WO2023071699A1

WO2023071699A1 - Data transmission method for multicast service, communication device and storage medium

Info

Publication number: WO2023071699A1
Application number: PCT/CN2022/122769
Authority: WO
Inventors: 项弘禹; 李秉肇; 许斌
Original assignee: 华为技术有限公司
Priority date: 2021-10-30
Filing date: 2022-09-29
Publication date: 2023-05-04
Also published as: CN116095611A

Abstract

Embodiments of the present application provide a data transmission method for a multicast service, a communication apparatus and a storage medium. The method comprises: sending a multicast radio configuration to a terminal, the multicast radio configuration being used to instruct the terminal to perform multicast transmission initialization; multicasting at least two subpackets of a data packet to be transmitted to the terminal, each subpacket corresponding to a sequence number; receiving an acknowledgment message from the terminal, the acknowledgment message being used to determine that the terminal receives the subpackets; determining a retransmission subpacket in the data packet to be transmitted; sending instruction information to the terminal, the instruction information being used to modify a lower boundary value of a reassembly window; and multicasting the retransmission subpacket to the terminal. Using embodiments of the present application, it is possible to prevent data packet loss caused by multicast initialization, increasing the success rate of data transmission and increasing the reliability of a multicast service.

Description

Data transmission method, communication device and storage medium for multicast service

This application claims the priority of the Chinese patent application with the application number 202111278465.X and the application name "Data transmission method, communication device and storage medium for multicast service" submitted to the China Patent Office on October 30, 2021, all of which The contents are incorporated by reference in this application.

technical field

The present application relates to the technical field of wireless communication, and in particular to a data transmission method, a communication device and a storage medium for a multicast service.

Background technique

Multicast services (for example, multimedia broadcast multicast service (MBMS in LTE), multicast broadcast service (MBS in NR), etc.), are mainly applicable to services for multiple terminals, for example, Video conferencing, TV broadcasting, video on demand, online education, etc. When a multicast service is multicast transmitted, a network device (for example, a base station) transmits data from a packet data convergence protocol (PDCP) through a radio link layer control protocol (radio link control, RLC) entity (entity). ) layer received packets are transmitted to the media access control (media access control, MAC) entity. Then, the data packet is sent to the physical layer entity through the MAC entity, and the data packet is sent out through the physical layer entity, so that multiple terminals receive the data packet.

Multicast services are transmitted through two transmission modes, point to multi-point (PTM) and point to point (PTP). The PTM RLC entity is configured in unacknowledge mode (unacknowledge Mode, UM). In the UM mode, the RLC entity may be called a UM RLC entity, and the protocol data unit (protocol data unit, PDU) received by the UM RLC entity may be called a UMD PDU. If the received UMD PDU includes the SN field (field), it means that the UMD PDU contains a segment of a service data unit (service data unit, SDU), and also indicates that the segment needs to be reassembled with other segments to Get the complete SDU, and then transmit the complete SDU for data.

When receiving data, the UM RLC entity needs to maintain a reassembly window (reassembly window). The range of the reorganization window can be set to [RX_Next_Highest-UM_Window_Size, RX_Next_Highest). Among them, UM_Window_Size is a constant. RX_Next_Highest indicates the next sequence number of the largest sequence number (sequence number, SN) in the received UMD PDU, that is, SN+1. As shown in Figure 1, the reassembly window is divided into two segments based on RX_Next_Reassembly. The RX_Next_Reassembly indicates the minimum SN waiting to be reassembled. That is to say, the data packets whose SN value is less than RX_Next_Reassembly have been reassembled. When PTM is initialized, the UM RLC entity will set both RX_Next_Reassembly and RX_Next_Highest as the first packet containing the SN received by the terminal. The SN value of the packet. If the terminal receives the first SDU containing the SN at time t1, its SN value is greater than the SN value of the SDU subsequently received by the terminal. For example, if the SN value of the SDU segment that the MAC layer retransmits to the UM RLC entity is smaller than the SN value of the first SDU containing the SN, that is, the SN value is smaller than RX_Next_Reassembly, the terminal will not cache the SDU segment, and The data packet corresponding to the SDU segment will be discarded. However, the terminal does not receive the data packet before time t1, resulting in that the RLC SDU is not reassembled and will not be delivered to the upper layer (ie, the PDCP layer). Therefore, setting the RX_Next_Reassembly and RX_Next_Highest of the PTM as the SN value of the first data packet containing the SN received by the terminal will affect the service performance.

Contents of the invention

The embodiment of the present application discloses a data transmission method, a communication device, and a storage medium for a multicast service, which can avoid the occurrence of data packet loss caused by PTM initialization, improve the success rate of data transmission, and improve the reliability of the multicast service sex.

In the first aspect, the embodiment of the present application discloses the first multicast service data transmission method, which is applied to network equipment. The method includes: sending multicast wireless configuration to the terminal; receiving a confirmation message from the terminal; determining the retransmission subpacket in the data packet to be transmitted; sending instruction information to the terminal; and multicasting the retransmission subpacket to the terminal.

Wherein, the multicast wireless configuration is used to instruct the terminal to perform multicast transmission initialization. Each sub-packet in the data packet to be transmitted corresponds to a sequence number. Acknowledgment messages are used to determine which subpackets have been received by the terminal. The instruction information is used to modify the lower boundary value of the reassembly window, so that the range of discarding data packets can be modified. In this way, the event of data packet loss caused by PTM initialization can be avoided, the success rate of data transmission can be improved, and the reliability of multicast service can be improved.

In the second aspect, the embodiment of the present application discloses a second data transmission method for multicast services, which is applied to network equipment. The method includes: sending multicast wireless configuration to terminals; sending multicast data packets to be transmitted to terminals At least two sub-data packets; receiving a confirmation message from the terminal; determining a retransmission sub-packet in the data packet to be transmitted; and sending the retransmission sub-packet to the terminal in unicast.

Wherein, the multicast wireless configuration is used to instruct the terminal to perform multicast transmission initialization. Each sub-packet in the data packet to be transmitted corresponds to a sequence number. Acknowledgment messages are used to determine which subpackets have been received by the terminal. In this way, the retransmission of data packets that failed in multicast transmission by means of unicast transmission can avoid the occurrence of data packet loss events caused by PTM initialization, improve the success rate of data transmission, and improve the reliability of multicast services.

In a possible example, the retransmission sub-packet is determined by the MAC layer of the network device, and the retransmission sub-packet is sent to the terminal in unicast, including: based on the terminal's cell-radio network temporary identifier, C-RNTI) unicasts the retransmission subpacket downwards from the MAC layer, so as to unicast the retransmission subpacket to the terminal. In this way, the MAC layer directly performs unicast transmission on the retransmission sub-packet through the PTP mode, which can increase the retransmission rate.

In a possible example, the retransmission subpacket is determined by the MAC layer of the network device, and after determining the retransmission subpacket in the data packet to be transmitted, further includes: sending layer signaling upward from the MAC layer, so that the network The PDCP layer of the device determines the sequence numbers of the retransmitted subpackets. In this way, the retransmission sub-packets to be retransmitted can be confirmed internally by the network device through hierarchical signaling.

The unicast sending of the retransmission sub-packet to the terminal includes: sending the retransmission sub-data unicast downward from the PDCP layer, so as to unicast the retransmission sub-packet to the terminal. That is to say, the PTP mode can be used to send down layer by layer from the PDCP layer of the network device, so that the retransmission subpacket (or the set of retransmission subpackets corresponding to the retransmission subpacket) is unicast sent to the terminal, data loss can be avoided.

In the third aspect, the embodiment of the present application discloses a third multicast service data transmission method, which is applied to the terminal, and the method includes: multicast receiving the multicast wireless configuration from the network device; multicast receiving the data packet to be transmitted from the network device sub-packet; send a confirmation message to the network device; receive indication information from the network device; modify the lower boundary value based on the indication information; receive retransmission sub-packet from the network device multicast.

In the fourth aspect, the embodiment of the present application discloses a fourth multicast service data transmission method, which is applied to a terminal, and the method includes: multicast receiving multicast wireless configuration from the network device; multicast receiving data packets to be transmitted from the network device sub-packet; sending a confirmation message to the network device; receiving a retransmission sub-packet in the data packet to be transmitted from the network device in unicast.

In the fifth aspect, the embodiment of the present application discloses a first communication device. The communication device includes network equipment, wherein: the transceiver unit is used to send multicast wireless configuration to the terminal; and multicast at least two sub-components of the data packet to be transmitted to the terminal. A data packet; receiving an acknowledgment message from the terminal; the processing unit is used to determine the retransmission sub-packet in the data packet to be transmitted; the transceiver unit is also used to send indication information to the terminal; and multicast the retransmission sub-packet to the terminal.

In the sixth aspect, the embodiment of the present application discloses a second communication device. The communication device includes network equipment, wherein: the transceiver unit is used to send multicast wireless configuration to the terminal; and multicast at least two sub-components of the data packet to be transmitted to the terminal. A data packet; receiving an acknowledgment message from the terminal; the processing unit is used to determine the retransmission sub-packet in the data packet to be transmitted; the transceiver unit is also used to unicast send the retransmission sub-packet to the terminal.

In a possible example, the communication device further includes a MAC layer, the retransmission sub-packet is determined by the MAC layer, and the transceiver unit is specifically configured to unicast the retransmission sub-packet downward from the MAC layer based on the C-RNTI of the terminal, to unicast the retransmission subpacket to the terminal. In this way, the MAC layer directly performs unicast transmission on the retransmission sub-packet through the PTP mode, which can increase the retransmission rate.

