MBS service transmission method and device, and communication equipment

Abstract

An embodiment of the present application provides a transmission method and apparatus for MBS services, and a communication device, the method comprising: a target base station receives MBS service data forwarded by an original base station, and the target base station sends the MBS service data forwarded by the original base station to a terminal device in a unicast manner; the target base station sends first indication information to the terminal device, and the first indication information is used to instruct the terminal device to reset a receiving window, and the reset receiving window is used by the terminal device to receive the MBS service data sent by the target base station in a multicast manner.

Description

[0001] This application is a divisional application of the PCT international patent application PCT / CN2020 / 105924 with an application date of July 30, 2020, which entered the Chinese national phase with Chinese patent application No. 202080101102.6 and the invention name “A transmission method and device, and communication equipment for MBS services”. Technical Field

[0002] The embodiments of the present application relate to the field of mobile communication technology, and specifically to a transmission method and apparatus, and communication equipment for a Multimedia Broadcast Service (MBS) service. Background Art

[0003] The terminal device can receive the Multimedia Broadcast Service (MBS) service only after entering the Radio Resource Control (RRC) connected state.

[0004] There may be a time difference in the transmission of MBS services in different cells, that is, the MBS services transmitted by different cells are not synchronized. For example, the MBS service transmitted by cell 1 is earlier or later than the MBS service transmitted by cell 2. In other words, the transmission time of the same MBS service in different cells may be earlier or later. Therefore, how to ensure the continuity of MBS services during the switching process is an issue that needs to be clarified. Summary of the invention

[0005] The embodiments of the present application provide a method and apparatus for transmitting MBS services, and a communication device.

[0006] The MBS service transmission method provided in the embodiment of the present application includes:

[0007] The target base station receives the MBS service data forwarded by the original base station, and the target base station sends the MBS service data forwarded by the original base station to the terminal device in a unicast manner;

[0008] The target base station sends first indication information to the terminal device, where the first indication information is used to instruct the terminal device to reset a receiving window, and the reset receiving window is used by the terminal device to receive MBS service data sent by the target base station in a multicast manner.

[0009] The MBS service transmission method provided in the embodiment of the present application includes:

[0010] The original base station sends first auxiliary information to the target base station, where the first auxiliary information is used by the target base station to determine whether the original base station needs to forward MBS service data to the target base station;

[0011] The source base station receives third indication information sent by the target base station, where the third indication information is used to instruct the source base station to forward the MBS service data to the target base station;

[0012] The source base station forwards the MBS service data to the target base station and sends a switching command to the terminal device, wherein the switching command is used to trigger the terminal device to switch from the original base station to the target base station and receive the MBS service data sent by the target base station in unicast mode and the MBS service data sent in multicast mode.

[0013] The MBS service transmission method provided in the embodiment of the present application includes:

[0014] The terminal device receives a switching command sent by the original base station, and switches from the source base station to the target base station;

[0015] The terminal device sends sixth indication information to the target base station, where the sixth indication information is used to indicate a second PDCP SN list, where the second PDCP SN list refers to a missing PDCP SN list between the original base station and the target base station;

[0016] The terminal device receives MBS service data sent by the target base station in a unicast manner and MBS service data sent in a multicast manner.

[0017] The MBS service transmission device provided in the embodiment of the present application is applied to a target base station, and the device includes:

[0018] A receiving unit, used for receiving MBS service data forwarded by an original base station;

[0019] A sending unit, used for sending the MBS service data forwarded by the original base station to the terminal device in a unicast manner; sending a first indication message to the terminal device, wherein the first indication message is used to instruct the terminal device to reset a receiving window, and the reset receiving window is used for the terminal device to receive the MBS service data sent by the target base station in a multicast manner.

[0020] The MBS service transmission device provided in the embodiment of the present application is applied to an original base station, and the device includes:

[0021] A sending unit, configured to send first auxiliary information to a target base station, where the first auxiliary information is used by the target base station to determine whether the original base station needs to forward MBS service data to the target base station;

[0022] a receiving unit, configured to receive third indication information sent by the target base station, wherein the third indication information is used to instruct the source base station to forward the MBS service data to the target base station;

[0023] The sending unit is also used to forward the MBS service data to the target base station and send a switching command to the terminal device, wherein the switching command is used to trigger the terminal device to switch from the original base station to the target base station and receive the MBS service data sent by the target base station in a unicast manner and the MBS service data sent in a multicast manner.

[0024] The MBS service transmission device provided in the embodiment of the present application is applied to a terminal device, and the device includes:

[0025] A receiving unit, configured to receive a handover command sent by an original base station, and to handover from the source base station to a target base station;

[0026] A sending unit, configured to send sixth indication information to the target base station, wherein the sixth indication information is used to indicate a second PDCP SN list, where the second PDCP SN list refers to a missing PDCP SN list between the original base station and the target base station;

[0027] The receiving unit is further configured to receive MBS service data sent by the target base station in a unicast manner and MBS service data sent in a multicast manner.

[0028] The communication device provided in the embodiment of the present application includes a processor and a memory. The memory is used to store a computer program, and the processor is used to call and run the computer program stored in the memory to execute the above-mentioned MBS service transmission method.

[0029] The chip provided in the embodiment of the present application is used to implement the above-mentioned MBS service transmission method.

[0030] Specifically, the chip includes: a processor, which is used to call and run a computer program from a memory, so that a device equipped with the chip executes the above-mentioned MBS service transmission method.

[0031] The computer-readable storage medium provided in the embodiments of the present application is used to store a computer program, and the computer program enables a computer to execute the above-mentioned MBS service transmission method.

[0032] The computer program product provided in the embodiment of the present application includes computer program instructions, and the computer program instructions enable a computer to execute the above-mentioned MBS service transmission method.

[0033] The computer program provided in the embodiment of the present application, when executed on a computer, enables the computer to execute the above-mentioned MBS service transmission method.

[0034] The above technical solution of the embodiment of the present application proposes a method for transmitting MBS services, which ensures the continuity of MBS service data during the switching process, avoids the loss of MBS service data, and improves the reliability of transmission of MBS service data during mobility. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0036] Figure 1 is a schematic diagram of a communication system architecture provided by an embodiment of the present application;

[0037] Figure 2 It is a schematic diagram of the MBS service provided by the embodiment of the present application being transmitted in a multicast manner and a unicast manner;

[0038] Figure 3 is a schematic diagram of cell switching provided in an embodiment of the present application;

[0039] Figure 4 This is a flow diagram of the MBS service transmission method provided in the embodiment of the present application. Figure 1 ;

[0040] Figure 5-1 is a schematic diagram of a receiving window before reset provided in an embodiment of the present application;

[0041] Figure 5-2 is a schematic diagram of a receiving window after reset provided in an embodiment of the present application;

[0042] Figure 6 This is a flow diagram of the MBS service transmission method provided in the embodiment of the present application. Figure 2 ;

[0043] Figure 7 This is a flow diagram of the MBS service transmission method provided in the embodiment of the present application. Figure 3 ;

[0044] Figure 8 This is a network architecture diagram provided by an embodiment of the present application;

[0045] Fig. 9 This is a flow diagram of the MBS service transmission method provided in the embodiment of the present application. Figure 4 ;

[0046] Fig.10 Schematic diagram 5 of the MBS service transmission method provided in an embodiment of the present application;

[0047] Fig.11 This is a flow diagram of the MBS service transmission method provided in the embodiment of the present application. Figure 6 ;

[0048] Fig.12 This is a schematic diagram of the structure of the transmission device of the MBS service provided in the embodiment of the present application. Figure 1 ;

[0049] Fig.13 This is a schematic diagram of the structure of the transmission device of the MBS service provided in the embodiment of the present application. Figure 2 ;

[0050] Fig.14 This is a schematic diagram of the structure of the transmission device of the MBS service provided in the embodiment of the present application. Figure 3 ;

[0051] Fig.15 is a schematic structural diagram of a communication device provided in an embodiment of the present application;

[0052] Fig.16 is a schematic structural diagram of a chip according to an embodiment of the present application;

[0053] Fig.17 It is a schematic block diagram of a communication system provided in an embodiment of the present application. DETAILED DESCRIPTION

[0054] The following will describe the technical solutions in the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0055] The technical solutions of the embodiments of the present application can be applied to various communication systems, such as: Long Term Evolution (LTE) system, LTE Frequency Division Duplex (FDD) system, LTE Time Division Duplex (TDD) system, 5G communication system or future communication system, etc.

[0056] For example, the communication system 100 used in the embodiment of the present application is as follows: Figure 1As shown. The communication system 100 may include a network device 110, which may be a device that communicates with a terminal 120 (or referred to as a communication terminal, terminal). The network device 110 may provide communication coverage for a specific geographical area, and may communicate with terminals located within the coverage area. Optionally, the network device 110 may be an evolved base station (eNB or eNodeB) in an LTE system, or a wireless controller in a cloud radio access network (CRAN), or the network device may be a mobile switching center, a relay station, an access point, a vehicle-mounted device, a wearable device, a hub, a switch, a bridge, a router, a network-side device in a 5G network, or a network device in a future communication system, etc.

[0057] The communication system 100 also includes at least one terminal 120 located within the coverage of the network device 110. As used herein, "terminal" includes but is not limited to connecting via a wired line, such as via a Public Switched Telephone Networks (PSTN), a Digital Subscriber Line (DSL), a digital cable, a direct cable connection; and / or another data connection / network; and / or via a wireless interface, such as, for a cellular network, a Wireless Local Area Network (WLAN), a digital television network such as a DVB-H network, a satellite network, an AM-FM broadcast transmitter; and / or another terminal configured to receive / send communication signals; and / or an Internet of Things (IoT) device. A terminal configured to communicate via a wireless interface may be referred to as a "wireless communication terminal", "wireless terminal" or "mobile terminal". Examples of mobile terminals include, but are not limited to, satellite or cellular telephones; Personal Communications System (PCS) terminals that may combine cellular radiotelephones with data processing, fax, and data communications capabilities; PDAs that may include radiotelephones, pagers, Internet / Intranet access, Web browsers, notepads, calendars, and / or Global Positioning System (GPS) receivers; and conventional laptop and / or palmtop receivers or other electronic devices that include radiotelephone transceivers. A terminal may refer to an access terminal, User Equipment (UE), a subscriber unit, a subscriber station, a mobile station, a mobile station, a remote station, a remote terminal, a mobile device, a user terminal, a terminal, a wireless communication device, a user agent, or a user device. The access terminal can be a cellular phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), a handheld device with wireless communication capabilities, a computing device or other processing device connected to a wireless modem, a vehicle-mounted device, a wearable device, a terminal in a 5G network, or a terminal in a future evolved PLMN, etc.

[0058] Optionally, the terminals 120 may perform device-to-device (D2D) communication.

[0059] Optionally, the 5G communication system or 5G network may also be referred to as a New Radio (NR) system or NR network.

[0060] Figure 1 One network device and two terminals are shown exemplarily. Optionally, the communication system 100 may include multiple network devices and each network device may include another number of terminals within its coverage area, which is not limited in the embodiments of the present application.

[0061] Optionally, the communication system 100 may also include other network entities such as a network controller and a mobility management entity, which is not limited in the embodiments of the present application.

[0062] It should be understood that the device with communication function in the network / system in the embodiment of the present application can be referred to as a communication device. Figure 1 Taking the communication system 100 shown as an example, the communication equipment may include a network device 110 and a terminal 120 with communication functions. The network device 110 and the terminal 120 may be the specific devices described above and will not be repeated here. The communication equipment may also include other devices in the communication system 100, such as a network controller, a mobile management entity and other network entities, which is not limited in the embodiments of the present application.

[0063] It should be understood that the terms "system" and "network" are often used interchangeably in this article. The term "and / or" in this article is only a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0064] To facilitate understanding of the technical solutions of the embodiments of the present application, the technical solutions related to the embodiments of the present application are described below.

