置有不同的C-RNTI。
G-RNTI在一般情况下是与MBS业务的标识(例如TMGI)一一对应的。但是，如果支持多个MBS业务复用在一个MAC PDU中，G-RNTI也可以对应多个MBS业务。
可选的，当gNB-DU的MAC层接收到MRB对应的LCID的上行数据时，可以根据上行数据加扰的C-RNTI，将该上行数据递交给为C-RNTI对应的终端设备提供服务的第二RLC实体进行处理。示例性的，MRB对应的LCID的上行数据可以为图9所示实施例中的第一信息。
可选的，当第一RLC实体接收到对应的PDCP实体发送的用于指示丢弃RLC SDU的指示信息时，如果被指示丢弃的RLC SDU交给过第二RLC实体，则第一RLC实体需要向第二RLC实体发送用于指示丢弃RLC SDU的指示信息。
S607、gNB-DU向gNB-CU发送UE上下文修改响应(UE context modification response)消息。
S608(可选的)、gNB-CU向UE发送MBS控制信息(MBS control info)。
其中，MBS控制信息包括UE所请求的MBS业务的TMGI。
可选的，MBS控制信息还可以包括MBS业务对应的MBS调度图案信息。其中，MBS调度图案信息用于指示传输MBS业务数据的时域资源位置和/或频域资源位置。示例性的，MBS调度图案信息包括以下参数中的一项或者多项：调度/传输周期、时间偏置、起始位置、频域资源位置。频域资源位置可以为带宽部分(bandwidth part,BWP)等，对此不作限定。
可选的，MBS控制信息可以通过***信息和/或MBS控制信道来发送。
可选的，在发送MBS控制信息之前，gNB-DU或gNB-CU可以发送寻呼(paging)消息或其他类型的通知消息，以使得第一终端设备获知MBS控制信息有更新。这样，第一终端设备可以准确接收到MBS控制信息，以获知新的MBS业务开始。
S609、gNB-CU向第一终端设备发送RRC重配置(RRC reconfiguration)消息。
其中，RRC重配置消息包含MBS业务对应的一个或多个MRB配置信息。可选的，MRB配置信息用于对PDCP层和RLC层进行配置。
在本申请实施例中，RRC重配置消息所包含的MRB配置信息可以参考图16所示的步骤S501中提及的MRB配置信息，在此不再赘述。
可选的，RRC重配置消息可以包含PDU会话建立接受消息。或者，gNB-CU可以通过另外的RRC消息向第一终端设备发送PDU会话建立接受消息。
S610、第一终端设备向gNB-CU发送RRC重配置完成(RRC reconfiguration complete)消息。
基于图17所示的实施例，在MBS会话建立的过程中，gNB和第一终端设备均可以进行相应的RLC层的配置，以使得gNB和第一终端设备可以执行图9所示的数据传输方法。
应理解，图17所示的实施例仅介绍了PDU会话建立流程的一部分步骤。PDU会话建立流程还可以包括其他步骤，在此不予赘述。
应理解，图17所示的实施例主要从接入网设备采用CU-DU架构的角度进行描述，实际上其也适用于接入网设备的其他架构，例如gNB一体化架构、或者gNB-CU CP/UP分离的架构等。其中，在图17所示实施例应用于gNB一体化架构的情况下，gNB-CU和gNB-DU之间的信息交互即为gNB的内部操作。
目前，由于终端设备具有移动性，当终端设备移动出当前连接的接入网设备的服 务范围时，可能会影响到终端设备的通信。因此，在终端设备的移动过程中，可以通过切换流程来将终端设备从源接入网设备切换到目标接入网设备，以保证终端设备的通信的连续性以及服务质量。
示例性的，如图18所示，相关技术提供的切换流程包括以下步骤：
S701、终端设备向源接入网设备发送测量报告(measurement report)。
作为一种可能的实现方式，在切换准备阶段，处于RRC连接态的终端设备可以根据源接入网设备配置的测量上报触发准则，发送测量报告。
S702、源接入网设备根据测量报告，确定目标接入网设备。
作为一种可能的实现方式，源接入网设备根据测量报告以及无线资源管理(radio resource manage，RRM)算法，确定终端设备是否满足切换条件。在终端设备满足切换条件的情况下，源接入网设备确定目标接入网设备。
S703、源接入网设备向目标接入网设备发送切换请求消息。
其中，切换请求消息可以包括终端设备的上下文。
S704、目标接入网设备向源接入网设备发送切换请求确认消息。
其中，切换请求确认消息可以包括目标接入网设备为终端设备分配的C-RNTI以及其他参数。
可选的，在源接入网设备接收到切换确认请求消息之后，源接入网设备可以准备将分组数据转发给目标接入网设备。
S705、源接入网设备向终端设备发送切换命令(handover command)。
其中，切换命令可以包括：目标接入网设备为终端设备分配的C-RNTI、随机接入信道(random access channel,RACH)参数、终端设备的协议层配置信息。其中，终端设备的协议层配置信息可以用于配置PHY、MAC、RLC、PDCP、SDAP等协议层。
可选的，终端设备在接收到切换命令之后，停止与源接入网设备进行上行数据或者下行数据传输，并准备与目标接入网设备进行同步。
可选的，终端设备不停止与源接入网设备进行数据传输，直至终端设备与目标接入网设备完成同步。
源接入网设备可以向目标接入网设备发送来自终端设备的上行数据和/或来自用户面网元的下行数据。
S706、源接入网设备向目标接入网设备发送SN状态信息(SN status transfer)。
S707、终端设备与目标接入网设备进行同步和随机接入流程。
基于步骤S707，终端设备可以获知上行的定时以及上行资源分配。
S708、终端设备向目标接入网设备发送切换确认消息。
其中，切换确认消息用于指示切换完成。
S709、目标接入网设备向源接入网设备发送切换完成消息。
其中，切换完成消息用于触发源接入网设备释放终端设备的上下文信息。
之后，目标接入网设备可以通知核心网网元更新终端设备的数据转发的目的接入网设备，以使得核心网可以将终端设备的数据转发给目标接入网设备。