In a possible example, the communication device further includes a MAC layer and a PDCP layer, the retransmission subpacket is determined by the MAC layer, and the transceiver unit is further configured to send layer signaling upward from the MAC layer, so that the PDCP layer determines the retransmission subpacket The sequence number of the data packet; the transceiver unit is specifically used to unicast downward the retransmission sub-data from the PDCP layer, so as to unicast the retransmission sub-data packet to the terminal. It can be understood that the retransmission subpacket to be retransmitted can be confirmed internally by the network device through hierarchical signaling. Then, the PTP mode can be used to send down layer by layer from the PDCP layer of the network device, so that the retransmission subpacket (or the set of retransmission subpackets corresponding to the retransmission subpacket) can be sent to the terminal in unicast, which can avoid data lost.

In the seventh aspect, the embodiment of the present application discloses a third communication device, the communication device includes a terminal, wherein: the transceiver unit is used to receive the multicast wireless configuration from the network device through multicast; A sub-packet; sending an acknowledgment message to the network device; receiving indication information from the network device; the processing unit is used to modify the lower boundary value based on the indication information; the transceiver unit is also used to multicast receive the retransmission sub-packet from the network device.

In the eighth aspect, the embodiment of the present application discloses a fourth communication device. The communication device includes a terminal, wherein: a transceiver unit is configured to receive a multicast wireless configuration from a network device; and receive a multicast data packet to be transmitted from a network device sub-packet; send a confirmation message to the network device; receive retransmission sub-packet from the network device multicast.

With reference to the first aspect, or the third aspect, or the fifth aspect, in a possible example, the indication information includes an absolute value of the retransmission subpacket. Wherein, the absolute value includes the minimum value of the sequence number in the retransmission subpacket, and the indication information is specifically used to indicate that the lower boundary value of the reassembly window is changed to an absolute value. In this way, the lower boundary value of the reorganization window can be directly set as the absolute value, so as to improve the setting efficiency. In the case where the absolute value is the minimum value of the sequence number in the retransmission sub-packet, packet loss of the retransmission sub-packet can be avoided, and service reliability can be improved.

With reference to the first aspect, or the third aspect, or the fifth aspect, in a possible example, the indication information includes an offset value of the retransmission subpacket. Wherein, the offset value is related to at least two items of the following information: the minimum value of the sequence number in the retransmitted sub-packet, the sequence number of the first sub-packet received by the terminal, and a preset constant, which is a positive integer. The instruction information is specifically used to instruct to adjust the lower boundary value of the reassembly window based on the offset value, so that the range of the reassembly window can be adjusted to avoid data packet loss.

With reference to the first aspect, or the third aspect, or the fifth aspect, in a possible example, the multicast wireless configuration includes an initial value of the lower boundary value, which is the minimum value of the sequence number in the subpacket. In this way, the boundary value of the reassembly window can be set when the multicast transmission is initialized. And the lower boundary value of the reassembly window is the value of the subpacket with the smallest sequence number in the data packet to be transmitted, then the sequence number of the lost data packet will not be greater than this value, which can improve the effectiveness of setting the boundary value of the reassembly window.

In the ninth aspect, the embodiment of the present application discloses that a fifth communication device is provided, including a processor, the processor is coupled with a memory, wherein the memory is used to store one or more programs, and the programs are executed by the processor to implement any of the above Aspects or methods of possible examples.

In the tenth aspect, the embodiment of the present application discloses a computer-readable storage medium. The computer-readable storage medium stores instructions, which, when run on a computer, cause the computer to execute the method of any one of the above-mentioned aspects or possible examples.

In the eleventh aspect, the embodiment of the present application discloses a computer program product, the computer program product is used to store a computer program, and when the computer program is run on the computer, the computer is made to execute the method of any one of the above aspects.

In the twelfth aspect, the embodiment of the present application discloses the first chip, including a processor, which is used to call and execute instructions stored in the memory from the memory, so that the terminal device installed with the chip executes any of the above aspects or possible examples Methods.

In the thirteenth aspect, the embodiment of the present application discloses a second chip. The chip may be a chip in a communication device. The chip includes: an input interface, an output interface, and a processing circuit. The input interface, the output interface, and the circuit are connected through an internal The connection paths are connected, and the processing circuit is used to execute the method of any one of the above aspects or possible examples.

In the fourteenth aspect, the embodiment of the present application discloses a third chip, including: an input interface, an output interface, and a processor, and optionally, a memory, and the input interface, the output interface, the processor, and the memory are connected internally The paths are connected, the processor is used to execute the code in the memory, and when the code is executed, the processor is used to execute the method in any of the above aspects or possible examples.

In a fifteenth aspect, an embodiment of the present application provides a communication system, including the communication device in any one of the foregoing aspects or possible examples.

Description of drawings

The accompanying drawings used in the embodiments of the present application are introduced below.

FIG. 1 is a schematic diagram of an effective range of an SN provided by an embodiment of the present application;

FIG. 2 is a schematic structural diagram of a communication system provided by an embodiment of the present application;

FIG. 3 is a schematic structural diagram of a data transmission device for a multicast service provided by an embodiment of the present application;

FIG. 4 is a schematic flowchart of a data transmission method for a multicast service provided by an embodiment of the present application;

FIG. 5 is a schematic diagram of a scenario of data transmission of a multicast service provided by an embodiment of the present application;

FIG. 6 is a schematic flowchart of another data transmission method for a multicast service provided by an embodiment of the present application;

FIG. 7 is a schematic flowchart of another data transmission method for a multicast service provided by an embodiment of the present application;

FIG. 8 is a schematic structural diagram of a communication device provided by an embodiment of the present application;

FIG. 9 is a schematic structural diagram of another communication device provided by an embodiment of the present application.

Detailed ways

The technical solutions of the embodiments of the present application can be applied to various communication systems, for example: the Global System for Mobile Communications (GSM) system corresponding to the second-generation mobile communication technology, the GSM system between the second-generation mobile communication technology and the third-generation mobile communication technology The general packet radio service (General Packet Radio Service, GPRS) among the mobile communication technologies of the first generation, the Code Division Multiple Access (CDMA) system corresponding to the third generation mobile communication technology (The 3rd Generation Telecommunication, 3G), Wideband Code Division Multiple Access (WCDMA) system and Universal Mobile Telecommunications System (Universal Mobile Telecommunications System, UMTS), Long Term Evolution (LTE) system corresponding to the fourth-generation mobile communication technology, the fifth The new air interface technology (New Radio, NR) system corresponding to the first generation of mobile communication technology and other current communication systems, and applied to future communication systems, such as 6G systems.

The present application presents various aspects, embodiments or features in terms of a system that can include a number of devices, components, modules and the like. It is to be understood and appreciated that the various systems may include additional devices, components, modules, etc. and/or may not include all of the devices, components, modules etc. discussed in connection with the figures. In addition, combinations of these schemes can also be used.

In addition, in the embodiments of the present application, the word "exemplary" is used as an example, illustration or illustration. Any embodiment or design described herein as "example" is not to be construed as preferred or advantageous over other embodiments or designs. Rather, the use of the word example is intended to present concepts in a concrete manner.

In this embodiment of the present application, information, signal, message, and channel may sometimes be used interchangeably. It should be noted that when the differences are not emphasized, the meanings they intend to express are consistent. "的(of)", "corresponding (corresponding, relevant)" and "corresponding (corresponding)" can sometimes be used interchangeably. It should be pointed out that when the difference is not emphasized, the meanings they intend to express are consistent.

The network architecture and business scenarios described in the embodiments of the present application are for more clearly illustrating the technical solutions of the embodiments of the present application, and do not constitute limitations on the technical solutions provided by the embodiments of the present application. For the evolution of architecture and the emergence of new business scenarios, the technical solutions provided by the embodiments of this application are also applicable to similar technical problems.

In order to make the purpose, technical solution and advantages of the present application clearer, the following describes the embodiments of the present application in conjunction with the drawings in the embodiments of the present application.

Firstly, the communication system applicable to the embodiment of the present application is described in detail by taking the communication system shown in FIG. 2 as an example. Fig. 2 shows a schematic diagram of a communication system applicable to the data transmission method for a multicast service according to the embodiment of the present application. As shown in Figure 2, the communication system includes access network equipment, terminals and core network equipment.

The terminal in the embodiment of the present application may be a device that provides voice or data connectivity to the user, and the terminal may be called user equipment (user equipment, UE), mobile station (mobile station), subscriber unit (subscriber unit), station (station), terminal equipment (terminal equipment, TE), etc. The terminal can be a cellular phone (cellular phone), a personal digital assistant (personal digital assistant, PDA), a wireless modem (modem), a handheld device (hand held), a laptop computer (laptop computer), a cordless phone (cordless phone), Wireless local loop (Wireless Local Loop, WLL) station, mobile phone (mobile phone), tablet computer (pad), etc. With the development of wireless communication technology, devices that can access a wireless communication network, communicate with a wireless network side, or communicate with other objects through a wireless network can all be terminals in the embodiments of the present application. For example, terminals and cars in intelligent transportation, household equipment in smart homes, power meter reading instruments in smart grids, voltage monitoring instruments, environmental monitoring instruments, video surveillance instruments in intelligent security networks, cash registers, etc. Terminals can be statically fixed or mobile.

As an embodiment, as shown in FIG. 2 , the terminal is a mobile phone. In this embodiment of the present application, a terminal refers to a terminal that has a wireless connection relationship with an access network device and supports a multicast service. The terminal may be within the coverage of the access network device, is receiving the multicast service, and/or is transmitting and/or is about to start transmitting and/or is interested in the multicast service, etc., which is not limited herein.

