WO2022012506A1 - 通信方法和通信装置 - Google Patents

通信方法和通信装置 Download PDF

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Publication number
WO2022012506A1
WO2022012506A1 PCT/CN2021/105944 CN2021105944W WO2022012506A1 WO 2022012506 A1 WO2022012506 A1 WO 2022012506A1 CN 2021105944 W CN2021105944 W CN 2021105944W WO 2022012506 A1 WO2022012506 A1 WO 2022012506A1
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WIPO (PCT)
Prior art keywords
multicast
tunnel
information
network device
network element
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Ceased
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PCT/CN2021/105944
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English (en)
French (fr)
Inventor
贾建鑫
吴问付
宗在峰
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Huawei Technologies Co Ltd
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Huawei Technologies Co Ltd
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Filing date
Publication date
Application filed by Huawei Technologies Co Ltd filed Critical Huawei Technologies Co Ltd
Priority to AU2021308253A priority Critical patent/AU2021308253B2/en
Priority to EP21842393.7A priority patent/EP4171074B1/en
Priority to JP2023501551A priority patent/JP7597904B2/ja
Priority to CA3186084A priority patent/CA3186084A1/en
Publication of WO2022012506A1 publication Critical patent/WO2022012506A1/zh
Priority to US18/152,985 priority patent/US20230164640A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W4/00—Services specially adapted for wireless communication networks; Facilities therefor
    • H04W4/06—Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0007—Control or signalling for completing the hand-off for multicast or broadcast services, e.g. MBMS
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/30—Connection release
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/30—Connection release
    • H04W76/32—Release of transport tunnels
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0011—Control or signalling for completing the hand-off for data sessions of end-to-end connection
    • H04W36/0016—Hand-off preparation specially adapted for end-to-end data sessions
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/40—Connection management for selective distribution or broadcast
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/14—Backbone network devices

Definitions

  • the present application relates to the field of communication, and more particularly, to a communication method and a communication device.
  • the promotion of multicast solutions encountered great difficulties .
  • the multicast solution in previous generations of mobile communication technologies needs to add dedicated network elements and interfaces that support multicast on the basis of the existing communication architecture, and also requires dedicated multicast channel support. This not only increases the overhead of the operator's corner, but also increases the complexity of the terminal.
  • the embodiments of the present application provide a communication method and apparatus for multicast services, which can realize the release of a tunnel for transmitting multicast service data between an access network device and a core network device, and help save network resource overhead .
  • a communication method comprising:
  • the first access network device in the handover preparation stage of the first terminal device switching from the first access network device to the second access network device, learns that the first terminal device has passed the first access network device the last terminal device that receives the data of the first multicast service;
  • the first access network device sends first information, where the first information is used to release a first tunnel, and the first tunnel is used to transmit the first access network device and the core network device Data of the first multicast service.
  • the first access network device may learn that the first terminal device has passed the The last terminal device that the first access network device receives the data of the first multicast service, and sends the first information to release the first access network device for transmitting the first multicast service between the first access network device and the core network device
  • the first tunnel of data helps to save network resource overhead.
  • the first access network device may be a source access network device
  • the second access network device may be a target access network device
  • the above-mentioned first multicast service may be one multicast service or multiple different multicast services, which is not limited.
  • the first information may include an indication for releasing the first tunnel and information of the first tunnel.
  • the first information may include an indication for releasing the first tunnel and identification information of the first multicast service.
  • the first information may include an indication for releasing the first tunnel, identification information of the first multicast service, and information of the first tunnel.
  • the information of the first tunnel can be used to uniquely determine the first tunnel, for example, it can be a tunnel endpoint identifier (tunnel endpoint identifier, TEID) of the first tunnel, or the ID of the first tunnel, which is not limited here.
  • the identification information of the first multicast service can be used to uniquely determine a multicast service, for example, it can be the ID of the multicast service, or the name of the multicast service, or the multicast address, or the multicast group ID, etc., which are not limited here.
  • the handover preparation stage may refer to source access network equipment, target access network equipment, or core network equipment (here, it may refer to AMF, SMF, or UPF, etc., without limitation) as the first A stage in which the terminal equipment prepares to hand over the required resources.