当图18所示的切换流程直接应用在MBS业务传输场景时，存在几种场景：1)源基站支持MBS，目标基站支持MBS；2)源基站支持MBS，目标基站不支持MBS； 3)源基站不支持MBS，目标基站支持MBS；4)源基站不支持MBS，目标基站不支持MBS。对于源基站不支持MBS的情况，核心网在收到目标基站的path switch之后，就不会继续给源基站发送给终端设备的MBS数据，源基站将缓存数据包转发给目标基站即可。对于源基站支持MBS的情况，目标站不支持MBS的情况，本文不做展开。对于源站支持MBS，目标站也支持MBS的情况。由于源基站不会由于UE的离开而停止从核心网接收MBS业务的数据，即在UE移动后，源站还会从MBS UPF源源不断收到MBS业务的数据。因此源基站不知道将哪些MBS业务的数据data forwarding给目标基站。目标基站需要明确告知源站：是否需要做data forwarding。如果需要，data forwarding到哪个SN号为止。否则，源接入网设备和目标接入网设备之间可能在切换流程中产生较多不必要的数据转发，导致***资源的浪费。
针对MBS传输场景，为了解决在切换流程中源基站不知道该data forwarding哪些MBS业务的数据包从而减少不必要的数据转发，本申请实施例提供一种数据传输方法。如图19所示，该数据传输方法包括以下步骤：
S801、源接入网设备向目标接入网设备发送切换请求信息。相应的，目标接入网设备从源接入网设备接收切换请求消息。
其中，切换请求消息用于请求将终端设备从源接入网设备切换到目标接入网设备。切换请求消息中包含MBS会话的相关信息，例如MBS会话对应的TMGI，MBS会话标识，MRB ID，MRB ID对应的QoS flow标识以及QoS参数等。从而目标接入网设备获知终端设备当前包含哪个MBS会话的业务。
S802、目标接入网设备向源接入网设备发送第四信息。相应的，源接入网设备从目标接入网设备接收第四信息。
其中，第四信息用于指示源接入网设备向目标接入网设备转发给终端设备的第一SN之前的至少一个SN对应的MBS业务数据。
可选的，“转发给终端设备的第一SN之前的至少一个SN对应的MBS业务数据”，可以包括转发第一SN对应的MBS业务数据；或者，不包括转发第一SN对应的MBS业务数据。
应理解，第一SN可以有其他名称，例如最后转发的SN(last forwarding SN)，对此不作限定。
可选的，第四信息可以包括第一SN信息。示例性的，第一SN可以为PDCP SN、COUNT值、GTP-U SN或者QFI和对应的QFI SN。其中COUNT值包含PDCP SN和超帧号(hyper frame number，HFN)。具体地，第四信息可能为以下几种类型：1)MBS会话信息(TMGI和/或MBS会话标识)以及对应的PDCP SN(或COUNT值)；2)MBS会话信息，MRB ID和对应的PDCP SN(或COUNT值)；3)MBS会话信息，QFI以及对应的QFI SN；3)MBS会话信息和GTP-U SN号。
示例性地，第四信息可以包含在目标接入网设备给源接入网设备发送的切换请求确认消息中。
下面结合不同的应用场景来进行介绍。
场景一、目标接入网设备与核心网网元之间还未建立MBS会话对应的用户面隧道。以下将MBS会话对应的用户面隧道简称为MBS隧道。其中，该MBS隧道是用 于传输终端设备的MBS业务数据的用户面隧道。示例性的，上述MBS隧道可以为Shared N3 GTP-U Tunnel。
示例性的，该核心网网元可以为用户面网元，对此不作限定。
基于场景一，目标接入网设备可以从核心网网元获取第二SN信息；目标接入网设备根据第二SN信息，确定第一SN信息。其中，第二SN信息用于指示第二SN，第一SN信息用于指示第一SN。第二SN为第一SN的下一个SN，或者第二SN等于第一SN。
示例性的，目标接入网设备向核心网网元发送路径切换请求消息，路径切换请求消息用于请求核心网网元切换终端设备的MBS业务数据的传输路径。目标接入网设备从核心网网元接收路径切换确认消息，路径切换确认消息包括第二SN信息。例如路径切换确认消息中包含的第二SN信息可以是1)MBS会话信息以及对应的GTP-U SN号；或者2)MBS会话信息，QFI以及QFI SN号。可选地，所述第二SN，或者第二SN和其他信息可以包含在其他目标接入网设备和核心网网元之间的接口消息中。当目标接入网设备从核心网网元获取MBS会话信息以及对应的GTP-U SN时，目标接入网设备确定第一SN信息为MBS会话信息和GTP-U SN。或者目标接入网设备确定GTP-USN对应的PDCP SN(或COUNT值)，从而确定第一SN信息为MBS会话信息和PDCP SN(或COUNT值)，或者MBS会话信息，MRB ID和对应的PDCP SN(或COUNT值)。当目标接入网设备从核心网网元获取MBS会话信息，QFI以及对应的QFI SN号时，目标接入网设备确定第一SN信息为MBS会话信息，QFI以及对应的QFI SN号。
可选的，第二SN为核心网网元向目标接入网设备发送的第一个终端设备的MBS业务数据对应的SN。
应理解，第二SN可以有其他名称，例如第一个转发的SN(first SN)，对此不作限定。
场景二、目标接入网设备与核心网网元之间已建立MBS隧道。
基于场景2，目标接入网设备可以通过该MBS隧道从核心网网元获取并缓存终端设备的MBS业务数据。
一种可能的设计中，目标接入网设备可以在接收到切换请求消息之后，向源接入网设备发送第四信息。第四信息包括第一SN，该第一SN为目标接入网设备所缓存的终端设备的第一个MBS业务数据对应的SN。
另一种可能的设计中，目标接入网设备在接收到切换请求消息之后，接收源接入网设备发送的SN状态报告信息，SN状态报告信息指示第三SN，第三SN为SN状态报告信息所指示的MBS业务对应的下一个COUNT值(包含PDCP SN和超帧号HFN)，即目标接入网设备根据第三SN可以获知当UE接入目标接入网设备后，应该从哪个COUNT值开始给UE下发MBS业务的数据。在第一SN大于第三SN的情况下，目标接入网设备向源接入网设备发送第四信息。第四信息包括第一SN，该第一SN为目标接入网设备所缓存的终端设备的第一个MBS业务数据对应的SN。
在本申请实施例中，为了保证目标接入网设备和源接入网设备对于相同内容的数据具有相同的编号(例如PDCP SN)，可以协议规定第二预设映射关系，或者核心网 或者网管配置第二预设映射关系。
示例性的，第二预设映射关系为PDCP SN(或COUNT值)和所述GTP-U SN之间的预设映射关系。或者，第二预设映射关系为QFI与QFI SN的组合和所述PDCP SN(或COUNT值)之间的预设映射关系。