The access network device in the embodiment of the present application is a device deployed in the wireless access network to provide wireless communication functions for terminals. Its main functions include: wireless resource management, Internet protocol (internet protocol, IP) header Compression of user data stream and encryption of user data flow, selection of mobile management entity (MME) when user equipment is attached, routing of user plane data to service gateway (service gateway, SGW), organization and sending of paging messages, broadcasting Organization and sending of messages, measurement for mobility or scheduling purposes, configuration of measurement reports, etc.

Access network equipment may include but not limited to: evolved Node B (evolved Node B, eNB), radio network controller (radio network controller, RNC), Node B (node B, NB), base station controller (base station controller) , BSC), base transceiver station (base transceiver station, BTS), home base station (for example, home evolved NodeB, or home Node B, HNB), baseband unit (baseband unit, BBU), wireless fidelity (wireless fidelity, WIFI) The access point (access point, AP), wireless relay node, wireless backhaul node, transmission point (transmission and reception point, TRP or transmission point, TP) in the system can also be 5G, such as NR, the system The gNB in, or, the transmission point (TRP or TP), one or a group (including multiple antenna panels) antenna panels of the base station in the 5G system, or, it can also be a network node that constitutes a gNB or a transmission point, such as a baseband Unit (BBU), or, distributed unit (DU, distributed unit), etc.

In some deployments, a gNB may include a centralized unit (CU) and a DU. The gNB may also include a radio unit (radio unit, RU). CU implements some functions of gNB, DU implements some functions of gNB, for example, CU implements radio resource control (radio resource control, RRC), packet data convergence layer protocol (packet data convergence protocol, PDCP) layer functions, DU implements wireless link Functions of the radio link control (radio link control, RLC), media access control (media access control, MAC) and physical (physical, PHY) layers. Since the information of the RRC layer will eventually be transformed into the information of the PHY layer, or transformed from the information of the PHY layer, under this framework, high-level signaling, such as RRC layer signaling or PDCP layer signaling, can also be It is considered to be sent by DU, or sent by DU+CU. It can be understood that the access network device may be a CU node, or a DU node, or a device including a CU node and a DU node. In addition, the CU can be divided into the access network equipment in the access network RAN, and the CU can also be divided into the access network equipment in the core network CN, which is not limited here.

In a specific implementation, as an embodiment, as shown in FIG. 2 , the access network device is a base station. In this embodiment of the present application, different base stations may be base stations with different identities, or may be base stations with the same identities deployed in different geographic locations. Before the base station is deployed, the base station does not know whether it will be involved in the scenario applied by the embodiment of the present application. Therefore, the base station or the baseband chip should support the method provided by the embodiment of the present application before deployment. It can be understood that the aforementioned base stations with different identities may be base station identities, cell identities, or other identities.

Access network devices and terminals can be deployed on land, for example, indoors or outdoors, handheld or vehicle-mounted, and so on. Access network equipment and terminals can also be deployed on the water, as well as on aircraft, balloons and satellites in the air. The embodiments of the present application do not limit the application scenarios of the access network device and the terminal.

Communication between access network devices and terminals, between access network devices and access network devices, and between terminals can be performed through licensed spectrum, or through unlicensed spectrum. , and can also communicate through the licensed spectrum and the unlicensed spectrum at the same time. The embodiments of the present application do not limit the frequency spectrum resources used between the access network device and the terminal.

It should be understood that one access network device can communicate with multiple terminals. A terminal can communicate with multiple access network devices at the same time. FIG. 2 is only a simplified schematic diagram for ease of understanding. The communication system may also include other network devices or other terminal devices, which are not shown in FIG. 2 .

In this embodiment of the present application, a core network device may also be referred to as a core network network element. The core network device can be connected to one or more access network devices, and can provide one or more functions in session management, access authentication, Internet protocol (internet protocol, IP) address allocation and data transmission for terminals in the system. For example, the core network equipment can be the mobile management entity (mobile management entity, MME) or serving gateway (serving gateway, SGW) in the 4G access technology communication system, and the access and mobility management function in the 5G access technology communication system (access and mobility management function, AMF) network element or user plane function (user plane function, UPF) network element, etc. In this embodiment of the present application, the network device may be the above-mentioned access network device or core network device, which is not limited here.

When describing the embodiments of the present application, some concepts used in the following description are explained below.

(1) Protocol data unit (protocol data unit, PDU) and service data unit (service data unit, SDU).

PDU refers to the unit of information exchanged between peer entities of each layer. SDU, also called business data unit, is a data set of user services at a specified layer. When it is transmitted to the receiver, the data does not change at the same protocol layer, that is, the business part. Then after sending it to the lower layer, the lower layer encapsulates it in a PDU and sends it out. SDU is an information unit from a high-level protocol to a low-level protocol. There is a one-to-one correspondence between the N-layer service data unit SDU and the PDU of the upper layer. According to the data of the protocol data unit, it is sent to the designated layer of the receiving end. That is to say, the PDU of this layer is the SDU of the lower layer, and the SDU of this layer is the PDU of the upper layer.

(2) Multicast business.

In systems using different wireless access technologies, the name of the multicast service may be different, for example, in the LTE system, it is called multimedia broadcast multicast service (MBMS); in the NR system , called multicast broadcast service (multicast broadcast service, MBS) and so on. Multicast services are mainly applicable to services for multiple terminals, such as video conferencing, TV broadcasting, video on demand, and online education.

When the multicast service performs multicast transmission, the network device (for example, base station) transmits the data packet to the media access control (media access control, MAC) through a radio link layer control protocol (radio link control, RLC) entity (entity). )entity. Then, the data packet is sent to the physical layer entity through the MAC entity, and the data packet is sent out through the physical layer entity, so that multiple terminals receive the data packet.

The following uses an example where the base station transmits the MBS service to the UE for illustration.

Multicast services are transmitted through two transmission technologies, point to multi-point (PTM) and point to point (PTP). PTM transmission technology, that is, establishes a dedicated bearer for MBS services, and transmits MBS services to multiple UEs simultaneously in the form of multicast through a public transmission channel or group scheduling, and supports RLC unacknowledged mode (unacknowledge Mode, UM). In the embodiment of the present application, the PTM transmission technology may also be referred to as a PTP transmission mode, a PTM mode, or a multicast form, and the like. Using the PTM transmission mode to perform multicast transmission may also be referred to as performing multicast transmission on a multicast service (for example, MBS).

The PTP transmission technology is to establish a UE-specific bearer, which is sent to the UE by the network device in the form of unicast, and supports RLC acknowledgment mode (acknowledge Mode, AM) or UM mode. In the embodiment of the present application, the PTP transmission technology may also be referred to as a PTP transmission mode, a PTP mode, or a unicast form, and the like. Using the PTP transmission mode to perform multicast transmission may also be referred to as unicast transmission to a multicast service (for example, MBS).

When the MBS service is transmitted from the base station to the UE, two transmission modes, PTP and PTM, can be used, and the two transmission modes can be switched dynamically. When a large number of UEs need to receive a certain MBS service, sending this service in unicast form needs to establish dedicated bearers for a large number of UEs, consuming resources. When it is sent to UEs in the form of multicast, all UEs interested in the service can receive the MBS through the MBS-dedicated bearer, which saves air interface resources, improves spectrum utilization, and improves transmission efficiency.

For a UE, if the quality of service (quality of service, QoS) requirements for sending MBS services through PTM cannot be met, it can support switching to RLC-AM mode, and use PTP transmission mode to transmit related services for the UE. For a split multicast radio bearer (multicast radio bearer, MRB), it can be switched between the RLC entity corresponding to PTM and the RLC entity corresponding to PTP. In the CU-DU scenario, the gNB-DU can judge to switch to work under a certain RLC entity. In some scenarios, such as retransmitting data or forwarding data from other access network devices, the CU may send indication information to the DU to instruct the DU to switch to which working mode. The indication information can be explicitly carried in at least one of the following signaling: F1 interface signaling, RRC message, MAC control element (control element, CE), PDCP control protocol data unit (protocol data unit, PDU) or RLC The control PDU or downlink control information (DCI).

Optionally, the PDCP layer can be notified in an implicit manner. For example, if PDCP only submits data packets to a unicast logical channel, the PTP transmission mode is used for multicast transmission; when PDCP only submits data packets to a multicast logical channel, then The PTM transmission method is used for multicast transmission; if the PDCP submits the data packet to the unicast logical channel and the multicast logical channel at the same time, the PTP transmission method can be used for multicast transmission, and the PTM transmission method can also be used for multicast transmission.

Taking the base station as gNB and the terminals as UE1 and UE2 as examples, the route transmitted in PTM mode can be called PTM leg, and the route transmitted in PTP mode can be called PTP leg. In the structural diagram of a data transmission device for a multicast service as shown in Figure 3, the gNB can send multicast data to UE1 and UE2 through the PTP leg, and can also send multicast data to UE1 and UE2 through the PTM leg. Specifically, gNB sends data packets to UE1 and/or UE2 through its PDCP layer, RLC layer and MAC layer respectively, and UE1 or UE2 receives data packets through its MAC layer, RLC layer and PDCP layer respectively. In PTM mode, UE needs to monitor cell-radio network temporary identifier (C-RNTI) and group network temporary identifier (group radio network temporary identifier, G-RNTI) at the same time, while in PTP mode, UE can only monitor Monitor C-RNTI or monitor C-RNTI and G-RNTI at the same time. If the UE uses a separate MRB to configure the PTP leg and PTM leg, the UE needs to monitor the C-RNTI all the time. Optionally, the deactivation process (the UE does not listen to the G-RNTI) and the activation process can be configured for the PTM leg.