[0065] With the pursuit of speed, latency, high-speed mobility, energy efficiency and the diversity and complexity of services in future life, the Third Generation Partnership Project (3GPP) rd The 3rd Generation Partnership Project (3GPP) international standard organization has begun to develop 5G. The main application scenarios of 5G are: enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine-type communications (mMTC).

[0066] On the one hand, eMBB still aims at users to obtain multimedia content, services and data, and its demand is growing rapidly. On the other hand, since eMBB may be deployed in different scenarios, such as indoors, in urban areas, and in rural areas, its capabilities and requirements vary greatly, so it cannot be generalized and must be analyzed in detail in combination with specific deployment scenarios. Typical applications of URLLC include: industrial automation, power automation, remote medical operations (surgery), traffic safety, etc. Typical features of mMTC include: high connection density, small data volume, latency-insensitive services, low cost and long service life of modules, etc.

[0067] In the early days of NR deployment, complete NR coverage was difficult to obtain, so the typical network coverage was wide-area LTE coverage and NR island coverage. In addition, a large number of LTEs are deployed below 6GHz, and there is little spectrum below 6GHz available for 5G. Therefore, NR must study spectrum applications above 6GHz, but high-frequency bands have limited coverage and fast signal fading. At the same time, in order to protect mobile operators' early investments in LTE, a tight interworking working mode between LTE and NR was proposed.

[0068] RRC Status

[0069] In order to reduce air interface signaling and quickly restore wireless connections and data services, 5G defines a new Radio Resource Control (RRC) state, namely the RRC inactive (RRC_INACTIVE) state. This state is different from the RRC idle (RRC_IDLE) state and the RRC active (RRC_ACTIVE) state.

[0070] 1) RRC_IDLE state (abbreviated as idle state): Mobility is based on cell selection and reselection of terminal equipment, paging is initiated by the core network (CN), and the paging area is configured by the CN. There is no terminal equipment context on the base station side, and there is no RRC connection.

[0071] 2) RRC_CONNECTED state (referred to as connected state): There is an RRC connection, and there is a terminal device context on the base station side and the terminal device side. The network side knows the location of the terminal device at the specific cell level. The mobility is the mobility controlled by the network side. Unicast data can be transmitted between the terminal device and the base station.

[0072] 3) RRC_INACTIVE state (abbreviated as inactive state): Mobility is based on cell selection reselection of the terminal device, there is a connection between CN-NR, the terminal device context exists on a certain base station, paging is triggered by RAN, and the paging area based on RAN is managed by RAN. The network side knows the location of the terminal device based on the paging area level of RAN.

[0073] MBMS

[0074] MBMS is a technology that transmits data from one data source to multiple terminal devices by sharing network resources. While providing multimedia services, this technology can effectively utilize network resources and achieve broadcast and multicast of multimedia services at a higher rate (such as 256kbps).

[0075] Since MBMS spectrum efficiency is low, it is not enough to effectively carry and support the operation of mobile TV services. Therefore, in LTE, 3GPP explicitly proposed to enhance the support capability for downlink high-speed MBMS services and determined the design requirements for the physical layer and air interface.

[0076] 3GPP R9 introduced evolved MBMS (eMBMS) into LTE. eMBMS proposed the concept of Single Frequency Network (SFN), namely Multimedia Broadcast multicast service Single Frequency Network (MBSFN). MBSFN uses a unified frequency to send service data in all cells at the same time, but synchronization between cells must be guaranteed. This method can greatly improve the overall signal-to-noise ratio distribution of the cell, and the spectrum efficiency will also be greatly improved accordingly. eMBMS implements broadcast and multicast of services based on the IP multicast protocol.

[0077] In LTE or enhanced LTE (LTE-Advanced, LTE-A), MBMS has only a broadcast bearer mode, but no multicast bearer mode. In addition, the reception of MBMS services is applicable to terminal devices in an idle state or a connected state.

[0078] 3GPP R13 introduced the concept of Single Cell Point To Multipoint (SC-PTM), which is based on the MBMS network architecture.

[0079] MBMS introduces new logical channels, including Single Cell-Multicast Control Channel (SC-MCCH) and Single Cell-Multicast Transport Channel (SC-MTCH). SC-MCCH and SC-MTCH are mapped to Downlink Shared Channel (DL-SCH), and further, DL-SCH is mapped to Physical Downlink Shared Channel (PDSCH), where SC-MCCH and SC-MTCH are logical channels, DL-SCH is a transport channel, and PDSCH is a physical channel. SC-MCCH and SC-MTCH do not support Hybrid Automatic Repeat reQuest (HARQ) operation.

[0080] MBMS introduces a new type of System Information Block (SIB), namely SIB20. Specifically, the configuration information of SC-MCCH is transmitted through SIB20, and there is only one SC-MCCH in a cell. The configuration information of SC-MCCH includes: the modification period of SC-MCCH, the repetition period of SC-MCCH, and the radio frame and subframe for scheduling SC-MCCH. Further, 1) The boundary of the modification period of SC-MCCH satisfies SFN mod m = 0, where SFN represents the system frame number of the boundary, and m is the modification period of SC-MCCH configured in SIB20 (i.e., sc-mcch-ModificationPeriod). 2) The radio frame for scheduling SC-MCCH satisfies: SFN mod mcch-RepetitionPeriod = mcch-Offset, where SFN represents the system frame number of the radio frame, mcch-RepetitionPeriod represents the repetition period of SC-MCCH, and mcch-Offset represents the offset of SC-MCCH. 3) The subframe for scheduling SC-MCCH is indicated by sc-mcch-Subframe.

[0081] SC-MCCH is scheduled through the Physical Downlink Control Channel (PDCCH). On the one hand, a new Radio Network Temporary Identity (RNTI), namely the Single Cell RNTI (SC-RNTI), is introduced to identify the PDCCH (such as SC-MCCHPDCCH) used to schedule SC-MCCH. Optionally, the SC-RNTI is fixed to FFFC. On the other hand, a new RNTI, namely the Single Cell Notification RNTI (SC-N-RNTI), is introduced to identify the PDCCH (such as the notification PDCCH) used to indicate the change notification of SC-MCCH. Optionally, the SC-N-RNTI is fixed to FFFB; further, one of the 8 bits of DCI 1C can be used to indicate the change notification. In LTE, the configuration information of SC-PTM is based on the SC-MCCH configured by SIB20, and then the SC-MCCH configures the SC-MTCH, which is used to transmit service data.

[0082] Specifically, SC-MCCH only transmits one message (i.e., SCPTMConfiguration), which is used to configure the configuration information of SC-PTM. The configuration information of SC-PTM includes: Temporary Mobile Group Identity (TMGI), session id, group RNTI (G-RNTI), discontinuous reception (DRX) configuration information, and SC-PTM service information of neighboring cells. It should be noted that SC-PTM in R13 does not support the robust header compression (ROHC) function.

[0083] The downlink discontinuous reception of SC-PTM is controlled by the following parameters: onDurationTimerSCPTM, drx-InactivityTimerSCPTM, SC-MTCH-SchedulingCycle, and SC-MTCH-SchedulingOffset.

[0084] When [(SFN*10)+subframe number]modulo(SC-MTCH-SchedulingCycle)=SC-MTCH-SchedulingOffset is satisfied, the timer onDurationTimerSCPTM is started;

[0085] When receiving downlink PDCCH scheduling, start the timer drx-InactivityTimerSCPTM;

[0086] Downlink SC-PTM services are received only when the timer onDurationTimerSCPTM or drx-InactivityTimerSCPTM is running.

[0087] SC-PTM service continuity adopts the MBMS service continuity concept based on SIB15, namely the "SIB15+MBMSInterestIndication" mode. The service continuity of idle terminal devices is based on the concept of frequency priority.

[0088] In the technical solution of the embodiment of the present application, a new SIB (called the first SIB) is defined. The first SIB includes configuration information of the first MCCH. Here, the first MCCH is the control channel of the MBMS service. In other words, the first SIB is used to configure the configuration information of the control channel of NRMBMS. Optionally, the control channel of NR MBMS can also be called NR MCCH (i.e., the first MCCH).

[0089] Further, the first MCCH is used to carry the first signaling. The embodiment of the present application does not limit the name of the first signaling. For example, the first signaling is signaling A. The first signaling includes configuration information of at least one first MTCH. Here, the first MTCH is a service channel (also called a data channel or a transmission channel) of the MBMS service. The first MTCH is used to transmit MBMS service data (such as service data of NR MBMS). In other words, the first MCCH is used to configure the configuration information of the service channel of NR MBMS. Optionally, the service channel of NR MBMS can also be called NR MTCH (i.e., the first MTCH).

[0090] Specifically, the first signaling is used to configure the service channel of NR MBMS, the service information corresponding to the service channel, and the scheduling information corresponding to the service channel. Further, optionally, the service information corresponding to the service channel, such as identification information of the service such as TMGI and session id. The scheduling information corresponding to the service channel, such as the RNTI used when the MBMS service data corresponding to the service channel is scheduled, such as G-RNTI, DRX configuration information, etc.

[0091] It should be noted that the transmission of the first MCCH and the first MTCH are both based on PDCCH scheduling. The RNTI used by the PDCCH for scheduling the first MCCH uses a network-wide unique identifier, that is, a fixed value. The RNTI used by the PDCCH for scheduling the first MTCH is configured through the first MCCH.

[0092] It should be noted that the embodiments of the present application do not limit the naming of the first SIB, the first MCCH and the first MTCH. For ease of description, the first SIB may also be referred to as SIB, the first MCCH may also be referred to as MCCH, and the first MTCH may also be referred to as MTCH. The PDCCH for scheduling MCCH (i.e., MCCHPDCCH) and notifying PDCCH are configured through SIB, wherein the DCI carried by MCCH PDCCH is scheduled for transmitting the PDSCH (i.e., MCCH PDSCH) for MCCH. Further, M PDCCHs for scheduling MTCH (i.e., MTCH 1PDCCH, MTCH2PDCCH, ..., MTCH MPDCCH) are configured through MCCH, wherein the DCI carried by MTCH n PDCCH is scheduled for transmitting the PDSCH for MTCH n (i.e., MTCH n PDSCH), and n is an integer greater than or equal to 1 and less than or equal to M. MCCH and MTCH are mapped to DL-SCH, and further, DL-SCH is mapped to PDSCH, wherein MCCH and MTCH belong to logical channels, DL-SCH belongs to a transport channel, and PDSCH belongs to a physical channel.

[0093] It should be noted that the MBMS service in the above solution includes but is not limited to multicast service and groupcast service. The embodiment of the present application takes the MBS service as an example for explanation, and the description of "MBS service" can also be replaced by "multicast service" or "groupcast service" or "MBMS service".

[0094] In the NR MBS service, in addition to sending the MBS service in multicast mode, the same cell may also transmit the MBS service to a specific user in unicast mode. For example, if the channel of the user is poor, the MBS service needs to be transmitted to the user in unicast mode. In a cell, there may be several users receiving a certain MBS service at the same time, but the base station sends the MBS service to each user in unicast mode. For example, if there are few users receiving MBS services in the cell, sending MBS services to each user in unicast mode can effectively improve the service transmission efficiency.

[0095] Reference Figure 2For a packet data unit (PDU) session of a certain MBS service, a shared GTP tunnel may be used between the 5G Core network (5GC) and the gNB to transmit the MBS service, that is, both unicast MBS services and multicast MBS services share this GTP tunnel. The gNB sends the MBS service to the multicast group in multicast mode, and sends the MBS service to a certain UE in unicast mode. Figure 2 Take UE3 as an example). The multicast group includes one or more UEs ( Figure 2 Take the multicast group including UE1 and UE2 as an example).

[0096] Considering the mobility of terminal devices, there may be scenarios where terminal devices switch from one cell to another. Figure 3 As shown, UE1 receives the MBS service sent by gNB1 in a multicast manner in the first cell. After UE1 switches from cell 1 to cell 2, it receives the MBS service sent by gNB2 in a multicast manner in the second cell. Different base stations (such as gNB1 and gNB2) may have a time difference in the transmission of MBS services, that is, the MBS services transmitted by different base stations are not synchronized. For example, the MBS service transmitted by gNB1 is earlier or later than the MBS service transmitted by gNB2. In other words, the same MBS service may be transmitted earlier or later at different gNBs. Therefore, how to ensure the continuity of MBS services during the switching process is a problem that needs to be clarified. To this end, the following technical solutions of the embodiments of the present application are proposed.