  • the resources required for handover may include forwarding tunnels, or radio bearer configuration information required by the first terminal device to receive service data through the target access network device, air interface resources configured by the target access network device for the first terminal device, etc.
  • the application examples are not limited.
  • the handover preparation stage may refer to the source access network device receiving the measurement report of the first terminal device, and making a handover decision on the first terminal device according to the measurement report, and the decision result is handover, and the source access network device receives the measurement report of the first terminal device.
  • the network access device sends a handover request to a target access network device, and receives a handover request response sent by the target access network device.
  • the handover preparation stage may refer to the source access network device receiving the measurement report of the first terminal device, and the source access network device sending the source access and mobility management function network element according to the measurement report Handover required, and the process by which the source access and mobility management function network element receives the create UE context response from the target access and mobility management network element.
  • the source access network device may learn at any time point in the handover preparation stage that the first terminal device is the last terminal device that receives data of the first multicast service through the first access network device.
  • the first terminal device that joins the first multicast service sends a measurement report to the source access network device, and the source access network device performs a measurement report on the first terminal device according to the measurement report.
  • the source access network device may update the number of terminal devices that join the first multicast service through the source access network device, for example, decrement the number of terminal devices by 1.
  • the source access network device may know that the first terminal device is the last terminal device that receives data of the first multicast service through the first access network device.
  • the number of terminal devices that join the multicast service through the source access network device may include a multicast context (Multicast Context) corresponding to the multicast service associated with the PDU session of the first terminal device or Multicast session context (Multicast Session Context) or multicast group context (Multicast Group Context) or multicast service context (Multicast Service Context).
  • Multicast Context Multicast context
  • Multicast Session Context Multicast Session Context
  • Multicast Group Context Multicast Group Context
  • Multicast Service Context Multicast Service Context
  • the core network device may be a multicast user plane functional network element, such as MUF, M-UPF, MS-UPF, or MB-UPF, etc., which are not limited.
  • the first tunnel may include a tunnel between the source access network device and a multicast user plane functional network element (for example, MUF or M-UPF, MS-UPF or MB-UPF) for transmitting the first multicast service tunnel.
  • the core network device may be a user plane functional network element, such as a UPF.
  • the first tunnel may include a tunnel between the source access network device and the user plane functional network element (eg, UPF) for transmitting the first multicast service.
  • the user plane functional network element may include a function for performing user plane correlation for multicast services, that is, it can be considered that the user plane function is used for multicast services.
  • the functions for example, MUF, M-UPF, MS-UPF or MB-UPF
  • MUF, M-UPF, MS-UPF or MB-UPF related to the user plane of the service may be combined with the user plane functional network element to form a functional network element.
  • the session management function network element may include a function used to correlate the control plane of the multicast service, that is, the function used to correlate the control plane of the multicast service (for example, MCF, M-SMF, MS- SMF or MB-SMF) can be combined with the session management function network element as one function network element.
  • the function used to correlate the control plane of the multicast service for example, MCF, M-SMF, MS- SMF or MB-SMF
  • the first access network device sends the first information, including:
  • the first access network device sends a handover request to the second access network device, where the handover request is used to request that the first terminal device be handed over from the first access network device to the second access network device An access network device, wherein the handover request includes the first information.
  • the first access network device may receive a measurement report from the first terminal device and determine, according to the measurement report, that it needs to be handed over to the second access network device, or when determining that it needs to switch to the second access network device.
  • the device sends the handover request it can learn that the first terminal device is the last terminal device that joins the first multicast service through the first access network device.
  • the handover request sent by the first access network device to the second access network device may carry the first information.
  • the second access network device may send a path switch request (for example, an N2 path switch request, N2 Path Switch Request), the path switching request includes the above-mentioned first information.
  • the access and mobility management function network element may send a PDU session context update request (eg, Nsmf_PDUSession_UpdateSMContext Request) to the session management function network element, where the PDU session context update request includes the first information.
  • the session management function network element may send a first message to the multicast session management function network element, the first message. includes the first information.
  • the first message may be an N16 message.
  • the multicast session management function network element may send a fifth message to the multicast user plane function network element, and the fifth message may include the first information.
  • the fifth message may be an N4 session update request.
  • the multicast user plane function network element may obtain the first information according to the fifth message, and then release the first tunnel.