In this embodiment of the present application, the multicast transmission means that the network device sends data by using the PTM transmission mode, and the multicast reception means that the terminal receives data from the network device based on the PTM transmission mode. Unicast transmission means that the network device sends data using the PTP transmission mode, and unicast reception means that the terminal receives data from the network device based on the PTP transmission mode. That is to say, the multicast sending and multicast receiving are based on the dedicated bearer of the MBS service established by the network device for data transmission. The unicast sending and unicast receiving are based on the dedicated bearer established by the network equipment for each terminal for data transmission. For multicast transmission, or if there is no limitation on multicast transmission or unicast transmission, the network device can send data in PTM transmission mode, or in PTP transmission mode. Multicast reception, or the case of multicast reception or unicast reception is not limited, the terminal can receive data from the network device based on the PTM transmission method, or receive data from the network device based on the PTP transmission method, which is not limited here.

(3) UM mode.

In UM mode, an RLC entity may be referred to as a UM RLC entity. The PDU between the UM RLC entity and the bottom layer (lower layer, or lower layer) may be called a UMD PDU, and the SDU between the UM RLC entity and the upper layer (upper layer) may be called an RLC SDU. UMD PDU contains data field (data field) and UMD PDU header block (header). It can be determined whether a complete RLC SDU is received according to whether the UMD PDU header contains the (sequence number, SN) field (field). That is to say, if the received UMD PDU includes the SN value, it means that the UMD PDU contains a segment of the RLC SDU, which can be understood as a subpacket of the RLC SDU. Otherwise, it means that the UMD PDU contains a complete RLC SDU. If the received UMD PDU contains a complete RLC SDU, the RLC header is removed directly, and then data transmission is performed. If the segment (or subpacket) of the RLC SDU in the UMD PDU is received, it is also necessary to reassemble the other RLC SDU segments in the UMD PDU to obtain a complete SDU, and then transmit the complete SDU for data.

When receiving data, the UM RLC entity needs to maintain a reassembly window (reassembly window). The range of the reorganization window can be set to [RX_Next_Highest-UM_Window_Size, RX_Next_Highest). Among them, UM_Window_Size is a constant. If the length of the SN is configured as 6 bits, the UM_Window_Size can be 32. If the length of SN is configured as 12bit, then UM_Window_Size can be 2048.

RX_Next_Highest indicates the next sequence number of the largest sequence number (sequence number, SN) in the received UMD PDU, that is, SN+1. In the schematic diagram of an SN effective range as shown in FIG. 1 , the reassembly window is divided into two sections based on RX_Next_Reassembly. The RX_Next_Reassembly is used to indicate the smallest SN waiting for reassembly.

If the SN value of the RLC SDU in the UMD PDU belongs to the interval corresponding to [RX_Next_Highest-UM_Window_Size, RX_Next_Reassembly), it means that the segment corresponding to the SN value has been received, and the UMD PDU needs to be discarded. Otherwise, put the UMD PDU into the receive buffer. The UMD PDU with SN=x is in the receive buffer, indicating that x is located on the right side of RX_Next_Reassembly in the figure. The right side is divided into the interval corresponding to [RX_Next_Reassembly, RX_Next_Highest) and the interval greater than or equal to RX_Next_Highest.

If x belongs to the interval corresponding to [RX_Next_Reassembly, RX_Next_Highest), and all byte segments of SN=x are received, the RLC SDU is reassembled, the RLC header is removed, and the reassembled SDU is delivered to the upper layer. If x=RX_Next_Reassembly, then update RX_Next_Reassembly to the minimum SN in the retransmission data packet set, which consists of packets that are not currently reassembled and delivered to the upper layer. Note that this is not simply SN+1, because the SNs in the interval corresponding to [RX_Next_Reassembly, RX_Next_Highest) may not be continuous.

If x is greater than RX_Next_Highest, it means that x falls outside the reassembly window. According to the definition, it is necessary to update RX_Next_Highest=x+1, discard the PDU whose SN falls outside the window, and move the reassembly window to the right by several lengths. If RX_Next_Reassembly is squeezed out of the reassembly window, the value of RX_Next_Reassembly needs to be updated, which can be determined according to the minimum value of SN>=(RX_Next_Highest-UM_Window_Size) in the package set that is not currently reassembled and delivered to the upper layer. If the current x is too large, the reorganization window will move a lot to the right, which will easily lead to the discarding of SNs that have not been recombined.

At PTM initialization, the PTM RLC entity is configured in UM mode. The UM RLC entity will set RX_Next_Highest and RX_Next_Reassembly to the SN value of the first packet containing the SN received by the terminal. If the terminal receives the first SDU containing the SN at time t1, its SN value is greater than the SN value of the SDU subsequently received by the terminal. For example, if the SN value of the SDU segment that the MAC layer retransmits to the UM RLC entity is smaller than the SN value of the first SDU containing the SN, that is, the SN value is smaller than RX_Next_Reassembly, the terminal will not cache the SDU segment, and The data packet corresponding to the SDU segment will be discarded. However, the terminal does not receive the data packet before time t1, resulting in that the RLC SDU is not reassembled and will not be delivered to the upper layer (ie, the PDCP layer). Therefore, setting the RX_Next_Reassembly and RX_Next_Highest of the PTM as the SN value of the first data packet containing the SN received by the terminal will affect the service performance. In particular, it affects multicast services that require high reliability, for example, Vehicle-to-Everything (V2X) and the like.

Based on this, the present application proposes a data transmission method for multicast services, which can avoid data packet loss events caused by PTM initialization, improve the success rate of data transmission, and improve the reliability of multicast services.

Please refer to FIG. 4 . FIG. 4 is a schematic flowchart of a data transmission method for a multicast service provided by the present application. The method is applied to the communication network shown in FIG. 2 . Hereinafter, without loss of generality, the embodiment of the present application will be described in detail by taking an interaction process between a terminal and a network device as an example. It can be understood that the network device can transmit data packets based on the same technical solution with multiple terminals having a wireless connection relationship in the wireless communication system. This application does not limit this. Specifically, as shown in FIG. 4, the method may include the following steps S400-S406.

S400: The network device sends the multicast wireless configuration to the terminal.

Correspondingly, the terminal receives the multicast wireless configuration from the network device.

In the embodiment of the present application, the multicast wireless configuration is used to instruct the terminal to perform multicast transmission initialization. That is to say, the terminal can perform PTM initialization based on the multicast wireless configuration, so that the terminal can receive data sent by the network device based on the dedicated bearer of the multicast service. The terminal can also perform PTP initialization based on the multicast wireless configuration, so that the terminal can receive data sent by the network device based on the dedicated bearer of each terminal. The multicast radio configuration may include MRBs as described above. The multicast radio configuration may include PDCP configuration and RLC configuration. Among them, the PDCP configuration may include the number of PDCP SN bits, header compression configuration, integrity protection, status report enabling, etc.; the RLC configuration may include the logical channel ID, the number of RLC SN bits, etc., which are not limited here.

In a possible example, the multicast wireless configuration includes an initial value of the lower boundary value of the reassembly window, and the initial value of the lower boundary value is the minimum value of the sequence number in the subpacket to be transmitted by the network device.

In this embodiment of the application, the reassembly window may be the above-mentioned reassembly window, and the lower boundary value may be RX_Next_Reassembly. The initial value of the lower boundary value is the minimum value of the sequence number in the subpacket to be transmitted by the network device, so it can ensure that the sequence number of the retransmitted subpacket is greater than or equal to the lower boundary value, thereby avoiding data packet loss. The upper boundary value of the reorganization window may be RX_Next_Highest. The setting of the upper boundary value may refer to the existing rules, and the initial value of the upper boundary is set as the serial number of the first sub-packet received by the terminal.

Exemplarily, assuming that the minimum SN value of the RLC layer packet to be transmitted in the MAC layer of the network device is 4, and the SN value of the first subpacket received by the terminal is 9, then the lower boundary value of the reassembly window (for example , RX_Next_Reassembly) may be set to 4, and the upper boundary value of the reassembly window (for example, RX_Next_Highest) may be set to 9.

Correspondingly, in a possible example, the terminal sets the initial value of the lower boundary value of the reassembly window based on the multicast wireless configuration; the initial value of the upper boundary value of the reassembly window is set as the first subpacket received by the terminal serial number. That is to say, the network device first determines the minimum value of the sequence number in the subpacket to be transmitted, and then transmits the minimum value as a parameter in the multicast wireless configuration to the terminal, so that the terminal can set the minimum value based on the multicast wireless configuration. Value is set to the initial value of the lower boundary value of the reorganization window. After the sequence number of the first sub-packet of data to be transmitted received by the terminal, the upper boundary value of the reassembly window is set based on the sequence number. In this way, the boundary value of the reassembly window can be set when the multicast transmission is initialized. And the lower boundary value of the reassembly window is the value of the subpacket with the smallest sequence number in the data packet to be transmitted, then the sequence number of the lost data packet will not be greater than this value, which can improve the effectiveness of setting the boundary value of the reassembly window.

If the multicast wireless configuration does not include the lower boundary value used when multicast transmission is initialized, then in a possible example, the initial value of the lower boundary value of the reassembly window is equal to the initial value of the upper boundary value, and is equal to The sequence number of the first subpacket of .

Correspondingly, in a possible example, the terminal sets the initial value of the lower boundary value and the initial value of the upper boundary value of the reassembly window as the sequence number of the first subpacket received by the terminal. That is, the network device does not take into account the size of the sequence numbers in the subpackets to be transmitted. The terminal can set the lower boundary value and the upper boundary value of the reassembly window based on the received sequence number of the first subpacket of the data to be transmitted according to the existing rules.

