A communication method, apparatus, and storage medium

Abstract

A communication method, device and storage medium are used to solve the discontinuity of multicast / broadcast services of a UE in a handover process in the prior art. The method comprises the following steps: a target access network device receives first multicast / broadcast service data from a source access network device and second multicast / broadcast service data from a core network device; if the target access network device determines that the first multicast / broadcast service data is synchronized with the second multicast / broadcast service data, the target access network device sends the second multicast / broadcast service data to a terminal device, so as to ensure the continuity of multicast / broadcast services of the UE in the handover process as much as possible.

Description

Technical Field

[0001] This application relates to the field of communication technology, and in particular to a communication method, apparatus and storage medium. Background Technology

[0002] With the development of mobile internet, multicast / broadcast services are widely used, for example in high-definition video, autonomous driving, IoT devices, and public safety early warning systems. The following explanation uses high-definition video services as an example. Currently, users are gradually shifting from watching popular programs on fixed televisions to watching them on mobile devices. Therefore, video services have a significant impact on mobile networks. Optimizing video transmission through over-the-air multicast can help reduce the impact of video data on mobile networks.

[0003] In 3G and 4G mobile communication technologies, it is necessary to add dedicated network elements and interfaces to support multicast services on the existing 3G or 4G communication network architecture, and dedicated multicast channel support is also required. This not only increases the overhead on the operator's side but also increases the complexity of the terminal. To overcome these difficulties, supporting multicast / broadcast service (MBS) on the 5G communication network architecture has become an important research focus.

[0004] In 5G, a key issue in MBS research is service continuity. How to ensure the continuity of multicast / broadcast services for terminal devices when they switch from source access network devices to target access network devices is an urgent problem to be solved. Summary of the Invention

[0005] This application provides a communication method, apparatus, and storage medium to ensure that the continuity of multicast / broadcast services of a terminal device is not affected during the process of a terminal device switching from a source access network device to a target access network device.

[0006] In a first aspect, this application provides a communication method, which includes a source access network device receiving first radio bearer configuration information and second radio bearer configuration information from a target access network device. The first radio bearer configuration information is used by a terminal device to receive first multicast / broadcast service data transmitted from the target access network device in an air interface unicast mode. The second radio bearer configuration information is used by the terminal device to receive second multicast / broadcast service data transmitted from the target access network device in an air interface multicast / broadcast mode or an air interface unicast mode. The source access network device sends the first radio bearer configuration information and the second radio bearer configuration information to the terminal device.

[0007] It should be noted that the first multicast / broadcast service data and the second multicast / broadcast service data are data from the same source service.

[0008] Based on this scheme, the terminal device can receive first multicast / broadcast service data through the first radio bearer configuration information and second multicast / broadcast service data through the second radio bearer configuration information. Therefore, during the handover process from the source access network device to the target access network device, the continuity of the multicast / broadcast service of the terminal device can be guaranteed to remain unaffected. In other words, packet loss during the handover process can be reduced, thus lowering latency.

[0009] In one possible implementation, the source access network device sends first multicast / broadcast service data to the target access network device, and the first multicast / broadcast service data is associated with the protocol data unit (PDU) session of the terminal device.

[0010] In one possible implementation, the source access network device sends first multicast / broadcast service data to the target access network device through a first forwarding tunnel or a second forwarding tunnel; wherein, the first forwarding tunnel is the forwarding tunnel corresponding to the first multicast / broadcast session of the terminal device, the second forwarding tunnel is the forwarding tunnel corresponding to the PDU session tunnel of the terminal device, and the first multicast / broadcast session corresponds to the first multicast / broadcast service.

[0011] In one possible implementation, the source access network device determines that the first timer has expired and stops sending the first multicast / broadcast service data to the target access network device.

[0012] In one possible implementation, the source access network device receives an end data packet from a session management network element or a user plane network element. The end data packet is used to instruct the target access network device to stop receiving the first multicast / broadcast service data through the first forwarding tunnel or the second forwarding tunnel. The end data packet is constructed by the session management network element after the third timer expires or by the user plane network element after the fourth timer expires. The source access network device sends the end data packet to the target access network device.

[0013] In one possible implementation, the source access network device receives an end packet from a session management network element or a user plane network element. The end packet is used to instruct the target access network device to stop receiving the first multicast / broadcast service data through the first forwarding tunnel or the second forwarding tunnel. The source access network device determines that the fifth timer has expired and sends an end packet to the target access network device.

[0014] Secondly, this application provides a communication method, which includes a target access network device determining first radio bearer configuration information and second radio bearer configuration information of a terminal device. The first radio bearer configuration information is used by the terminal device to receive first multicast / broadcast service data transmitted from the target access network device in an air interface unicast mode. The second radio bearer configuration information is used by the terminal device to receive second multicast / broadcast service data transmitted from the target access network device in an air interface multicast / broadcast mode or an air interface unicast mode. The target access network device sends the first radio bearer configuration information and the second radio bearer configuration information to the source access network device.

[0015] In one possible implementation, the target access network device receives first multicast / broadcast service data from the source access network device, and the first multicast / broadcast service data is associated with the PDU session of the terminal device.

[0016] In one possible implementation, the target access network device receives first multicast / broadcast service data from the source access network device through a first forwarding tunnel or a second forwarding tunnel; wherein, the first forwarding tunnel is the forwarding tunnel corresponding to the first multicast / broadcast session of the terminal device, the second forwarding tunnel is the forwarding tunnel corresponding to the PDU session tunnel of the terminal device, and the first multicast / broadcast session corresponds to the first multicast / broadcast service.

[0017] In one possible implementation, the target access network device receives a first request message from the source access network device. The first request message is used to request the target access network device to establish a forwarding tunnel corresponding to the first multicast / broadcast service with the source access network device.

[0018] In one possible implementation, the target access network device sends the first multicast / broadcast service data to the terminal device via air interface unicast mode, and sends the second multicast / broadcast service data to the terminal device via air interface multicast / broadcast mode or air interface unicast mode.

[0019] In one possible implementation, after the target access network device receives the termination data packet from the source access network device, it stops receiving the first multicast / broadcast service data through the first forwarding tunnel or the second forwarding tunnel; wherein the termination data packet is constructed and sent by the session management network element after the third timer expires; or, constructed and sent by the user plane network element after the fourth timer expires; or, sent by the source access network device after determining that the fifth timer has expired.

[0020] Thirdly, this application provides a communication method, which includes a terminal device receiving first radio bearer configuration information and second radio bearer configuration information from a source access network device. The first radio bearer configuration information is used by the terminal device to receive first multicast / broadcast service data transmitted from a target access network device in an air interface unicast mode. The second radio bearer configuration information is used by the terminal device to receive second multicast / broadcast service data transmitted from the target access network device in an air interface multicast / broadcast mode or an air interface unicast mode. The terminal device receives the first multicast / broadcast service data from the target access network device through an air interface unicast mode, and also receives the second multicast / broadcast service data from the target access network device through an air interface multicast / broadcast mode or an air interface unicast mode. The first multicast / broadcast service data is associated with a Protocol Data Unit (PDU) session of the terminal device.

[0021] In one possible implementation, the terminal device removes duplicate data from the first multicast / broadcast service data and the second multicast / broadcast service data.

[0022] Fourthly, this application provides a communication method, which includes a session management network element constructing an end data packet after determining that a third timer has expired. The end data packet is used to instruct the target access network device to stop receiving first multicast / broadcast service data through the forwarding tunnel corresponding to the PDU session tunnel of the terminal device. The session management network element sends the end data packet to the target access network device through the source access network device.

[0023] Fifthly, this application provides a communication method, which includes a user plane network element sending a fourth response message to a session management network element, the user plane network element receiving an end data packet constructed by the session management network element, the end data packet being constructed by the session management network element after receiving the fourth response message sent by the user plane network element, the fourth response message being an N4 session response message; and the user plane network element sending an end data packet to a target access network device after determining that a second timer has expired.

[0024] Sixthly, this application provides a communication method, which includes a user plane network element constructing an end data packet after determining that a fourth timer has expired. The end data packet is used to instruct the target access network device to stop receiving first multicast / broadcast service data through the forwarding tunnel corresponding to the PDU session tunnel of the terminal device; the user plane network element sends the end data packet to the target access network device.

[0025] In a seventh aspect, this application provides a communication method, the method comprising: a source access network device receiving first radio bearer configuration information from a target access network device, the first radio bearer configuration information being used by a terminal device to receive first multicast / broadcast service data transmitted from the target access network device in an air interface unicast mode; the source access network device sending the first radio bearer configuration information to the terminal device; and, after receiving first information from the target access network device, the source access network device stopping sending the first multicast / broadcast service data to the target access network device, the first information being used to instruct the source access network device to stop sending the first multicast / broadcast service data to the target access network device, the first multicast / broadcast service data being associated with the terminal device's PDU session, and the first multicast / broadcast service data being forwarded by the source access network device to the target access network device.

[0026] In one possible implementation, the source access network device sends the first multicast / broadcast service data to the target access network device.

[0027] In one possible implementation, the source access network device sends first multicast / broadcast service data to the target access network device through a first forwarding tunnel or a second forwarding tunnel; wherein, the first forwarding tunnel is the forwarding tunnel corresponding to the first multicast / broadcast session of the terminal device, the second forwarding tunnel is the forwarding tunnel corresponding to the PDU session tunnel of the terminal device, and the first multicast / broadcast session corresponds to the first multicast / broadcast service.

[0028] Eighthly, this application provides a communication method, the method comprising: a target access network device determining first radio bearer configuration information and second radio bearer configuration information of a terminal device; the first radio bearer configuration information being used by the terminal device to receive first multicast / broadcast service data transmitted from an air interface unicast mode corresponding to the target access network device; and the second radio bearer configuration information being used by the terminal device to receive second multicast / broadcast service data transmitted from an air interface multicast / broadcast mode or an air interface unicast mode corresponding to the target access network device; the target access network device sending the first radio bearer configuration information to a source access network device; and the target access network device receiving data from the source access network device. The first multicast / broadcast service data is associated with the PDU session of the terminal device. If the target access network device determines that the received first multicast / broadcast service data is synchronized with the second multicast / broadcast service data, it sends a first message to the source access network device. The first message is used to instruct the source access network device to stop sending the first multicast / broadcast service data to the target access network device. The target access network device sends a second radio bearer configuration information to the terminal device. The second radio bearer configuration information is used by the terminal device to receive the second multicast / broadcast service data transmitted from the target access network device in the corresponding air interface multicast / broadcast mode or air interface unicast mode.

[0029] In one possible implementation, the target access network device sends the first multicast / broadcast service data to the terminal device via air interface unicast mode, and sends the second multicast / broadcast service data to the terminal device via air interface multicast / broadcast mode or air interface unicast mode.

[0030] In one possible implementation, if the target access network device determines that the sequence number of the first multicast / broadcast service data is equal to the sequence number of the second multicast / broadcast service data, then the first multicast / broadcast service data and the second multicast / broadcast service data are synchronized.

[0031] In one possible implementation, if the target access network device determines that the first multicast / broadcast service data it received is earlier than the second multicast / broadcast service data, it sends the first information to the source access network device.

[0032] In one possible implementation, if the target access network device determines that the sequence number of the first multicast / broadcast service data is greater than the sequence number of the second multicast / broadcast service data, it determines that the first multicast / broadcast service data is earlier than the second multicast / broadcast service data.

[0033] In one possible implementation, if the target access network device determines that the sequence number of the first multicast / broadcast service data is greater than the sequence number of the second multicast / broadcast service data, then: the transmission rate of the first multicast / broadcast service data in air interface unicast mode is slowed down, and / or the transmission rate of the second multicast / broadcast service data in air interface multicast / broadcast mode or air interface unicast mode is increased.

[0034] In one possible implementation, if the target access network device determines that the received first multicast / broadcast service data is later than the second multicast / broadcast service data, then: the transmission rate of the first multicast / broadcast service data in air interface unicast mode is increased, and / or the transmission rate of the second multicast / broadcast service data in air interface multicast / broadcast mode or air interface unicast mode is decreased.

[0035] In one possible implementation, the target access network device determines that the sequence number of the first multicast / broadcast service data is less than the sequence number of the second multicast / broadcast service data, and determines that the received first multicast / broadcast service data is later than the second multicast / broadcast service data.

[0036] Ninthly, this application provides a communication method, the method comprising: a source access network device sending first multicast / broadcast service data to a target access network device through a forwarding tunnel corresponding to a PDU session tunnel of a terminal device; the source access network device receiving an end data packet from a session management network element or a user plane network element, wherein the end data packet is used to instruct the target access network device to stop receiving the first multicast / broadcast service data through the forwarding tunnel corresponding to the PDU session tunnel of the terminal device, and the end data packet is constructed by the session management network element after a third timer expires, or by the user plane network element after a fourth timer expires; and the source access network device sending the end data packet to the target access network device.

[0037] In one possible implementation, the source access network device receives first radio bearer configuration information from the target access network device. The first radio bearer configuration information is used by the terminal device to receive first multicast / broadcast service data transmitted in the air interface unicast mode corresponding to the target access network device. The source access network device sends the first radio bearer configuration information to the terminal device.

[0038] In a tenth aspect, this application provides a communication method, the method comprising: a target access network device receiving first multicast / broadcast service data from a source access network device, the first multicast / broadcast service data being sent through a forwarding tunnel corresponding to a PDU session tunnel of a terminal device; the target access network device receiving an end data packet from the source access network device and ceasing to receive the first multicast / broadcast service data through the forwarding tunnel corresponding to the PDU session tunnel of the terminal device; wherein the end data packet is constructed by a session management network element after a third timer expires, or by a user plane network element after a fourth timer expires.

[0039] In one possible implementation, the target access network device sends the first multicast / broadcast service data to the terminal device via air interface unicast mode.

[0040] Eleventhly, this application provides a communication method, which includes a source access network device sending first multicast / broadcast service data to a target access network device through a forwarding tunnel corresponding to the PDU session tunnel of a terminal device; the source access network device receiving an end data packet from a session management network element or a user plane network element, wherein the end data packet is used to instruct the target access network device to stop receiving the first multicast / broadcast service data through the forwarding tunnel corresponding to the PDU session tunnel of the terminal device; and the source access network device determining that a fifth timer has expired and sending an end data packet to the target access network device.

[0041] In one possible implementation, the source access network device receives first radio bearer configuration information from the target access network device. The first radio bearer configuration information is used by the terminal device to receive first multicast / broadcast service data transmitted in the air interface unicast mode corresponding to the target access network device. The source access network device sends the first radio bearer configuration information to the terminal device.

[0042] In a twelfth aspect, this application provides a communication method, the method comprising: a target access network device receiving first multicast / broadcast service data from a source access network device, the first multicast / broadcast service data being sent through a forwarding tunnel corresponding to a PDU session tunnel of a terminal device; the target access network device receiving an end data packet from the source access network device and stopping receiving the first multicast / broadcast service data through the forwarding tunnel corresponding to the PDU session tunnel of the terminal device; wherein the end data packet is sent by the source access network device after determining that a fifth timer has expired.