以第二预设映射关系为PDCP SN(或COUNT值)和所述GTP-U SN之间的预设映射关系为例进行介绍。其中，PDCP SN(或COUNT值)的尺寸小于或等于GTP-U SN的尺寸，以保证一个GTP-U SN仅能推导出唯一个的一个PDCP SN。
可选的，由于当前协议中PDCP SN size为12bit或18bit，而GTP-U SN size为16bit，从而为了保证PDCP SN的尺寸小于或等于GTP-U SN的尺寸，本申请实施例中的PDCP SN size可以仅支持12bit。
应理解，本申请实施例中的PDCP SN的尺寸并不是固定的。在协议中更改了PDCP SN的尺寸，或者更改了GTP-U SN的尺寸的情况下，本申请实施例中的PDCP SN的尺寸也可以更改。
可选的，第二预设映射关系可以为PDCP_SN＝GTP-U SN mod(max PDCP SN+1)。其中，maxPDCP SN为PDCP SN最能取的最大值。
基于图19所示的实施例，在切换流程中，目标接入网设备通过向源接入网设备发送第四信息，以使得源接入网设备向目标接入网设备转发第一SN之前的至少一个SN对应的终端设备的MBS业务数据，而不是转发终端设备的所有MBS业务数据，从而减少了需要转发的数据的数目，有利于节省***开销。
另外，源接入网设备将第一SN之前的至少一个SN对应的终端设备的MBS业务数据转发给目标接入网设备，可以实现切换过程中无损或者最小丢包传输。
针对MBS传输场景，在切换之前，目标接入网设备可能已与核心网网元建立MBS会话对应的用户面隧道，目标接入网设备可以从核心网网元获取终端设备的MBS业务数据。但是，源接入网设备并不能感知目标接入网设备已与核心网网元建立MBS会话对应的用户面隧道这一信息，因此在切换过程中，源接入网设备按照图18所示的切换流程执行时，源接入网设备会向目标接入网设备转发不必要的MBS数据，从而导致***资源的浪费。
因此，针对目标接入网设备在切换前已与核心网网元建立MBS会话对应的隧道的场景，为了减少在切换流程中不必要的数据转发，本申请实施例提供一种数据传输方法。如图20所示，该数据传输方法包括以下步骤：
S901、源接入网设备向目标接入网设备发送切换请求信息。相应的，目标接入网设备从源接入网设备接收切换请求消息。
其中，切换请求消息用于请求将终端设备从源接入网设备切换到目标接入网设备。
切换请求消息中包含MBS会话的相关信息，例如MBS会话对应的TMGI，MBS会话标识，MRB ID，MRB ID对应的QoS flow标识以及QoS参数等。从而目标接入网设备获知终端设备当前包含哪个MBS会话的业务。
S902、目标接入网设备向源接入网设备发送第五信息。相应的，源接入网设备从目标接入网设备接收第五信息。
其中，第五信息用于指示源接入网设备不用向目标接入网设备转发终端设备的 MBS业务数据。
一种可能的设计中，在步骤S901之前，目标接入网设备与核心网网元之间已经建立MBS隧道。并且，目标接入网设备已对从MBS隧道接收到的MBS业务数据进行足够长时间的缓存，因此目标接入网设备可以在接收到终端设备切换之后从自身的缓存中获取终端设备在源接入网设备的接收断点处的MBS业务数据，并将该MBS业务数据发送给终端设备，以保证终端设备对MBS业务数据的接收连续性。针对这一情况，目标接入网设备无需从源接入网设备获取MBS业务数据，因此目标接入网设备可以向源接入网设备发送第五信息。
另一种可能的设计中，在步骤S901之前，目标接入网设备与核心网网元之间已经建立MBS隧道。目标接入网设备从MBS隧道接收并缓存了终端设备的一些MBS业务数据。在目标接入网设备接收到切换请求消息之后，接收源接入网设备发送的SN状态报告信息，SN状态报告信息指示第三SN，第三SN为SN状态报告信息所指示的第一个未成功接收的MBS业务数据对应的SN。在第一SN小于等于第三SN的情况下，目标接入网设备向源接入网设备发送第五信息。
上述MBS隧道用于传输终端设备正在接收的MBS业务数据。示例性的，上述MBS隧道可以为Shared N3 GTP-U Tunnel。
可选的，为了保证核心网发送给源接入网设备和目标接入网设备的相同内容的数据具有相同的PDCP SN，可以协议规定第二预设映射关系，或者核心网或者网管配置第二预设映射关系。其中，第二预设映射关系的具体介绍可以参考图19所示实施例中的描述，在此不再赘述。
示例性的，第五信息可以承载于切换请求确认消息中。
一种可能的设计中，第五信息可以为“不用转发”指示，或者“MBS已经存在”指示。应理解，“MBS已经存在”指示用于指示目标接入网设备已经缓存MBS业务数据。
另一种可能的设计中，切换请求确认消息中不携带MBS会话的Xn转发隧道信息，以隐含指示切换请求确认消息包含第五信息。
示例性的，第三代合作伙伴计划(3rd generation partnership project，3GPP)38.423协议中定义切换请求确认消息包括：“来自目标接入网设备的数据转发信息(data forwarding info from target NG-RAN node)”信元。在本申请实施例中，若切换请求确认消息不包括“data forwarding info from target NG-RAN node”信元，隐式指示切换请求确认消息包含第五信息。
基于图20所示的实施例，在切换流程中，目标接入网设备通过向源接入网设备发送第五信息，以使得源接入网设备不用向目标接入网设备转发终端设备的MBS业务数据，从而减少了需要转发的数据的数目，有利于节省***开销。
应理解，图19或图20仅介绍了切换流程中的一部分步骤。切换流程中的其他部分，在此不再赘述。
目前，在CU-DU架构下，同一个gNB-CU可能同时连接支持MBS业务的gNB-DU和不支持MBS业务的gNB-DU。MBS数据在UPF到gNB-CU之间是以共享的传输模式进行传输。如果gNB-DU不支持MBS业务，则gNB-CU到gNB-DU之间的F1- U接口应该建立单独的传输通道；如果gNB-DU支持MBS业务，则gNB-CU到gNB-DU之间的F1-U接口建立共享的传输通道。但是，目前gNB-CU不能准确获知gNB-DU是否支持MBS业务，因此gNB-CU不能准确确定应与gNB-DU建立的传输通道的类型。
为了解决这一技术问题，本申请实施例提供一种数据传输方法。如图21所示，该数据传输方法包括以下步骤：
S1001、gNB-DU生成第一能力指示信息。