Exemplarily, assuming that the SN value of the first subpacket received by the terminal is 9, the initial values of the lower boundary value (for example, RX_Next_Reassembly) and the upper boundary value (for example, RX_Next_Highest) of the reassembly window are both set to 9.

S401: The network device multicasts at least two subpackets of the data packet to be transmitted to the terminal.

Correspondingly, the terminal multicast receives the sub-packets of the data packet to be transmitted from the network device.

The present application does not limit the data packet to be transmitted, and the data packet to be transmitted includes at least two sub-data packets. That is to say, a subpacket is a segment of a packet to be transmitted. Each sub-packet corresponds to a sequence number SN. The sub-data packet may be a data packet to be newly transmitted, or may include a retransmitted data packet.

In this embodiment of the present application, the subpacket in the PDCP layer may be transmitted to the MAC entity of the network device through the RLC entity of the network device. Then, the sub-packet is sent to the physical layer entity of the network device through the MAC entity of the network device, and the sub-packet is sent out through the physical layer entity of the network device, so that the terminal receives the sub-packet.

Correspondingly, the terminal transmits the sub-packet to the MAC entity of the terminal through the physical layer of the terminal. Then the MAC entity transmits the sub-packet to the RLC entity of the terminal. Since the sub-packets are segments of the data packets to be transmitted, the RLC entity of the terminal reassembles the sub-packets in the data packets to be transmitted to obtain a complete data packet to be transmitted. Then transmit the complete data packet to be transmitted to the PDCP layer of the terminal, so that the terminal receives the data packet to be transmitted. If there is an unreceived sub-packet in the terminal, the sub-packet needs to be retransmitted. In the embodiment of the present application, sub-packets in the data packets to be transmitted that are not received by the terminal may be referred to as retransmission sub-packets.

It can be understood that the MAC PDU of the network device may include one or more MAC subPDUs, and each MAC subPDU may include a MAC SDU. Therefore, one MAC PDU corresponds to multiple MAC SDUs, and one MAC SDU corresponds to one RLC PDU. Taking the MAC layer transmission of the network device as an example, the MAC layer of the network device can send the MAC subPDU in the MAC layer to the MAC layer of the terminal in the form of MAC PDU through the physical layer of the network device and the physical layer of the terminal. The MAC layer of the terminal can receive the MAC PDU, and then transmit it to the RLC layer of the terminal. The RLC layer of the terminal needs to reassemble the MAC subPDU in the MAC PDU to obtain a complete MAC SDU. Then the RLC layer of the terminal sends the MAC SDU to the PDCP layer as an RLC PDU.

S402: The terminal sends a confirmation message to the network device.

Accordingly, the network device receives an acknowledgment message from the terminal.

In this embodiment of the present application, the confirmation message is used to determine the sub-packets that the terminal has received. The acknowledgment message may be an acknowledgment message (acknowledgment, ACK), or may be a non-acknowledgment message (negative acknowledgment, NACK). Wherein, the sequence number in the ACK is used to determine that the terminal has received the sub-packet corresponding to the sequence number. The sequence number in the NACK is used to determine that the terminal has not received the sub-packet corresponding to the sequence number. It can be understood that after receiving the sub-packet, the terminal feeds back a confirmation message to the network device to inform that the sub-packet has been received. As such, non-received subpackets can be determined based on the acknowledgment message.

Exemplarily, after the base station receives the ACK for#9 after sending the MAC packet corresponding to RLC SN=9 at its MAC layer, it can be determined that the terminal has received the sub-packet with the sequence number 9. The MAC layer also receives NACKs corresponding to RLC SN=4, 5, and 6 respectively, so it can be determined that the terminal has not received the subpackets with

sequence numbers

4, 5, and 6, so that it can be determined that the sequence numbers of the retransmitted subpackets are 4, 5, 6.

S403: The network device determines a retransmission sub-packet in the data packet to be transmitted.

In this embodiment of the application, the retransmission sub-packet includes the sub-packet retransmitted by the network device before the confirmation message sent by the terminal after receiving the first sub-packet, or may include the sub-packet retransmitted by the terminal after receiving the first sub-packet A subpacket retransmitted by a network device following an acknowledgment message sent. It can be understood that after receiving the acknowledgment message, the network device may determine, based on the acknowledgment message, the retransmission sub-packets in the data packets to be transmitted that need to be retransmitted.

As an example, refer to FIG. 5 for a schematic diagram of a data transmission scenario of a multicast service. As shown in Figure 5, the network device sends #9 (MAC) to the terminal at time t1 (indicating that the MAC PDU sent by the network device to the terminal includes a subpacket with a sequence number of 9). After time t1, the network device sends #4 (MAC) to the terminal (indicating that the MAC PDU sent by the network device to the terminal includes a subpacket with a sequence number of 4). After that, the terminal sends ACK for #9 (MAC) to the network device (indicating that the MAC PDU received by the terminal includes a subpacket with a sequence number of 9), and this subpacket is the first subdata received by the terminal. Therefore, #4 (MAC) sent before ACK for #9 (MAC), and #5, 6 (MAC) sent after ACK for #9 (MAC) (indicating that the MAC PDU sent by the network device to the terminal includes a sequence number of 5 and 6 subpackets) are all retransmission subpackets. That is to say, from time t1 to time t2 (before step S404), the sub-packets that have not received ACK are retransmission sub-packets.

S404: The network device sends indication information to the terminal.

Correspondingly, the terminal receives indication information from the network device.

In this embodiment of the present application, the indication information is used to modify the lower boundary value of the reorganization window. As mentioned above, if there is an initial value of the lower boundary value in the multicast wireless configuration instructing the terminal to initialize the multicast transmission, then the initial value of the lower boundary value is the minimum value of the sequence number in the subpacket. If there is no initial value of the lower boundary value in the multicast wireless configuration, the initial value of the lower boundary value may be equal to the initial value of the upper boundary value, and equal to the sequence number of the first subpacket received by the terminal. It can be understood that modifying the lower boundary value of the reassembly window can modify the range of the reassembly window, thereby avoiding data packet loss.

In a possible example, the indication information includes an absolute value of the retransmission sub-packet, for example, a minimum value of a sequence number in the retransmission sub-packet. The indication information is specifically used to indicate that the lower boundary value of the reorganization window is modified to the absolute value. Exemplarily, the sequence numbers of the retransmission subpackets are 4, 5, and 6, and the absolute value of the retransmission subpackets may be 4. In this way, the lower boundary value of the reorganization window can be directly set as the absolute value, so as to improve the setting efficiency. In the case where the absolute value is the minimum value of the sequence number in the retransmission sub-packet, packet loss of the retransmission sub-packet can be avoided, and service reliability can be improved.

In another possible example, the indication information includes an offset value (offset) of retransmitting the sub-packet. The indication information is specifically used to indicate to adjust the lower boundary value of the reorganization window based on the offset value. In this way, the initial value of the lower boundary value can be adjusted based on the offset value, and the range of the reassembly window can be adjusted to avoid packet loss.

The offset value may be related to the following at least two items of information: the minimum value of the sequence number in the retransmission sub-packet, the sequence number of the first sub-packet received by the terminal, and a preset constant. Wherein, the preset constant may be a positive integer. This application does not limit the calculation method of the offset value, for example, the offset value is the first difference between the sequence number of the first sub-packet received by the terminal and the minimum value of the sequence number in the retransmitted sub-packet value. Exemplarily, the sequence numbers of the retransmitted subpackets are 4, 5, and 6, and the sequence number of the first subpacket received by the terminal is 9, then the offset value can be the difference between 9 and 4, That is 5. For another example, the offset value is a second difference obtained based on the above-mentioned first difference and a preset constant. Exemplarily, the sequence numbers of the retransmitted subpackets are 4, 5, and 6, the sequence number of the first subpacket received by the terminal is 9, and the preset constant is 3, then the offset value can be 2 (9 -4-3), in this way, the initial value of the lower boundary value can be adjusted based on the offset value. That is to say, setting the lower boundary value as the difference between the initial value of the lower boundary value and the offset value expands the range between the lower boundary value and the upper boundary value, thereby expanding the scope of the reorganization window, which can avoid Packets are lost.

This application does not limit the signaling that bears the indication information. If the indication information is sent by the MAC layer of the network device, the indication information can be the CE of the MAC layer, or the DCI of the PHY layer, or it can be a new addition of the RLC layer. Status PDU etc. The indication information may also include the identifier of the terminal, so that the terminal modifies the lower boundary value of the reassembly window based on the offset value of the retransmission subpacket after receiving the indication information.

S405: The terminal modifies the lower boundary value based on the indication information.

This application does not limit the method of modifying the lower boundary value. You can refer to the above. In the case where the indication information includes the absolute value of the retransmission subpacket, the lower boundary value can be modified to the absolute value of the retransmission subpacket. . In the case that the indication information includes the offset value of the retransmission subpacket, the lower boundary value may be adjusted based on the offset value.

S406: The network device multicasts the retransmission sub-packet to the terminal.

Correspondingly, the terminal multicasts and receives the retransmission sub-packet from the network device.

In the embodiment of the present application, step S406 may be performed after step S404, so as to perform the retransmission subpacket of the network device before receiving the first confirmation message and the retransmission subpacket of the network device after receiving the first confirmation message. Retransmission. And after the terminal modifies the lower boundary value of the reassembly window, since the value corresponding to the modified lower boundary value will be less than or equal to the sequence number of the retransmitted subpacket, data packet loss can be avoided.