[0043] In one possible implementation, the target access network device sends the first multicast / broadcast service data to the terminal device via air interface unicast mode.

[0044] In a thirteenth aspect, this application provides a communication method, which includes a session management network element setting an eighth timer to store (or cache) second multicast / broadcast service data in a user plane network element, the session management network element determining that the eighth timer has expired, and causing the UPF to send the second multicast / broadcast service data stored in the UPF to a target access network device.

[0045] In one possible implementation, the session management network element sends an N4 session update request message to the user plane network element. The N4 session update request message may include PDU session tunnel identification information allocated by the target access network device and / or tunnel identification information allocated by the session management network element to the user plane network element. In other words, the N4 session update request is used to request a switch of the downlink path of the Protocol Data Unit (PDU) session to the target access network device.

[0046] In one possible implementation, the session management network element starts the eighth timer in response to the core network device sending the second multicast / broadcast service data to the target access network device.

[0047] In one possible implementation, the session management network element sends a first instruction message to the user plane network element, which instructs the user plane network element to save the second multicast / broadcast service data.

[0048] In one possible implementation, the session management network element determines that the eighth timer has expired and sends a second indication message to the user plane network element. The second indication message is used to instruct the user plane network element to send the stored second multicast / broadcast service data to the target access network device.

[0049] Optionally, the first indication information may be carried in the N4 session update request message; or, the second indication information may be carried in the N4 session update request message.

[0050] In a fourteenth aspect, this application provides a communication method, which includes a session management network element sending a first indication message to a user plane network element, and sending a second indication message to the user plane network element after determining that an eighth timer has expired; wherein the first indication message is used to instruct the user plane network element to save second multicast / broadcast service data, and the second indication message is used to instruct the user plane network element to send the saved second multicast / broadcast service data to a target access network device.

[0051] In one possible implementation, the first indication information may be carried in the N4 session update request message; or, the second indication information may be carried in the N4 session update request message.

[0052] In a fifteenth aspect, this application provides a communication method, the method comprising a target access network device receiving first multicast / broadcast service data from a source access network device and second multicast / broadcast service data from a core network device; if the target access network device determines that the first multicast / broadcast service data and the second multicast / broadcast service data are synchronized, sending the second multicast / broadcast service data to a terminal device.

[0053] Based on this scheme, the target access network device, upon determining that the first multicast / broadcast service data and the second multicast / broadcast service data are synchronized, sends the second multicast / broadcast service data to the terminal device. Thus, during the handover process from the source access network device to the target access network device, the continuity of the terminal device's multicast / broadcast services is guaranteed to remain unaffected. In other words, packet loss during the handover process is reduced, lowering latency.

[0054] In one possible implementation, the target access network device determines that the sequence number of the first multicast / broadcast service data plus one is greater than or equal to the sequence number of the second multicast / broadcast service data, and determines that the first multicast / broadcast service data and the second multicast / broadcast service data are synchronized.

[0055] In one possible implementation, the target access network device discards first multicast / broadcast service data whose sequence number is greater than the sequence number of the second multicast / broadcast service data. Further, optionally, the target access network device increases the transmission rate of the second multicast / broadcast service data and / or decreases the transmission rate of the first multicast / broadcast service data.

[0056] In one possible implementation, if the target access network device determines that the first multicast / broadcast service data and the second multicast / broadcast service data are out of sync, it adjusts the first multicast / broadcast service data and the second multicast / broadcast service data to be synchronized.

[0057] In one possible implementation, if the target access network device determines that the sequence number of the first multicast / broadcast service data plus one is less than the sequence number of the second multicast / broadcast service data, it caches the second multicast / broadcast service data; if the target access network device determines that the sequence number of the received first multicast / broadcast service data plus one is equal to the sequence number of the first cached second multicast / broadcast service data, it determines that the first multicast / broadcast service data and the second multicast / broadcast service data are synchronized.

[0058] In one possible implementation, if the target access network device determines that the sequence number of the first multicast / broadcast service data plus one is less than the sequence number of the second multicast / broadcast service data, it slows down the transmission rate of the second multicast / broadcast service data and / or speeds up the transmission rate of the first multicast / broadcast service data. This facilitates rapid synchronization between the first and second multicast / broadcast service data.

[0059] In one possible implementation, the target access network device determines first radio bearer configuration information and second radio bearer configuration information of the terminal device. The first radio bearer configuration information is used by the terminal device to receive first multicast / broadcast service data sent by the target access network device, and the second radio bearer configuration information is used by the terminal device to receive second multicast / broadcast service data sent by the target access network device. The target access network device sends the second radio bearer configuration information to the terminal device.

[0060] In one possible implementation, if the target access network device determines that the first multicast / broadcast service data is synchronized with the second multicast / broadcast service data, it sends a first message to the source access network device. The first message is used to instruct the source access network device to stop sending the first multicast / broadcast service data to the target access network device.

[0061] In a sixteenth aspect, this application provides a communication method, the method comprising a target access network device receiving first multicast / broadcast service data from a source access network device and second multicast / broadcast service data from a core network device; the target access network device determining the time to send the second multicast / broadcast service data to a terminal device based on the sequence number of the first multicast / broadcast service data and the sequence number of the second multicast / broadcast service data.

[0062] In one possible implementation, the target access network device can determine the time when the first multicast / broadcast service data is synchronized with the second multicast / broadcast service data as the time to send the second multicast / broadcast service data to the terminal device.

[0063] In a seventeenth aspect, this application provides a communication apparatus for implementing the functions of a source access network device as described in the first, seventh, ninth, or eleventh aspects above; or for implementing the functions of a target access network device as described in the second, eighth, tenth, twelfth, fifteenth, or sixteenth aspects above; or for implementing the functions of a terminal device as described in the third aspect; or for implementing the functions of a session management network element as described in the fourth, thirteenth, or fourteenth aspects above; or for implementing the functions of a user plane network element as described in the fifth or sixth aspect. This function can be implemented in hardware or by hardware executing corresponding software. The hardware or software includes one or more units or modules corresponding to the above functions.

[0064] In one possible implementation, the communication device can be a terminal device, or a module that can be used in a terminal device, such as a chip, chip system, or circuit. The beneficial effects are described above and will not be repeated here. The communication device may include a transceiver and a processor. The processor can be configured to support the communication device in performing the corresponding functions of the terminal device described above, and the transceiver is used to support communication between the communication device and network devices and other terminal devices. The transceiver can be a standalone receiver, a standalone transmitter, a transceiver with integrated transceiver functions, or an interface circuit. Optionally, the communication device may also include a memory, which can be coupled to the processor, and stores the necessary program instructions and data of the communication device.

[0065] For example, the transceiver and processor can perform the corresponding functions of the terminal device in the above method examples, as detailed in the method examples, which will not be repeated here.

[0066] In another possible implementation, the communication device can be an access network device, or a component that can be used in an access network device, such as a chip, chip system, or circuit. The communication device may include a transceiver and a processor. The processor can be configured to support the communication device in performing the corresponding functions of the access network device described above, and the transceiver is used to support communication between the communication device and other access network devices and terminal devices. The transceiver can be a standalone receiver, a standalone transmitter, a transceiver with integrated transceiver functions, or an interface circuit. Optionally, the communication device may also include a memory, which can be coupled to the processor, and stores the necessary program instructions and data of the communication device.

[0067] For example, the transceiver and processor can perform the corresponding functions of the source access network device in the above method examples, as detailed in the method examples, and will not be repeated here. Alternatively, the transceiver and processor can perform the corresponding functions of the target access network device in the above method examples, as detailed in the method examples, and will not be repeated here.

[0068] In an eighteenth aspect, this application provides a communication device for implementing the first aspect or any one of the methods described above, or for implementing the second aspect or any one of the methods described above, or for implementing the third aspect or any one of the methods described above, or for implementing the fourth aspect or any one of the methods described above, or for implementing the fifth aspect or any one of the methods described above, or for implementing the sixth aspect or any one of the methods described above, or for implementing the seventh aspect or any one of the methods described above, or for implementing the eighth aspect or any one of the methods described above, or for implementing the ninth aspect or any one of the methods described above, or for implementing the tenth aspect or any one of the methods described above, or for implementing the eleventh aspect or any one of the methods described above, or for implementing the twelfth aspect or any one of the methods described above, or for implementing the fourteenth aspect or any one of the methods described above, or for implementing the fifteenth aspect or any one of the methods described above, or for implementing the sixteenth aspect or any one of the methods described above, including corresponding functional modules, each used to implement the steps in the above methods. The functions can be implemented by hardware or by hardware executing corresponding software. The hardware or software includes one or more modules corresponding to the functions described above.

[0069] In one possible implementation, the communication device may be a terminal device, which may include a processing module and a transceiver module. These modules may perform the corresponding functions of the terminal device in the above method example, as detailed in the method example, and will not be repeated here.

[0070] In another possible implementation, the communication device may also be a network device, which may include a transceiver module and a processing module. These modules can perform the corresponding functions of the network device in the above method example, as detailed in the method example, and will not be repeated here.

[0071] In a nineteenth aspect, this application provides a communication system comprising a terminal device, a source access network device, and a target access network device, and may further include a session management network element and / or a user plane network element. The source access network device can be used to execute the first aspect or any method thereof, or to execute the seventh aspect or any method thereof, or to execute the ninth aspect or any method thereof, or to execute the eleventh aspect or any method thereof; the target access network device can be used to execute the second aspect or any method thereof, or to execute the eighth aspect or any method thereof, or to execute the eleventh aspect or any method thereof, or to execute the twelfth aspect or any method thereof, and to execute the twelfth aspect or any method thereof. The terminal device can be used to execute the above-described fourteenth aspect or any one of the above-described methods, or to implement the above-described fifteenth aspect or any one of the above-described methods, or to implement the above-described sixteenth aspect or any one of the above-described methods; the session management network element can be used to execute the above-described fourth aspect or any one of the above-described methods, or to execute the above-described thirteenth aspect or any one of the above-described methods, or to execute the above-described fourteenth aspect or any one of the above-described methods; the user plane network element is used to execute the above-described fifth aspect or any one of the above-described methods, or to execute the above-described sixth aspect or any one of the above-described methods.

[0072] In a twentieth aspect, this application provides a communication system including a session management network element and a user plane network element. Optionally, it may also include a target access network device. The session management network element can be used to perform the methods described in the fourth aspect or any one of the fourth aspects, or to perform the methods described in the thirteenth aspect or any one of the thirteenth aspects, or to perform the methods described in the fourteenth aspect or any one of the fourteenth aspects. The user plane network element is used to perform the methods described in the fifth aspect or any one of the fifth aspects, or to perform the methods described in the sixth aspect or any one of the sixth aspects.

[0073] In a twentieth aspect, this application provides a computer-readable storage medium storing a computer program or instructions that, when executed by a communication device, cause the communication device to perform the method of the first aspect or any possible implementation thereof, or cause the communication device to perform the method of the second aspect or any possible implementation thereof, or be used to implement the third aspect or any method thereof, or be used to implement the fourth aspect or any method thereof, or be used to implement the fifth aspect or any method thereof, or be used to implement the sixth aspect or any method thereof, or be used to implement the seventh aspect or any method thereof. Any one of the methods described above, or used to implement the eighth aspect or any one of the eighth aspects, or used to implement the ninth aspect or any one of the ninth aspects, or used to implement the tenth aspect or any one of the tenth aspects, or used to implement the eleventh aspect or any one of the eleventh aspects, or used to implement the twelfth aspect or any one of the twelfth aspects, or used to implement the thirteenth aspect or any one of the thirteenth aspects, or used to implement the fourteenth aspect or any one of the fourteenth aspects, or used to implement the fifteenth aspect or any one of the fifteenth aspects, or used to implement the sixteenth aspect or any one of the sixteenth aspects.

[0074] In a twentieth aspect, this application provides a computer program product comprising a computer program or instructions that, when executed by a communication device, implement the method of the first aspect or any possible implementation thereof, or implement the method of the second aspect or any possible implementation thereof, or implement the third aspect or any one of the methods therein, or implement the fourth aspect or any one of the methods therein, or implement the fifth aspect or any one of the methods therein, or implement the sixth aspect or any one of the methods therein, or implement the seventh aspect or any one of the methods therein. Or, it can be used to implement the eighth aspect or any one of the eighth aspects, or to implement the ninth aspect or any one of the ninth aspects, or to implement the tenth aspect or any one of the tenth aspects, or to implement the eleventh aspect or any one of the eleventh aspects, or to implement the twelfth aspect or any one of the twelfth aspects, or to implement the thirteenth aspect or any one of the thirteenth aspects, or to implement the fourteenth aspect or any one of the fourteenth aspects, or to implement the fifteenth aspect or any one of the fifteenth aspects, or to implement the sixteenth aspect or any one of the sixteenth aspects. Attached Figure Description

[0075] Figure 1 A schematic diagram of a communication system architecture is provided for this application;

[0076] Figure 2 This application provides a schematic diagram of a unicast method for transmitting data.

[0077] Figure 3 This application provides a schematic diagram of a multicast method for transmitting data.

[0078] Figure 4 A schematic diagram illustrating one application scenario provided in this application;

[0079] Figure 5 A flowchart illustrating a communication method provided in this application;

[0080] Figure 6 A flowchart illustrating another communication method provided in this application;

[0081] Figure 7a This application provides a flowchart illustrating a method for establishing a downlink data transmission tunnel between a target access network and a terminal device.