其中，第一能力指示信息用于指示gNB-DU对MBS的空口支持能力。也就是说，第一能力指示信息可以用于指示gNB-DU是否支持MBS。或者说，第一能力指示信息用于指示gNB-DU是否可以支持空口广播以及组播MBS业务。
S1002、gNB-DU向gNB-CU发送第一能力指示信息。相应的，gNB-CU从gNB-DU获取第一能力指示信息。
示例性的，第一能力指示信息承载在F1AP消息，或者F1-U建立请求消息，又或者gNB-DU Configuration Update消息，对此不作限定。
基于图21所示的实施例，gNB-CU可以根据第一能力指示信息，确定gNB-DU是否支持MBS业务，进而选择与gNB-DU建立的传输通道的类型。例如当UE向核心网申请建立MBS会话，核心网判断该gNB-CU所在的基站支持MBS，则通知gNB-CU建立MBS业务对应的共享用户面隧道。gNB-CU进一步通过UE接入的gNB-DU上报的第一能力指示信息，判断UE所在的gNB-DU是否支持MBS。如果gNB-DU支持MBS，则gNB-CU到gNB-DU之间的F1-U接口建立共享的传输通道。如果gNB-DU不支持MBS，则gNB-CU到gNB-DU之间的F1-U接口应该建立单独的传输通道。
可选的，gNB-DU对MBS的空口支持能力可能发生改变，例如gNB-DU可以从支持MBS改变到不支持MBS；或者，gNB-DU可以从不支持MBS改变到支持MBS。这种情况下，gNB-DU可以向gNB-CU发送配置更新(configuration update)消息以指示gNB-DU最新的对MBS的空口支持能力。
可选的，在gNB-DU对MBS的空口支持能力发生改变的情况下，gNB-CU可以向gNB-DU发送gNB-DU配置更新通知(gNB-DU Configuration Update Acknowledge)消息，以指示gNB-DU更改F1-U接口所建立的传输通道的类型。
可选的，如图22所示，本申请实施例提供一种数据传输方法，该方法包括以下步骤：
S1101、gNB-CU-UP生成第二能力指示信息。
其中，第二能力指示信息用于指示gNB-CU-UP对MBS的空口支持能力。也就是，第二能力指示信息用于指示gNB-CU-UP是否支持MBS。
S1102、gNB-CU-UP向gNB-CU-CP发送第二能力指示信息。
示例性的，第二能力指示信息可以承载于gNB-CU-UP E1建立消息，或者gNB-CU-UP配置更新消息中，对此不作限定。
基于图22所示的实施例，gNB-CU-CP可以根据第二能力指示信息，并向核心网上报是否支持MBS的能力信息。核心网根据gNB-CU-CP上报的是否支持MBS的能力信息，进而确定UPF和gNB-CU-UP之间的NG-U接口建立的传输通道的类型。例 如，在gNB-CU-UP支持MBS业务的情况下，UPF和gNB-CU-UP之间的NG-U接口建立共享的传输通道；或者，在gNB-CU-UP不支持MBS业务的情况下，UPF和gNB-CU-UP之间的NG-U接口建立单独的传输通道。
上述单独的传输通道还可以有其他名称，例如专用的传输通道，对此不作限定。
上述主要从方法的角度对本申请实施例提供的方案进行了介绍。可以理解的是，通信装置(例如接入网设备、终端设备)为了实现上述功能，其包含了执行各个功能相应的硬件结构和/或软件模块。结合本申请中所公开的实施例描述的各示例的单元及算法步骤，本申请实施例能够以硬件或硬件和计算机软件的结合形式来实现。某个功能究竟以硬件还是计算机软件驱动硬件的方式来执行，取决于技术方案的特定应用和设计约束条件。本领域技术人员可以对每个特定的应用来使用不同的方法来实现所描述的功能，但是这种实现不应认为超出本申请实施例的技术方案的范围。
本申请实施例可以根据上述方法示例对通信装置进行功能模块的划分，例如，可以对应各个功能划分各个功能模块，也可以将两个或两个以上的功能集成在一个处理单元中。上述集成的单元既可以采用硬件的形式实现，也可以采用软件功能模块的形式实现。需要说明的是，本申请实施例中对单元的划分是示意性的，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式。
如图23所示，为本申请实施例提供的一种通信装置，该通信装置包括处理模块101和通信模块102。
一种可能的示例中，以通信装置为接入网设备为例，处理模块101用于支持接入网设备执行图15中的步骤S401，图16中的步骤S501，和/或本申请实施例中接入网设备需要执行的其他处理操作。通信模块102用于支持接入网设备执行图9中的步骤S101～S103，图15中的步骤S402，图16中的步骤S502，和/或本申请实施例中接入网设备需要执行的其他通信操作。
另一种可能的示例中，以通信装置为终端设备为例，处理模块101用于支持终端设备解析信息(例如MRB配置信息)，和/或本申请实施例中终端设备需要执行的其他处理操作，例如处理模块101用于执行图12中的步骤S202，S203，图14中的步骤S302。通信模块102用于支持终端设备执行图12中的步骤S201，S204，图15中的步骤S402，图16中的步骤S502，和/或本申请实施例中终端设备需要执行的其他通信操作。
另一种可能的示例中，以通信装置为目标接入网设备为例，处理模块101用于支持目标接入网设备生成信息(例如第四信息或第五信息)，和/或本申请实施例中目标接入网设备需要执行的其他处理操作。通信模块102用于支持目标接入网设备执行图19中的步骤S801-S802，图20中的步骤S901和S902，和/或本申请实施例中目标接入网设备需要执行的其他通信操作。
另一种可能的示例中，以通信装置为源接入网设备为例，处理模块101用于支持源接入网设备解析信息(例如第四信息或第五信息)，和/或本申请实施例中源接入网设备需要执行的其他处理操作。通信模块102用于支持源接入网设备执行图19中的步骤S801-S802，图20中的步骤S901和S902，和/或本申请实施例中源接入网设备需要执行的其他通信操作。
另一种可能的示例中，以通信装置为gNB-DU为例，处理模块101用于支持gNB-DU执行图21中的步骤S1001。通信模块用于支持gNB-DU执行图21中的步骤S1002。
另一种可能的示例中，以通信装置为gNB-CU为例，处理模块101用于支持gNB-CU解析第一能力指示信息。通信模块用于支持gNB-CU执行图21中的步骤S1002。