Exemplarily, as shown in FIG. 5, the first confirmation message received by the network device is ACK for #9 (MAC), and then the initial value of the lower boundary value and the initial value of the upper boundary value are 9. The retransmission subpacket includes #4 (MAC) sent before ACK for #9 (MAC), and #5 and 6 (MAC) sent after ACK for #9 (MAC). If the network device sends the absolute value of the retransmission subpacket to the terminal at time t2, for example, the absolute value is 4, then the terminal may modify the lower boundary value to 4. If the network device sends the offset value of the retransmission subpacket to the terminal at time t2, for example, the offset value is 5, the lower boundary value may be modified to 4 (9-5). Then send the retransmission sub-packet sets corresponding to #4 (MAC), #5, and 6 (MAC) to the terminal multicast, and the retransmission subpackets corresponding to #4 (MAC), #5 (MAC) and #6 (MAC) respectively Sub-packets will not be discarded, but will be reassembled. and transmit after reassembly is complete.

In the method shown in FIG. 4 , the network device first sends the multicast wireless configuration to the terminal before multicasting the subpacket of the data packet to be transmitted to the terminal, so that the terminal performs multicast transmission initialization. After receiving the sub-packet sent by the terminal, the terminal sends an acknowledgment message of the sub-packet to the terminal. After receiving the first acknowledgment message, the network device determines the retransmission sub-packet in the data packet to be transmitted. Then, the instruction information is sent to the terminal, so that the terminal modifies the lower boundary value of the reassembly window, thereby modifying the range of discarding data packets. Then the network device multicasts the retransmission sub-packet to the terminal, which can avoid the occurrence of the packet loss event caused by PTM initialization, improve the success rate of data transmission, and improve the reliability of the multicast service.

Please refer to FIG. 6 . FIG. 6 is a schematic flowchart of another multicast service data transmission method provided by the present application. The method is applied to a communication network as shown in FIG. 2 . As shown in FIG. 6, the method may include the following steps S600-S604, wherein:

S600: The network device sends the multicast wireless configuration to the terminal.

S601: The network device multicasts to the terminal at least two subpackets of the data packet to be transmitted.

S602: The terminal sends a confirmation message to the network device.

S603: The network device determines a retransmission subpacket in the data packet to be transmitted.

Wherein, for steps S600-S603, reference may be made to the description of steps S400-S403, which will not be repeated here.

S604: The network device unicasts the retransmission sub-packet to the terminal.

Correspondingly, the terminal unicast receives the retransmission sub-packet from the network device.

In a possible example, step S603 is specifically for the MAC layer in the network device to determine the retransmission sub-packet in the data packet to be transmitted. Step S604 may specifically include sending the retransmission sub-packet to the terminal in unicast from the MAC layer in the network device to the terminal based on the C-RNTI of the terminal.

Exemplarily, the network device is gNB in FIG. 3 , and the terminal is UE1 in FIG. 3 . Referring to FIG. 3 , the MAC layer of the gNB may send the retransmission subpacket set corresponding to the retransmission subpacket to UE1 through the C-RNTI. In this way, the MAC layer directly performs unicast transmission on the retransmission sub-packet through the PTP mode, which can increase the retransmission rate.

In another possible example, step S603 specifically determines the retransmission sub-packet in the data packet to be transmitted for the MAC layer in the network device. After step S603, before step S604, further include the step of: sending layer signaling upward from the MAC layer of the network device, so that the PDCP layer of the network device determines the sequence number of the retransmission sub-packet. Step S604 specifically includes unicasting the retransmission sub-data downward from the PDCP layer, so as to unicast the retransmission sub-data packet to the terminal.

It can be understood that the retransmission subpacket to be retransmitted can be confirmed internally by the network device through hierarchical signaling. For example, the MAC layer of the network device sends the layer signaling to the RLC layer of the network device, and then the RLC layer sends it to the PDCP layer of the network device. In this way, the PDCP layer can determine to retransmit the subpacket. Then use the PTP mode to send down layer by layer from the PDCP layer of the network device, so that the retransmission subpacket (or the retransmission subpacket set corresponding to the retransmission subpacket) is sent to the terminal in unicast, which can avoid data loss .

For example, please refer to FIG. 7 , which is a schematic flowchart of another data transmission method for a multicast service provided by the present application. As shown in FIG. 7 , the sequence numbers of the subpackets in the data packets to be transmitted sent by the PDCP layer of the network device to the RLC layer of the network device are 3, 4, 5, 6, 7, 8, and 9. And the RLC layer of the network device sends the above data packets to be transmitted to the MAC layer of the network device. However, after the MAC layer of the network device sends the data packet to be transmitted to the MAC of the terminal through the physical layer, the sequence number of the subpacket corresponding to the first ACK received by the MAC layer of the network device is 9, and the received The sequence numbers of the subpackets corresponding to the NACK are 4, 5, and 6, and the MAC layer of the network device can determine that the sequence numbers of the retransmitted subpackets are 4, 5, and 6. In addition, the MAC layer of the network device may also notify the RLC layer of the network device through layer signaling. The RLC layer of the network device informs the PDCP layer of the network device through hierarchical signaling, so that the PDCP layer determines that the sequence numbers of the retransmitted sub-packets are 4, 5, and 6, and then these retransmitted sub-packets can be retransmitted. The PDCP layer may record the set of retransmission data packets corresponding to the retransmission sub-packets as {PDCP SN}={4, 5, 6}. Through the downward unicast transmission of the PDCP layer, RLC layer, MAC layer and PHY layer of the network device, the terminal can pass through its PHY layer, MAC layer, and RLC layer. The set of data packets received is recorded as {SN}={4, 5, 6}, that is, the sequence numbers of the retransmission subpackets of the RLC layer to be received by the terminal are 4, 5, and 6. The PTP leg shown in Figure 3 can be used to perform unicast transmission of the retransmitted sub-packet to realize sub-packet retransmission and avoid packet loss.

In a CU-DU scenario, in a possible example, signaling is transmitted to the DU through the F1 interface, which may include the terminal's identifier and the sequence number of the retransmission subpacket, which is used to indicate that the retransmission subpacket of the terminal is Retransmission. In this way, the retransmission sub-packet can be unicast transmitted through the PTP mode, so as to realize the retransmission of the sub-packet and avoid data packet loss.

In the method shown in FIG. 6 , the network device first sends the multicast wireless configuration to the terminal before multicasting the subpacket of the data packet to be transmitted to the terminal, so that the terminal performs multicast transmission initialization. After the terminal receives the sub-packet sent by the network device in multicast, it sends an acknowledgment message of the sub-packet to the terminal. After receiving the first acknowledgment message, the network device determines the retransmission sub-packet in the data packet to be transmitted. Then unicast the retransmission subpacket to the terminal. In this way, the retransmission of data packets that failed in multicast transmission by means of unicast transmission can avoid the occurrence of data packet loss events caused by PTM initialization, improve the success rate of data transmission, and improve the reliability of multicast services.

The method of the embodiment of the present application has been described in detail above, and the device of the embodiment of the present application is provided below.

Please refer to FIG. 8 . FIG. 8 is a schematic structural diagram of a communication device provided by an embodiment of the present application. The communication device may include a transceiver unit 801 and a processing unit 802 as shown in FIG. 8 . In a possible example, the communication device may be a network device, where:

The transceiver unit 801 is configured to send a multicast wireless configuration to the terminal, and the multicast wireless configuration is used to instruct the terminal to perform multicast transmission initialization; to multicast at least two subpackets of the data packet to be transmitted to the terminal, each A sub-packet corresponds to a sequence number; receiving an acknowledgment message from the terminal, where the acknowledgment message is used to determine the sub-packet that the terminal has received;

The processing unit 802 is configured to determine a retransmission sub-packet in the data packet to be transmitted;

The transceiver unit 801 is further configured to send indication information to the terminal, where the indication information is used to modify the lower boundary value of the reassembly window; and send the retransmission subpacket to the terminal in multicast.

Optionally, the indication information includes an absolute value of the retransmission subpacket, and the indication information is specifically used to indicate that the lower boundary value of the reassembly window is modified to the absolute value, and the absolute value includes the The minimum value of the sequence number in the retransmission subpacket.

Optionally, the indication information includes an offset value of the retransmission subpacket, and the indication information is specifically used to indicate that the lower boundary value of the reassembly window is adjusted based on the offset value, and the offset value It is related to the following at least two pieces of information: the minimum value of the sequence number in the retransmission sub-packet, the sequence number of the first sub-packet received by the terminal, and a preset constant, the preset constant is positive integer.

Optionally, the multicast wireless configuration includes an initial value of the lower boundary value, which is a minimum value of sequence numbers in the subpacket.

In a possible example, the communication device may be a network device, where:

The transceiver unit 801 is further configured to unicast send the retransmission sub-packet to the terminal.

Optionally, the communication device further includes a MAC layer, the retransmission sub-packet is determined by the MAC layer, and the transceiver unit is specifically configured to transfer from the MAC layer to a single sending the retransmission sub-packet by broadcasting, so as to unicast the retransmission sub-packet to the terminal.

Optionally, the communication device further includes a MAC layer and a PDCP layer, the retransmission sub-packet is determined by the MAC layer, and the transceiver unit is further configured to send hierarchical signaling upward from the MAC layer, so that The PDCP layer determines the sequence number of the retransmission sub-data packet; the transceiver unit is specifically configured to unicast downward the retransmission sub-data from the PDCP layer, so as to unicast send the retransmission sub-data to the terminal. Retransmit the subpacket.

In a possible example, the communication device may be a terminal, where:

The transceiver unit 801 is configured to multicast receive multicast wireless configuration from the network device, and the multicast wireless configuration is used to instruct the communication device to perform multicast transmission initialization; multicast receive the sub-data of the data packet to be transmitted from the network device packet, the sub-packet corresponds to a sequence number; send an acknowledgment message to the network device, the acknowledgment message is used to determine that the communication device has received the sub-packet; receive indication information from the network device, the The above instruction information is used to modify the lower boundary value of the reorganization window;

The processing unit 802 is configured to modify the lower boundary value based on the indication information;

The transceiver unit 801 is further configured to multicast receive the retransmission sub-packet from the network device.