[0082] Figure 7bA schematic diagram of another communication method provided in this application;

[0083] Figure 7c A flowchart illustrating a method for determining the start of the eighth timer provided in this application;

[0084] Figure 7d A flowchart illustrating another method for determining the start of the eighth timer provided in this application;

[0085] Figure 7e A flowchart illustrating another method for determining the start of the eighth timer provided in this application;

[0086] Figure 7f A flowchart illustrating another method for determining the start of the eighth timer provided in this application;

[0087] Figure 8 A flowchart illustrating a method for a target access network device to stop receiving first multicast / broadcast service data sent by a source access network device, provided in this application;

[0088] Figure 9 A flowchart illustrating a method for a target access network device to stop receiving first multicast / broadcast service data sent by a source access network device, provided in this application;

[0089] Figure 10 A flowchart illustrating a method for a target access network device to stop receiving first multicast / broadcast service data sent by a source access network device, provided in this application;

[0090] Figure 11 A schematic diagram of the structure of a communication device provided in this application;

[0091] Figure 12 A schematic diagram of the structure of a communication device provided in this application;

[0092] Figure 13 A schematic diagram of the structure of a terminal device provided in this application;

[0093] Figure 14 This is a schematic diagram of the structure of an access network device provided in this application. Detailed Implementation

[0094] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0095] Figure 1 This is a schematic diagram of the architecture of a communication system applicable to this application. For example... Figure 1As shown, the communication system may include data management network elements, authentication service network elements, mobility management network elements, session management network elements, policy control network elements, and user plane network elements. Furthermore, the communication system architecture also includes access network equipment, terminal equipment, and data network (DN) network elements. Further, the communication system may also include multicast / broadcast control function (MBCF) network elements and multicast / broadcast user plane function (MBUF) network elements. The policy control network elements, data management network elements, authentication service network elements, mobility management network elements, and session management network elements can be connected via a bus. Here, the bus refers to the logical connection and communication between the network elements in the communication system; the network elements in the communication system can achieve connection and communication through interfaces or networks. Figure 1 The following example illustrates the network elements used: UDM (Data Management), ASF (Authentication Service), AMF (Mobility Management), SMF (Session Management), PCF (Policy Control), UPF (User Plane Function), DN (Data Network), and UE (User Equipment). Terminal devices can communicate with AMF network elements through the next generation (NG) 1 interface (N1), access network devices can communicate with AMF network elements through the N2 interface (N2), access network devices can communicate with UPF network elements through the N3 interface (N3), AMF network elements can communicate with SMF network elements through the N11 interface (N11), AMF network elements can communicate with UDM network elements through the N8 interface (N8), AMF network elements can communicate with AUSF network elements through the N12 interface (N12), AMF network elements can communicate with PCF network elements through the N15 interface (N15), SMF network elements can communicate with PCF network elements through the N7 interface (N7), SMF network elements can communicate with UPF network elements through the N4 interface (N4), and UPF network elements can access the data network (DN) through the N6 interface (N6).

[0096] Data management network elements are primarily used to manage and store user data, such as subscription information and authentication / authorization information. In 5G, data management network elements can be unified data management (UDM) network elements or unified data repository (UDR) network elements. In future communications such as 6G, data management network elements can still be UDM network elements or UDR network elements, or have other names; this application does not impose any limitations.

[0097] The authentication service network element is mainly used to verify service functions and store keys using the Extensible Authentication Protocol (EAP) to achieve user authentication and authorization. In 5G, the authentication server network element can be an Authentication Server Function (AUSF) network element. In future communications such as 6G, the user plane network element can still be an AUSF network element, or it may have other names; this application does not limit this.

[0098] Session management network elements are primarily used for session management and the selection and control of user plane network elements in mobile networks. Session management includes functions such as session creation, modification, and release. Specific functions include assigning Internet Protocol (IP) addresses to users and selecting user plane network elements that provide packet forwarding capabilities. In 5G, the session management network element can be a Session Management Function (SMF) network element. In future communications such as 6G, the session management network element can still be an SMF network element, or it may have other names; this application does not impose any limitations.

[0099] Mobility management network elements are primarily used for registration, mobility management, and tracking area update processes for terminal devices in mobile networks. These elements terminate non-access stratum (NAS) messages, complete registration management, connection management, reachability management, allocate tracking area lists (TA lists), and manage mobility. They also transparently route session management (SM) messages to session management network elements. In 5G communication, the mobility management network element can be an access and mobility management function (AMF) network element. In future communication such as 6G, the mobility management network element can still be an AMF network element, or it may have other names; this application does not limit this.

[0100] Policy control network elements are mainly used for managing user subscription data, controlling billing policies, and controlling quality of service (QoS). In 5G, policy control network elements can be policy control function (PCF) network elements. In future communications such as 6G, policy control network elements can still be PCF network elements, or have other names; this application does not limit this.

[0101] User plane network elements are primarily used for user plane service processing, such as packet routing and transmission, packet inspection, service usage reporting, quality of service (QoS) processing, lawful interception, uplink packet inspection, and downlink packet storage. In 5G, user plane network elements can be user plane function (UPF) network elements. In future communications such as 6G, user plane network elements can still be UPF network elements, or have other names; this application does not impose any limitations.

[0102] Data network elements are primarily used to provide services to users, such as operator services, internet access services, and third-party services. In 5G, data network elements can be data network (DN) elements. In future communications such as 6G, data network elements can still be DN elements, or have other names; this application does not impose any restrictions.

[0103] Access network equipment refers to the access devices that enable terminal devices to wirelessly access the communication system, providing wireless communication functions for the terminal devices. These devices can be base stations, evolved NodeBs (eNodeBs), transmission reception points (TRPs), next-generation NodeBs (gNBs) in 5G communication systems, base stations in future communication systems, or access nodes in wireless-fidelity (WiFi) systems; they can also be modules or units that perform some of the functions of a base station, such as centralized units (CUs) or distributed units (DUs). The embodiments in this application do not limit the specific technologies or device forms used in the access network equipment.

[0104] Terminal equipment, also known as terminal, user equipment (UE), mobile station, mobile terminal, etc., can include mobile phones, tablets, computers with wireless transceiver capabilities, virtual reality terminal devices, augmented reality terminal devices, wireless terminals in industrial control, wireless terminals in autonomous driving, wireless terminals in remote surgery, wireless terminals in smart grids, wireless terminals in transportation safety, wireless terminals in smart cities, wireless terminals in smart homes, and so on. This application does not limit the specific technologies or equipment forms used in the terminal equipment.

[0105] The MBCF (Multicast Flow Control Component) implements the control plane functions for multicast / broadcast services, managing these services. The MBCF can connect to the server providing the multicast / broadcast service to receive relevant information (see the multicast / broadcast service introduction below, which will not be repeated here). Furthermore, the MBCF can connect to the PCF (Power Processor Component) to create resources for multicast / broadcast services, such as QoS requirements (see related introductions below). It should be noted that the MBCF can be integrated into the PCF or SMF as a functional module; or it can function as a standalone network element (e.g., ...). Figure 1 (As shown), this application does not limit this.

[0106] MBUF can be used to transmit service data for multicast / broadcast services. It should be noted that MBUF can be integrated into UPF as a functional module; or it can be used as a standalone network element (such as...). Figure 1 (As shown), this application does not limit this.

[0107] It should be noted that the above Figure 1 The form and number of network elements shown are for illustrative purposes only and do not constitute a limitation of this application. Figure 1 The network architecture involved may also include other network elements, such as network slice selection function (NSSF), unified data repository (UDR), or network repository function (NRF), etc., without specific limitations. Additionally, Figure 1 The names of the network elements and the interfaces between them are just examples. In the actual implementation, the names of the network elements and the interfaces between them may be different. This application does not specifically limit them.

[0108] For ease of explanation, this application will subsequently use the following examples: Session Management Function (SMF) network element, User Plane Function (UPF) network element, Data Management (UDM) network element, Authentication Service (AUSF) network element, Data Network (DN) network element, and UE (User Equipment) terminal device. That is, the SMF network element described below can be replaced with the Session Management Function (SMF) network element, the UPF network element can be replaced with the User Plane Function (UPF) network element, the UDM network element can be replaced with the Data Management (UDM) network element, and the UE can be replaced with the terminal device.

[0109] The following explanations of some terms used in this application are provided to facilitate understanding by those skilled in the art. It should be noted that these explanations are not intended to limit the scope of protection claimed in this application.

[0110] I. Unicast

[0111] Unicast can be understood as point-to-point (PTP) communication. At the service level, unicast service refers to data being sent to a single terminal device. At the core network service level, unicast refers to sending service data to a terminal device through a PDU session. Between network elements (or devices), unicast refers to a unicast tunnel between the source and destination network elements (i.e., the IP address of the destination network element is a unicast IP address). For the air interface, air interface unicast mode (or point-to-point mode) refers to the access network device sending service data to a single terminal device; this can be understood as the access network device sending service data to a single terminal device through an air interface unicast radio bearer.

[0112] II. Multicast / Broadcast

[0113] Multicast / broadcast refers to either multicast or broadcast, which can be understood as point-to-multipoint (PTM) communication. At the service level, multicast / broadcast service refers to the transmission of service data to multiple terminal devices. At the core network service level, multicast / broadcast service refers to the transmission of service data to terminal devices through multicast / broadcast sessions. Between network elements, multicast refers to a multicast tunnel between the source and destination network elements (i.e., the IP address of the destination network element is a multicast IP address). For the air interface, air interface multicast / broadcast mode means that multiple terminal devices can simultaneously and / or receive the same service data sent by the access network device on the same frequency. Therefore, the embodiments in this application can be applied to both multicast and broadcast service transmission.

[0114] III. Multicast / Broadcast Session Tunnel

[0115] Access network devices and core network devices can establish multicast / broadcast session tunnels for multicast services. Multicast / broadcast service data is transmitted within these tunnels. Access network devices can send the multicast / broadcast service data received through these tunnels to multiple terminal devices that have joined the multicast / broadcast service. The multicast / broadcast service data within the tunnels can be transmitted as multicast / broadcast quality of service (QoS) streams. Specifically, multicast / broadcast services can be transmitted within the tunnels as one or more multicast / broadcast QoS streams.

[0116] It should be understood that a multicast / broadcast session tunnel can correspond one-to-one with a multicast / broadcast service, that is, one multicast / broadcast service corresponds to one multicast / broadcast session tunnel (Per MB service); a multicast / broadcast service may include one or more multicast / broadcast service streams, multiple multicast / broadcast service streams may correspond to one or more multicast / broadcast QoS streams, and a multicast / broadcast session may include one or more multicast / broadcast QoS streams.

[0117] IV. Multicast / Broadcast Services

[0118] Multicast / broadcast services can be described using multicast / broadcast service information. This information includes at least a descriptive profile of the multicast / broadcast service, which may contain descriptions of one or more multicast / broadcast service flows. The descriptive profile of each multicast / broadcast service flow includes at least one of the following: a Quality of Service (QoS) flow identifier (QFI) that the multicast / broadcast service flow should possess; characteristic information of the multicast / broadcast service flow (such as the destination address, destination port number, source address, etc.); and QoS requirements of the multicast / broadcast service flow (such as jitter, latency, packet loss rate, bandwidth, etc.). The QoS requirements of the multicast / broadcast service flow are used to establish the multicast / broadcast QoS flow. In addition to the descriptive profile, the multicast / broadcast service information may also include information about the terminal devices, such as identifiers of one or more terminal devices that are allowed (or request) to join the multicast / broadcast service, and identifiers of terminal device groups.

[0119] V. Multicast / Broadcast Sessions

[0120] Multicast / broadcast sessions include unicast tunnels between network elements, multicast tunnels, unicast-mode air interface radio bearers, or multicast / broadcast-mode air interface radio bearers. It should be noted that multicast / broadcast sessions can be used to send multicast service data to terminal devices, and can also be used to send broadcast service data to terminal devices; this application embodiment does not limit this.

[0121] VI. PDU Session Tunnel

[0122] The PDU session tunnel corresponds to the UE, and service data within the PDU session tunnel can be transmitted in the form of a unicast QoS stream. In this application, the PDU session tunnel can also be used to transmit the unicast QoS stream mapped to the multicast / broadcast QoS stream corresponding to multicast / broadcast services.

[0123] It should be noted that a PDU session is at the UE level, while a multicast / broadcast session is at the service level. A single PDU session for a UE can be associated with multiple multicast / broadcast services; that is, the UE can join at least one multicast / broadcast service through this PDU session. A multicast / broadcast session can provide services for one multicast / broadcast service. A multicast / broadcast session includes a unicast tunnel or multicast tunnel from the data network to the core network equipment and then to the access network equipment, as well as unicast air interface resources or multicast / broadcast air interface resources allocated by the access network equipment for transmitting the multicast / broadcast service.

[0124] The preceding text has introduced some of the terms used in this application. The following section describes the technical features involved in this application. It should be noted that these explanations are not intended to limit the scope of protection claimed in this application.

[0125] Please refer to Figure 2 , Figure 2 An exemplary diagram of data transmission via unicast is shown. Figure 2 The transmission process shown can be used to transmit both unicast and multicast / broadcast service data.

[0126] exist Figure 2 In this architecture, each of UEs (UE1, UE2, and UE3) corresponds to a different PDU session. The service provider (CP / SP) can send its respective service data to UE1, UE2, and UE3 through these three PDU sessions. It should be understood that the service data for each of the three UEs is different, the destination address can be the IP address of each UE, and each UE's service data can be sent to each UE through its own independent transmission path. Specifically, the service transmission path from the CP / SP to the RAN can include the transmission path between the CP / SP and the UPF, and the transmission path between the UPF and the RAN. The transmission path between the UPF and the RAN can be called the PDU session tunnel, and different PDU sessions have different PDU session tunnels. On the air interface, the RAN can send service data to UE1, UE2, and UE3 respectively via unicast, i.e., PTP.

[0127] Please refer to Figure 3 , Figure 3 An exemplary diagram illustrating data transmission via multicast / broadcast is shown. Figure 3 The transmission process shown can be used to transmit multicast / broadcast service data.

[0128] exist Figure 3In this system, multicast / broadcast service data can be sent from the CP / SP to UE1, UE2, and UE3. The multicast / broadcast service transmission path from the CP / SP to the RAN can include the transmission path between the CP and the UPF, and the transmission path between the UPF and the RAN. The transmission path from the UPF to the RAN can transmit multicast / broadcast service data via tunnels. For example, a tunnel based on the general tunnel protocol (GTP) can be used. The transmission path between the UPF and the RAN can be called a multicast / broadcast session tunnel, which is shared by UE1, UE2, and UE3. On the air interface, the RAN can send multicast / broadcast service data to UE1, UE2, and UE3 via PTM, meaning the RAN only needs to send one copy of the data, which UE1, UE2, and UE3 can receive simultaneously.

[0129] Multicast can transmit service data to all target nodes at once, or transmit service data to only specific objects. Therefore, in multicast, point-to-multipoint transmission can be achieved between a sending node and multiple receiving nodes, thus solving the problem of low efficiency in unicast.

[0130] The above is an introduction to unicast and multicast. It can be understood that if an access network device supports multicast / broadcast functionality, it means that the access network device supports transmitting multicast / broadcast service data in a multicast / broadcast manner. If an access network device does not support multicast / broadcast functionality, it means that the access network device does not support transmitting multicast / broadcast service data in a multicast / broadcast manner, or that the access network device only supports transmitting multicast / broadcast service data or PDU session data in a unicast manner. For access network devices that do not support multicast / broadcast functionality, multicast / broadcast services can be sent to terminal devices through PDU sessions, that is, multicast / broadcast services are mapped to PDU sessions. For access network devices that support multicast / broadcast functionality, multicast / broadcast service data can be received from the core network through a multicast / broadcast session tunnel and sent to multiple terminal devices that have joined the multicast / broadcast service. It should be understood that after multicast / broadcast service data arrives at the RAN, it is processed by the RAN's Service Data Adaptation Protocol (SDAP) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, Media Access Control (MAC) layer, and Physical (PHY) layer before being sent to each UE receiving the multicast / broadcast service data.