另一种可能的示例中，以通信装置为gNB-CU-UP为例，处理模块101用于支持gNB-CU-UP执行图22中的步骤S1101，通信模块用于支持gNB-CU-UP执行图22中的步骤S1102。
另一种可能的示例中，以通信装置为gNB-CU-CP为例，处理模块101用于支持gNB-CU-CP解析第二能力指示信息，通信模块用于支持gNB-CU-CP执行图22中的步骤S1102。
可选的，该通信装置还可以包括存储模块103，用于存储通信装置的程序代码和数据，数据可以包括不限于原始数据或者中间数据等。
其中，处理模块101可以是处理器或控制器，例如可以是CPU，通用处理器，专用集成电路(application specific integrated circuit，ASIC)，现场可编程逻辑门阵列(field programmable gate array，FPGA)或者其他可编程逻辑器件、晶体管逻辑器件、硬件部件或者其任意组合。其可以实现或执行结合本申请公开内容所描述的各种示例性的逻辑方框，模块和电路。处理器也可以是实现计算功能的组合，例如包含一个或多个微处理器组合，DSP和微处理器的组合等等。
通信模块102可以是通信接口、收发器或收发电路等，其中，该通信接口是统称，在具体实现中，该通信接口可以包括多个接口，例如可以包括：基站和终端之间的接口和/或其他接口。
存储模块103可以是存储器。
当处理模块101为处理器，通信模块102为通信接口，存储模块103为存储器时，本申请实施例所涉及的通信装置可以为图24所示。
参阅图24所示，该通信装置包括：处理器201、通信接口202、存储器203。可选的，通信装置还可以包括总线204。其中，通信接口202、处理器201以及存储器203可以通过总线204相互连接；总线204可以是外设部件互连标准(peripheral component interconnect，PCI)总线或扩展工业标准结构(extended industry standard architecture，EISA)总线等。所述总线204可以分为地址总线、数据总线、控制总线等。为便于表示，图24中仅用一条粗线表示，但并不表示仅有一根总线或一种类型的总线。
可选的，本申请实施例还提供一种携带计算机指令的计算机程序产品，当该计算机指令在计算机上运行时，使得计算机执行上述实施例所介绍的方法。
可选的，本申请实施例还提供一种计算机可读存储介质，所述计算机可读存储介质存储计算机指令，当该计算机指令在计算机上运行时，使得计算机执行上述实施例所介绍的方法。
可选的，本申请实施例还提供一种芯片，包括：处理电路和收发管脚，处理电路和收发管脚用于实现上述实施例所介绍的方法。其中，处理电路用于执行相应方法中的处理动作，收发管脚用于执行相应方法中的接收/发送的动作。
本领域普通技术人员可以理解：在上述实施例中，可以全部或部分地通过软件、 硬件、固件或者其任意组合来实现。当使用软件实现时，可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括一个或多个计算机指令。在计算机上加载和执行所述计算机程序指令时，全部或部分地产生按照本申请实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、光纤、数字用户线(Digital Subscriber Line，DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包括一个或多个可用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质(例如，软盘、硬盘、磁带)、光介质(例如，数字视频光盘(Digital Video Disc，DVD))、或者半导体介质(例如固态硬盘(Solid State Disk，SSD))等。
在本申请所提供的几个实施例中，应该理解到，所揭露的***，装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述模块的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个模块或组件可以结合或者可以集成到另一个***，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或模块的间接耦合或通信连接，可以是电性或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个设备上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
通过以上的实施方式的描述，所属领域的技术人员可以清楚地了解到本申请可借助软件加必需的通用硬件的方式来实现，当然也可以通过硬件，但很多情况下前者是更佳的实施方式。基于这样的理解，本申请的技术方案本质上或者说做出贡献的部分可以以软件产品的形式体现出来，该计算机软件产品存储在可读取的存储介质中，如计算机的软盘，硬盘或光盘等，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)执行本申请各个实施例所述的方法。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，在本申请揭露的技术范围内的变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (61)

  1. 一种数据传输方法，其特征在于，所述方法应用于接入网设备，所述接入网设备配置有分组数据汇聚协议PDCP实体、第一无线链路控制RLC实体和第二RLC实体，所述第一RLC实体和所述第二RLC实体分别和所述PDCP实体关联，所述第一RLC实体用于支持点对多点PTM传输方式发送多播广播业务MBS业务数据，所述第二RLC实体用于支持点对点PTP传输方式发送MBS业务数据，所述第一RLC实体和所述第二RLC实体关联到相同的多播无线承载MRB，所述方法包括：
    所述第一RLC实体向包括第一终端设备在内的至少一个终端设备发送至少一个RLC服务数据单元SDU；
    所述第二RLC实体从所述第一终端设备接收第一信息，所述第一信息用于指示第一RLC SDU的RLC序列号SN，所述第一RLC SDU属于所述至少一个RLC SDU中未成功接收到的RLC SDU；