  • the session management function network element may send an N4 session update request to the user plane function network element, and the N4 session update request may include the first a message.
  • the user plane function network element may obtain the first information according to the N4 session update request, and then release the first tunnel.
  • the embodiment of the present application transmits the first information to the core network device by carrying the first information in the handover request sent by the first access network device to the second access network device, so that the The core network device may release the first tunnel according to the first information. Therefore, the embodiments of the present application can realize the release of the first tunnel for transmitting the data of the first multicast service between the access network device and the core network device in the Xn handover scenario, which helps to save network resource overhead.
  • the first access network device can carry the first information through existing signaling (such as a handover request), so that the first information is finally sent to the multicast user plane function network element, or
  • the user plane functional network element helps to further save the network resource overhead.
  • the first access network device sends the first information, including:
  • the first access network device sends a handover requirement (for example, handover required) to the first access and mobility management function network element, where the handover requirement includes the first information.
  • a handover requirement for example, handover required
  • the first access network device may learn about the first terminal device when it receives a measurement report from the first terminal device, or when it is determined to send a handover request to the first access and mobility management function network element. It is the last terminal device that joins the first multicast service through the first access network device. At this time, the handover requirement sent by the first access network device to the first access and mobility management function network element may include the above-mentioned first information.
  • the first access and mobility management function network element may be a source access and mobility management function network element.
  • the first access and mobility management function network element may send a request for creating a UE context (for example, Namf_Communication_CreateUEContext Request) to the second access and mobility management function network element, the request for creating a UE context includes the first information.
  • the second access and mobility management function network element sends a PDU session update context request to the session management function network element, and the PDU session update context request may include the first information.
  • the second access and mobility management function network element may be referred to as a target access and mobility management function network element.
  • the session management function network element may send a first message to the multicast session management function network element, the first message. includes the first information.
  • the first message may be an N16 message.
  • the multicast session management function network element may send a fifth message to the multicast user plane function network element, and the fifth message may include the first information.
  • the fifth message may be an N4 session update request.
  • the multicast user plane function network element may obtain the first information according to the fifth message, and then release the first tunnel. The multicast user plane function network element may also release the first tunnel according to the fifth message.
  • the session management function network element may send a session update request (such as an N4 session update request) to the user plane function network element, and the session update request can include the first information.
  • the multicast user plane function network element may obtain the first information according to the session update request, and then release the first tunnel.
  • the embodiment of the present application transmits the first information to The core network device enables the core network device to release the first tunnel according to the first information. Therefore, the embodiment of the present application can realize the release of the first tunnel between the access network device and the core network device for transmitting the data of the first multicast service in the N2 handover scenario, which helps to save network resource overhead.
  • the first access network device can carry the first information through existing signaling (for example, handover needs), so that the first information is finally sent to the multicast user plane function network element, or
  • the user plane functional network element helps to further save the network resource overhead.
  • the first access network device sends the first information, including:
  • the first access network device sends a third message to a third access and mobility management function network element, the third message includes the first information, and the third access and mobility management function network element When joining the first multicast service for the first terminal device, the access and mobility management function network element selected by the first access network device to serve the first multicast service.
  • the first access network device may learn at any time point in the handover preparation phase that the first terminal device is the last terminal device that joins the first multicast service through the first access network device.
  • the first access network device may learn at any time point in the handover preparation phase that the first terminal device is the last terminal device that joins the first multicast service through the first access network device.
  • the management function network element sends the above-mentioned third message, which is not limited in this application.
  • the third access and mobility management function network element receives the third message. Afterwards, the third access and mobility management function network element may send a fourth message to the multicast session management function network element, where the fourth message carries the first information. Exemplarily, the fourth message may be an N11 message. After receiving the fourth message, the multicast session management function network element may send a fifth message to the multicast user plane function network element, which carries the first information. Exemplarily, the fifth message may be an N4 session update request. Correspondingly, the multicast user plane function network element may obtain the first information according to the fifth message, and then release the first tunnel.
  • the third access and mobility management function network element may also be other access and mobility management function network elements related to or unrelated to the first terminal device.
  • the access and mobility management function network element related to the first terminal device may refer to the access for the non-access stratum (non-access stratum, NAS) signaling service of the first terminal device.