[0131] Based on the above, Figure 4An exemplary scenario is illustrated, to which this application can be applied. It should be noted that the system architecture and application scenario described in this application are for the purpose of more clearly illustrating the technical solution of this application, and do not constitute a limitation on the technical solution provided by this application. As those skilled in the art will know, with the evolution of system architecture and the emergence of new business scenarios, the technical solution provided by this application is also applicable to similar technical problems.

[0132] like Figure 4 As shown, the source base station (singal g-NB, S-gNB) supports multicast / broadcast functionality (or multicast / broadcast service support), and the target base station (target g-NB, T-gNB) also supports multicast / broadcast functionality. This means the S-gNB can simultaneously send multicast / broadcast service data to UE1, UE2, and UE3, and the T-gNB can simultaneously send multicast / broadcast service data to UE4, UE5, and UE6. Since both the S-gNB and T-gNB support multicast / broadcast functionality, a multicast / broadcast session tunnel can be established between the UPF and the S-gNB, or between the UPF and the T-gNB. This multicast / broadcast session tunnel can then be used to send multicast / broadcast service data to both the S-gNB and T-gNB. Figure 4 This example illustrates the handover process using UE3, where a forwarding tunnel corresponding to the UE3 PDU session tunnel and a forwarding tunnel corresponding to the multicast / broadcast session tunnel are established between the T-gNB and S-gNB. Of course, it's also possible to establish only the forwarding tunnel corresponding to the UE3 PDU session tunnel between the T-gNB and S-gNB. For the UE3 PDU session handover from S-gNB to T-gNB, during the handover process, the SMF and anchor point serving the UE3 PDU session (e.g., ...) Figure 4 The UPF in the text remains unchanged. Figure 4 The multicast / broadcast network elements serving the multicast / broadcast services of the S-gNB are the MBCF and MBUF. The MBUF can be connected to the anchor UPF where the PDU session of UE3 is located, or it can be directly connected to the S-gNB, or it can be connected to the S-gNB through a non-anchor UPF. This embodiment of the application does not limit this. The multicast / broadcast services related to the PDU session of the switched UE3 may be served by the MBCF and MBUF, or other MBCFs and MBUFs. The MBUF can be directly connected to the T-gNB, or it can be connected to the anchor UPF of the switched UE3's PDU session, or it can be connected to the T-gNB through other non-anchor UPFs. This embodiment of the application does not limit this.

[0133] It should be noted that if the source base station (singal g-NB, S-gNB) does not support multicast / broadcast functionality, but the target base station (target g-NB, T-gNB) does, then a multicast / broadcast session tunnel can be established between the UPF and the T-gNB, but there is no multicast / broadcast session tunnel between the UPF and the S-gNB; moreover, only a forwarding tunnel corresponding to the PDU session tunnel is established between the T-gNB and the S-gNB; that is... Figure 4 The multicast / broadcast session tunnel between the UPF and S-gNB is gone, and the forwarding tunnel corresponding to the multicast / broadcast session tunnel between the T-gNB and S-gNB is also gone. If the source base station (singal g-NB, S-gNB) supports multicast / broadcast functionality, but the target base station (target g-NB, T-gNB) does not, then a multicast / broadcast session tunnel can be established between the UPF and S-gNB, but there is no multicast / broadcast session tunnel between the UPF and T-gNB; moreover, only the forwarding tunnel corresponding to the PDU session tunnel is established between the T-gNB and S-gNB. Figure 4 The multicast / broadcast session tunnel between the UPF and T-gNB is gone, and the forwarding tunnel corresponding to the multicast / broadcast session tunnel between T-gNB and S-gNB is also gone.

[0134] When a multicast / broadcast service with the T-gNB is sending multicast / broadcast service data to UE1, UE2, and UE3 through a multicast / broadcast session tunnel, and UE3 switches from the S-gNB to the T-gNB, if UE3 is directly integrated into the T-gNB's air interface PTM mode after UE3 accesses the T-gNB, the sequential synchronization of multicast / broadcast service data forwarded by the forwarding tunnel corresponding to the S-gNB's multicast / broadcast session tunnel with the same source service data sent by the T-gNB's multicast / broadcast session tunnel cannot be guaranteed. That is, the arrival times of each data packet in the same MB service at the S-gNB and T-gNB may not be the same. Therefore, this will affect the continuity of data received by the currently switching UE3 or other UEs (i.e., UE4, UE5, and UE6) from the multicast / broadcast service on the T-gNB. For example, if the T-gNB uses air interface PTM mode to send data from UE3 received from the forwarding tunnel corresponding to the multicast / broadcast session tunnel, the data packets originally received by UE4, UE5, and UE6 on the T-gNB may be out of order. If the T-gNB discards the data received from UE3 from the forwarding tunnel corresponding to the multicast / broadcast session tunnel, it will cause packet loss of UE3's service data.

[0135] In view of this, this application provides a communication method that can ensure the continuity of multicast / broadcast services of the terminal device and other terminal devices is not affected during the process of a terminal device switching from a source access network device to a target access network device.

[0136] like Figure 5 The image shows a communication method provided in this application. This communication method can be applied to... Figure 1 The system architecture is shown. The method includes the following steps:

[0137] Step 501: The terminal device sends a measurement report to the source access network device. Correspondingly, the source access network device receives the measurement report from the terminal device.

[0138] Step 501 is optional. The measurement report can be a signal measurement report.

[0139] In step 502, when the source access network device determines that the terminal device needs to switch access network devices, it sends a first request message to the target access network device. Correspondingly, the target access network device receives the first request message from the source access network device.

[0140] Here, the first request message can be used to request the target access network device to establish a forwarding tunnel corresponding to the first multicast / broadcast service with the source access network device. The first request message can also be used to request the terminal device to be switched from the source access network device to the target access network device.

[0141] In one possible implementation, the first request message includes PDU session information of the terminal device. The PDU session information includes a PDU session identifier, QoS information corresponding to the service included in the PDU session, a multicast / broadcast service identifier associated with the PDU session, and QoS information for the multicast / broadcast service. Optionally, the QoS information corresponding to the service included in the PDU session includes a unicast QFI and its corresponding QoS parameters. The QoS parameters for the unicast QFI are used by the source access network device for configuring air interface resources and can be represented by 5QI. The QoS information for the multicast / broadcast service includes a multicast QFI and its corresponding QoS parameters.

[0142] It should be understood that the multicast / broadcast service identifier associated with a PDU session includes, but is not limited to, the multicast / broadcast service identifier stored in the context of the PDU session, and the multicast / broadcast service identifier corresponding to the PDU session identifier.

[0143] Step 503: The target access network device determines the first radio bearer configuration information and the second radio bearer configuration information of the terminal device.

[0144] Here, the first radio bearer configuration information is used by the terminal device to receive first multicast / broadcast service data transmitted from the target access network device in air interface unicast mode, and the second radio bearer configuration information is used by the terminal device to receive second multicast / broadcast service data transmitted from the target access network device in air interface multicast / broadcast mode or air interface unicast mode. The first radio bearer configuration information may include a cell radio network temporary identifier (C-RNTI), and the second radio bearer configuration information may include a group radio network temporary identifier (G-RNTI). Air interface unicast mode is also called air interface point-to-point mode, and air interface multicast / broadcast mode is also called air interface point-to-multipoint mode.

[0145] In one possible implementation, the target access network device may allocate first radio bearer configuration information and second radio bearer configuration information to the terminal device. Further, optionally, the target access network device may also determine the radio resources of the terminal device based on the QoS information corresponding to the services included in the terminal device's PDU session and the QoS information corresponding to the multicast / broadcast services. For example, the target access network device may determine the number of air interface data radio bearers (DRBs) and the mapping relationship between QFIs and DRBs based on the QoS parameters corresponding to each unicast QFI and each multicast QFI in the first request message.

[0146] Step 504: The target access network device sends a first response message to the source access network device. Correspondingly, the source access network device receives the first response message from the target access network device.

[0147] Here, the first response message may include first radio bearer configuration information and second radio bearer configuration information.

[0148] In one possible implementation, the first response message may also include the QFI corresponding to the QoS that the target access network device supports forwarding.

[0149] Step 505: The source access network device sends the first multicast / broadcast service data to the target access network device.

[0150] Here, the first multicast / broadcast service is associated with the PDU session of the terminal device. Further, optionally, the forwarding method of the first multicast / broadcast service data that needs to be forwarded by the source access network device can refer to Implementation Method 1 and Implementation Method 2 below, which will not be repeated here.

[0151] It should be noted that step 505 can also be performed after step 506 and before step 507.

[0152] Step 506: The source access network device sends the first radio bearer configuration information and the second radio bearer configuration information to the terminal device. Correspondingly, the terminal device receives the first radio bearer configuration information and the second radio bearer configuration information from the source access network device.

[0153] Here, after the source access network device sends the first radio bearer configuration information and the second radio bearer configuration information to the terminal device, the air interface connection between the terminal device and the source access network device is disconnected. At this time, the PDU session tunnel of the terminal device in the source access network device stops sending data of the services contained in the PDU session to the terminal device, and the multicast / broadcast session tunnel of the source access network device stops sending multicast / broadcast service data to the terminal device. It should be noted that other terminal devices connected to the source access network device can still normally receive the multicast / broadcast service data that has stopped being sent to the terminal device.

[0154] It should be noted that there is no specific order between steps 505 and 506. Step 505 can be executed first and then step 506, or step 506 can be executed first and then step 505, or steps 505 and 506 can be executed simultaneously.

[0155] Step 507: The terminal device connects to the target access network device.

[0156] Step 508: The target access network device sends first multicast / broadcast service data to the terminal device via air interface unicast mode, and sends second multicast / broadcast service data to the terminal device via air interface multicast / broadcast mode or air interface unicast mode. Correspondingly, the terminal device receives the first multicast / broadcast service data via air interface unicast mode, and receives the second multicast / broadcast service data via air interface multicast / broadcast mode or air interface unicast mode.

[0157] This can also be understood as the terminal device receiving first multicast / broadcast service data according to the first radio bearer configuration information, and receiving second multicast / broadcast service data according to the second radio bearer configuration information.

[0158] Step 509: The terminal device removes duplicate data from the first multicast / broadcast service data and the second multicast / broadcast service data.

[0159] In one possible implementation, since the first multicast / broadcast service data cached by the terminal device in the target access network device needs to be sent to the terminal device via air interface unicast mode, when the terminal device connects to the target access network device, it simultaneously receives the first multicast / broadcast service data sent in air interface unicast mode and the second multicast / broadcast service data sent in air interface unicast mode or air interface unicast mode. For multicast / broadcast services associated with the PDU session, the terminal device may receive duplicate service data (i.e., multicast / broadcast service data from the same source arrives at the source access network device and is forwarded to the target access network device faster than it arrives at the target access network device). Therefore, the terminal device may receive duplicate data. To address the issue of the terminal device receiving duplicate data packets, the TCP / UDP layer can perform deduplication automatically.

[0160] like Figure 6 As shown, another communication method provided in this application can be applied to the above-described communication method. Figure 1 The system architecture is shown. The method includes the following steps:

[0161] Step 601: The terminal device sends a measurement report to the source access network device. Correspondingly, the source access network device receives the measurement report from the terminal device.

[0162] This step 601 can be found in the description of step 501 above.

[0163] In step 602, when the source access network device determines that the terminal device needs to switch access network devices, it sends a first request message to the target access network device. Correspondingly, the target access network device receives the first request message from the source access network device.

[0164] The first request message in step 602 can be the same as the first request message in step 502 above. Step 602 can be found in the description of step 502 above, and will not be repeated here.

[0165] Step 603: The source access network device sends the first multicast / broadcast service data to the target access network device.

[0166] Here, the first multicast / broadcast service data is associated with the PDU session of the terminal device. Further, optionally, the forwarding method of the first multicast / broadcast service data that needs to be forwarded by the source access network device can refer to Implementation Method 1 and Implementation Method 2 below, which will not be repeated here.

[0167] It should be noted that step 603 can also be performed after step 606 and before step 607.

[0168] In one possible implementation, the first multicast / broadcast service data is associated with the PDU session of the terminal device. Further, optionally, the forwarding method of the first multicast / broadcast service data that the source access network device needs to forward can refer to implementation methods 1 and 2 of the above scenario, and will not be repeated here. Correspondingly, the target access network device can receive the first multicast / broadcast service data from the source access network device.

[0169] Step 604: The target access network device determines the first radio bearer configuration information and the second radio bearer configuration information of the terminal device.

[0170] Here, the first radio bearer configuration information is used by the terminal device to receive first multicast / broadcast service data transmitted from the target access network device in the corresponding air interface unicast mode, and the second radio bearer configuration information is used by the terminal device to receive second multicast / broadcast service data transmitted from the target access network device in the corresponding air interface multicast / broadcast mode or air interface unicast mode. Alternatively, it can be understood that the first radio bearer configuration information is used by the terminal device to receive the first multicast / broadcast service data sent by the target access network device, and the second radio bearer configuration information is used by the terminal device to receive the second multicast / broadcast service data sent by the target access network device. The first radio bearer configuration information may include C-RNTI, and the second radio bearer configuration information may include G-RNTI.

[0171] It should be noted that the target access network device may determine the first radio bearer configuration information first, or the second radio bearer configuration information first, or both simultaneously; this application does not limit this.

[0172] Step 605: The target access network device sends a first response message to the source access network device. Correspondingly, the source access network device receives the first response message from the target access network device.

[0173] Here, the first response message may include the first radio bearer configuration information. For more information on the first radio bearer configuration information, please refer to the relevant introduction above. It will not be repeated here.

[0174] In one possible implementation, the first response message may also include the QFI corresponding to the quality of service (QoS) flow that the target access network device supports forwarding.

[0175] Step 606: The source access network device sends the first radio bearer configuration information to the terminal device. Correspondingly, the terminal device receives the first radio bearer configuration information from the source access network device.

[0176] Step 607: The terminal device connects to the target access network device.

[0177] Step 608: The target access network device sends the first multicast / broadcast service data to the terminal device via air interface unicast mode. Correspondingly, the terminal device receives the first multicast / broadcast service data from the target access network device via air interface unicast mode.

[0178] In other words, the target access network device sends the first multicast / broadcast service data to the terminal device. Correspondingly, the terminal device receives the first multicast / broadcast service data from the target access network device. Here, the terminal device can receive the first multicast / broadcast service data from the target access network device through the first radio bearer configuration information.

[0179] Step 609: The target access network device determines whether the received first multicast / broadcast service data and the second multicast / broadcast service data are synchronized; if yes, proceed to steps 610 and 612; if no, proceed to step 613.

[0180] It should be noted that steps 610 and 612 can be executed simultaneously, or step 610 can be executed first and then step 612; or step 612 can be executed first and then step 610.

[0181] Here, step 610 can also be executed after the target access network device determines that the first multicast / broadcast service data is earlier than the second multicast / broadcast service data. It should be understood that this method can be implemented in parallel with step 609 above.