[0097] Figure 4 This is a flow diagram of the MBS service transmission method provided in the embodiment of the present application. Figure 1 ,like Figure 4 As shown, the MBS service transmission method includes the following steps:

[0098] Step 401: The target base station receives MBS service data forwarded by the original base station, and the target base station sends the MBS service data forwarded by the original base station to the terminal device in a unicast manner.

[0099] In the embodiment of the present application, considering the mobility scenario of the terminal device, the terminal device may switch from one base station (i.e., the original base station) to another base station (i.e., the target base station). For example, the original base station is the original gNB (Source gNB), and the target base station is the target gNB (Target gNB).

[0100] In the embodiment of the present application, the MBS service data on the original base station side is sent to the original base station by the core network through the first tunnel, and the MBS service data on the target base station side is sent to the target base station by the core network through the second tunnel. That is to say, the original base station receives the MBS service data sent by the core network through the first tunnel, and sends the MBS service data through unicast and / or multicast. The target base station receives the MBS service data sent by the core network through the second tunnel, and sends the MBS service data through unicast and / or multicast. The MBS service data on the original base station side and the MBS service data on the target base station side are not synchronized.

[0101] In the embodiment of the present application, before switching, the terminal device can receive the MBS service data sent by the original base station in a multicast manner or a unicast manner.

[0102] In the embodiment of the present application, before the target base station receives the MBS service data forwarded by the original base station, the method further includes:

[0103] The target base station receives a handover request (HANDOVER REQUEST) message sent by the original base station, where the handover request message carries relevant information of a first MBS service, where the first MBS service refers to an MBS service received by the terminal device at the original base station;

[0104] The target base station sends a handover request confirmation (HANDOVER REQUESTACKNOWLEDGE) message to the original base station, where the handover request confirmation message carries a first tunnel identifier, and the first tunnel identifier is used by the original base station to forward MBS service data to the target base station.

[0105] In the above solution, optionally, the relevant information of the first MBS service includes at least one of the following: a service identifier, a session identifier, physical channel configuration information, and logical channel configuration information.

[0106] Here, the service identifier may be, for example, the MBS TMGI of the MBS service.

[0107] Here, the session identifier refers to the MBS session identifier (MBS session id) of the MBS service.

[0108] Here, the physical channel configuration information refers to the configuration information of the MBS physical channel of the MBS service.

[0109] Here, the logical channel configuration information refers to the configuration information of the MBS logical channel of the MBS service.

[0110] In the above solution, the first tunnel identifier is allocated by the target base station to the original base station, and is used by the original base station to forward the MBS service data to the target base station. Optionally, the first tunnel identifier is a GTP tunnel identifier (GTP TEID).

[0111] In the embodiment of the present application, the original base station forwards the MBS service data to the target base station based on the first tunnel identifier, and sends a handover command (HO-Command) to the terminal device. Here, it should be noted that the steps of the original base station forwarding the MBS service data to the target base station and sending the handover command to the terminal device do not limit the execution order.

[0112] In the embodiment of the present application, the target base station receives the MBS service data forwarded by the original base station, which may be:

[0113] i) the target base station receives a Packet Data Convergence Protocol (PDCP) service data unit (SDU) and a serial number (SN) forwarded by the original base station, wherein the PDCP SDU carries MBS service data; or,

[0114] ii) the target base station receives a PDCP protocol data unit (PDU) forwarded by the original base station, wherein the PDCP PDU carries the SN and MBS service data; or,

[0115] iii) the target base station receives the IP data packet and the SN forwarded by the original base station, wherein the IP data packet carries the MBS service data; or,

[0116] iv) The target base station receives a Service Data Adaptation Protocol (SDAP) SDU and a SN forwarded by the original base station, wherein the SDAP SDU carries MBS service data.

[0117] v) The target base station receives the IP data packet forwarded by the original base station, where the IP data packet carries MBS service data.

[0118] In the embodiment of the present application, for the scenario where the MBS service data forwarded by the original base station to the target base station is an IP data packet, the target base station transmits the MBS service data forwarded by the original base station to the terminal device in a unicast manner. At this time, the target base station performs the following processing on the MBS service data transmitted to the terminal device:

[0119] 1) The target base station adds a PDCP SN to the MBS service data forwarded from the original base station, and the PDCP SN is determined based on the PDCP SN of the MBS service data transmitted in multicast mode. Optionally, the added PDCP SN is determined based on the PDCP SN of the first MBS service data transmitted to the terminal device in multicast mode and the total number of forwarded MBS service data. For example: if the target base station expects the PDCP SN of the first MBS service data received by the terminal device in multicast mode to be n, and the number of forwarded MBS service data waiting for unicast transmission is m, then the PDCP SNs of the MBS service data transmitted in unicast mode are nm, n-m+1...n-1 respectively, and the target base station will add these PDCP SNs to the MBS service data corresponding to the unicast mode in turn. At this time, the receiving window of the terminal device will not be reset during the switching process. Or,

[0120] 2) The target base station adds a PDCP SN to the MBS service data forwarded from the original base station, and the PDCP SN is set from the initial value. Here, the moment when the target base station sends the first indication information to the terminal device is after the first moment and before the second moment. The first moment refers to the moment when the terminal device has finished receiving the MBS service data in unicast mode, and the second moment refers to the moment when the terminal device starts to receive the MBS service data in multicast mode. Specifically, after the MBS service data in unicast mode is transmitted and before the terminal device receives the MBS service data in multicast mode, the target base station sends an indication message to tell the terminal device to reset the receiving window. Optionally, it can also tell the terminal device the size of the initial value of the variable of the receiving window.

[0121] In the embodiment of the present application, after receiving the MBS service data forwarded by the original base station, the target base station can determine whether to trigger the original base station to stop forwarding the MBS service data in one of the following ways.

[0122] Method 1: The target base station determines whether the MBS service data forwarded by the original base station has been transmitted on the air interface of the target base station side; if the MBS service data forwarded by the original base station has not been transmitted on the air interface of the target base station side, the target base station sends a second indication message to the original base station, and the second indication message is used to instruct the original base station to stop forwarding the MBS service data.

[0123] Method 2: The target base station determines whether the MBS service data forwarded by the original base station exists in the memory of the target base station; if the MBS service data forwarded by the original base station exists in the memory of the target base station, the target base station sends a second indication message to the original base station, and the second indication message is used to instruct the original base station to stop forwarding the MBS service data.

[0124] Step 402: The target base station sends first indication information to the terminal device, where the first indication information is used to instruct the terminal device to reset a receiving window, and the reset receiving window is used by the terminal device to receive MBS service data sent by the target base station in a multicast manner.

[0125] In an embodiment of the present application, after receiving a handover command sent by an original base station, the terminal device switches from the original base station to the target base station, i.e., initiates a random access process to the target base station. The terminal device sends a handover completion (HOComplete) message to the target base station, and after receiving the handover completion message sent by the terminal device, the target base station sends the MBS service data forwarded by the original base station to the terminal device in a unicast manner. Afterwards, the target base station sends a first indication message to the terminal device, and the first indication message is used to instruct the terminal device to reset the receiving window. Furthermore, the first indication message is also used to instruct the terminal device to update the value of at least one variable of the reset receiving window to a default value.

[0126] Optionally, the first indication information is also used to instruct the terminal device to submit all PDCP SDUs in the receiving window before reset to the upper layer.

[0127] It should be noted that the receiving window before the reset is used by the terminal device to receive the MBS service data on the original base station side, wherein the MBS service data on the original base station side includes the MBS service data sent by the original base station and / or the MBS service data sent by the target base station and forwarded from the original base station. The receiving window after the reset is used by the terminal device to receive the MBS service data sent by the target base station in a multicast manner.

[0128] Reference Figure 5-1 , the receiving window before the terminal device receives the first indication information is the receiving window before reset. Figure 5-2 , the receiving window after the terminal device receives the first indication information is the reset receiving window. Among them, at least one variable of the receiving window includes at least one of the following:

[0129] RX_DELIV: This variable is used to indicate the COUNT value of the first MBS service data association in the receiving window that has not been submitted to the upper layer. The COUNT value is determined based on the SN.

[0130] RX_REORD: This variable is used to indicate the COUNT value corresponding to the MBS service data for which the t-Reordering timer is started in the receiving window. The COUNT value is determined based on the SN.

[0131] RX_Next: This variable is used to indicate the COUNT value corresponding to the next MBS service data expected to be received. The COUNT value is determined based on the SN.

[0132] In the embodiment of the present application, the first indication information instructs the terminal device to update the value of at least one variable of the reset receiving window to a default value, which can be implemented in the following manners:

[0133] Mode a) The default value is a set initial value, for example, 0. The first indication information instructs the terminal device to update the value of at least one variable of the reset receiving window to an initial value.

[0134] Mode b) The default value is indicated by displaying first indication information. The first indication information instructs the terminal device to update the value of at least one variable of the reset receiving window to a given default value.

[0135] In an embodiment of the present application, the first indication information is carried in a media access control control element (MAC CE), or in a PDCCH, or in an RRC signaling.

[0136] In an embodiment of the present application, after the terminal device receives the first indication information to reset the receiving window, it receives the MBS service data sent by the target base station in a multicast manner based on the reset receiving window. At this point, the terminal device can receive the MBS service data on the target base station side from the target base station.

[0137] In the embodiment of the present application, the receiving window in the above scheme refers to the receiving window of the PDCP layer.

[0138] Figure 6 This is a flow diagram of the MBS service transmission method provided in the embodiment of the present application. Figure 2 , wherein UE corresponds to the terminal device in the embodiment of the present application, such as Figure 6 As shown, the MBS service transmission method includes the following steps:

[0139] The UE is in the RRC connection state at the original base station, and receives the MBS service data sent by the original base station on the air interface in a unicast or multicast manner. Among them, the GTP tunnel from the core network (such as UPF) to the original base station for sending MBS service data can be a shared GTP tunnel (i.e., shared GTP tunnel 1) or a UE-specific GTP tunnel (i.e., a unicast GTP tunnel). The shared GTP tunnel refers to the transmission of MBS service data of an MBS service from the UPF to the base station, and the MBS service data is transmitted on the air interface at the base station in a unicast manner and a multicast manner respectively.

[0140] Step 601: the original base station makes a handover decision and sends a handover request message to the target base station. The handover request message carries relevant information of the MBS service that the UE is receiving in the original cell.

[0141] Here, optionally, the original base station may make a switching decision based on the measurement result reported by the UE.

[0142] Here, optionally, the relevant information of the MBS service being received by the UE in the original cell includes at least one of the following: MBSTMGI, MBS session id, configuration information of the MBS physical channel, and configuration information of the MBS logical channel.

[0143] Step 602: The target base station replies with a handover confirmation message, wherein the handover confirmation message carries a GTP tunnel identifier allocated by the target base station and used for the original base station to forward MBS service data to the target base station.

[0144] Step 603.1: The original base station forwards the MBS service data to the target base station on the GTP tunnel indicated by the GTP tunnel identifier.

[0145] Here, the MBS service data forwarded on the GTP tunnel may be: PDCP SDU+SN, or PDCP PDU, or IP data packet+SN, or SDAP SDU+SN, or IP data packet. Among them, PDCP SDU carries MBS service data, PDCP PDU carries MBS service data and SN, IP data packet carries MBS service data, and SDAP SDU carries MBS service data.