Optionally, the indication information includes an offset value of the retransmission subpacket, and the indication information is specifically used to indicate that the lower boundary value of the reassembly window is adjusted based on the offset value, and the offset value Related to the following at least two items of information: the minimum value of the sequence number in the retransmission sub-packet, the sequence number of the first sub-packet received by the communication device, a preset constant, the preset constant is a positive integer.

In a possible example, the communication device may be a terminal, where:

The transceiver unit 801 is configured to multicast receive a multicast wireless configuration from a network device, and the multicast wireless configuration is used to instruct the communication device to perform multicast transmission initialization; receive a multicast subclass of a data packet to be transmitted from the network device A data packet, the sub-packet corresponds to a sequence number; send an acknowledgment message to the network device, the acknowledgment message is used to determine that the communication device has received the sub-packet; receive the multicast from the network device Describe the retransmission subpacket.

It should be noted that the implementation of each unit may also refer to the corresponding description of the method embodiment shown in FIG. 4 or FIG. 6 .

Please refer to FIG. 9 . FIG. 9 is a schematic structural diagram of another communication device provided by an embodiment of the present application. The communication device includes a processor 901 , a memory 902 and a communication interface 903 . The processor 901 , memory 902 and communication interface 903 are connected to each other through a bus 904 .

Wherein, the processor 901 may be a device having a processing function, and may include one or more processors. The processor may be a general purpose processor or a special purpose processor or the like. The processor can be a baseband processor, or a central processing unit. The baseband processor can be used to process communication protocols and communication data, and the central processing unit can be used to control the communication device, execute software programs, and process data of the software programs.

The communication interface 903 is used to communicate with external devices, for example, the network device sends a sub-packet of the data packet to be transmitted to the terminal. For another example, the network device receives the confirmation message sent by the terminal. The communication interface 903 is also used for information exchange within the network device, for example, the MAC layer sends a message to the RLC layer. For another example, the PDCP layer sends a message to the RLC layer.

The memory 902 can be a device with a storage function, including but not limited to random access memory (random access memory, RAM), read-only memory (read-only memory, ROM), erasable programmable read-only memory (erasable programmable read only memory, EPROM), or portable read-only memory (compact disc read-only memory, CD-ROM). The memory 902 is used to store one or more related programs and sub-packets of the data packets to be transmitted, and the sub-packets of the data packets to be transmitted include retransmission sub-packets in the data packets to be transmitted. The one or more programs are executed by the processor 901 according to any one of the methods described above.

Specifically, in a possible example, the communication device may be a network device, and the processor 901 in the network device is configured to perform the following operations:

Sending a multicast wireless configuration to the terminal, where the multicast wireless configuration is used to instruct the terminal to perform multicast transmission initialization;

Multicast sending at least two subpackets of the data packet to be transmitted to the terminal, each subpacket corresponds to a sequence number;

receiving an acknowledgment message from the terminal, the acknowledgment message being used to determine the subpackets that the terminal has received;

Determine the retransmission sub-packet in the data packet to be transmitted;

sending indication information to the terminal, where the indication information is used to modify the lower boundary value of the reassembly window;

and sending the retransmission subpacket to the terminal in multicast.

Optionally, the multicast wireless configuration includes an initial value of the lower boundary value, which is the minimum value of the sequence number in the subpacket.

In a possible example, the communication apparatus may be a network device, and the processor 901 in the network device is configured to perform the following operations:

Multicasting the multicast wireless configuration to the terminal, where the multicast wireless configuration is used to instruct the terminal to perform multicast transmission initialization;

Determine the retransmission sub-packet in the data packet to be transmitted;

Sending the retransmission sub-packet to the terminal in unicast.

Optionally, the retransmission sub-packet is determined by the MAC layer of the network device, and in terms of unicast sending the retransmission sub-packet to the terminal, the processor 901 is specifically configured to perform the following operations:

and unicast sending the retransmission subpacket downward from the MAC layer based on the C-RNTI of the terminal, so as to unicast send the retransmission subpacket to the terminal.

Optionally, the retransmission subpacket is determined by the MAC layer of the network device, and after the determination of the retransmission subpacket in the to-be-transmitted data packet, the processor 901 is further configured to perform the following operations:

sending layer signaling upwards from the MAC layer, so that the PDCP layer of the network device determines the sequence number of the retransmission sub-packet;

Regarding the unicast sending of the retransmission sub-packet to the terminal, the processor 901 is specifically configured to perform the following operations:

Sending the retransmission sub-data in unicast downward from the PDCP layer, so as to unicast the retransmission sub-data packet to the terminal.

In a possible example, the communication device may be a terminal, and the processor 901 in the terminal is configured to perform the following operations:

Multicast receiving multicast wireless configuration from the network device, the multicast wireless configuration is used to instruct the terminal to perform multicast transmission initialization;

Multicast receiving a sub-packet of the data packet to be transmitted from the network device, and the sub-packet corresponds to a sequence number;

sending an acknowledgment message to the network device, where the acknowledgment message is used to determine that the terminal has received the sub-packet;

receiving indication information from the network device, where the indication information is used to modify the lower boundary value of the reassembly window;

modifying the lower boundary value based on the indication information;

The retransmission subpacket is multicast received from the network device.

The retransmission sub-packet in the data packet to be transmitted is received by unicast from the network device.

It should be noted that the implementation of each operation may also refer to the corresponding description of the method embodiment shown in FIG. 4 or FIG. 6 .

The embodiment of the present application also provides a communication device, configured to execute any method and function related to a network device or a terminal in any one of the foregoing embodiments.

It should be noted that the above-mentioned communication device may be a network device or a terminal, or may be a chip applied in a network device or a terminal, or other combined devices, components, etc. that can realize the functions of the above-mentioned devices. When the communication device is a network device or a terminal, the receiving unit can be a receiver, the sending unit can be a transmitter, the receiving unit and the sending unit can also be an integrated transceiver, antenna or radio frequency circuit, etc., and the processing unit can be a processor, such as Baseband chips, etc. When the communication device is a component having the above-mentioned device functions, the receiving unit and the sending unit may be an integrated radio frequency unit, and the processing unit may be a processor. When the communication device is a chip system, the receiving unit may be an input interface of the chip system, the sending unit may be an output interface of the chip system, and the processing unit may be a processor of the chip system, for example: a central processing unit (central processing unit, CPU) .

An embodiment of the present application further provides a communication system, where the system includes at least one network device and at least one terminal involved in any one of the foregoing embodiments.

An embodiment of the present application also provides a computer-readable storage medium, where instructions are stored in the computer-readable storage medium, and when the computer-readable storage medium is run on a computer, the method flow shown in FIG. 4 or FIG. 6 is implemented.

An embodiment of the present application also provides a computer program product, the computer program product is used to store a computer program, and when the computer program is run on a computer, the method flow shown in FIG. 4 or FIG. 6 is realized.

The embodiment of the present application also provides a first chip, including a processor and a memory, and the processor is used to call and execute instructions stored in the memory from the memory, so that the device installed with the chip executes the instructions shown in Figure 4 or The method shown in Figure 6.

The embodiment of the present application also provides a second chip, including: an input interface, an output interface, and a processing circuit, wherein the input interface, the output interface, and the processing circuit are connected through an internal connection path, and the processing circuit It is used to execute the method shown in FIG. 4 or FIG. 6 .

The embodiment of the present application also provides a third chip, including: an input interface, an output interface, a processor, and optionally a memory, wherein the input interface, the output interface, the processor, and the memory The processors are used to execute the codes in the memory, and when the codes are executed, the processors are used to execute the method shown in FIG. 4 or FIG. 6 .

The embodiment of the present application also provides a chip system, the chip system includes at least one processor, a memory and an interface circuit, the memory, the transceiver and the at least one processor are interconnected through lines, and the at least one memory Instructions are stored in; when the instructions are executed by the processor, the method flow shown in FIG. 4 or FIG. 6 is realized.

To sum up, by implementing the embodiment of the present application, the network device first sends the multicast wireless configuration to the terminal before multicasting the subpacket of the data packet to be transmitted to the terminal, so that the terminal performs multicast transmission initialization. After receiving the sub-packet sent by the terminal, the terminal sends an acknowledgment message of the sub-packet to the terminal. After receiving the first confirmation message, the network device determines the retransmission subpacket in the data packet to be transmitted. Then, the instruction information is sent to the terminal, so that the terminal modifies the lower boundary value of the reassembly window, thereby modifying the range of discarding data packets. Then the network device multicasts the retransmission sub-packet to the terminal, which can avoid the occurrence of the packet loss event caused by PTM initialization, improve the success rate of data transmission, and improve the reliability of the multicast service.

On the other hand, after the network device determines the retransmission sub-packet in the data packet to be transmitted, it unicasts the retransmission sub-packet to the terminal. In this way, the retransmission of data packets that failed in multicast transmission by means of unicast transmission can avoid the occurrence of data packet loss events caused by PTM initialization, improve the success rate of data transmission, and improve the reliability of multicast services.

Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments are realized. The processes can be completed by computer programs or hardware related to the computer programs. The computer programs can be stored in computer-readable storage media. The computer programs During execution, it may include the processes of the foregoing method embodiments. The aforementioned storage medium includes: ROM or random access memory RAM, magnetic disk or optical disk, and other various media that can store computer program codes.