[0182] It should be noted that the speed at which same-source multicast / broadcast service data reaches the target access network device through the forwarding tunnel corresponding to the first multicast / broadcast session tunnel of the source access network device is different from the speed at which the same-source service reaches the target access network device through the multicast / broadcast session tunnel of the target access network device. Therefore, it may cause the target access network device to determine that the first multicast / broadcast service data received is out of sync with the second multicast / broadcast service data.

[0183] In one possible implementation, the target access network device can determine whether the first multicast / broadcast service data is synchronized with the second multicast / broadcast service data based on the sequence numbers of the received first multicast / broadcast service data and the second multicast / broadcast service data. Further, optionally, the sequence number can also be called a sequence number, and the sequence number of the multicast / broadcast service data (e.g., the first multicast / broadcast service data and the second multicast / broadcast service data) can be the sequence number in the user plane packet header of the General Tunnel Protocol (GTP), i.e., the sequence number in the GTP-U header.

[0184] The following examples illustrate two ways to determine whether the first multicast / broadcast service data and the second multicast / broadcast service data are synchronized.

[0185] Method 1: If the target access network device determines that the sequence number of the first multicast / broadcast service data plus one is greater than or equal to the sequence number of the second multicast / broadcast service data, it determines that the first multicast / broadcast service data and the second multicast / broadcast service data are synchronized.

[0186] For example, for the same-source multicast / broadcast service, the sequence number of the first multicast / broadcast service data (service data packets arriving at the target access network device through the forwarding tunnel) received by the target access network device is X, and the sequence number of the second multicast / broadcast service data (service data packets arriving at the target access network device through the multicast / broadcast session tunnel of the target access network device) of the same-source service received by the target access network device from the core network device is Y; when X+1≥Y, it is determined that the first multicast / broadcast service data and the second multicast / broadcast service data are synchronized.

[0187] Further, optionally, when X+1 = Y, the first multicast / broadcast service data and the second multicast / broadcast service data received by the target access network device can be seamlessly concatenated. When X+1 > Y, the first multicast / broadcast service data and the second multicast / broadcast service data received by the target access network device will be duplicated. In one possible implementation, the target access network device discards the first multicast / broadcast service data whose sequence number is greater than the sequence number of the second multicast / broadcast service data.

[0188] If the target access network device determines that the sequence number of the first multicast / broadcast service data plus one is less than the sequence number of the second multicast / broadcast service data, it can be determined that the first multicast / broadcast service data and the second multicast / broadcast service data are out of sync.

[0189] Method 2: If the target access network device determines that the sequence number of the first multicast / broadcast service data is greater than or equal to the sequence number of the second multicast / broadcast service data, it determines that the first multicast / broadcast service data and the second multicast / broadcast service data are synchronized.

[0190] In one possible implementation, if the target access network device determines that the sequence number of the first multicast / broadcast service data is greater than or equal to the sequence number of the second multicast / broadcast service data, then the first multicast / broadcast service data and the second multicast / broadcast service data are synchronized. For example, for the same-source multicast / broadcast service, at the same time, the sequence number of the first multicast / broadcast service data (i.e., the service data packet arriving at the target access network device through the forwarding tunnel) received by the target access network device is X, and the sequence number of the second multicast / broadcast service data (i.e., the service data packet arriving at the target access network device through the multicast / broadcast session tunnel) received by the same-source service at the same time is Y; when X = Y, the first multicast / broadcast service data and the second multicast / broadcast service data are synchronized, indicating that the speed of the first multicast / broadcast service data of the same-source multicast / broadcast service through the forwarding tunnel corresponding to the first multicast / broadcast session tunnel of the source access network device is equal to the speed of the second multicast / broadcast service data received by the target access network device through the multicast / broadcast session tunnel. When X > Y, it indicates that the first multicast / broadcast service data is earlier than the second multicast / broadcast service data. This means that the speed at which the first multicast / broadcast service data from the same source reaches the target access network device through the forwarding tunnel corresponding to the first multicast / broadcast session tunnel of the source access network device is faster than the speed at which the target access network device receives the second multicast / broadcast service data through the multicast / broadcast session tunnel. Here, the target access network device can also determine that the first multicast / broadcast service data is synchronized with the second multicast / broadcast service data.

[0191] If the target access network device determines that the sequence number of the first multicast / broadcast service data is greater than the sequence number of the second multicast / broadcast service data, it means that the speed at which the first multicast / broadcast service data from the same source reaches the target access network device through the forwarding tunnel corresponding to the first multicast / broadcast session tunnel of the source access network device is faster than the speed at which the second multicast / broadcast service data is received by the target access network device through the multicast / broadcast session tunnel. In this case, the transmission rate of the second multicast / broadcast service data can be increased, and / or the transmission rate of the first multicast / broadcast service data can be decreased.

[0192] Step 610: The target access network device sends the first information to the source access network device.

[0193] Here, the first information is used to instruct the source access network device to stop sending the first multicast / broadcast service data to the target access network device; or, it is used to instruct the source access network device to synchronize the first multicast / broadcast service data received by the target access network device with the second multicast / broadcast service data.

[0194] In one possible implementation, the first information can be a data packet, which can be sent through a forwarding tunnel between the target access network device and the source access network device. In another possible implementation, the first information can be a signaling message.

[0195] Step 610 is optional. In another possible implementation, the source access network device is equipped with a ninth timer. When the ninth timer expires, the source access network device stops sending the first multicast / broadcast service data to the target access network device. The duration of the ninth timer can be set according to the actual situation; for example, it can be tens of milliseconds or several seconds.

[0196] Step 611: The target access network device sends the second radio bearer configuration information to the terminal device. Correspondingly, the terminal device receives the second radio bearer configuration information from the target access network device.

[0197] It should be noted that step 611 can be performed after step 609 and before step 612; or it can be performed after step 604 and before step 609. This application does not limit this.

[0198] Step 612: The target access network device sends the second multicast / broadcast service data to the terminal device via air interface multicast / broadcast mode or air interface unicast mode. Correspondingly, the terminal device receives the second multicast / broadcast service data via air interface multicast / broadcast mode or air interface unicast mode.

[0199] This can also be understood as the target access network device sending second multicast / broadcast service data to the terminal device. This can be done either through air interface unicast mode or through air interface multicast / broadcast mode. Correspondingly, the terminal device can receive the first multicast / broadcast service data according to the first radio bearer configuration information and the second multicast / broadcast service data according to the second radio bearer configuration information.

[0200] Step 613: The target access network device adjusts the synchronization of the first multicast / broadcast service data with the second multicast / broadcast service data.

[0201] In one possible implementation, the target access network device may cache the second multicast / broadcast service data if it determines that the sequence number of the first multicast / broadcast service data plus one is less than the sequence number of the second multicast / broadcast service data. When the target access network device determines that the sequence number of the received first multicast / broadcast service data plus one is equal to the sequence number of the first cached second multicast / broadcast service data, it can determine that the first multicast / broadcast service data and the second multicast / broadcast service data are synchronized. Further, optionally, after the target access network device determines that the first multicast / broadcast service data and the second multicast / broadcast service data are synchronized, it may then execute steps 610 and 612 as described above.

[0202] Furthermore, optionally, if the target access network device determines that the sequence number of the first multicast / broadcast service data plus one is less than the sequence number of the second multicast / broadcast service data, it may slow down the transmission rate of the second multicast / broadcast service data and / or speed up the transmission rate of the first multicast / broadcast service data. In this way, synchronization between the first and second multicast / broadcast service data can be achieved more quickly.

[0203] If the target access network device determines that the first multicast / broadcast service data received is later than the second multicast / broadcast service data, for example, if the target access network device determines that the sequence number of the first multicast / broadcast service data is less than the sequence number of the second multicast / broadcast service data, it means that the speed at which the first multicast / broadcast service data from the same source reaches the target access network device through the forwarding tunnel corresponding to the first multicast / broadcast session tunnel of the source access network device is slower than the speed at which the second multicast / broadcast service data received by the target access network device through the multicast / broadcast session tunnel. In this case, the transmission rate of the second multicast / broadcast service data in air interface unicast mode can be slowed down, and / or the transmission rate of the first service data in air interface multicast / broadcast mode or air interface unicast mode can be accelerated.

[0204] It should be noted that, if the above Figure 6 When the time between steps 605 and 611 approaches 0, then Figure 6 The method shown can be used with Figure 5 The method shown is the same.

[0205] The following is a detailed description of three scenarios based on whether the source access network device and the target access network device support multicast / broadcast functions.

[0206] Scenario 1: The target access network device supports multicast / broadcast functions, and the source access network device supports multicast / broadcast functions.

[0207] Based on scenario one, a forwarding tunnel corresponding to the PDU session tunnel of the terminal device can be established between the target access network device and the source access network device; alternatively, a forwarding tunnel corresponding to the PDU session tunnel of the terminal device and a forwarding tunnel corresponding to the first multicast / broadcast session can be established.

[0208] The following examples illustrate three possible implementations of the first multicast / broadcast service data sent by the source access network device to the target access network device.

[0209] Implementation method 1: through the forwarding tunnel corresponding to the PDU session tunnel of the terminal device.

[0210] In one possible implementation, the source access network device can send the first multicast / broadcast service data to the target access network device through the forwarding tunnel corresponding to the PDU session tunnel of the terminal device. Accordingly, the target access network device can buffer the received first multicast / broadcast service data.

[0211] It should be noted that in this implementation method 1, the first multicast / broadcast service data can be mapped to a unicast QoS stream. That is, the source access network device can send the unicast QoS stream mapped from the first multicast / broadcast service data to the target access network device through the forwarding tunnel corresponding to the PDU session tunnel of the terminal device. Further, optionally, the source access network device can first copy the first multicast / broadcast service data, map it to a unicast QoS stream, and then send it through the forwarding tunnel corresponding to the PDU session tunnel of the terminal device. This helps to avoid affecting the service continuity of other terminal devices receiving the first multicast / broadcast service data.

[0212] Based on implementation method 1, in one possible implementation, the first request message in step 502 includes the identification information of the forwarding tunnel corresponding to the PDU session tunnel of the terminal device; correspondingly, the first response message in step 504 may also include the identification information of the forwarding tunnel corresponding to the PDU session tunnel of the terminal device, so as to realize the establishment of the forwarding tunnel corresponding to the PDU session tunnel between the target access network device and the source access network device. Further, optionally, the first request message only includes the unicast QFI corresponding to the unicast QoS stream, and these unicast QFIs include the unicast QFI that maps the multicast / broadcast QoS stream of the first multicast / broadcast QoS service to the unicast QoS stream. Alternatively, it can be understood that the QoS information of the multicast / broadcast service includes the unicast QFI mapped by the multicast / broadcast QFI and the QoS parameters corresponding to the unicast QFI mapped by the multicast / broadcast QFI.

[0213] Implementation method 2, through the forwarding tunnel corresponding to the first multicast / broadcast session.

[0214] In one possible implementation, the source access network device can send the first multicast / broadcast service data to the target access network device through the forwarding tunnel corresponding to the first multicast / broadcast session. Accordingly, the target access network device can buffer the received first multicast / broadcast service data.

[0215] It should be noted that in this implementation method 2, the source access network device can send the multicast / broadcast QoS stream included in the first multicast / broadcast service to the target access network device through the forwarding tunnel corresponding to the first multicast / broadcast session. Further, optionally, the first request message may include the multicast / broadcast QFI corresponding to the multicast / broadcast QoS stream.

[0216] Furthermore, the source access network device can first copy the first multicast / broadcast service data, and then send it through the forwarding tunnel corresponding to the first multicast / broadcast session. This helps to avoid affecting the service continuity of other terminal devices receiving the first multicast / broadcast service data.

[0217] Based on this implementation method 2, in one possible implementation, the first request message in step 502 may include the identification information of the forwarding tunnel corresponding to the first multicast / broadcast session tunnel; correspondingly, the first response message in step 504 may also include the identification information of the forwarding tunnel corresponding to the first multicast / broadcast session tunnel, so as to enable the target access network device and the source access network device to establish the forwarding tunnel corresponding to the first multicast / broadcast session tunnel.

[0218] Scenario 2: The target access network device supports multicast / broadcast functions, while the source access network device does not support multicast / broadcast functions.

[0219] Based on this second scenario, a forwarding tunnel corresponding to the PDU session tunnel can be established between the target access network device and the source access network device.

[0220] In one possible implementation, the source access network device can send the first multicast / broadcast service data to the target access network device through the forwarding tunnel corresponding to the PDU session tunnel of the terminal device.

[0221] In this second scenario, the first multicast / broadcast service data can be mapped to a unicast QoS stream. That is, the source access network device can send the unicast QoS stream mapped to the first multicast / broadcast service to the target access network device through the forwarding tunnel corresponding to the PDU session tunnel of the terminal device.

[0222] In one possible implementation, the first request message in step 502 includes the identification information of the forwarding tunnel corresponding to the PDU session tunnel of the terminal device; correspondingly, the first response message in step 504 may also include the identification information of the forwarding tunnel corresponding to the PDU session tunnel of the terminal device, so as to enable the target access network device and the source access network device to establish a forwarding tunnel corresponding to the PDU session tunnel.

[0223] Based on the above scenarios one and two, the method by which the source access network device stops sending the first multicast / broadcast service data to the target access network device can be that the source access network device sets a first timer. When the source access network device determines that the first timer has expired, it stops sending the first multicast / broadcast service data to the target access network device.

[0224] In one possible implementation, the first timer can be started at any time when the source access network device begins to send the first multicast / broadcast service data to the target access network device, or before the first multicast / broadcast service data is sent to the target access network device.

[0225] Based on scenarios one and two above, please refer to Figure 7a This application provides a method for establishing a downlink data transmission tunnel between a target access network and a terminal device. The method includes the following steps:

[0226] Step 701: The target access network device sends a second request message to the AMF. Correspondingly, the AMF receives the second request message from the target access network device.

[0227] The second request message can be an N2 path handover request message, which may include successfully forwarded QFIs and failed forwarding QFIs in the PDU session of the terminal device. These QFIs can be encapsulated in an N2 SM message. Further, it may also include identification information of the PDU session tunnel allocated by the target access network device. Optionally, the handover request message may also include indication information as to whether the multicast / broadcast service associated with the PDU session of the terminal device is running on the target access network device. It should be noted that if the associated multicast / broadcast service is not running on the target access network device (i.e., the multicast / broadcast session tunnel between the target access network device and the UPF has not yet been established), the handover request message may also include identification information of the multicast / broadcast session tunnel allocated by the target access network device; if the multicast / broadcast service is already running on the target access network device, the handover request message does not include identification information of the multicast / broadcast session tunnel allocated by the target access network device.