[0146] In the embodiment of the present application, for the scenario where the MBS service data forwarded by the original base station to the target base station is an IP data packet, the target base station transmits the MBS service data forwarded by the original base station to the UE in a unicast manner. At this time, the target base station performs the following processing on the MBS service data transmitted to the UE:

[0147] 1) The target base station adds a PDCP SN to the MBS service data forwarded from the original base station. The PDCP SN is determined based on the PDCP SN of the MBS service data transmitted in multicast mode. For example: if the target base station expects the PDCP SN of the first MBS service data received by the UE in multicast mode to be n, and the number of MBS service data forwarded in unicast mode is m, then the PDCP SNs of the MBS service data transmitted in unicast mode are nm, n-m+1...n-1 respectively. The target base station will add these PDCP SNs to the MBS service data corresponding to the unicast mode in turn. At this time, the UE's receiving window will not be reset during the switching process. Or,

[0148] 2) The target base station adds a PDCP SN to the MBS service data forwarded from the original base station, and the PDCP SN is set from the initial value. After the unicast MBS service data is transmitted and before the UE receives the multicast MBS service data, the target base station sends an indication message to tell the UE to reset the receiving window. Optionally, the UE can also be informed of the initial value of the variable of the receiving window.

[0149] Step 603.2: The original base station sends a handover command to the UE.

[0150] Here, the handover command in the NR system is an RRC reconfiguration message.

[0151] It should be noted that the order of step 603.1 and step 603.2 is not limited.

[0152] Step 604: The target base station caches the MBS service data forwarded by the original base station, and determines whether the forwarded MBS service data has been transmitted on the air interface of the target base station, or whether the MBS service data exists in the memory of the target base station; if the forwarded MBS service data has not been transmitted on the air interface of the target base station or the MBS service data exists in the memory of the target base station, the target base station determines that the original base station stops forwarding the MBS service data.

[0153] Step 605: The target base station sends an indication message to the original base station, where the indication message is used to instruct the original base station to stop forwarding MBS service data.

[0154] Step 606: After receiving the handover command, the UE initiates a random access process to the target base station and sends a handover completion message to the target base station.

[0155] Here, in the NR system, the switching completion message is an RRC reconfiguration completion (RRCReconfigurationComplete) message.

[0156] During the handover process, the receiving window and its variables of the PDCP layer remain the same as before the handover until the UE receives new MBS service data on the target base station side, and then the receiving window and / or the receiving window variables are reset. In other words, the receiving window and the receiving window variables will not be reset or changed during the handover process.

[0157] Step 607: the target base station sends the MBS service data forwarded by the original base station to the UE in a unicast manner, and the UE receives the MBS service data sent by the target base station in a unicast manner.

[0158] Step 608: If the target base station has completed sending the MBS service data forwarded by the original base station, the target base station sends an indication message to the UE, which is used to instruct the UE to submit all PDCP SDUs in the receiving window to the upper layer and reset the receiving window and the values ​​of the variables of the receiving window.

[0159] Here, optionally, the value of the variable of the receiving window is given in the indication information or is a default value.

[0160] Here, optionally, the indication information may be carried in a MAC CE, or in a PDCCH, or in an RRC signaling. If it is carried in a MAC CE, the protocol defines a logical channel ID (ie, LCID) of the MAC CE to identify the MAC CE.

[0161] After receiving the above indication information, the UE submits all PDCP SDUs in the receiving window to the upper layer, and resets the values ​​of the receiving window and the variables of the receiving window.

[0162] Step 609: After receiving the above instruction information, the UE starts to receive the MBS service data sent by the target base station in a multicast manner.

[0163] In the technical solution of the embodiment of the present application, during the mobility process, the target base station determines the stop condition of MBS service data forwarding, thereby triggering the forwarding and stopping of MBS service data. The target base station controls the UE to reset the receiving window to achieve continuity and reliability of service reception.

[0164] Figure 7 This is a flow diagram of the MBS service transmission method provided in the embodiment of the present application. Figure 3 ,like Figure 7 As shown, the MBS service transmission method includes the following steps:

[0165] Step 701: an original base station sends first auxiliary information to a target base station, where the first auxiliary information is used by the target base station to determine whether the original base station needs to forward MBS service data to the target base station.

[0166] In the embodiment of the present application, considering the mobility scenario of the terminal device, the terminal device may switch from one base station (i.e., the original base station) to another base station (i.e., the target base station). For example, the original base station is the original gNB (Source gNB), and the target base station is the target gNB (Target gNB).

[0167] In the embodiment of the present application, the MBS service data on the original base station side is sent by the core network to the original base station through the first tunnel, and the MBS service data on the target base station side is sent by the original base station to the target base station through the second tunnel. That is to say, the original base station receives the MBS service data sent by the core network through the first tunnel, and sends the MBS service data through unicast and / or multicast. The target base station receives the MBS service data from the core network forwarded by the original base station through the second tunnel, and sends the MBS service data through unicast and / or multicast. There is a situation where the MBS service data on the original base station side and the MBS service data on the target base station side are not synchronized.

[0168] In the embodiment of the present application, the original base station and the target base station may adopt one of the following network architectures:

[0169] 1) DU and CU integrated architecture, specifically, the original base station and the target base station have independent total protocol stacks, wherein the total protocol stack includes a first protocol stack and a second protocol stack, wherein the first protocol stack refers to the protocol stack corresponding to the DU, and the second protocol stack refers to the protocol stack corresponding to the CU.

[0170] Here, the protocol stack corresponding to DU includes RLC layer, MAC layer, and PHY layer. The protocol stack corresponding to CU includes SDAP layer and PDCP layer.

[0171] Reference Figure 8 The original base station has a total protocol stack: SDAP layer, PDCP layer, RLC layer, MAC layer, PHY layer. The target base station also has a total protocol stack: SDAP layer, PDCP layer, RLC layer, MAC layer, PHY layer ( Figure 8 The SDAP layer and PDCP layer on the target base station side are not shown). The total protocol stack of the original base station and the target base station are independent. After the original base station receives the MBS service data sent by the core network, it copies a copy of the RLC layer sent to the target base station through the PDCP layer, and sends the original MBS service data to the RLC layer of itself (i.e., the original base station).

[0172] 2) Distributed unit (DU) and centralized unit (CU) separation architecture, specifically, the original base station and the target base station have an independent first protocol stack and a shared second protocol stack, wherein the first protocol stack refers to the protocol stack corresponding to the distributed unit DU, and the second protocol stack refers to the protocol stack corresponding to the centralized unit CU.

[0173] Here, the protocol stack corresponding to DU includes RLC layer, MAC layer, and PHY layer. The protocol stack corresponding to CU includes SDAP layer and PDCP layer. Compared with the DU and CU integrated architecture, the DU and CU separation architecture is equivalent to the original DU, the target base station is equivalent to the target DU, and the original DU and the target DU are connected to the same CU. The signaling between the two base stations is equivalent to the signaling between the two DUs. Furthermore, the signaling between the two DUs can be transmitted directly between the two DUs, or indirectly transmitted by CU forwarding. Most of the following embodiments are described with the DU and CU integrated architecture as the network background, but the DU and CU separation architecture is also applicable to the technical solutions of the embodiments of the present application.

[0174] In the embodiment of the present application, before switching, the terminal device can receive the MBS service data sent by the original base station in a multicast manner or a unicast manner.

[0175] In an embodiment of the present application, the original base station sends a switching request message to the target base station, and the switching request message carries relevant information of a first MBS service and the first auxiliary information. The first MBS service refers to the MBS service received by the terminal device at the original base station.

[0176] In the above solution, optionally, the relevant information of the first MBS service includes at least one of the following: a service identifier, a session identifier, physical channel configuration information, and logical channel configuration information.

[0177] Here, the service identifier may be, for example, the MBS TMGI of the MBS service.

[0178] Here, the session identifier refers to the MBS session identifier (MBS session id) of the MBS service.

[0179] Here, the physical channel configuration information refers to the configuration information of the MBS physical channel of the MBS service.

[0180] Here, the logical channel configuration information refers to the configuration information of the MBS logical channel of the MBS service.

[0181] In the above scheme, the first auxiliary information is used to determine the first PDCP SN, and the first PDCP SN is the PDCP SN of the last MBS service data sent by the original base station to the terminal device or the PDCP SN of the next MBS service data to be sent.

[0182] In the embodiment of the present application, after receiving the first auxiliary information forwarded by the original base station, the target base station can determine whether the original base station needs to forward the MBS service data in one of the following ways.

[0183] Mode 1: The first PDCP SN and the PDCP SN of the MBS service data in the memory of the target base station are used by the target base station to determine whether the original base station needs to forward the MBS service data to the target base station.

[0184] Mode 2: The first PDCP SN and the PDCP SN of the MBS service data being sent by the target base station are used by the target base station to determine whether the original base station needs to forward the MBS service data to the target base station.

[0185] Specifically, the target base station can determine whether the MBS service data corresponding to the first PDCP SN has been sent on the target base station side according to the first PDCP SN and the PDCP SN of the MBS service data existing in the memory of the target base station or the PDCP SN of the MBS service data being sent by the target base station. If it has not been sent, it is determined that the original base station does not need to forward the MBS service data to the target base station; if it has been sent, it is determined that the original base station needs to forward the MBS service data to the target base station. Here, whether the MBS service data corresponding to the first PDCP SN has been sent on the target base station side can be determined based on the following method: if the first PDCP SN is less than or equal to the PDCP SN of the MBS service data existing in the memory of the target base station or the PDCP SN of the MBS service data being sent by the target base station, it is determined that the MBS service data corresponding to the first PDCP SN has been sent on the target base station side. If the first PDCP SN is greater than or equal to the PDCP SN of the MBS service data in the memory of the target base station or the PDCP SN of the MBS service data being sent by the target base station, it is determined that the MBS service data corresponding to the first PDCP SN has not yet been sent on the target base station side.

[0186] Further, in an optional manner, the first PDCP SN and the PDCP SN of the MBS service data being sent by the target base station are used by the target base station to determine a first PDCP SN list of MBS service data forwarded by the original base station to the target base station.

[0187] For example, the PDCP SNs between the PDCP SN of the MBS service data being sent by the target base station and the first PDCP SN form a first PDCP SN list.

[0188] Step 702: The source base station receives third indication information sent by the target base station, where the third indication information is used to instruct the source base station to forward MBS service data to the target base station.

[0189] In the embodiment of the present application, the original base station receives a handover request confirmation message sent by the target base station; wherein, when the original base station needs to forward MBS service data to the target base station,

[0190] The handover request confirmation message carries a first tunnel identifier, where the first tunnel identifier is used by the original base station to forward MBS service data to the target base station.

[0191] In the above solution, the first tunnel identifier is allocated by the target base station to the original base station, and is used by the original base station to forward the MBS service data to the target base station. Optionally, the first tunnel identifier is a GTP tunnel identifier (GTP TEID).

[0192] It should be noted that the first tunnel identifier may also implicitly indicate that the source base station forwards the MBS service data to the target base station. That is, the first tunnel identifier may be understood as the third indication information. Alternatively, an explicit third indication information is carried in the handover request confirmation message, and the third indication information is used to indicate that the source base station forwards the MBS service data to the target base station.

[0193] Further, optionally, the switching request confirmation message also carries fourth indication information, and the fourth indication information is used to indicate a first PDCP SN list or a first quantity, and the first quantity and the first PDCP SN are used to determine a first PDCP SN list, and the first PDCP SN list refers to a PDCP SN list of MBS service data forwarded by the original base station to the target base station.

[0194] Here, the first PDCP SN in the first PDCP SN list is the first PDCP SN, and the last PDCP SN in the first PDCP SN list is the second PDCP SN, wherein the second PDCP SN=the first PDCP SN+the first quantity.

[0195] Step 703: The source base station forwards the MBS service data to the target base station, and sends a switching command to the terminal device, wherein the switching command is used to trigger the terminal device to switch from the original base station to the target base station, and receive the MBS service data sent by the target base station in unicast mode and the MBS service data sent in multicast mode.

[0196] In an embodiment of the present application, the source base station forwards MBS service data to the target base station on the tunnel indicated by the first tunnel identifier, and here, the PDCP SN list of the MBS service data forwarded by the original base station to the target base station is the first PDCP SN list. In addition, the source base station sends a handover command to the terminal device. Here, it should be noted that the steps of forwarding the MBS service data from the original base station to the target base station and sending the handover command to the terminal device do not limit the execution order.