    所述第二RLC实体向所述第一RLC实体或者所述PDCP实体递交第二信息，所述第二信息指示所述第一RLC SDU的RLCSN；
    第一实体向所述第一终端设备发送所述第一RLC SDU，所述第一实体为所述第一RLC实体或者所述第二RLC实体。
  2. 根据权利要求1所述的方法，其特征在于，所述第一实体为所述第一RLC实体；在所述第一实体向所述第一终端设备发送所述第一RLC SDU之前，所述方法还包括：
    所述第一RLC实体根据所述第二信息，获取所述第一RLC SDU。
  3. 根据权利要求1所述的方法，其特征在于，所述第一实体为所述第二RLC实体；在所述第一实体向所述第一终端设备发送所述第一RLC SDU之前，所述方法还包括：
    所述第一RLC实体根据所述第二信息，向所述第二RLC实体递交所述第一RLC SDU。
  4. 根据权利要求1所述的方法，其特征在于，在所述第一实体向所述第一终端设备发送所述第一RLC SDU之前，所述方法还包括：
    所述PDCP实体根据所述第二信息，向所述第一实体递交所述第一RLC SDU。
  5. 根据权利要求4所述的方法，其特征在于，所述第二信息包括所述第一RLC SDU的RLC SN，所述PDCP实体根据所述第二信息，向所述第一实体递交所述第一RLC SDU，包括：
    所述PDCP实体根据所述第一RLC SDU的RLC SN，以及预设映射关系，确定第一PDCP PDU的PDCP SN，所述预设映射关系用于指示PDCP SN与RLC SN之间的映射关系；
    所述PDCP实体根据所述第一PDCP PDU的PDCP SN，获取所述第一PDCP PDU，所述第一PDCP PDU为所述第一RLC SDU；
    所述PDCP实体向所述第一实体递交所述第一RLC SDU。
  6. 根据权利要求4所述的方法，其特征在于，所述第二信息包括第一PDCP PDU的PDCP SN，所述PDCP实体根据所述第二信息，向所述第一实体递交所述第 一RLC SDU，包括：
    所述PDCP实体根据所述第一PDCP PDU的PDCP SN，获取所述第一PDCP PDU，所述第一PDCP PDU为所述第一RLC SDU；
    所述PDCP实体向所述第一实体递交所述第一RLC SDU。
  7. 根据权利要求6所述的方法，其特征在于，在所述第二RLC实体向所述PDCP实体递交第二信息之前，所述方法还包括：
    所述第二RLC实体根据所述第一RLC SDU的RLC SN，以及预设映射关系，确定所述第一PDCP PDU的PDCP SN，所述预设映射关系用于指示PDCP SN与RLC SN之间的映射关系。
  8. 根据权利要求1至7任一项所述的方法，其特征在于，所述方法还包括：
    所述接入网设备向所述第一终端设备发送第一指示信息，所述第一指示信息用于指示所述第一终端设备接收所述MBS业务数据的起始数据序列号信息。
  9. 根据权利要求8所述的方法，其特征在于，所述起始数据序列号信息包括PDCP SN、PDCP计数值和/或起始的RLC SN。
  10. 根据权利要求1至9任一项所述的方法，其特征在于，所述方法还包括：
    所述接入网设备向所述第一终端设备发送MRB配置信息，所述MRB配置信息用于配置所述第一终端设备与所述接入网设备之间的MBS会话。
  11. 根据权利要求10所述的方法，其特征在于，所述MRB配置信息包括两个RLC承载配置信息，所述两个RLC承载配置信息关联相同的MRB，所述两个RLC承载配置信息中至少一个RLC承载配置信息包括PTM标识或者MBS会话信息。
  12. 一种数据传输方法，其特征在于，所述方法应用于第一终端设备，所述第一终端设备配置有第三RLC实体和第四RLC实体，所述第三RLC实体用于接收接入网设备以PTM方式发送的MBS业务数据，所述第四RLC实体用于接收所述接入网设备以PTP方式发送的MBS业务数据，所述第三RLC实体和所述第四RLC实体关联到相同的MRB，所述方法包括：
    所述第三RLC实体从所述接入网设备接收至少一个RLC SDU；
    所述第四RLC实体从所述第三RLC实体接收第三信息，所述第三信息指示至少一个RLC SDU中第一RLC SDU的RLC SN；
    所述第四RLC实体根据所述第三信息生成第一信息；
    所述第四RLC实体向所述接入网设备发送所述第一信息，所述第一信息用于指示所述第一RLC SDU的RLC SN，所述第一RLC SDU属于所述至少一个RLC SDU中未成功接收到的RLC SDU。
  13. 根据权利要求12所述的方法，其特征在于，在第四RLC实体从所述第三RLC实体接收第三信息之前，所述方法还包括：
    所述第三RLC实体确定所述第一RLC SDU未成功接收到；
    所述第三RLC实体根据所述第一RLC SDU的RLC SN生成所述第三信息。
  14. 根据权利要求12所述的方法，其特征在于，在第四RLC实体从所述第三RLC实体接收第三信息之前，所述方法还包括：
    所述第三RLC实体确定所述至少一个RLC SDU中的第二RLC SDU成功接收 到；
    所述第三RLC实体根据所述第二RLC SDU的RLC SN生成所述第三信息。
  15. 根据权利要求12至14任一项所述的方法，其特征在于，在所述第四RLC实体向所述接入网设备发送所述第一信息之后，所述方法还包括：
    所述第四RLC实体从所述接入网设备接收所述第一RLC SDU。
  16. 根据权利要求12至14任一项所述的方法，其特征在于，在所述第四RLC实体向所述接入网设备发送所述第一信息之后，所述方法还包括：
    所述第三RLC实体从所述接入网设备接收所述第一RLC SDU。
  17. 根据权利要求16所述的方法，其特征在于，所述方法还包括：
    所述第三RLC实体向所述第四RLC实体指示成功接收到所述第一RLC SDU。
  18. 根据权利要求12至17任一项所述的方法，其特征在于，所述方法还包括：
    所述第一终端设备从所述接入网设备接收第一指示信息，所述第一指示信息用于指示所述第一终端设备接收所述MBS业务数据的起始数据序列号信息。
  19. 根据权利要求18所述的方法，其特征在于，所述第一指示信息具体用于指示起始的PDCP SN、PDCP计数值和/或起始的RLC SN。
  20. 根据权利要求12至19任一项所述的方法，其特征在于，所述方法还包括：