  • the access and mobility management function network element not related to the first terminal device may refer to an access and mobility management function network that is not serving the NAS signaling of the first terminal device Yuan.
  • the third access and mobility management function network element may be the same network element as the source access and mobility management function network element above, or the same network element as the target access and mobility management function network element above.
  • the mobility management function network element is the same network element, which is not limited in this embodiment of the present application.
  • the first information is transmitted to the core network device by carrying the first information in the third message sent by the first access network device to the third access and mobility management function network element.
  • the core network device can release the first tunnel according to the first information. Therefore, the embodiments of the present application can realize the release of the first tunnel between the access network device and the core network device for transmitting the data of the first multicast service, which helps to save network resource overhead.
  • a communication method comprising:
  • the second access network device receives a handover request from the first access network device, where the handover request is used to request that the first terminal device be handed over from the first access network device to the second access network device, the handover request includes first information, where the first information is used to release a first tunnel, and the first tunnel is used to transmit the first group between the first access network device and the core network device broadcast service data;
  • the second access network device sends a path switching request to the access and mobility management function network element, where the path switching request includes the first information.
  • a communication method comprising:
  • the access and mobility management function network element receives a path switch request from the second access network device, the path switch request includes first information, and the first information is used to release the first tunnel, the first tunnel for transmitting the data of the first multicast service between the first access network device and the core network device;
  • the access and mobility management function network element sends a protocol data unit PDU session context update request to the session management function network element, where the PDU session context update request includes the first information.
  • a communication method comprising:
  • the session management function network element receives a protocol data unit PDU session context update request from the access and mobility management function network element, the PDU session context update request includes first information, and the first information is used to release the first tunnel, The first tunnel is used to transmit data of the first multicast service between the first access network device and the core network device;
  • the session management function network element sends a first message to the multicast session management function network element, where the first message includes the first information.
  • the first message is an N16 message.
  • a communication method comprising:
  • the session management function network element receives a protocol data unit PDU session context update request from the access and mobility management function network element, the PDU session context update request includes first information, and the first information is used to release the first tunnel, The first tunnel is used to transmit data of the first multicast service between the first access network device and the core network device;
  • the session management function network element sends a session update request to the user plane function network element, where the session update request includes the first information.
  • a communication method comprising:
  • the multicast session management function network element receives a first message from the session management function network element, the first message includes first information, and the first information is used to release the first tunnel, and the first tunnel is used for data of the first multicast service is transmitted between the first access network device and the core network device;
  • the multicast session management function network element sends a fifth message to the multicast user plane function network element, where the fifth message includes the first information.
  • the first message is an N16 message.
  • the fifth message is an N4 session update request.
  • a communication method comprising:
  • the first access and mobility management function network element receives a handover requirement from the first access network device, the handover requirement includes first information, and the first information is used to release a first tunnel, the first tunnel for transmitting the data of the first multicast service between the first access network device and the core network device;
  • the first access and mobility management function network element sends a user equipment UE context creation request to the second access and mobility management function network element, where the first information is included in the UE context creation request.
  • a communication method comprising:
  • the second access and mobility management function network element receives a request for creating a user equipment UE context from the first access and mobility management function network element, where the request for creating a UE context includes first information, and the first information is used in releasing the first tunnel, the first tunnel is used to transmit the data of the first multicast service between the first access network device and the core network device;
  • the second access and mobility management function network element sends a protocol data unit PDU session context update request to the session management function network element, where the PDU session context update request includes the first information.
  • a communication method comprising:
  • the third access and mobility management function network element receives a third message from the first access network device, the third message includes first information, the first information is used to release the first tunnel, the first The tunnel is used to transmit the data of the first multicast service between the first access network device and the core network device, and the third access and mobility management function network element is added to the first terminal device.
  • the access and mobility management function network element selected by the first access network device for the first multicast service is used, the access and mobility management function network element selected by the first access network device for the first multicast service;
  • the third access and mobility management function network element sends a fourth message to the multicast session management function network element, where the fourth message includes the first information.
  • the third message is an N2 message.
  • a tenth aspect provides a communication method, comprising:
  • the multicast session management function network element receives a fourth message from the third access and mobility management function network element, where the fourth message includes first information, and the first information is used to release the first tunnel, and the The first tunnel is used to transmit the data of the first multicast service between the first access network device and the core network device, and the third access and mobility management function network element is added to the first terminal device.