[0197] In the embodiment of the present application, the target base station receives the MBS service data forwarded by the original base station, which may be: the target base station receives the PDCP PDU forwarded by the original base station, and the PDCP PDU carries the SN and the MBS service data.

[0198] In an embodiment of the present application, optionally, the switching command carries fifth indication information, and the fifth indication information is used to instruct the terminal device to simultaneously receive the MBS service data sent by the target base station in a unicast manner and the MBS service data sent in a multicast manner.

[0199] In an embodiment of the present application, after receiving the handover command sent by the original base station, the terminal device switches from the original base station to the target base station, that is, initiates a random access process to the target base station. The terminal device sends a handover completion message to the target base station. After receiving the handover completion message sent by the terminal device, the target base station sends the MBS service data forwarded by the original base station to the terminal device in a unicast manner. Here, the MBS service data sent by the target base station in a unicast manner refers to the MBS service data forwarded from the source base station. The terminal device receives the MBS service data sent by the target base station in a unicast manner and the MBS service data sent by the target base station in a multicast manner based on the fifth indication information in the handover command.

[0200] It should be noted that during the handover process of the terminal device, the receiving window and its variables of the PDCP layer remain the same as before the handover, until the terminal device receives new MBS service data on the target base station side, and then the receiving window and / or the receiving window variable are reset. In other words, the receiving window and the receiving window variable will not be reset or changed during the handover process.

[0201] In the embodiment of the present application, the receiving window in the above scheme refers to the receiving window of the PDCP layer.

[0202] Fig. 9 This is a flow diagram of the MBS service transmission method provided in the embodiment of the present application. Figure 4 , UE corresponds to the terminal device in the embodiment of the present application, such as Fig. 9 As shown, the MBS service transmission method includes the following steps:

[0203] The UE is in the RRC connection state at the original base station, and receives the MBS service data sent by the original base station on the air interface in unicast or multicast mode. Among them, the GTP tunnel from the core network (such as UPF) to the original base station for sending MBS service data can be a shared GTP tunnel (i.e., shared GTP tunnel 1) or a UE-specific GTP tunnel (i.e., a unicast GTP tunnel). A shared GTP tunnel refers to the transmission of MBS service data of an MBS service from the UPF to the base station, and the MBS service data is transmitted on the air interface at the base station in unicast mode and multicast mode respectively. Based on Figure 8 In the network architecture shown, the original base station forwards the MBS service data (ie, PDCP PDU) from the core network to the target base station through the GTP tunnel.

[0204] Step 901: the original base station makes a handover decision and sends a handover request message to the target base station. The handover request message carries relevant information of the MBS service being received by the UE in the original cell and the first PDCP SN.

[0205] Here, optionally, the original base station may make a switching decision based on the measurement result reported by the UE.

[0206] Here, optionally, the relevant information of the MBS service being received by the UE in the original cell includes at least one of the following: MBSTMGI, MBS session id, configuration information of the MBS physical channel, and configuration information of the MBS logical channel.

[0207] Here, the first PDCP SN is the PDCP SN of the last MBS service data received by the UE at the original base station or the PDCP SN of the next MBS service data to be received.

[0208] Step 902: The target base station determines whether the original base station needs to forward the MBS service data according to the first PDCP SN.

[0209] Specifically, if the target base station determines according to the first PDCP SN that the MBS service data corresponding to the first PDCP SN has not been sent in the target base station, the original base station does not need to forward the MBS service data; otherwise, the original base station needs to forward the MBS service data.

[0210] If the target base station determines that the original base station needs to forward the MBS service data, the target base station allocates a GTP tunnel identifier for the original base station to forward the MBS service data to the target base station. Further, the target base station also determines which PDCP SNs (i.e., the first PDCP SN list) of MBS service data need to be forwarded, or determines how many PDCP SNs (i.e., the first value) after the first PDCP SN need to be forwarded to forward the MBS service data, based on the PDCP SN of the MBS service data currently in the memory or the PDCP SN of the MBS service data currently being sent.

[0211] Step 903: The target base station replies with a handover confirmation message, where the handover confirmation message carries a GTP tunnel identifier allocated by the target base station and used by the original base station to forward MBS service data to the target base station.

[0212] Further, optionally, the reply handover confirmation message also carries an indication information, which is used to indicate the PDCP SN of the MBS service data to be forwarded, such as indicating N PDCP SNs starting from the first PDCP SN, where N is a positive integer, for example, indicating a PDCP SN list.

[0213] Step 904.1: The original base station forwards the MBS service data to the target base station on the GTP tunnel indicated by the GTP tunnel identifier.

[0214] Here, the MBS service data forwarded on the GTP tunnel may be: PDCP PDU, wherein the PDCP PDU carries the MBS service data and the SN.

[0215] Step 904.2: The original base station sends a handover command to the UE.

[0216] Here, the handover command in the NR system is an RRC reconfiguration message.

[0217] It should be noted that the order of step 904.1 and step 9034.2 is not limited.

[0218] Furthermore, the handover command carries an indication information, and the indication information is used to instruct the UE to simultaneously receive the MBS service in unicast mode and the MBS service in multicast mode at the target base station.

[0219] Step 905: After receiving the handover command, the UE initiates a random access process to the target base station and sends a handover completion message to the target base station.

[0220] Here, in the NR system, the switching completion message is an RRC reconfiguration completion (RRCReconfigurationComplete) message.

[0221] During the handover process, the receiving window and its variables of the PDCP layer remain the same as before the handover until the UE receives new MBS service data on the target base station side, and then the receiving window and / or the receiving window variables are reset. In other words, the receiving window and the receiving window variables will not be reset or changed during the handover process.

[0222] Step 906: The target base station sends the MBS service data forwarded by the original base station to the UE in a unicast manner.

[0223] Step 907: The target base station sends the MBS service data to the UE in a multicast manner.

[0224] It should be noted that the above step 906 and step 907 may be performed simultaneously, and the UE receives the MBS service data in unicast mode and the MBS service data in multicast mode simultaneously according to the indication information in the switching command.

[0225] In the technical solution of the embodiment of the present application, during the mobility process, the target base station determines whether to trigger the original base station to forward MBS service data and what the forwarded MBS service data are based on the assistance of the original base station. Based on the network side (i.e., the original base station), the UE is controlled to simultaneously receive the multicast MBS service data and the unicast MBS service data on the target base station side to achieve the continuity and reliability of service reception.

[0226] Fig.10 FIG. 5 is a flow chart of a method for transmitting MBS services provided in an embodiment of the present application. Fig.10 As shown, the MBS service transmission method includes the following steps:

[0227] Step 1001: The terminal device receives a switching command sent by an original base station, and switches from the source base station to a target base station.

[0228] In the embodiment of the present application, considering the mobility scenario of the terminal device, the terminal device may switch from one base station (i.e., the original base station) to another base station (i.e., the target base station). For example, the original base station is the original gNB (Source gNB), and the target base station is the target gNB (Target gNB).

[0229] In the embodiment of the present application, the MBS service data on the original base station side is sent by the core network to the original base station through the first tunnel, and the MBS service data on the target base station side is sent by the original base station to the target base station through the second tunnel. That is to say, the original base station receives the MBS service data sent by the core network through the first tunnel, and sends the MBS service data through unicast and / or multicast. The target base station receives the MBS service data from the core network forwarded by the original base station through the second tunnel, and sends the MBS service data through unicast and / or multicast. There is a situation where the MBS service data on the original base station side and the MBS service data on the target base station side are not synchronized.

[0230] In the embodiment of the present application, the original base station and the target base station may adopt one of the following network architectures:

[0231] 1) DU and CU integrated architecture, specifically, the original base station and the target base station have independent total protocol stacks, wherein the total protocol stack includes a first protocol stack and a second protocol stack, wherein the first protocol stack refers to the protocol stack corresponding to the DU, and the second protocol stack refers to the protocol stack corresponding to the CU.

[0232] Here, the protocol stack corresponding to DU includes RLC layer, MAC layer, and PHY layer. The protocol stack corresponding to CU includes SDAP layer and PDCP layer.

[0233] Reference Figure 8 The original base station has a total protocol stack: SDAP layer, PDCP layer, RLC layer, MAC layer, PHY layer. The target base station also has a total protocol stack: SDAP layer, PDCP layer, RLC layer, MAC layer, PHY layer ( Figure 8 The SDAP layer and PDCP layer on the target base station side are not shown). The total protocol stack of the original base station and the target base station are independent. After the original base station receives the MBS service data sent by the core network, it copies a copy of the RLC layer sent to the target base station through the PDCP layer, and sends the original MBS service data to the RLC layer of itself (i.e., the original base station).

[0234] 2) Distributed unit (DU) and centralized unit (CU) separation architecture, specifically, the original base station and the target base station have an independent first protocol stack and a shared second protocol stack, wherein the first protocol stack refers to the protocol stack corresponding to the distributed unit DU, and the second protocol stack refers to the protocol stack corresponding to the centralized unit CU.

[0235] Here, the protocol stack corresponding to DU includes RLC layer, MAC layer, and PHY layer. The protocol stack corresponding to CU includes SDAP layer and PDCP layer. Compared with the DU and CU integrated architecture, the DU and CU separation architecture is equivalent to the original DU, the target base station is equivalent to the target DU, and the original DU and the target DU are connected to the same CU. The signaling between the two base stations is equivalent to the signaling between the two DUs. Furthermore, the signaling between the two DUs can be transmitted directly between the two DUs, or indirectly transmitted by CU forwarding. Most of the following embodiments are described with the DU and CU integrated architecture as the network background, but the DU and CU separation architecture is also applicable to the technical solutions of the embodiments of the present application.

[0236] In the embodiment of the present application, before switching, the terminal device can receive the MBS service data sent by the original base station in a multicast manner or a unicast manner.

[0237] In the embodiment of the present application, before the terminal device receives the handover command sent by the original base station, the original base station sends a handover request message to the target base station, and the handover request message carries the relevant information of the first MBS service. The original base station receives the handover request confirmation message sent by the target base station. Then, the terminal device receives the handover command sent by the original base station.

[0238] In the above solution, optionally, the relevant information of the first MBS service includes at least one of the following: a service identifier, a session identifier, physical channel configuration information, and logical channel configuration information.

[0239] Here, the service identifier may be, for example, the MBS TMGI of the MBS service.

[0240] Here, the session identifier refers to the MBS session identifier (MBS session id) of the MBS service.

[0241] Here, the physical channel configuration information refers to the configuration information of the MBS physical channel of the MBS service.

[0242] Here, the logical channel configuration information refers to the configuration information of the MBS logical channel of the MBS service.

[0243] In the above scheme, optionally, the switching command carries seventh indication information, and the seventh indication information is used to indicate whether the terminal device reports the second PDCP SN list to the target base station. Here, the second PDCP SN list refers to the missing PDCP SN list between the original base station and the target base station (that is, the missing PDCP SN list is used to determine the SN gap).

[0244] Step 1002: The terminal device sends sixth indication information to the target base station, where the sixth indication information is used to indicate a second PDCP SN list, and the second PDCP SN list refers to a missing PDCP SN list between the original base station and the target base station.

[0245] In the embodiment of the present application, after receiving the handover command sent by the original base station, the terminal device switches from the original base station to the target base station, that is, initiates a random access process to the target base station. The terminal device sends a handover completion message to the target base station, and the handover completion message carries the sixth indication information, and the sixth indication information is used to indicate the missing PDCP SN list between the original base station and the target base station.

[0246] Step 1003: The terminal device receives the MBS service data sent by the target base station in a unicast manner and the MBS service data sent in a multicast manner.

[0247] In the embodiment of the present application, after receiving the handover completion message sent by the terminal device, the target base station sends the MBS service data to the terminal device in a unicast manner, and also sends the MBS service data to the terminal device in a multicast manner. The MBS service data sent by the target base station in a unicast manner is determined based on the second PDCP SN list.