    所述第一终端设备从所述接入网设备接收MRB配置信息，所述MRB配置信息用于配置所述第一终端设备与所述接入网设备之间的MBS会话。
  21. 根据权利要求20所述的方法，其特征在于，所述MRB配置信息包含两个RLC承载配置信息，所述两个RLC承载配置信息关联相同的MRB，所述两个RLC承载配置信息中至少一个RLC承载配置信息包括PTM标识或者MBS会话信息。
  22. 一种数据传输方法，其特征在于，所述方法包括：
    目标接入网设备从源接入网设备接收切换请求消息，所述切换请求消息用于请求将终端设备从所述源接入网设备切换到所述目标接入网设备；
    所述目标接入网设备向所述源接入网设备发送第四信息，所述第四信息用于指示所述源接入网设备向所述目标接入网设备转发第一序列号SN之前的至少一个SN对应的所述终端设备的MBS业务数据。
  23. 根据权利要求22所述的方法，其特征在于，在所述目标接入网设备向所述源接入网设备发送第四信息之前，所述方法还包括：
    所述目标接入网设备从核心网网元获取第二SN信息；
    所述目标接入网设备根据所述第二SN信息，确定第一SN信息，所述第一SN信息用于指示第一SN。
  24. 根据权利要求23所述的方法，其特征在于，所述目标接入网设备从所述核心网网元获取第二SN信息，包括：
    所述目标接入网设备向所述核心网网元发送路径切换请求消息，所述路径切换请求消息用于请求所述核心网网元切换所述终端设备的MBS业务数据的传输路径；
    所述目标接入网设备从所述核心网网元接收路径切换确认消息，所述路径切换确认消息包括所述第二SN信息。
  25. 根据权利要求22至24任一项所述的方法，其特征在于，所述第一SN为 PDCP SN、通用分组无线业务隧道协议GTP-用户面U SN或者服务质量流标识QFI SN。
  26. 根据权利要求25所述的方法，其特征在于，所述PDCP SN和所述GTP-U SN之间存在预设的映射关系；或者，所述QFI与QFI SN的组合和所述PDCP SN之间存在预设的映射关系。
  27. 一种数据传输方法，其特征在于，所述方法包括：
    源接入网设备向目标接入网设备发送切换请求消息，所述切换请求消息用于请求将终端设备从所述源接入网设备切换到所述目标接入网设备；
    所述源接入网设备从所述目标接入网设备接收第四信息，所述第四信息用于指示所述源接入网设备向所述目标接入网设备转发第一SN之前的至少一个SN对应的所述终端设备的MBS业务数据。
  28. 根据权利要求27所述的方法，其特征在于，所述第一SN为PDCP SN、GTP-U SN或者QFI SN。
  29. 根据权利要求28所述的方法，其特征在于，所述PDCP SN和所述GTP-U SN之间存在预设的映射关系；或者，QFI与QFI SN的组合和所述PDCP SN之间存在预设的映射关系。
  30. 一种通信装置，其特征在于，所述通信装置包括PDCP实体、第一RLC实体和第二RLC实体，所述第一RLC实体和所述第二RLC实体分别和所述PDCP实体关联，所述第一RLC实体用于支持PTM传输方式发送MBS业务数据，所述第二RLC实体用于PTP传输方式发送MBS业务数据，所述第一RLC实体和所述第二RLC实体关联到相同的MRB；
    所述第一RLC实体，用于向包括第一终端设备在内的至少一个终端设备发送至少一个RLC SDU；
    所述第二RLC实体，用于从所述第一终端设备接收第一信息，所述第一信息用于指示第一RLC SDU的RLC序列号SN，所述第一RLC SDU属于所述至少一个RLC SDU中未成功接收到的RLC SDU；
    所述第二RLC实体，还用于向所述第一RLC实体或者所述PDCP实体递交第二信息，所述第二信息用于指示所述第一RLC SDU的RLC SN；
    第一实体，用于向所述第一终端设备发送所述第一RLC SDU，所述第一实体为所述第一RLC实体或者所述第二RLC实体。
  31. 根据权利要求30所述的装置，其特征在于，所述第一实体为所述第一RLC实体；在所述第一实体，用于向所述第一终端设备发送所述第一RLC SDU之前，所述第一RLC实体，还用于根据所述第二信息，获取所述第一RLC SDU。
  32. 根据权利要求30所述的装置，其特征在于，所述第一实体为所述第二RLC实体；在所述第一实体，用于向所述第一终端设备发送所述第一RLC SDU之前，所述第一RLC实体，还用于根据所述第二信息，向所述第二RLC实体递交所述第一RLC SDU。
  33. 根据权利要求32所述的装置，其特征在于，在所述第一实体，用于向所述第一终端设备发送所述第一RLC SDU之前，所述PDCP实体，用于根据所述第二信 息，向所述第一实体递交所述第一RLC SDU。
  34. 根据权利要求33所述的装置，其特征在于，所述第二信息包括所述第一RLC SDU的RLC SN，所述PDCP实体，具体用于根据所述第一RLC SDU的RLC SN，以及预设映射关系，确定第一PDCP PDU的PDCP SN，所述预设映射关系用于指示PDCP SN与RLC SN之间的映射关系；根据所述第一PDCP PDU的PDCP SN，获取所述第一PDCP PDU，所述第一PDCP PDU为所述第一RLC SDU；向所述第一实体递交所述第一RLC SDU。
  35. 根据权利要求33所述的装置，所述第二信息包括第一PDCP PDU的PDCP SN，所述PDCP实体，具体用于根据所述第一PDCP PDU的PDCP SN，获取所述第一PDCP PDU，所述第一PDCP PDU为所述第一RLC SDU；向所述第一实体递交所述第一RLC SDU。
  36. 根据权利要求35所述的装置，其特征在于，所述第二RLC实体，根据所述第一RLC SDU的RLC SN，以及预设映射关系，确定所述第一PDCP PDU的PDCP SN，所述预设映射关系用于指示PDCP SN与RLC SN之间的映射关系。
  37. 根据权利要求30至36任一项所述的装置，其特征在于，所述装置还包括通信模块：所述通信模块，用于向所述第一终端设备发送第一指示信息，所述第一指示信息用于指示所述第一终端设备接收所述MBS业务数据的起始数据序列号信息。
  38. 根据权利要求37所述的装置，其特征在于，所述起始数据序列号信息包括PDCP SN、PDCP计数值和/或起始的RLC SN。