[0228] It should be noted that if the target access network device supports multicast / broadcast functionality, the N2 path switching request message may include the identification information of the PDU session tunnel allocated by the target access network device and the identification information of the multicast / broadcast session tunnel. If the target access network device does not support multicast / broadcast functionality, the N2 path switching request message may include the identification information of the PDU session tunnel of the terminal device, but not the identification information of the multicast / broadcast session tunnel.

[0229] In step 702, the AMF sends a third request message to the SMF. Correspondingly, the SMF receives the third request message from the AMF.

[0230] The third request message can be a PDU session context update request message, which may include the information from step 602 above. Furthermore, since the AMF can collect the capability information of the target access network device (i.e., whether it supports multicast / broadcast functions) before the handover, the AMF will also send the target access network device's capability information to the SMF. Furthermore, if step 701 includes indication information on whether multicast / broadcast services are running on the target access network device, the SMF can also know whether the multicast / broadcast services associated with the PDU session of the terminal device are running on the target access network device.

[0231] Step 703: If the multicast / broadcast service is not running on the target access network device, the SMF sends a fourth request message to the UPF.

[0232] The fourth request message can be an N4 session update request message, which may carry the PDU session tunnel identifier information allocated by the target access network device and the PDU session tunnel identifier information allocated by the SMF to the UPF, for establishing a PDU session tunnel between the target access network device and the UPF. The fourth request message also carries the multicast / broadcast session tunnel identifier information allocated by the target access network device, for establishing a multicast / broadcast session tunnel between the target access network device and the UPF.

[0233] Step 704: UPF sends a fourth response message to SMF.

[0234] Here, if the fourth request message can be an N4 session update request message, then the fourth response message is an N4 session update response message.

[0235] Step 705: SMF sends the first message to MBCF.

[0236] The first message is used to notify the MBCF that the terminal device has switched to the target access network device. Optionally, if the multicast / broadcast service data transmission tunnel between the MBUF and UPF has not yet been established, the first message may also include the tunnel identification information of the UPF allocated by the SMF, that is, the SMF may also notify the MBCF to establish the service data transmission tunnel between the MBUF and UPF.

[0237] Step 706: MBCF and MBUF perform N4 session update.

[0238] If a service data transmission tunnel has not yet been established between MBUF and UPF, MBCF will send the tunnel information of UPF allocated by SMF in step 704 and the tunnel identification information allocated by MBCF to MBUF to MBUF. MBUF will then establish a service data transmission tunnel between MBUF and UPF based on the tunnel information of UPF and the tunnel identification information of MBUF.

[0239] In step 707, the MBCF sends a second message to the SMF. Correspondingly, the SMF receives the second message from the MBCF.

[0240] The second message can serve as a response to the first message.

[0241] In step 708, the SMF sends a third response message to the AMF. Correspondingly, the AMF receives the third response message from the SMF.

[0242] The third response message can be a PDU session context update response message, which may contain the identification information of the PDU session tunnel assigned by the SMF to the UPF. Furthermore, it may also contain the tunnel identification information of the multicast / broadcast session assigned by the SMF to the UPF.

[0243] Step 709: AMF sends a second response message to the target access network device.

[0244] The second response message may be an N2 path switching response message, which may include the identification information of the PDU session tunnel assigned by the SMF to the UPF, and may also include the tunnel identification information of the multicast / broadcast session assigned by the SMF to the UPF.

[0245] In step 710, the target access network device sends a UE context release message to the source access network device. Correspondingly, the source access network device receives the UE context release message from the target access network device.

[0246] Step 711: The source access network device releases the relevant resources of the terminal device according to the UE context release message.

[0247] Through steps 701 to 711 above, a downlink transmission tunnel can be established between the target access network device and the terminal settings.

[0248] Scenario 3: The target access network device does not support multicast / broadcast functions, while the source access network device does support multicast / broadcast functions.

[0249] Based on scenario three, the source access network device can send the first multicast / broadcast service data to the target access network device through the forwarding tunnel corresponding to the PDU session tunnel of the terminal device. Correspondingly, the target access network device can buffer the received first multicast / broadcast service data. Specifically, the source access network device can map the first multicast / broadcast service data to a unicast QoS stream, and send the mapped unicast QoS stream (which may include service data originally contained in the PDU session and multicast / broadcast service data mapped to the PDU session) to the target access network device through the forwarding tunnel corresponding to the PDU session of the terminal device.

[0250] It should be noted that in this scenario three, the first request message in step 502 includes the identification information of the forwarding tunnel corresponding to the PDU session tunnel of the terminal device; correspondingly, the first response message in step 504 may also include the identification information of the forwarding tunnel corresponding to the PDU session tunnel of the terminal device, so as to realize the establishment of the forwarding tunnel corresponding to the PDU session tunnel between the target access network device and the source access network device. Further, optionally, the first request message only includes the unicast QFI corresponding to the unicast QoS stream, and these unicast QFIs include the unicast QFI that maps the multicast / broadcast QoS stream of the first multicast / broadcast QoS service to the unicast QoS stream. The QoS information of the multicast / broadcast service includes the unicast QFI mapped by the multicast / broadcast QFI and the QoS parameters corresponding to the unicast QFI mapped by the multicast / broadcast QFI.

[0251] In one possible implementation, the source access network device can first copy the first multicast / broadcast service data, map the first multicast / broadcast service data to a unicast QoS stream, and then send it through the forwarding tunnel corresponding to the PDU session tunnel of the terminal device. This helps to avoid affecting the service continuity of other terminal devices receiving the first multicast / broadcast service data.

[0252] Please see Figure 7b This application provides another communication method. The method includes the following steps:

[0253] Step 7001: SMF determines to start the eighth timer.

[0254] In one possible implementation, the session management network element sets an eighth timer to store the second multicast / broadcast service data in the user plane network element. Further, optionally, the SMF can start the eighth timer in response to the second multicast / broadcast service data sent by the core network device to the target access network device. Specific implementation methods for determining the start of the eighth timer by the SMF can be found in implementation methods A, B, C, D, E, and F below.

[0255] In step 7002, the SMF determines that the eighth timer has timed out and sends a third message to the UPF.

[0256] In one possible implementation, the third message could be an N4 session update request message.

[0257] If the target access network device supports multicast / broadcast functions and multicast / broadcast services are already running on the target access network device, the SMF, upon determining that the eighth timer has expired, sends an N4 session update request message to the UPF. This N4 session update request message may include PDU session tunnel identifier information allocated by the target access network device and / or tunnel identifier information allocated by the SMF to the UPF, in order to establish a PDU session tunnel between the UPF and the target access network device. It should be understood that the duration of the eighth timer is set according to the actual situation and is not limited here. For example, it can be set to tens of milliseconds or several seconds, the purpose of which is to reduce packet loss of multicast / broadcast service data during handover of the UE.

[0258] Step 7003: UPF sends a response message for the third message to SMF.

[0259] If the third message is an N4 session update request message, then the third response message can be an N4 session update response message.

[0260] It should be noted that the UPF can assign its own PDU session tunnel identifier, and the SMF can obtain the PDU session tunnel identifier assigned by the UPF through the N4 session update response message.

[0261] Furthermore, the SMF sends the PDU session tunnel identifier assigned by the UPF to the MBCF. The MBCF can then send the PDU session tunnel identifier to the MBUF, which can establish a tunnel with the anchor UPF, allowing multicast / broadcast service data to reach the anchor UPF.

[0262] In one possible implementation, the SMF sends a first indication message to the UPF, the first indication message being used to instruct the UPF to save the second multicast / broadcast service data.

[0263] In one possible implementation, when the SMF determines that the eighth timer has timed out, it sends a second indication message to the UPF, the second indication message being used to instruct the UPF to send the stored second multicast / broadcast service data to the target access network device.

[0264] Furthermore, optionally, the N4 session update request message may include a first indication message or a second indication message.

[0265] Implementation Method A

[0266] like Figure 7c The image shows a method for determining the start of the eighth timer provided in this application. The method includes the following steps:

[0267] Step 7101, SMF sends message 001 to MBCF.

[0268] Message 001 can be used to request the establishment of a multicast / broadcast session tunnel between the target access network device and the MBUF. Message 001 may include the identification information of the multicast / broadcast session tunnel allocated by the target access network device.

[0269] Step 7102, MBCF sends message 002 to MBUF.

[0270] By sending the identification information of the multicast / broadcast session tunnel to the MBUF, the MBUF can establish a multicast / broadcast session tunnel with the target access network device. In this way, the second multicast / broadcast service data can reach the target access network device.

[0271] Step 7103, MBUF sends a response message 002 to MBCF.

[0272] In step 7104, the MBCF sends message 003 to the SMF. Correspondingly, the SMF receives message 003 from the MBCF.

[0273] Message 003 is a response message to message 001.

[0274] Step 7105, SMF starts the eighth timer.

[0275] Implementation Method B

[0276] like Figure 7d The image shows another method for determining the start of the eighth timer provided in this application. The method includes the following steps:

[0277] Step 7201: SMF sends message 0011 to MBCF.

[0278] Message 0011 can be used to request the establishment of a transmission tunnel for multicast / broadcast service data between the UPF and the MBUF. Message 0011 includes the identification information of the PDU session tunnel of the UPF allocated by the SMF.

[0279] Step 7202, MBCF sends message 0022 to MBUF.

[0280] Here, message 0022 may include the identification information of the PDU session tunnel of the UPF. By sending the identification information of the PDU session tunnel of the UPF allocated by the SMF to the MBUF, the MBUF can establish a transmission tunnel for multicast / broadcast service data with the UPF. In this way, the second multicast / broadcast service data can reach the UPF.

[0281] Step 7203: MBUF sends a response message 0022 to MBCF.

[0282] Step 7204, MBCF sends message 0033 to SMF.

[0283] Message 0033 is a response message to message 0011.

[0284] Step 7205, SMF sends message 0044 to UPF.

[0285] Message 0044 includes identification information for the multicast / broadcast session tunnel assigned to the target access network device.

[0286] Step 7206: UPF sends response message 0044 to SMF.

[0287] Here, the UPF can establish a multicast / broadcast session tunnel with the target access network device.

[0288] Step 7207: SMF starts the eighth timer.

[0289] It should be noted that a multicast / broadcast service data transmission tunnel can be established between the MBUF and UPF first, or a multicast / broadcast session tunnel can be established between the UPF and the target access network device first. Figure 7d This is illustrated by taking the establishment of a multicast / broadcast service data transmission tunnel between the MBUF and UPF as an example.

[0290] In implementation method C, when the SMF receives a PDU session context update request (Nsmf_PDUSession_Update SMContext Request) from the AMF, the eighth timer is started.

[0291] Implementation method D

[0292] like Figure 7eThe image shows another method for determining the start of the eighth timer provided in this application. The method includes the following steps:

[0293] Step 7301: SMF sends message 005 to UPF.

[0294] The message 005 includes a first instruction message, which instructs the UPF to save the second multicast / broadcast service data from the MBUF.

[0295] Step 7302: UPF sends a response message 005 to SMF.

[0296] If the UPF allocates the identification information of the tunnel for its own PDU session, the response to message 005 may include the identification information of the PDU session tunnel allocated by the UPF.

[0297] Step 7303, SMF sends message 006 to MBCF.

[0298] Message 006 can be used to request the establishment of a multicast / broadcast session tunnel between the target access network device and the MBUF. Message 006 may include the identification information of the PDU session tunnel of the UPF in step 7302.

[0299] Step 7304, MBCF sends message 007 to MBUF.

[0300] Message 007 may include the identification information of the PDU session tunnel of the UPF. At this time, the MBUF can establish a multicast / broadcast session tunnel with the UPF, that is, the second multicast / broadcast service data can reach the UPF.

[0301] Step 7305, MBUF sends a response message 007 to MBCF.

[0302] Step 7306, MBCF sends message 008 to SMF.

[0303] Message 008 is a response message to message 006.

[0304] Step 7307: SMF starts the eighth timer.

[0305] Implementation method E

[0306] like Figure 7f The image shows another method for determining the start of the eighth timer provided in this application. The method includes the following steps:

[0307] Step 7401, SMF sends message 009 to UPF.

[0308] Message 009 may include identification information of the PDU session tunnel of the target access network device. Further, optionally, if the SMF allocates identification information of the PDU session tunnel of the UPF, then message 009 may also carry the identification information of the PDU session tunnel of the UPF allocated by the SMF. Further, optionally, message 009 may also include packet detection rule (PDR) information for multicast / broadcast services.

[0309] Step 7402, UPF sends a response message 009 to SMF.

[0310] The UPF assigns its own PDU session tunnel identifier, and the response message for message 009 may include the identifier information of the UPF's PDU session tunnel.

[0311] Step 7403, SMF sends message 010 to MBCF.

[0312] The message 010 may include the identification information of the PDU session tunnel of the UPF in step 1702.

[0313] Step 7404, MBCF sends message 011 to MBUF.

[0314] Message 011 may include the identification information of the PDU session tunnel of the UPF. At this time, the MBUF can establish a transmission tunnel for multicast / broadcast service data with the UPF, that is, the second multicast / broadcast service data can reach the UPF.

[0315] Step 7405, MBUF sends a response message 011 to MBCF.

[0316] Step 7406, MBCF sends message 012 to SMF.

[0317] Message 012 is a response message to message 010.

[0318] Step 7407: SMF starts the eighth timer.

[0319] The following examples illustrate four methods for a target access network device to stop receiving first multicast / broadcast service data sent by a source access network device.

[0320] Method 1: Set the third timer using SMF.

[0321] like Figure 8 The diagram shown is a flowchart illustrating a method provided in this application for a target access network device to stop receiving first multicast / broadcast service data sent by a source access network device. The method includes the following steps:

[0322] Step 801: SMF determines that the third timer has timed out and constructs an end marker.

[0323] Here, the third timer is used to control the SMF to trigger the construction and send an End Marker to the target access network device. The End Marker is used to instruct the target access network device to stop receiving the first multicast / broadcast service data through the forwarding tunnel corresponding to the PDU session tunnel of the terminal device. This end marker can be a data packet. Alternatively, it can be understood that the third timer is used to control the SMF to trigger the construction of an End Marker and send the End Marker to the target access network device via the source access network device. It should be understood that, in conjunction with the above... Figure 7a The third timer can be started after the SMF receives the fourth response message.

[0324] Step 802: The SMF sends an End Marker to the source access network device. Correspondingly, the source access network device receives the End Marker from the SMF.

[0325] Step 803: The source access network device sends an End Marker to the target access network device. Correspondingly, the target access network device receives the End Marker from the source access network device.

[0326] Here, the source access network device can send an End Marker to the target access network device through the forwarding tunnel corresponding to the PDU session of the terminal device.

[0327] Step 804: The target access network device stops receiving the first multicast / broadcast service data through the forwarding tunnel corresponding to the PDU session of the terminal device. Further, optionally, the resources of the forwarding tunnel corresponding to the PDU session are released.