[0248] It should be noted that during the handover process of the terminal device, the receiving window and its variables of the PDCP layer remain the same as before the handover, until the terminal device receives new MBS service data on the target base station side, and then the receiving window and / or the receiving window variable are reset. In other words, the receiving window and the receiving window variable will not be reset or changed during the handover process.

[0249] In the embodiment of the present application, the receiving window in the above scheme refers to the receiving window of the PDCP layer.

[0250] Fig.11 This is a flow diagram of the MBS service transmission method provided in the embodiment of the present application. Figure 6 , UE corresponds to the terminal device in the embodiment of the present application, such as Fig.11 As shown, the MBS service transmission method includes the following steps:

[0251] The UE is in the RRC connection state at the original base station, and receives the MBS service data sent by the original base station on the air interface in unicast or multicast mode. Among them, the GTP tunnel from the core network (such as UPF) to the original base station for sending MBS service data can be a shared GTP tunnel (i.e., shared GTP tunnel 1) or a UE-specific GTP tunnel (i.e., a unicast GTP tunnel). A shared GTP tunnel refers to the transmission of MBS service data of an MBS service from the UPF to the base station, and the MBS service data is transmitted on the air interface at the base station in unicast mode and multicast mode respectively. Based on Figure 8 In the network architecture shown, the original base station forwards the MBS service data (ie, PDCP PDU) from the core network to the target base station through the GTP tunnel.

[0252] Step 1101: the original base station makes a handover decision and sends a handover request message to the target base station. The handover request message carries relevant information of the MBS service that the UE is receiving in the original cell.

[0253] Here, optionally, the original base station may make a switching decision based on the measurement result reported by the UE.

[0254] Here, optionally, the relevant information of the MBS service being received by the UE in the original cell includes at least one of the following: MBSTMGI, MBS session id, configuration information of the MBS physical channel, and configuration information of the MBS logical channel.

[0255] Step 1102: The target base station replies with a handover confirmation message.

[0256] Step 1103: The original base station sends a handover command to the UE.

[0257] Here, the handover command in the NR system is an RRC reconfiguration message.

[0258] Furthermore, the handover command carries an indication information, and the indication information is used to indicate whether the UE can report the gap of the PDCP PDU between the original base station and the target base station to the target base station, that is, the missing PDCP SN list between the original base station and the target base station.

[0259] Step 1104: After receiving the handover command, the UE initiates a random access process to the target base station and sends a handover completion message to the target base station.

[0260] Here, in the NR system, the switching completion message is an RRC reconfiguration completion (RRCReconfigurationComplete) message.

[0261] Furthermore, the handover completion message carries an indication information, and the indication information is used to indicate a missing PDCP SN list between the original base station and the target base station.

[0262] During the handover process, the receiving window and its variables of the PDCP layer remain the same as before the handover until the UE receives new MBS service data on the target base station side, and then the receiving window and / or the receiving window variables are reset. In other words, the receiving window and the receiving window variables will not be reset or changed during the handover process.

[0263] Step 1105: The target base station sends the MBS service data corresponding to the missing PDCP SN list to the UE in a unicast manner.

[0264] Step 1106: The target base station sends the MBS service data to the UE in a multicast manner.

[0265] It should be noted that the above step 1105 and step 1106 may be performed simultaneously, and the UE receives the MBS service data in unicast mode and the MBS service data in multicast mode simultaneously.

[0266] In the technical solution of the embodiment of the present application, during the mobility process, the network side (ie, the original base station) controls the UE to report the missing PDCP SN list, triggering the target base station to send the missing MBS service data, so as to achieve continuity and reliability of service reception.

[0267] Fig.12 This is a schematic diagram of the structure of the transmission device of the MBS service provided in the embodiment of the present application. Figure 1 , applied to a target base station, the device comprises:

[0268] The receiving unit 1201 is configured to receive MBS service data forwarded by an original base station;

[0269] The sending unit 1202 is used to send the MBS service data forwarded by the original base station to the terminal device in a unicast manner; send a first indication message to the terminal device, the first indication message is used to instruct the terminal device to reset the receiving window, and the reset receiving window is used for the terminal device to receive the MBS service data sent by the target base station in a multicast manner.

[0270] In an optional manner, the receiving unit 1201 is further configured to receive a handover request message sent by the original base station, where the handover request message carries relevant information of a first MBS service, where the first MBS service refers to an MBS service received by the terminal device at the original base station;

[0271] The sending unit 1202 is further configured to send a handover request confirmation message to the original base station, where the handover request confirmation message carries a first tunnel identifier, and the first tunnel identifier is used by the original base station to forward MBS service data to the target base station.

[0272] In an optional manner, the relevant information of the first MBS service includes at least one of the following: a service identifier, a session identifier, physical channel configuration information, and logical channel configuration information.

[0273] In an optional manner, the receiving unit 1201 is used to receive a PDCP SDU and SN forwarded by the original base station, wherein the PDCP SDU carries MBS service data; or, to receive a PDCP PDU forwarded by the original base station, wherein the PDCP PDU carries SN and MBS service data; or, to receive an IP data packet and SN forwarded by the original base station, wherein the IP data packet carries MBS service data; or, to receive an SDAP SDU and SN forwarded by the original base station, wherein the SDAP SDU carries MBS service data; or, to receive an IP data packet forwarded by the original base station, wherein the IP data packet carries MBS service data.

[0274] In an optional manner, when the receiving unit 1201 receives the IP data packet forwarded by the original base station, the device further includes:

[0275] The processing unit (not shown in the figure) is used to add a PDCP SN to the forwarded MBS service data, and the added PDCP SN is determined based on the PDCP SN of the MBS service data transmitted in a multicast manner.

[0276] In an optional manner, the added PDCP SN is determined based on the PDCP SN of the first MBS service data transmitted to the terminal device in a multicast manner and the total number of the forwarded MBS service data.

[0277] In an optional manner, when the receiving unit 1201 receives the IP data packet forwarded by the original base station, the device further includes:

[0278] The processing unit is used to add a PDCP SN to the forwarded MBS service data, and the added PDCP SN is set from an initial value.

[0279] In an optional manner, the moment when the sending unit 1202 sends the first indication information to the terminal device is after the first moment and before the second moment, the first moment refers to the moment when the terminal device completes receiving the MBS service data in unicast mode, and the second moment refers to the moment when the terminal device starts receiving the MBS service data in multicast mode.

[0280] In an optional manner, the device further includes:

[0281] A processing unit, configured to determine whether the MBS service data forwarded by the original base station has been transmitted on the air interface of the target base station side;

[0282] The sending unit 1202 is further configured to send second indication information to the original base station if the MBS service data forwarded by the original base station has not been transmitted on the air interface of the target base station side, wherein the second indication information is used to instruct the original base station to stop forwarding the MBS service data.

[0283] In an optional manner, the device further includes:

[0284] a processing unit, configured to determine whether the MBS service data forwarded by the original base station exists in the memory of the target base station;

[0285] The sending unit 1202 is further configured to send second indication information to the original base station if the target base station has the MBS service data forwarded by the original base station in its memory, wherein the second indication information is configured to instruct the original base station to stop forwarding the MBS service data.

[0286] In an optional manner, the receiving unit 1201 is further used to receive a switching completion message sent by the terminal device.

[0287] In an optional manner, the first indication information is also used to instruct the terminal device to submit all PDCP SDUs in the receiving window before the reset to the upper layer, and the receiving window before the reset is used by the terminal device to receive the MBS service data on the original base station side, wherein the MBS service data on the original base station side includes the MBS service data sent by the original base station and / or the MBS service data sent by the target base station and forwarded from the original base station.

[0288] In an optional manner, the first indication information is also used to instruct the terminal device to update the value of at least one variable of the reset receiving window to a default value.

[0289] In an optional manner, the first indication information is carried in MAC CE, or in PDCCH, or in RRC signaling.

[0290] In an optional manner, the MBS service data on the original base station side is sent by the core network to the original base station through a first tunnel, and the MBS service data on the target base station side is sent by the core network to the target base station through a second tunnel.

[0291] Those skilled in the art should understand that the relevant description of the above-mentioned MBS service transmission device in the embodiment of the present application can be understood by referring to the relevant description of the MBS service transmission method in the embodiment of the present application.

[0292] Fig.13 This is a schematic diagram of the structure of the transmission device of the MBS service provided in the embodiment of the present application. Figure 2 , applied to an original base station, the device comprises:

[0293] A sending unit 1301 is configured to send first auxiliary information to a target base station, where the first auxiliary information is used by the target base station to determine whether the original base station needs to forward MBS service data to the target base station;

[0294] The receiving unit 1302 is configured to receive third indication information sent by the target base station, where the third indication information is used to instruct the source base station to forward the MBS service data to the target base station;

[0295] The sending unit 1301 is also used to forward the MBS service data to the target base station and send a switching command to the terminal device, wherein the switching command is used to trigger the terminal device to switch from the original base station to the target base station and receive the MBS service data sent by the target base station in a unicast manner and the MBS service data sent in a multicast manner.

[0296] In an optional manner, the sending unit 1301 is used to send a switching request message to the target base station, and the switching request message carries relevant information of the first MBS service and the first auxiliary information. The first MBS service refers to the MBS service received by the terminal device at the original base station.

[0297] In an optional manner, the relevant information of the first MBS service includes at least one of the following: a service identifier, a session identifier, physical channel configuration information, and logical channel configuration information.

[0298] In an optional manner, the first auxiliary information is used to determine a first PDCP SN, where the first PDCP SN is the PDCP SN of the last MBS service data sent by the original base station to the terminal device or the PDCP SN of the next MBS service data to be sent.

[0299] In an optional manner, the first PDCP SN and the PDCP SN of the MBS service data in the memory of the target base station are used by the target base station to determine whether the original base station needs to forward the MBS service data to the target base station; or,

[0300] The first PDCP SN and the PDCP SN of the MBS service data being sent by the target base station are used by the target base station to determine whether the original base station needs to forward the MBS service data to the target base station.

[0301] In an optional manner, the first PDCP SN and the PDCP SN of the MBS service data being sent by the target base station are used by the target base station to determine a first PDCP SN list of MBS service data forwarded by the original base station to the target base station.

[0302] In an optional manner, the receiving unit 1302 is also used to receive a switching request confirmation message sent by the target base station; wherein, when the original base station needs to forward the MBS service data to the target base station, the switching request confirmation message carries a first tunnel identifier, and the first tunnel identifier is used by the original base station to forward the MBS service data to the target base station.

[0303] In an optional manner, the switching request confirmation message also carries fourth indication information, and the fourth indication information is used to indicate a first PDCP SN list or a first number, and the first number and the first PDCP SN are used to determine a first PDCP SN list, and the first PDCP SN list refers to a PDCP SN list of MBS service data forwarded by the original base station to the target base station.

[0304] In an optional manner, the switching command carries fifth indication information, and the fifth indication information is used to instruct the terminal device to simultaneously receive the MBS service data sent by the target base station in a unicast manner and the MBS service data sent in a multicast manner.

[0305] In an optional manner, the MBS service data sent by the target base station in a unicast manner refers to the MBS service data forwarded by the source base station.

[0306] In an optional manner, the MBS service data on the original base station side is sent by the core network to the original base station through a first tunnel, and the MBS service data on the target base station side is sent by the original base station to the target base station through a second tunnel.

[0307] In an optional manner, the original base station and the target base station have an independent first protocol stack and a shared second protocol stack, wherein the first protocol stack refers to a protocol stack corresponding to the DU, and the second protocol stack refers to a protocol stack corresponding to the CU; or,

[0308] The original base station and the target base station have independent overall protocol stacks, wherein the overall protocol stack includes the first protocol stack and the second protocol stack.

[0309] Those skilled in the art should understand that the relevant description of the above-mentioned MBS service transmission device in the embodiment of the present application can be understood by referring to the relevant description of the MBS service transmission method in the embodiment of the present application.