  39. 根据权利要求30至38任一项所述的装置，其特征在于，所述通信模块，还用于向所述第一终端设备发送MRB配置信息，所述MRB配置信息用于配置所述第一终端设备与接入网设备之间的MBS会话。
  40. 根据权利要求39所述的装置，其特征在于，所述MRB配置信息包括两个RLC承载配置信息，所述两个RLC承载配置信息关联相同的MRB，所述两个RLC承载配置信息中至少一个RLC承载配置信息包括PTM标识或者MBS会话信息。
  41. 一种通信装置，其特征在于，所述装置包括第三RLC实体和第四RLC实体，所述第三RLC实体用于接收接入网设备以PTM方式发送的MBS业务数据，所述第四RLC实体用于接收所述接入网设备以PTP方式发送的所述MBS业务数据，所述第三RLC实体和所述第四RLC实体关联到相同的MRB；
    所述第三RLC实体，用于从所述接入网设备接收至少一个RLC SDU；
    所述第四RLC实体，用于从所述第三RLC实体接收第三信息，所述第三信息指示至少一个RLC SDU中第一RLC SDU的RLC SN；
    所述第四RLC实体，还用于根据所述第三信息生成第一信息；向所述接入网设备发送所述第一信息，所述第一信息用于指示所述第一RLC SDU的RLC SN，所述第一RLC SDU属于所述至少一个RLC SDU中未成功接收到的RLC SDU。
  42. 根据权利要求41所述的装置，其特征在于，所述第三RLC实体，还用于确定所述第一RLC SDU未成功接收到；根据所述第一RLC SDU的RLC SN生成所述第三信息。
  43. 根据权利要求41所述的装置，其特征在于，所述第三RLC实体，还用于确 定所述至少一个RLC SDU中的第二RLC SDU成功接收到；根据所述第二RLC SDU的RLC SN生成所述第三信息。
  44. 根据权利要求41至43任一项所述的装置，其特征在于，所述第四RLC实体，还用于从所述接入网设备接收所述第一RLC SDU。
  45. 根据权利要求41至43任一项所述的装置，其特征在于，所述第三RLC实体，还用于从所述接入网设备接收所述第一RLC SDU。
  46. 根据权利要求45所述的装置，其特征在于，所述第三RLC实体，还用于向所述第四RLC实体指示成功接收到所述第一RLC SDU。
  47. 根据权利要求41至46任一项所述的装置，其特征在于，所述装置还包括通信模块；所述通信模块，用于从所述接入网设备接收第一指示信息，所述第一指示信息用于指示第一终端设备接收所述MBS业务数据的起始数据序列号信息。
  48. 根据权利要求47所述的装置，其特征在于，所述第一指示信息具体用于指示起始的PDCP SN、PDCP计数值和/或起始的RLC SN。
  49. 根据权利要求41至48任一项所述的装置，其特征在于，所述通信模块，还用于从所述接入网设备接收MRB配置信息，所述MRB配置信息用于配置所述第一终端设备与所述接入网设备之间的MBS会话。
  50. 根据权利要求49所述的装置，其特征在于，所述MRB配置信息包含两个RLC承载配置信息，所述两个RLC承载配置信息关联相同的MRB，所述两个RLC承载配置信息中至少一个RLC承载配置信息包括PTM标识或者MBS会话信息。
  51. 一种通信装置，其特征在于，包括处理模块和与处理模块连接的通信模块；
    所述通信模块，用于从源接入网设备接收切换请求消息，所述切换请求消息用于请求将终端设备从所述源接入网设备切换到目标接入网设备；
    所述处理模块，用于生成第四信息，所述第四信息用于指示所述源接入网设备向所述目标接入网设备转发第一序列号SN之前的至少一个SN对应的所述终端设备的MBS业务数据；
    所述通信模块，还用于向所述源接入网设备发送所述第四信息。
  52. 根据权利要求51所述的装置，其特征在于，所述通信模块，还用于在向所述源接入网设备发送第四信息之前，从核心网网元获取第二SN信息；
    所述处理模块，还用于根据所述第二SN信息，确定第一SN信息，所述第一SN信息用于指示第一SN。
  53. 根据权利要求52所述的装置，其特征在于，所述通信模块，还用于向所述核心网网元发送路径切换请求消息，所述路径切换请求消息用于请求所述核心网网元切换所述终端设备的MBS业务数据的传输路径；从所述核心网网元接收路径切换确认消息，所述路径切换确认消息包括所述第二SN信息。
  54. 根据权利要求51至53任一项所述的装置，其特征在于，所述第一SN为PDCP SN、通用分组无线业务隧道协议GTP-用户面U SN或者服务质量流标识QFI SN。
  55. 根据权利要求54所述的装置，其特征在于，所述PDCP SN和所述GTP-U SN之间存在预设的映射关系；或者，所述QFI与QFI SN的组合和所述PDCP SN之 间存在预设的映射关系。
  56. 一种通信装置，其特征在于，所述装置包括处理模块和与处理模块连接的通信模块；所述处理模块，用于生成切换请求消息，所述切换请求消息用于请求将终端设备从源接入网设备切换到目标接入网设备；
    所述通信模块，用于向目标接入网设备发送所述切换请求消息；
    所述通信模块，还用于从所述目标接入网设备接收第四信息，所述第四信息用于指示所述源接入网设备向所述目标接入网设备转发第一SN之前的至少一个SN对应的所述终端设备的MBS业务数据。
  57. 根据权利要求56所述的装置，其特征在于，所述第一SN为PDCP SN、GTP-U SN或者QFI SN。
  58. 根据权利要求57所述的装置，其特征在于，所述PDCP SN和所述GTP-U SN之间存在预设的映射关系；或者，QFI与QFI SN的组合和所述PDCP SN之间存在预设的映射关系。
  59. 一种计算机可读存储介质，其特征在于，所述计算机可读存储介质存储计算机指令，当所述计算机指令在计算机上运行时，使得所述计算机执行权利要求1至29任一项所述的方法。
  60. 一种芯片，其特征在于，所述芯片包括处理电路和收发管脚；所述处理电路用于执行权利要求1至29中任一项所涉及的方法中的处理操作，所述收发管脚用于执行权利要求1至29中任一项所涉及的方法中的通信操作。
  61. 一种计算机程序产品，其特征在于，当所述计算机程序产品在计算机上运行时，使得所述计算机执行权利要求1至29任一项所述的方法。
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