[0328] In combination with the above Figure 7a In method 1, after receiving the fourth response message in step 704, the SMF does not immediately construct and send the End Marker. Instead, it waits until the third timer expires before constructing and sending the End Marker. The duration of the third timer is determined based on the actual situation and is not limited here. For example, it can be set to tens of milliseconds or a few seconds to reduce packet loss of multicast / broadcast service data caused by the terminal device during the handover process.

[0329] Method 2: Set the fourth timer in UPF.

[0330] like Figure 9 The diagram shown illustrates a method for a target access network device to stop receiving first multicast / broadcast service data sent by a source access network device, as provided in this application. The method includes the following steps:

[0331] In step 900, the SMF sends a fifth request message to the UPF.

[0332] The fifth request message includes information about the fourth timer configured for the UPF. This fourth timer is used to control the UPF to trigger the construction and send the End Marker. It should be understood that this fifth request message can be an N4 update session request message.

[0333] Step 901: UPF sends the fifth response message to SMF.

[0334] Here, if the fifth request message can be an N4 update session request message, then the fifth response message is an N4 update session response message.

[0335] Step 902: UPF determines that the fourth timer has timed out and constructs the first end marker.

[0336] Here, the fourth timer is used to control the UPF to trigger the construction and send an End Marker to the target access network device. The End Marker is used to instruct the target access network device to stop receiving the first multicast / broadcast service data through the forwarding tunnel corresponding to the PDU session tunnel of the terminal device. Alternatively, the fourth timer can be understood as controlling the UPF to trigger the construction of an End Marker and sending it to the target access network device via the source access network device. It should be understood that the fourth timer can be started after the UPF sends the fifth response message.

[0337] In step 903, the UPF sends an End Marker to the source access network device. Correspondingly, the source access network device receives the End Marker from the UPF.

[0338] Step 904: The source access network device sends an End Marker to the target access network device. Correspondingly, the target access network device receives the End Marker from the source access network device.

[0339] This step 904 is similar to the description of step 803 above, and will not be repeated here.

[0340] Step 905: The target access network device stops receiving the first multicast / broadcast service data through the forwarding tunnel corresponding to the PDU session of the terminal device. Further, optionally, the resources of the forwarding tunnel corresponding to the PDU session are released.

[0341] In combination with the above Figure 7aThe UPF will not immediately construct and send the EndMarker after replying to the SMF with the fourth response message. Instead, it will wait until the fourth timer expires before constructing and sending the EndMarker to the target access network device. The duration of the fourth timer can be set according to the actual situation and is not limited here. For example, it can be set to tens of milliseconds or a few seconds to reduce packet loss of multicast / broadcast service data caused by terminal devices during handover.

[0342] Method 3: UPF sets a second timer, SMF constructs an End Marker.

[0343] In one possible implementation, the SMF receives the fourth response message, immediately constructs an End Marker, and then sends the End Marker to the UPF. The UPF, upon determining that the second timer has expired, sends an end data packet to the target access network device. The target access network device stops receiving the first multicast / broadcast service data through the forwarding tunnel corresponding to the PDU session of the terminal device and releases the resources of the forwarding tunnel corresponding to the PDU session. It should be understood that the second timer can be started after the UPF receives the End Marker from the SMF. Alternatively, it can be understood that the second timer is used to control the UPF to send the End Marker to the target access network device via the source access network device.

[0344] Method 4: Set the fifth timer on the source access network device.

[0345] like Figure 10 The diagram shown illustrates a method for a target access network device to stop receiving first multicast / broadcast service data sent by a source access network device, as provided in this application. The method includes the following steps:

[0346] Step 1001: The source access network device receives the End Marker from the UPF or SMF.

[0347] Here, the UPF or SMF constructs and sends the End Marker to the source access network device, as described above. Figure 9 , Figure 8 The relevant descriptions will not be repeated here.

[0348] Step 1002: The source access network device determines that the fifth timer has expired and sends an EndMarker to the target access network device.

[0349] The fifth timer is used to control the source access network device to trigger the sending of an EndMarker to the target access network device. Possible implementations of sending the EndMarker to the target access network device in step 1002 can be found in the description of step 803 above, and will not be repeated here. It should be understood that the fifth timer can be started after the source access network device receives the EndMarker.

[0350] Step 1003: The target access network device stops receiving the first multicast / broadcast service data through the forwarding tunnel corresponding to the PDU session of the terminal device. Further, optionally, the resources of the forwarding tunnel corresponding to the PDU session are released.

[0351] In combination with the above Figure 7a The source access network device sets a fifth timer, which is used to prevent the End Marker from being immediately forwarded to the target access network device through the PDU session forwarding tunnel after receiving the End Marker. Instead, the End Marker is forwarded to the target access network device only after the fifth timer expires. The duration of the timer is set according to the actual situation and is not limited here. For example, it can be set to tens of milliseconds or a few seconds. The purpose is to reduce packet loss of multicast / broadcast service data during the handover process of the terminal device.

[0352] Method 5: Set the sixth timer for the source access network device and the seventh timer for the target access network device.

[0353] In one possible implementation, the source access network device determines that the sixth timer has expired and stops sending the first multicast / broadcast service data to the target access network device through the PDU session forwarding tunnel. Further, after receiving the End Marker from the source access network device, the target access device does not immediately stop receiving the first multicast / broadcast service data through the forwarding tunnel corresponding to the terminal device's PDU session. The target access network device has a sixth timer set; upon determining that the sixth timer has expired, it stops receiving the first multicast / broadcast service data through the forwarding tunnel corresponding to the terminal device's PDU session. The duration of the sixth timer is set according to actual conditions and is not limited here; for example, it can be set to tens of milliseconds or several seconds to reduce packet loss of the multicast / broadcast service data of the terminal device. Further, optionally, the target access network device releases the resources of the forwarding tunnel corresponding to the PDU session.

[0354] It should be noted that in method 5, the sixth timer can start at the same time as the first timer mentioned above, which will not be repeated here. The seventh timer can be started after the target access network device receives the End Marker. Furthermore, the duration of the timer set by the target access network device can be greater than or equal to the duration of the timer set by the source access network device. When the durations of the timers set by the target access network device and the source access network device are consistent, the setting information can be synchronized and matched through the Xn interface between the target access network device and the source access network device.

[0355] It should be noted that the order of steps in the above embodiments is merely an example and does not constitute a limitation on this application.

[0356] It is understood that, in order to achieve the functions in the above embodiments, the access network device and the terminal device include hardware structures and / or software modules corresponding to perform each function. Those skilled in the art should readily recognize that, based on the modules and method steps described in conjunction with the embodiments disclosed in this application, this application can be implemented in hardware or a combination of hardware and computer software. Whether a function is executed in hardware or by computer software driving hardware depends on the specific application scenario and design constraints of the technical solution.

[0357] Based on the above content and the same concept, Figure 11 and Figure 12 This is a schematic diagram of the possible communication devices provided in this application. These communication devices can be used to implement the functions of the terminal device or access network device in the above method embodiments, and therefore can also achieve the beneficial effects of the above method embodiments. In this application, the communication device can be as follows: Figure 1 The terminal device shown can also be as follows: Figure 1 The access network device shown can also be a module (such as a chip) applied to terminal equipment or access network equipment.

[0358] like Figure 11 As shown, the communication device 1100 includes a processing module 1101 and a transceiver module 1102. The communication device 1100 is used to implement the above-mentioned... Figures 5 to 10 The method embodiments shown illustrate the functions of the terminal device or access network device.

[0359] When the communication device 1100 is used to implement Figure 5The source access network device in the method embodiment shown functions as follows: the transceiver module 1102 is used to receive first radio bearer configuration information and second radio bearer configuration information from the target access network device. The first radio bearer configuration information is used by the terminal device to receive first multicast / broadcast service data transmitted from the air interface unicast mode corresponding to the target access network device. The second radio bearer configuration information is used by the terminal device to receive second multicast / broadcast service data transmitted from the air interface multicast / broadcast mode or air interface unicast mode corresponding to the target access network device, and to send the first radio bearer configuration information and the second radio bearer configuration information to the terminal device.

[0360] When the communication device 1100 is used to implement Figure 5 The target access network device in the method embodiment shown functions as follows: the processing module 1101 is used to determine the first radio bearer configuration information and the second radio bearer configuration information of the terminal device. The first radio bearer configuration information is used by the terminal device to receive the first multicast / broadcast service data transmitted from the air interface unicast mode corresponding to the target access network device. The second radio bearer configuration information is used by the terminal device to receive the second multicast / broadcast service data transmitted from the air interface multicast / broadcast mode or air interface unicast mode corresponding to the target access network device. The transceiver module 1102 is used to send the first radio bearer configuration information and the second radio bearer configuration information.

[0361] When the communication device 1100 is used to implement Figure 5 The terminal device in the illustrated method embodiment functions as follows: the transceiver module 1102 is used to receive first radio bearer configuration information and second radio bearer configuration information from the source access network device. The first radio bearer configuration information is used by the terminal device to receive first multicast / broadcast service data transmitted from the target access network device in the corresponding air interface unicast mode. The second radio bearer configuration information is used by the terminal device to receive second multicast / broadcast service data transmitted from the target access network device in the corresponding air interface multicast / broadcast mode or air interface unicast mode. The terminal device also receives the first multicast / broadcast service data from the target access network device in the air interface unicast mode and the second multicast / broadcast service data from the target access network device in the air interface multicast / broadcast mode or air interface unicast mode. The first multicast / broadcast service data is associated with the terminal device's PDU session.

[0362] For a more detailed description of the aforementioned processing module 1101 and transceiver module 1102, please refer to [link / reference]. Figure 5 The relevant descriptions in the method embodiments shown are directly obtained and will not be repeated here.

[0363] It should be understood that the processing module 1101 in the embodiments of this application can be implemented by a processor or processor-related circuit components, and the transceiver module 1102 can be implemented by a transceiver or transceiver-related circuit components.

[0364] When the communication device 1100 is used to implement Figure 6 The source access network device in the illustrated method embodiment functions as follows: the transceiver module 1102 and the processing module 1101 cooperate to receive first radio bearer configuration information from the target access network device. The first radio bearer configuration information is used by the terminal device to receive first multicast / broadcast service data transmitted in the air interface unicast mode corresponding to the target access network device, and to send the first radio bearer configuration information to the terminal device. After receiving the first information from the target access network device, the terminal device sends second radio bearer configuration information to stop sending the first multicast / broadcast service data to the target access network device. The first information is used to instruct the source access network device to stop sending the first multicast / broadcast service data to the target access network device. The first multicast / broadcast service data is associated with the PDU session of the terminal device.

[0365] When the communication device 1100 is used to implement Figure 6 The target access network device in the method embodiment shown functions as follows: Processing module 1101 is used to determine first radio bearer configuration information and second radio bearer configuration information of the terminal device. The first radio bearer configuration information is used for the terminal device to receive first multicast / broadcast service data transmitted from the air interface unicast mode corresponding to the target access network device. The second radio bearer configuration information is used for the terminal device to receive second multicast / broadcast service data transmitted from the air interface multicast / broadcast mode or air interface unicast mode corresponding to the target access network device. Transceiver module 1102 is used to receive the first radio bearer configuration information from the source access network device. The first radio bearer configuration information is used for the terminal device to receive data from the air interface unicast mode corresponding to the target access network device. The transceiver module 1101 receives first multicast / broadcast service data transmitted in a certain manner; and receives first multicast / broadcast service data from the source access network device, wherein the first multicast / broadcast service data is associated with the PDU session of the terminal device; the processing module 1101 is used to determine that the received first multicast / broadcast service data is synchronized with the second multicast / broadcast service data, and sends first information to the source access network device, wherein the first information is used to instruct the source access network device to stop sending the first multicast / broadcast service data to the target access network device; the transceiver module 1102 is also used to send second radio bearer configuration information to the terminal device, wherein the second radio bearer configuration information is used for the terminal device to receive the second multicast / broadcast service data transmitted from the target access network device in the corresponding air interface multicast / broadcast mode or air interface unicast mode.

[0366] When the communication device 1100 is used to implement Figure 6The target access network device in the method embodiment shown functions as follows: the transceiver module 1102 is used to receive first multicast / broadcast service data from the source access network device and second multicast / broadcast service data from the core network device; the processing module 1101 is used to determine that the first multicast / broadcast service data and the second multicast / broadcast service data are synchronized, and to send the second multicast / broadcast service data to the terminal device.

[0367] Based on the above content and the same concept, such as Figure 12 As shown, this application also provides a communication device 1200. The communication device 1200 may include a processor 1201 and a transceiver 1202. The processor 1201 and the transceiver 1202 are coupled to each other. It is understood that the transceiver 1202 may be an interface circuit or an input / output interface. Optionally, the communication device 1200 may also include a memory 1203 for storing instructions executed by the processor 1201, or storing input data required by the processor 1201 to execute instructions, or storing data generated after the processor 1201 executes instructions.

[0368] When the communication device 1200 is used to implement Figure 5 , Figure 6 , Figure 7a , Figure 7b , Figure 7c , Figure 7d , Figure 7e , Figure 7f , Figure 8 , Figure 9 or Figure 10 In the method shown, processor 1201 is used to execute the functions of the above-mentioned processing module 1101, and transceiver 1202 is used to execute the functions of the above-mentioned transceiver module 1102.

[0369] When the aforementioned communication device is a chip applied to a terminal device, the terminal device chip implements the functions of the terminal device in the above method embodiments. The terminal device chip receives information from other modules (such as a radio frequency module or antenna) in the terminal device, which is sent to the terminal device by the access network device; or, the terminal device chip sends information to other modules (such as a radio frequency module or antenna) in the terminal device, which is sent to the access network device by the terminal device.

[0370] When the aforementioned communication device is a chip applied to an access network device, the access network device chip implements the functions of the access network device in the above method embodiments. The access network device chip receives information from other modules (such as radio frequency modules or antennas) in the access network device, which is information sent by the terminal device to the access network device; or, the access network device chip sends information to other modules (such as radio frequency modules or antennas) in the access network device, which is information sent by the access network device to the terminal device.

[0371] When the communication device is a terminal device Figure 13 A simplified schematic diagram of a terminal device is shown. This is for ease of understanding and illustration. Figure 13 In this context, the terminal device is taken as a mobile phone. Figure 13 As shown, the terminal device 1300 includes a processor, a memory, a radio frequency (RF) circuit, an antenna, and input / output devices. The processor is primarily used to process communication protocols and data, control the entire terminal device, execute software programs, and process data from these programs, for example, to support the terminal device 1300 in executing the methods described in any of the above embodiments. The memory is primarily used to store software programs and data. The RF circuit is primarily used for converting baseband signals to RF signals and processing RF signals. The antenna is primarily used for transmitting and receiving RF signals in the form of electromagnetic waves. Input / output devices, such as touchscreens, displays, and keyboards, are primarily used to receive user input data and output data to the user. It should be noted that some types of terminal devices may not have input / output devices.