[0310] Fig.14 This is a schematic diagram of the structure of the transmission device of the MBS service provided in the embodiment of the present application. Figure 3 , applied to a terminal device, the device comprises:

[0311] The receiving unit 1401 is configured to receive a handover command sent by an original base station, and to handover from the source base station to a target base station;

[0312] The sending unit 1402 is configured to send sixth indication information to the target base station, where the sixth indication information is used to indicate a second PDCP SN list, where the second PDCP SN list refers to a missing PDCP SN list between the original base station and the target base station;

[0313] The receiving unit 1401 is further configured to receive MBS service data sent by the target base station in a unicast manner and MBS service data sent in a multicast manner.

[0314] In an optional manner, the switching command carries seventh indication information, and the seventh indication information is used to indicate whether the terminal device reports the second PDCP SN list to the target base station.

[0315] In an optional manner, the sending unit 1402 is used to send a switching completion message to the target base station, and the switching completion message carries the sixth indication information.

[0316] In an optional manner, the MBS service data sent by the target base station in unicast mode is determined based on the second PDCP SN list.

[0317] In an optional manner, the MBS service data on the original base station side is sent by the core network to the original base station through a first tunnel, and the MBS service data on the target base station side is sent by the original base station to the target base station through a second tunnel.

[0318] In an optional manner, the original base station and the target base station have an independent first protocol stack and a shared second protocol stack, wherein the first protocol stack refers to a protocol stack corresponding to the DU, and the second protocol stack refers to a protocol stack corresponding to the CU; or,

[0319] The original base station and the target base station have independent overall protocol stacks, wherein the overall protocol stack includes the first protocol stack and the second protocol stack.

[0320] Those skilled in the art should understand that the relevant description of the above-mentioned MBS service transmission device in the embodiment of the present application can be understood by referring to the relevant description of the MBS service transmission method in the embodiment of the present application.

[0321] Fig.15 1500 is a schematic structural diagram of a communication device 1500 provided in an embodiment of the present application. The communication device may be a terminal device or a network device. Fig.15 The communication device 1500 shown includes a processor 1510, and the processor 1510 can call and run a computer program from a memory to implement the method in the embodiment of the present application.

[0322] Alternatively, if Fig.15 As shown, the communication device 1500 may further include a memory 1520. The processor 1510 may call and run a computer program from the memory 1520 to implement the method in the embodiment of the present application.

[0323] The memory 1520 may be a separate device independent of the processor 1510 , or may be integrated into the processor 1510 .

[0324] Alternatively, if Fig.15 As shown, the communication device 1500 may further include a transceiver 1530, and the processor 1510 may control the transceiver 1530 to communicate with other devices, specifically, may send information or data to other devices, or receive information or data sent by other devices.

[0325] The transceiver 1530 may include a transmitter and a receiver. The transceiver 1530 may further include an antenna, and the number of antennas may be one or more.

[0326] Optionally, the communication device 1500 may specifically be a network device of an embodiment of the present application, and the communication device 1500 may implement corresponding processes implemented by the network device in each method of the embodiment of the present application, which will not be described in detail here for the sake of brevity.

[0327] Optionally, the communication device 1500 may specifically be a mobile terminal / terminal device of an embodiment of the present application, and the communication device 1500 may implement the corresponding processes implemented by the mobile terminal / terminal device in each method of the embodiment of the present application, which will not be described again for the sake of brevity.

[0328] Fig.16 It is a schematic structural diagram of the chip of an embodiment of the present application. Fig.16 The chip 1600 shown includes a processor 1610, which can call and run a computer program from a memory to implement the method in the embodiment of the present application.

[0329] Alternatively, if Fig.16 As shown, the chip 1600 may further include a memory 1620. The processor 1610 may call and run a computer program from the memory 1620 to implement the method in the embodiment of the present application.

[0330] The memory 1620 may be a separate device independent of the processor 1610 , or may be integrated into the processor 1610 .

[0331] Optionally, the chip 1600 may further include an input interface 1630. The processor 1610 may control the input interface 1630 to communicate with other devices or chips, and specifically, may obtain information or data sent by other devices or chips.

[0332] Optionally, the chip 1600 may further include an output interface 1640. The processor 1610 may control the output interface 1640 to communicate with other devices or chips, and specifically, may output information or data to other devices or chips.

[0333] Optionally, the chip can be applied to the network device in the embodiments of the present application, and the chip can implement the corresponding processes implemented by the network device in each method of the embodiments of the present application. For the sake of brevity, they will not be repeated here.

[0334] Optionally, the chip can be applied to the mobile terminal / terminal device in the embodiments of the present application, and the chip can implement the corresponding processes implemented by the mobile terminal / terminal device in the various methods of the embodiments of the present application. For the sake of brevity, they will not be repeated here.

[0335] It should be understood that the chip mentioned in the embodiments of the present application can also be called a system-level chip, a system chip, a chip system or a system-on-chip chip, etc.

[0336] Fig.17 1700 is a schematic block diagram of a communication system 1700 provided in an embodiment of the present application. Fig.17 As shown, the communication system 1700 includes a terminal device 1710 and a network device 1720 .

[0337] Among them, the terminal device 1710 can be used to implement the corresponding functions implemented by the terminal device in the above method, and the network device 1720 can be used to implement the corresponding functions implemented by the network device in the above method. For the sake of brevity, they are not repeated here.

[0338] It should be understood that the processor of the embodiment of the present application may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method embodiment can be completed by the hardware integrated logic circuit or software instructions in the processor. The above processor can be a general processor, a digital signal processor (Digital Signal Processor, DSP), an application-specific integrated circuit (Application Specific Integrated Circuit, ASIC), a field programmable gate array (Field Programmable Gate Array, FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present application can be implemented or executed. The general processor can be a microprocessor or the processor can also be any conventional processor. The steps of the method disclosed in the embodiment of the present application can be directly embodied as a hardware decoding processor to perform, or the hardware and software modules in the decoding processor are combined and performed. The software module can be located in a random access memory, a flash memory, a read-only memory, a programmable read-only memory or an electrically erasable programmable memory, a register, and other mature storage media in the art. The storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.

[0339] It can be understood that the memory in the embodiments of the present application can be a volatile memory or a non-volatile memory, or can include both volatile and non-volatile memories. Among them, the non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory can be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct RAM bus random access memory (DR RAM). It should be noted that the memory of the systems and methods described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0340] It should be understood that the above-mentioned memory is exemplary but not restrictive. For example, the memory in the embodiments of the present application may also be static random access memory (static RAM, SRAM), dynamic random access memory (dynamic RAM, DRAM), synchronous dynamic random access memory (synchronous DRAM, SDRAM), double data rate synchronous dynamic random access memory (double data rate SDRAM, DDR SDRAM), enhanced synchronous dynamic random access memory (enhanced SDRAM, ESDRAM), synchronous link dynamic random access memory (synch link DRAM, SLDRAM) and direct memory bus random access memory (Direct Rambus RAM, DR RAM), etc. That is to say, the memory in the embodiments of the present application is intended to include but not limited to these and any other suitable types of memory.

[0341] An embodiment of the present application also provides a computer-readable storage medium for storing a computer program.

[0342] Optionally, the computer-readable storage medium can be applied to the network device in the embodiments of the present application, and the computer program enables the computer to execute the corresponding processes implemented by the network device in the various methods of the embodiments of the present application. For the sake of brevity, they are not repeated here.

[0343] Optionally, the computer-readable storage medium can be applied to the mobile terminal / terminal device in the embodiments of the present application, and the computer program enables the computer to execute the corresponding processes implemented by the mobile terminal / terminal device in the various methods of the embodiments of the present application. For the sake of brevity, they are not repeated here.

[0344] An embodiment of the present application also provides a computer program product, including computer program instructions.

[0345] Optionally, the computer program product can be applied to the network device in the embodiments of the present application, and the computer program instructions enable the computer to execute the corresponding processes implemented by the network device in the various methods of the embodiments of the present application. For the sake of brevity, they are not repeated here.

[0346] Optionally, the computer program product can be applied to the mobile terminal / terminal device in the embodiments of the present application, and the computer program instructions enable the computer to execute the corresponding processes implemented by the mobile terminal / terminal device in the various methods of the embodiments of the present application. For the sake of brevity, they are not repeated here.

[0347] The embodiment of the present application also provides a computer program.

[0348] Optionally, the computer program can be applied to the network device in the embodiments of the present application. When the computer program runs on a computer, the computer executes the corresponding processes implemented by the network device in the various methods in the embodiments of the present application. For the sake of brevity, they are not described here.

[0349] Optionally, the computer program can be applied to the mobile terminal / terminal device in the embodiments of the present application. When the computer program runs on the computer, the computer executes the corresponding processes implemented by the mobile terminal / terminal device in the various methods of the embodiments of the present application. For the sake of brevity, they are not repeated here.

[0350] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0351] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0352] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0353] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0354] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0355] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application can be essentially or partly embodied in the form of a software product that contributes to the prior art. The computer software product is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0356] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for transmitting a multimedia multicast service MBS service, the method include: The target base station receives the first auxiliary information sent by the original base station, where the first auxiliary information is used by the target base station to determine whether the original base station needs to forward the MBS service data to the target base station; the first auxiliary information is used to determine a first packet data convergence protocol PDCP sequence number SN, where the first PDCP SN is the PDCP SN of the last MBS service data sent by the original base station to the terminal device or the PDCP SN of the next MBS service data to be sent; The target base station sends third indication information to the original base station, where the third indication information is used to instruct the original base station to forward the MBS service data to the target base station; The target base station receives the MBS service data forwarded by the original base station, and the target base station sends the MBS service data forwarded by the original base station to the terminal device in a unicast manner; The target base station sends first indication information to the terminal device, wherein the first indication information is used to instruct the terminal device to reset a receiving window, and to instruct the terminal device to update a value of at least one variable of the reset receiving window to a default value; the reset receiving window is used for the terminal device to receive MBS service data sent by the target base station in a multicast manner; The target base station determines whether the original base station needs to forward the MBS service data to the target base station, including: The target base station determines, according to the first PDCP SN and the PDCP SN of the MBS service data existing in the memory of the target base station or the PDCP SN of the MBS service data being sent by the target base station, whether the MBS service data corresponding to the first PDCP SN has been sent at the target base station side; If not, it is determined that the original base station does not need to forward the MBS service data to the target base station; If it has been sent, it is determined that the original base station needs to forward the MBS service data to the target base station; Whether the MBS service data corresponding to the first PDCP SN has been sent on the target base station side is determined based on the following method: If the first PDCP SN is less than or equal to the PDCP SN of the MBS service data existing in the memory of the target base station or the PDCP SN of the MBS service data being sent by the target base station, it is determined that the MBS service data corresponding to the first PDCP SN has been sent on the target base station side; If the first PDCP SN is greater than or equal to the PDCP SN of the MBS service data existing in the memory of the target base station or the PDCP SN of the MBS service data being sent by the target base station, it is determined that the MBS service data corresponding to the first PDCP SN has not been sent on the target base station side; The target base station receives the MBS service data forwarded by the original base station, including: The target base station receives the IP data packet and the SN forwarded by the original base station, wherein the IP data packet carries the MBS service data; The MBS service data on the original base station side is sent from the core network to the original base station through the first tunnel, and the MBS service data on the target base station side is sent from the original base station to the target base station through the second tunnel.

2. The method according to claim 1, in, Before the target base station receives the MBS service data forwarded by the original base station, the method further includes: The target base station receives a handover request message sent by the original base station, where the handover request message carries relevant information of a first MBS service, where the first MBS service refers to an MBS service received by the terminal device at the original base station; The target base station sends a switching request confirmation message to the original base station, wherein, when the original base station needs to forward the MBS service data to the target base station, the switching request confirmation message carries a first tunnel identifier, and the first tunnel identifier is used by the original base station to forward the MBS service data to the target base station.

3. The method according to claim 2, in, The relevant information of the first MBS service includes at least one of the following: a service identifier, a session identifier, physical channel configuration information, and logical channel configuration information.

4. The method according to claim 1, in, The method further includes: the target base station determining, based on the first PDCP SN and the PDCP SN of the MBS service data being sent by the target base station, a first PDCP SN list of the MBS service data forwarded by the original base station to the target base station.