  • the access and mobility management function network element selected by the first access network device for the first multicast service;
  • the multicast session management function network element sends a fifth message to the multicast user plane function network element, where the fifth message includes the first information.
  • the fifth message is an N4 session update request.
  • the fourth message is an N11 message.
  • a communication method comprising:
  • the multicast user plane function network element receives a fifth message from the multicast session management function network element, where the fifth message includes first information, and the first information is used to release the first tunnel, and the first tunnel is used for for transmitting data of the first multicast service between the first access network device and the core network device;
  • the multicast user plane functional network element releases the first tunnel according to the first information.
  • a twelfth aspect provides a communication method, the method comprising:
  • the user plane function network element receives a session update request from the session management network element, where the session update request includes first information, and the first information is used to release the first tunnel, and the first tunnel is used to The data of the first multicast service is transmitted between the network access device and the core network device;
  • the user plane function network element releases the first tunnel according to the first information.
  • the first tunnel may be released by removing related resources of the first tunnel, such as tunnel endpoint identifiers.
  • the first information includes an indication for releasing the first tunnel and the first tunnel Information
  • the releasing the first tunnel includes releasing the first tunnel according to the instruction for releasing the first tunnel and the information of the first tunnel.
  • the multicast user plane function network element or the user plane function network element can correspond to the first tunnel (for example, it may be one first tunnel, or multiple first tunnels, without limitation) to release.
  • the first information includes an indication for releasing the first tunnel and the first group The identification information of the broadcast service
  • the releasing the first tunnel includes:
  • the first tunnel is released.
  • the multicast session function network element or the session function network element can tunnel all the multicast sessions corresponding to the first multicast service indicated in the first information, that is, to be used between the source access network device and the core network device.
  • the first tunnel (eg, all first tunnels) transmitting the data of the first multicast service is released.
  • the first information includes an indication for releasing the first tunnel, the first group of the identification information of the broadcast service and the information of the first tunnel;
  • the releasing the first tunnel includes:
  • the first tunnel is determined in the tunnel for transmitting the data of the first multicast service between the first access network device and the core network device;
  • the first tunnel is released.
  • the multicast user plane function network element or the user plane function network element can release the first tunnel corresponding to the information of the first tunnel included in the first information.
  • the first tunnel is determined according to both the identification information of the first multicast service and the information of the first tunnel, it is only necessary to determine the first tunnel in one or more multicast session tunnels corresponding to the first multicast service.
  • a tunnel can help to determine the first tunnel more accurately and quickly, thereby helping to improve the efficiency of releasing the first tunnel.
  • a thirteenth aspect provides a communication apparatus, the apparatus comprising a module for performing any one of the first to twelfth aspects, or the communication method in any possible implementation manner of any aspect, or unit.
  • a fourteenth aspect provides a communication device comprising a processor for invoking and running a computer program from a memory to perform any one of the first to twelfth aspects, or any The communication method in any one possible implementation of an aspect.
  • the communication apparatus may further include a memory, where the memory is used to store the program executed by the processor.
  • An example of the communication apparatus may be an access network device, an access and mobility management function network element, a session management function network element, a multicast session management function network element, a multicast user plane function network element, and the like.
  • a fifteenth aspect provides a chip, the chip includes a processor and a communication interface, the communication interface is used to communicate with an external device or an internal device, and the processor is used to implement any one of the first to twelfth aspects above Aspect, or a method in any one possible implementation of any aspect.
  • the chip may further include a memory in which instructions are stored, and the processor is configured to execute the instructions stored in the memory or derived from other instructions.
  • the processor is configured to implement the method in any one of the above-mentioned first to twelfth aspects, or any possible implementation manner of any one aspect.
  • the chip may be integrated in an access network device, an access and mobility management function network element, a session management function network element, a multicast session management function network element or a multicast user plane function network element.
  • a computer-readable storage medium stores program codes executed by an apparatus for synchronizing, the program codes including a method for implementing any one of the first to twelfth aspects. , or an instruction of the method in any of the possible implementations of any aspect.
  • a seventeenth aspect provides a computer program product comprising instructions that, when the computer program product is run on a computer, cause the computer to perform any one of the first to twelfth aspects, or any one of the aspects method in one possible implementation.