[0372] When the terminal device is powered on, the processor can read the software program in the memory, interpret and execute the instructions of the software program, and process the data of the software program. When data needs to be transmitted, the processor performs baseband processing on the data to be transmitted and outputs the baseband signal to the radio frequency (RF) circuit. The RF circuit then processes the baseband signal and transmits the RF signal outward in the form of electromagnetic waves through the antenna. When data is sent to the terminal device 1300, the RF circuit receives the RF signal through the antenna, converts the RF signal into a baseband signal, and outputs the baseband signal to the processor. The processor converts the baseband signal back into data and processes the data.

[0373] As an optional implementation, the processor may include a baseband processor and a central processing unit. The baseband processor is mainly used to process communication protocols and communication data, while the central processing unit is mainly used to control the entire terminal device 1300, execute software programs, and process the data of the software programs. Figure 13The processor in the terminal device 1300 integrates the functions of a baseband processor and a central processing unit (CPU). It should be noted that the baseband processor and CPU can also be independent processors, interconnected via technologies such as buses. Furthermore, the terminal device 1300 can include multiple baseband processors to adapt to different network standards, and multiple CPUs to enhance its processing capabilities. The various components of the terminal device 1300 can be connected via various buses. The baseband processor can also be described as a baseband processing circuit or a baseband processing chip. Similarly, the CPU can be described as a central processing circuit or a central processing chip. The functions for processing communication protocols and communication data can be built into the processor or stored as software programs in the storage module, with the processor executing the software programs to implement the baseband processing functions.

[0374] In this application, the antenna and radio frequency circuit with transceiver functions can be regarded as the transceiver module of the terminal device, and the processor with processing functions can be regarded as the processing module of the terminal device. Figure 13 As shown, the terminal device includes a processing module 1301 and a transceiver module 1302. The transceiver module can also be called a transceiver, transceiver unit, transceiver device, etc., and the processing module can also be called a processor, processing board, processing unit, processing device, etc. Optionally, the device in the transceiver module used to implement the receiving function can be considered as a receiving module, and the device in the transceiver module used to implement the sending function can be considered as a sending module. That is, the transceiver module includes both a receiving module and a sending module. For example, the receiving module can also be called a receiver, receiver circuit, etc., and the sending module can be called a transmitter, transmitter, or transmitting circuit, etc.

[0375] On the downlink, the processor receives downlink signals (including data and / or control information) transmitted by the access network equipment via an antenna. On the uplink, it transmits uplink signals (including data and / or control information) to the access network equipment or other terminal equipment via an antenna. The processor processes service data and signaling messages, and these modules perform processing according to the radio access technology adopted by the radio access network (e.g., LTE, NR, and other evolved system access technologies). The processor is also used to control and manage the actions of the terminal equipment, and to execute the processing performed by the terminal equipment in the above embodiments. The processor is also used to support the terminal equipment in performing... Figure 5 or Figure 6 The execution method involves the terminal device.

[0376] It should be noted that, Figure 13Only one memory, one processor, and one antenna are shown. In actual terminal devices, the terminal device can contain any number of antennas, memory, processors, etc. The memory can also be referred to as a storage medium or storage device. Furthermore, the memory can be set up independently of the processor or integrated with the processor; this application does not impose any limitations on this.

[0377] It should be understood that the transceiver module 1302 is used to perform the above... Figure 5 or Figure 6 In the method embodiment shown, the sending and receiving operations on the terminal device side are executed by the processing module 1301. Figure 5 or Figure 6 The method embodiment shown includes operations on the terminal device side other than the transmit / receive operation. For example, the transmit / receive module 1302 is used to perform... Figure 5 The transmitting and receiving steps on the terminal device side in the illustrated embodiment, such as steps 501 and 507, are shown. Processing module 1301 is used to execute... Figure 5 In the illustrated embodiment, the terminal device performs operations other than the transmit / receive operation, such as step 509. For example, the transmit / receive module 1302 is used to perform... Figure 6 The transmitting and receiving steps on the terminal device side in the illustrated embodiment, such as steps 601 and 607, are shown. Processing module 1301 is used to execute... Figure 6 The terminal device side in the illustrated embodiment performs operations other than sending and receiving.

[0378] When the communication device is a chip-based device or circuit, it may include a transceiver module and a processing module. The transceiver module may be an input / output circuit and / or an interface circuit; the processing module may be a processor, microprocessor, or integrated circuit integrated on the chip.

[0379] When the communication device is an access network device Figure 14 An exemplary schematic diagram of an access network device provided in this application is shown. Figure 14As shown, the access network device 1400 may include one or more radio frequency (RF) units, such as a remote radio unit (RRU) 1402 and one or more baseband units (BBUs) 1401. The RRU 1402 can be referred to as a transceiver module, transceiver, transceiver circuit, or transceiver unit, etc., and may include at least one antenna 14021 and an RF unit 14022. The RRU 1402 is mainly used for transmitting and receiving RF signals and converting RF signals to baseband signals. The BBU 1401 can be referred to as a processing module, processor, etc., and is mainly used for baseband processing, such as channel coding, multiplexing, modulation, and spread spectrum, and also for controlling the access network device. The RRU 1402 and BBU 1401 may be physically installed together or physically separated, i.e., a distributed access network device.

[0380] The BBU 1401 is the control center of the base station, also known as the processing module, and can communicate with... Figure 12 The corresponding processing module 1201 is mainly used to complete baseband processing functions, such as channel coding, multiplexing, modulation, spreading, etc. For example, the BBU (processing module) can be used to control the base station to execute the operation procedures of the access network equipment in the above method embodiments.

[0381] As an optional implementation, the BBU1401 can consist of one or more boards. These boards can collectively support a single access standard wireless access network (such as an LTE network), or they can each support different access standards wireless access networks (such as LTE, 5G, or other networks). The BBU1401 also includes a memory 14012 and a processor 14011. The memory 14012 stores necessary instructions and data. The processor 14011 controls the access network device to perform necessary actions, such as controlling the access network device to execute the methods performed by the access network device in any of the above embodiments. The memory 14012 and the processor 14011 can serve one or more boards. That is, each board can have its own memory and processor, or multiple boards can share the same memory and processor. Furthermore, each board also has necessary circuitry.

[0382] On the uplink, antenna 14021 receives uplink signals (including data, etc.) transmitted by the terminal device. On the downlink, antenna 14021 transmits downlink signals (including data and / or control information) to the terminal device. Processor 14011 processes service data and signaling messages. These modules process data according to the radio access technology adopted by the radio access network (e.g., LTE, NR, and other evolved system access technologies). Processor 14011 is also used to control and manage the actions of the access network device, and to execute the processing performed by the access network device in the above embodiments. Processor 14011 is also used to support the access network device in performing... Figure 5 or Figure 6 The method executed by the source access network device and the target access network device.

[0383] It should be noted that, Figure 14 This illustration only shows a simplified design of the access network device. In practical applications, the access network device can contain any number of antennas, memory, processors, radio frequency units, RRUs, BBUs, etc., and all access network devices that can implement this application are within the scope of protection of this application.

[0384] It should be understood that the transceiver module 1402 is used to perform the above... Figure 5 or Figure 6 In the method embodiment shown, the transmission and reception operations on the access network device side are executed by the processing module 1401. Figure 5 The method embodiment shown includes operations on the access network device side other than the transmit / receive operation. For example, the transmit / receive module 1402 is used to perform... Figure 5 The transmit / receive steps on the access network device side in the illustrated embodiment include, for example, steps 502, 504, 505, and 508. Processing module 1401 is used to execute... Figure 5 In the illustrated embodiment, the access network device performs operations other than the transmit / receive operation, such as step 503. For example, the transmit / receive module 1402 is used to perform... Figure 6 The transmit / receive steps on the access network device side in the illustrated embodiment include, for example, steps 602, 603, 605, 606, 608, and 612. The processing module 1401 is used to execute... Figure 6 In the illustrated embodiment, the access network device side performs operations other than the transmit and receive operations, such as steps 604 and 609.

[0385] It is understood that the processor in the embodiments of this application may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. A general-purpose processor may be a microprocessor or any conventional processor.

[0386] The method steps in the embodiments of this application can be implemented in hardware or by a processor executing software instructions. The software instructions can consist of corresponding software modules, which can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, portable hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. Furthermore, the ASIC can reside in an access network device or a terminal device. Alternatively, the processor and storage medium can exist as discrete components in the access network device or terminal device.

[0387] In the above embodiments, implementation can be achieved, in whole or in part, through software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer programs or instructions. When a computer program or instruction is loaded and executed on a computer, the processes or functions of the embodiments of this application are performed, in whole or in part. The computer can be a general-purpose computer, a special-purpose computer, a computer network, an access network device, a user equipment, or other programmable device. The computer program or instructions can be stored in a computer-readable storage medium or transferred from one computer-readable storage medium to another. For example, a computer program or instructions can be transferred from one website, computer, server, or data center to another website, computer, server, or data center via wired or wireless means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium, such as a floppy disk, hard disk, or magnetic tape; it can also be an optical medium, such as a digital video disc (DVD); or it can be a semiconductor medium, such as a solid-state drive (SSD).

[0388] In the various embodiments of this application, unless otherwise specified or in case of logical conflict, the terminology and / or descriptions of different embodiments are consistent and can be referenced by each other. The technical features of different embodiments can be combined to form new embodiments according to their inherent logical relationship.

[0389] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, at least one of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. In the textual description of this application, the character " / " generally indicates an "or" relationship between the preceding and following related objects; in the formulas of this application, the character " / " indicates a "division" relationship between the preceding and following related objects.

[0390] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application. The order of the process numbers described above does not imply the order of execution; the execution order of each process should be determined by its function and inherent logic. Terms such as "first," "second," and similar expressions are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion, such as including a series of steps or modules. A method, system, product, or device is not necessarily limited to those steps or modules explicitly listed, but may include other steps or modules not explicitly listed or inherent to these processes, methods, products, or devices.

[0391] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the scope of protection of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A communication method, characterized in that, Chips used in terminal devices or terminal devices include: The terminal receives first radio bearer configuration information and second radio bearer configuration information from the source access network device. The first radio bearer configuration information is used for the terminal to receive first multicast / broadcast service data from the target access network device through air interface unicast mode. The second radio bearer configuration information is used for the terminal to receive second multicast / broadcast service data from the target access network device through air interface multicast mode. The second multicast / broadcast service data is received from the target access network device through the air interface unicast mode or the air interface multicast mode; wherein the second multicast / broadcast service data is synchronized with the first multicast / broadcast service data.

2. The method as described in claim 1, characterized in that, The first multicast / broadcast service is associated with the Protocol Data Unit (PDU) session of the terminal device.

3. The method as described in claim 1 or 2, characterized in that, The first multicast / broadcast service data and the second multicast / broadcast service data are data from the same source service.

4. A communication method, characterized in that, Chips used in source access network devices or source access network devices include: The terminal receives first radio bearer configuration information and second radio bearer configuration information from the target access network device. The first radio bearer configuration information is used by the terminal to receive first multicast / broadcast service data from the target access network device through air interface unicast mode, and the second radio bearer configuration information is used by the terminal to receive second multicast / broadcast service data from the target access network device through air interface multicast mode. Send the first radio bearer configuration information and the second radio bearer configuration information to the terminal; Send the first multicast / broadcast service data to the target access network device; The system receives first information from the target access network device, the first information being used to instruct the system to stop sending the first multicast / broadcast service data to the target access network device; wherein the first multicast / broadcast service data is synchronized with the second multicast / broadcast service data.

5. The method as described in claim 4, characterized in that, The first multicast / broadcast service is associated with the Protocol Data Unit (PDU) session of the terminal.

6. The method as described in claim 4, characterized in that, The first multicast / broadcast service data and the second multicast / broadcast service data are data from the same source service.

7. The method according to any one of claims 4-6, characterized in that, Sending the first multicast / broadcast service data to the target access network device includes: The first multicast / broadcast service data is sent to the target access network device via a forwarding tunnel; The forwarding tunnel is the forwarding tunnel corresponding to the first multicast / broadcast session of the terminal, and the first multicast / broadcast session corresponds to the first multicast / broadcast service.

8. The method as described in claim 7, characterized in that, The method further includes: A first request message is sent to the target access network device, the first request message being used to request the target access network device to establish the forwarding tunnel between the target access network device and the source access network device.

9. A communication method, characterized in that, Chips used in target access network devices or target access network devices include: The terminal determines a first radio bearer configuration information and a second radio bearer configuration information. The first radio bearer configuration information is used for the terminal to receive first multicast / broadcast service data from the source access network device transmitted by the target access network device through air interface unicast mode. The second radio bearer configuration information is used for the terminal to receive second multicast / broadcast service data transmitted by the target access network device through air interface multicast mode. The source access network device sends the first radio bearer configuration information and the second radio bearer configuration information to the terminal. The second multicast / broadcast service data is sent to the terminal via the air interface unicast mode or the air interface multicast mode; wherein the second multicast / broadcast service data is synchronized with the first multicast / broadcast service data.

10. The method as described in claim 9, characterized in that, The first multicast / broadcast service data and the second multicast / broadcast service data are data from the same source service.

11. The method as described in claim 9 or 10, characterized in that, The method further includes: Receive the first multicast / broadcast service data from the source access network device.

12. The method as described in claim 11, characterized in that, Receiving the first multicast / broadcast service data from the source access network device includes: The first multicast / broadcast service data is received from the source access network device through a forwarding tunnel; the forwarding tunnel is the forwarding tunnel corresponding to the first multicast / broadcast session of the terminal, and the first multicast / broadcast session corresponds to the first multicast / broadcast service.

13. The method as described in claim 12, characterized in that, The method further includes: A first request message is received from the source access network device, the first request message being used to request the target access network device to establish the forwarding tunnel between the target access network device and the source access network device.

14. The method according to any one of claims 9-13, characterized in that, The method further includes: The first multicast / broadcast service data is sent to the terminal via the air interface unicast mode, and the second multicast / broadcast service data is sent to the terminal via the air interface multicast mode.

15. The method according to any one of claims 9-14, characterized in that, The first multicast / broadcast service is associated with the Protocol Data Unit (PDU) session of the terminal.

16. A communication device, characterized in that, Includes modules for performing the methods as described in any one of claims 1 to 3, 4 to 8, or 9 to 15.

17. A communication system, characterized in that, It includes a communication device for performing the method as described in any one of claims 1 to 3, a communication device for performing the method as described in any one of claims 4 to 8, and a communication device for performing the method as described in any one of claims 9 to 15.

18. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program or instructions that, when executed by a communication device, cause the communication device to perform the method as described in any one of claims 1 to 3, 4 to 8, or 9 to 15.

19. A computer program product, characterized in that, The computer program product includes a computer program or instructions that, when executed by a communication device, implement the method as described in any one of claims 1 to 3, 4 to 8, or 9 to 15.

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