Claims

A data transmission method for a multicast service, comprising:

Sending a multicast wireless configuration to the terminal, where the multicast wireless configuration is used to instruct the terminal to perform multicast transmission initialization;

Multicast sending at least two subpackets of the data packet to be transmitted to the terminal, each subpacket corresponds to a sequence number;

receiving an acknowledgment message from the terminal, the acknowledgment message being used to determine the subpackets that the terminal has received;

Determine the retransmission sub-packet in the data packet to be transmitted;

sending indication information to the terminal, where the indication information is used to modify the lower boundary value of the reassembly window;

and sending the retransmission subpacket to the terminal in multicast.
The method according to claim 1, wherein the indication information includes the absolute value of the retransmission subpacket, and the indication information is specifically used to indicate that the lower boundary value of the reassembly window is modified to the absolute value value, the absolute value includes the minimum value of the sequence number in the retransmission subpacket.
The method according to claim 1, wherein the indication information includes an offset value of the retransmission subpacket, and the indication information is specifically used to indicate the adjustment of the reassembly window based on the offset value The lower boundary value, the offset value is related to at least two of the following items of information: the minimum value of the sequence number in the retransmission sub-packet, the sequence number of the first sub-packet received by the terminal, and the pre-set A constant is set, and the preset constant is a positive integer.
The method according to claim 1, wherein the multicast wireless configuration includes an initial value of the lower boundary value, which is the minimum value of the sequence number in the sub-packet.
A data transmission method for a multicast service, comprising:

Multicasting the multicast wireless configuration to the terminal, where the multicast wireless configuration is used to instruct the terminal to perform multicast transmission initialization;

Multicast sending at least two subpackets of the data packet to be transmitted to the terminal, each subpacket corresponds to a sequence number;

receiving an acknowledgment message from the terminal, the acknowledgment message being used to determine the subpackets that the terminal has received;

Determine the retransmission sub-packet in the data packet to be transmitted;

Sending the retransmission sub-packet to the terminal in unicast.
The method according to claim 5, wherein the retransmission sub-packet is determined by a media access control MAC layer of the network device, and sending the retransmission sub-packet to the terminal in unicast comprises:

Sending the retransmission sub-packet unicast downward from the MAC layer based on the cell radio network temporary identifier C-RNTI of the terminal, so as to unicast the retransmission sub-packet to the terminal.
The method according to claim 5, wherein the retransmission subpacket is determined by the media access control MAC layer of the network device, and after the retransmission subpacket in the data packet to be transmitted is determined, further include:

Sending hierarchical signaling upwards from the MAC layer, so that the packet data convergence layer protocol PDCP layer of the network device determines the sequence number of the retransmission sub-packet;

The unicast sending of the retransmission subpacket to the terminal includes:

Sending the retransmission sub-data in unicast downward from the PDCP layer, so as to unicast the retransmission sub-data packet to the terminal.
A data transmission method for a multicast service, comprising:

Multicast receiving multicast wireless configuration from the network device, the multicast wireless configuration is used to instruct the terminal to perform multicast transmission initialization;

Multicast receiving a sub-packet of the data packet to be transmitted from the network device, and the sub-packet corresponds to a sequence number;

sending an acknowledgment message to the network device, where the acknowledgment message is used to determine that the terminal has received the sub-packet;

receiving indication information from the network device, where the indication information is used to modify the lower boundary value of the reassembly window;

modifying the lower boundary value based on the indication information;

The retransmission subpacket is multicast received from the network device.
The method according to claim 8, wherein the indication information includes the absolute value of the retransmission subpacket, and the indication information is specifically used to indicate that the lower boundary value of the reassembly window is modified to the absolute value value, the absolute value includes the minimum value of the sequence number in the retransmission subpacket.
The method according to claim 8, wherein the indication information includes an offset value of the retransmission subpacket, and the indication information is specifically used to indicate the adjustment of the reassembly window based on the offset value The lower boundary value, the offset value is related to at least two of the following items of information: the minimum value of the sequence number in the retransmission sub-packet, the sequence number of the first sub-packet received by the terminal, and the pre-set A constant is set, and the preset constant is a positive integer.
The method according to claim 8, wherein the multicast wireless configuration includes an initial value of the lower boundary value, which is the minimum value of the sequence number in the sub-packet.
A data transmission method for a multicast service, comprising:

Multicast receiving multicast wireless configuration from the network device, the multicast wireless configuration is used to instruct the terminal to perform multicast transmission initialization;

Multicast receiving a sub-packet of the data packet to be transmitted from the network device, and the sub-packet corresponds to a sequence number;

sending an acknowledgment message to the network device, where the acknowledgment message is used to determine that the terminal has received the sub-packet;

The retransmission sub-packet in the data packet to be transmitted is received by unicast from the network device.
A communication device, characterized by comprising:

The transceiver unit is configured to send a multicast wireless configuration to the terminal, and the multicast wireless configuration is used to instruct the terminal to perform multicast transmission initialization; to multicast at least two subpackets of the data packet to be transmitted to the terminal, each A sub-packet corresponds to a sequence number; receiving an acknowledgment message from the terminal, where the acknowledgment message is used to determine the sub-packet that the terminal has received;

a processing unit, configured to determine a retransmission sub-packet in the data packet to be transmitted;

The transceiver unit is further configured to send indication information to the terminal, where the indication information is used to modify the lower boundary value of the reassembly window; and multicast the retransmission sub-packet to the terminal.
The communication device according to claim 13, wherein the indication information includes the absolute value of the retransmission subpacket, and the indication information is specifically used to indicate that the lower boundary value of the reassembly window is modified to the An absolute value, where the absolute value includes a minimum value of sequence numbers in the retransmission subpacket.
The communication device according to claim 13, wherein the indication information includes an offset value of the retransmission subpacket, and the indication information is specifically used to indicate that the reassembly window is adjusted based on the offset value The lower boundary value of , the offset value is related to at least two items of the following information: the minimum value of the sequence number in the retransmitted sub-packet, the sequence number of the first sub-packet received by the terminal, A preset constant, the preset constant is a positive integer.
The communication device according to claim 13, wherein the multicast wireless configuration includes an initial value of the lower boundary value, which is the minimum value of the sequence number in the sub-packet.
A communication device, characterized by comprising:

The transceiver unit is configured to send a multicast wireless configuration to the terminal, and the multicast wireless configuration is used to instruct the terminal to perform multicast transmission initialization; to multicast at least two subpackets of the data packet to be transmitted to the terminal, each A sub-packet corresponds to a sequence number; receiving an acknowledgment message from the terminal, where the acknowledgment message is used to determine the sub-packet that the terminal has received;

a processing unit, configured to determine a retransmission sub-packet in the data packet to be transmitted;

The transceiver unit is further configured to unicast send the retransmission sub-packet to the terminal.
The communication device according to claim 17, wherein the communication device further comprises a MAC layer, the retransmission sub-packet is determined by the MAC layer, and the transceiver unit is specifically configured to - the RNTI unicasts the retransmission sub-packet downward from the MAC layer, so as to unicast the retransmission sub-packet to the terminal.
The communication device according to claim 17, wherein the communication device further comprises a MAC layer and a PDCP layer, the retransmission sub-packet is determined by the MAC layer, and the transceiver unit is also used for The MAC layer sends hierarchical signaling upwards, so that the PDCP layer determines the sequence number of the retransmission sub-data packet; the transceiver unit is specifically configured to unicast downward from the PDCP layer to send the retransmission sub-data, and sending the retransmission sub-packet to the terminal in unicast.
A communication device, characterized by comprising:

The transceiver unit is used to multicast receive multicast wireless configuration from the network device, and the multicast wireless configuration is used to instruct the communication device to perform multicast transmission initialization; multicast receive the sub-data of the data packet to be transmitted from the network device packet, the sub-packet corresponds to a sequence number; send an acknowledgment message to the network device, the acknowledgment message is used to determine that the communication device has received the sub-packet; receive indication information from the network device, the The above instruction information is used to modify the lower boundary value of the reorganization window;

a processing unit, configured to modify the lower boundary value based on the indication information;

The transceiver unit is further configured to multicast receive the retransmission sub-packet from the network device.
The communication device according to claim 20, wherein the indication information includes the absolute value of the retransmission subpacket, and the indication information is specifically used to indicate that the lower boundary value of the reassembly window is modified to the An absolute value, where the absolute value includes a minimum value of sequence numbers in the retransmission subpacket.
The communication device according to claim 20, wherein the indication information includes an offset value of the retransmission subpacket, and the indication information is specifically used to indicate that the reassembly window is adjusted based on the offset value The lower boundary value of , the offset value is related to at least two of the following items of information: the minimum value of the sequence number in the retransmitted sub-packet, the sequence number of the first sub-packet received by the communication device , a preset constant, where the preset constant is a positive integer.
The communication device according to claim 20, wherein the multicast wireless configuration includes an initial value of the lower boundary value, which is the minimum value of the sequence number in the sub-packet.
A communication device, characterized by comprising:

The transceiver unit is used to multicast receive multicast wireless configuration from the network device, and the multicast wireless configuration is used to instruct the communication device to perform multicast transmission initialization; multicast receive the sub-data of the data packet to be transmitted from the network device packet, the sub-packet corresponds to a sequence number; send an acknowledgment message to the network device, the acknowledgment message is used to determine that the communication device has received the sub-packet; receive the multicast from the network device Retransmit the subpacket.
A communication device, characterized by comprising a processor and a memory, wherein the processor is coupled to the memory, and the memory is used to store one or more programs, and the one or more programs are processed by the The device is executed to perform the method according to any one of claims 1-12.
A computer-readable storage medium is characterized in that it is used to store a computer program, wherein the computer program causes a computer to execute the method according to any one of claims 1-12.