5. The method according to claim 2, in, The switching request confirmation message also carries fourth indication information, and the fourth indication information is used to indicate a first PDCP SN list or a first number, and the first number and the first PDCPSN are used to determine the first PDCP SN list, and the first PDCP SN list refers to the PDCP SN list of MBS service data forwarded by the original base station to the target base station.

6. The method according to any one of claims 1 to 5, in, The target base station sends the MBS service data forwarded by the original base station to the terminal device in a unicast manner, including: After receiving the switching completion message sent by the terminal device, the target base station sends the MBS service data forwarded by the original base station to the terminal device in the unicast manner.

7. The method according to any one of claims 1 to 5, in, The first indication information is carried in a media access control control element MAC CE, or a physical downlink control channel PDCCH, or a radio resource control RRC signaling.

8. A method for transmitting MBS services, the method include: The original base station sends first auxiliary information to the target base station, where the first auxiliary information is used by the target base station to determine whether the original base station needs to forward MBS service data to the target base station; The first auxiliary information is used to determine a first PDCP SN, and the first PDCP SN is the PDCP SN of the last MBS service data sent by the original base station to the terminal device or the PDCP SN of the next MBS service data to be sent; wherein, the first PDCP SN and the PDCP SN of the MBS service data existing in the memory of the target base station or the PDCP SN of the MBS service data being sent by the target base station are used to determine whether the MBS service data corresponding to the first PDCP SN has been sent on the target base station side; if not sent, the MBS service data is not used for the original base station to forward to the target base station; if already sent, the MBS service data is used for the original base station to forward to the target base station; wherein, if the first PDCP SN is less than or equal to the PDCP SN of the MBS service data existing in the memory of the target base station or the PDCP SN of the MBS service data being sent by the target base station, the MBS service data corresponding to the first PDCP SN has been sent on the target base station side; if the first PDCP SN is greater than or equal to the PDCP SN of the MBS service data existing in the memory of the target base station or the PDCP SN of the MBS service data being sent by the target base station SN, the MBS service data corresponding to the first PDCP SN has not been sent on the target base station side; The original base station receives third indication information sent by the target base station, where the third indication information is used to instruct the original base station to forward MBS service data to the target base station; The original base station forwards the MBS service data to the target base station, and sends a switching command to the terminal device, wherein the switching command is used to trigger the terminal device to switch from the original base station to the target base station, and receive the MBS service data sent by the target base station in a unicast manner and the MBS service data sent in a multicast manner; the MBS service data forwarded by the original base station is sent by the target base station to the terminal device in a unicast manner; The original base station forwarding the MBS service data to the target base station includes: The original base station forwards an IP data packet and an SN to the target base station, wherein the IP data packet carries the MBS service data; The MBS service data on the original base station side is sent from the core network to the original base station through the first tunnel, and the MBS service data on the target base station side is sent from the original base station to the target base station through the second tunnel.

9. The method according to claim 8, in, The original base station sends first auxiliary information to the target base station, including: The original base station sends a switching request message to the target base station, where the switching request message carries relevant information of a first MBS service and the first auxiliary information, where the first MBS service refers to an MBS service received by the terminal device at the original base station.

10. The method according to claim 9, in, The relevant information of the first MBS service includes at least one of the following: a service identifier, a session identifier, physical channel configuration information, and logical channel configuration information.

11. The method according to claim 8, in, The first PDCP SN and the PDCP SN of the MBS service data being sent by the target base station are used by the target base station to determine a first PDCP SN list of the MBS service data forwarded by the original base station to the target base station.

12. The method according to claim 11, in, The method further comprises: The original base station receives a switching request confirmation message sent by the target base station; wherein, when the original base station needs to forward MBS service data to the target base station, the switching request confirmation message carries a first tunnel identifier, and the first tunnel identifier is used by the original base station to forward the MBS service data to the target base station.

13. The method according to claim 12, in, The switching request confirmation message also carries fourth indication information, and the fourth indication information is used to indicate the first PDCP SN list or the first number, and the first number and the first PDCP SN are used to determine the first PDCP SN list, and the first PDCP SN list refers to the PDCP SN list of MBS service data forwarded by the original base station to the target base station.

14. A target base station, include: A processor and a memory, the memory being used to store a computer program, and the processor being used to call and run the computer program stored in the memory so that the target base station executes: receiving first auxiliary information sent by the original base station, where the first auxiliary information is used by the target base station to determine whether the original base station needs to forward MBS service data to the target base station; the first auxiliary information is used to determine a first PDCP SN, where the first PDCP SN is the PDCP SN of the last MBS service data sent by the original base station to the terminal device or the PDCP SN of the next MBS service data to be sent; Sending third indication information to the original base station, where the third indication information is used to instruct the original base station to forward the MBS service data to the target base station; Receiving MBS service data forwarded by the original base station; receiving an IP data packet and an SN forwarded by the original base station, wherein the IP data packet carries the MBS service data; Sending the MBS service data forwarded by the original base station to the terminal device in a unicast manner; sending first indication information to the terminal device, the first indication information being used to instruct the terminal device to reset a receiving window, and being used to instruct the terminal device to update the value of at least one variable of the reset receiving window to a default value; the reset receiving window is used by the terminal device to receive the MBS service data sent by the target base station in a multicast manner; Determining whether the original base station needs to forward the MBS service data to the target base station; Determining, according to the first PDCP SN and the PDCP SN of the MBS service data existing in the memory of the target base station or the PDCP SN of the MBS service data being sent by the target base station, whether the MBS service data corresponding to the first PDCP SN has been sent at the target base station side; If not sent, it is determined that the original base station does not need to forward the MBS service data to the target base station; if it has been sent, it is determined that the original base station needs to forward the MBS service data to the target base station; wherein, whether the MBS service data corresponding to the first PDCP SN has been sent on the target base station side is determined based on the following method: if the first PDCP SN is less than or equal to the PDCP SN of the MBS service data existing in the memory of the target base station or the PDCP SN of the MBS service data being sent by the target base station, it is determined that the MBS service data corresponding to the first PDCP SN has been sent on the target base station side; if the first PDCP SN is greater than or equal to the PDCP SN of the MBS service data existing in the memory of the target base station or the PDCP SN of the MBS service data being sent by the target base station, it is determined that the MBS service data corresponding to the first PDCP SN has not been sent on the target base station side; The MBS service data on the original base station side is sent from the core network to the original base station through the first tunnel, and the MBS service data on the target base station side is sent from the original base station to the target base station through the second tunnel.

15. The target base station according to claim 14, wherein the target base station further performs: receiving a handover request message sent by the original base station, where the handover request message carries relevant information of a first MBS service, where the first MBS service refers to an MBS service received by the terminal device at the original base station; Sending a handover request confirmation message to the original base station, in, When the original base station is required to forward the MBS service data to the target base station, the switching request confirmation message carries a first tunnel identifier, and the first tunnel identifier is used by the original base station to forward the MBS service data to the target base station.

16. The target base station according to claim 15, in, The relevant information of the first MBS service includes at least one of the following: a service identifier, a session identifier, physical channel configuration information, and logical channel configuration information.

17. The target base station according to claim 14, wherein the target base station further performs: Based on the first PDCP SN and the PDCP SN of the MBS service data being sent by the target base station, a first PDCP SN list of the MBS service data forwarded by the original base station to the target base station is determined.

18. The target base station according to claim 15, in, The switching request confirmation message also carries fourth indication information, and the fourth indication information is used to indicate a first PDCP SN list or a first number, and the first number and the first PDCP SN are used to determine the first PDCP SN list, and the first PDCP SN list refers to the PDCP SN list of MBS service data forwarded by the original base station to the target base station.

19. The target base station according to any one of claims 14 to 18, wherein the target base station further performs: After receiving the switching completion message sent by the terminal device, the MBS service data forwarded by the original base station is sent to the terminal device in the unicast manner.

20. The target base station according to any one of claims 14 to 18, in, The first indication information is carried in MAC CE, or in PDCCH, or in RRC signaling.

21. An original base station, the original base station include: A sending unit, configured to send first auxiliary information to a target base station, wherein the first auxiliary information is used by the target base station to determine whether the original base station needs to forward MBS service data to the target base station; the first auxiliary information is used to determine a first PDCPSN, wherein the first PDCPSN is the PDCP SN of the last MBS service data sent by the original base station to the terminal device or the PDCP SN of the next MBS service data to be sent; wherein the first PDCP SN and the PDCP SN of the MBS service data existing in the memory of the target base station or the PDCP SN of the MBS service data being sent by the target base station are used to determine whether the MBS service data corresponding to the first PDCP SN has been sent on the target base station side; if not sent, the MBS service data is not used for the original base station to forward to the target base station; if already sent, the MBS service data is used for the original base station to forward to the target base station; wherein, if the first PDCP SN is less than or equal to the PDCP SN of the MBS service data existing in the memory of the target base station or the PDCP SN of the MBS service data being sent by the target base station, the MBS service data corresponding to the first PDCP SN has been sent on the target base station side; if the first PDCP SN is less than or equal to the PDCP SN of the MBS service data existing in the memory of the target base station or the PDCP SN of the MBS service data being sent by the target base station If the SN is greater than or equal to the PDCP SN of the MBS service data in the memory of the target base station or the PDCP SN of the MBS service data being sent by the target base station, the MBS service data corresponding to the first PDCP SN has not been sent on the target base station side; a receiving unit, configured to receive third indication information sent by the target base station, wherein the third indication information is used to instruct the original base station to forward the MBS service data to the target base station; The sending unit is further used to forward the MBS service data to the target base station, and send a switching command to the terminal device, wherein the switching command is used to trigger the terminal device to switch from the original base station to the target base station, and receive the MBS service data sent by the target base station in a unicast manner and the MBS service data sent in a multicast manner; the MBS service data forwarded by the original base station is sent by the target base station to the terminal device in a unicast manner; The sending unit is specifically configured to forward an IP data packet and an SN to the target base station, wherein the IP data packet carries the MBS service data; The MBS service data on the original base station side is sent from the core network to the original base station through the first tunnel, and the MBS service data on the target base station side is sent from the original base station to the target base station through the second tunnel.

22. The original base station according to claim 21, in, The sending unit is used to send a switching request message to the target base station, where the switching request message carries relevant information of a first MBS service and the first auxiliary information, where the first MBS service refers to the MBS service received by the terminal device at the original base station.

23. The original base station according to claim 22, in, The relevant information of the first MBS service includes at least one of the following: a service identifier, a session identifier, physical channel configuration information, and logical channel configuration information.

24. The original base station according to claim 21, in, The first PDCP SN and the PDCP SN of the MBS service data being sent by the target base station are used by the target base station to determine a first PDCP SN list of the MBS service data forwarded by the original base station to the target base station.

25. The original base station according to claim 24, in, The receiving unit is also used to receive a switching request confirmation message sent by the target base station; wherein, when the original base station needs to forward the MBS service data to the target base station, the switching request confirmation message carries a first tunnel identifier, and the first tunnel identifier is used by the original base station to forward the MBS service data to the target base station.

26. The original base station according to claim 25, in, The switching request confirmation message also carries fourth indication information, and the fourth indication information is used to indicate the first PDCP SN list or the first number, and the first number and the first PDCP SN are used to determine the first PDCP SN list, and the first PDCP SN list refers to the PDCP SN list of MBS service data forwarded by the original base station to the target base station.

27. A communication device, include: A processor and a memory, the memory being used to store a computer program, the processor being used to call and run the computer program stored in the memory to execute the method according to any one of claims 1 to 7, or the method according to any one of claims 8 to 13.

28. A chip, include: A processor, configured to call and run a computer program from a memory, so that a device equipped with the chip executes a method as claimed in any one of claims 1 to 7, or a method as claimed in any one of claims 8 to 13.

29. A computer-readable storage medium for storing a computer program, wherein the computer program causes a computer to execute the method according to any one of claims 1 to 7 or any one of claims 8 to 13.

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