  • a communication system comprising means for performing the method in the first aspect or any possible implementation manner of the first aspect, for performing the second aspect, the third aspect and the fourth aspect
  • the apparatus of the method of the aspect, and the apparatus of the method of the eleventh aspect or any possible implementation manner of the eleventh aspect are provided, comprising means for performing the method in the first aspect or any possible implementation manner of the first aspect, for performing the second aspect, the third aspect and the fourth aspect.
  • a nineteenth aspect provides a communication system, comprising a device for performing the method in the first aspect or any possible implementation manner of the first aspect, for performing the second aspect, the third aspect, the fifth aspect Aspects and apparatus of the method in the sixth aspect, and apparatus of the method in the twelfth aspect or any possible implementation manner of the twelfth aspect.
  • a communication system comprising means for performing the method in the first aspect or any possible implementation manner of the first aspect, for performing the seventh aspect, the eighth aspect and the fourth aspect
  • the apparatus of the method of the aspect, and the apparatus of the method of the eleventh aspect or any possible implementation manner of the eleventh aspect comprising
  • a communication system including a device for performing the method in the first aspect or any possible implementation manner of the first aspect, for performing the seventh aspect, the eighth aspect, the first aspect
  • a communication system including a device for performing the method in the first aspect or any possible implementation manner of the first aspect, for performing the method in the ninth aspect and the tenth aspect An apparatus for the method, and the apparatus for the method in the eleventh aspect or any possible implementation manner of the eleventh aspect.
  • FIG. 1 is a schematic diagram of a system architecture provided by an embodiment of the present application.
  • FIG. 2 is a schematic diagram of another system architecture according to an embodiment of the present application.
  • FIG. 3A is a schematic diagram of transmission of service data provided by an embodiment of the present application.
  • FIG. 3B is a schematic diagram of another service data transmission provided by an embodiment of the present application.
  • FIG. 4 is a schematic flowchart of a terminal device joining a multicast service.
  • FIG. 5A shows a schematic diagram of an application scenario applicable to the solution of the embodiment of the present application.
  • FIG. 5B shows a schematic diagram of an application scenario applicable to the solution of the embodiment of the present application.
  • FIG. 5C shows a schematic diagram of an application scenario applicable to the solution of the embodiment of the present application.
  • FIG. 6 shows a schematic flowchart of a communication method provided by an embodiment of the present application.
  • FIG. 7 is a specific example of a communication method provided by an embodiment of the present application.
  • FIG. 8 shows a schematic flowchart of another communication method provided by an embodiment of the present application.
  • FIG. 9 is a specific example of another communication method provided by an embodiment of the present application.
  • FIG. 10 is a specific example of another communication method provided by an embodiment of the present application.
  • FIG. 11 is a schematic structural diagram of a wireless communication device provided by an embodiment of the present application.
  • FIG. 12 is a schematic structural diagram of a network device provided by an embodiment of the present application.
  • GSM global system for mobile communications
  • CDMA code division multiple access
  • CDMA wideband code division multiple access
  • WCDMA wideband code division multiple access
  • general packet radio service general packet radio service, GPRS
  • long term evolution long term evolution
  • LTE long term evolution
  • SAE system architecture evolution
  • TDD LTE time division duplex
  • UMTS universal mobile telecommunication system
  • WiMAX worldwide interoperability for microwave access
  • FIG. 1 shows a schematic diagram of a communication system according to an embodiment of the present application.
  • 1 includes access network equipment, core network equipment and terminal equipment.
  • the terminal device is connected to the access network device, and the access network device is connected to the core network device, so that the terminal device can communicate with the core network device through the access network device.
  • the terminal equipment in the embodiments of the present application may also be referred to as: user equipment (user equipment, UE), mobile station (mobile station, MS), mobile terminal (mobile terminal, MT), access terminal, user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent or user device, etc.
  • user equipment user equipment
  • MS mobile station
  • MS mobile terminal
  • MT mobile terminal
  • access terminal user unit, user station, mobile station, mobile station, remote station, remote terminal, mobile device, user terminal, terminal, wireless communication device, user agent or user device, etc.
  • the terminal device may be a device that provides voice/data connectivity to the user, such as a handheld device with a wireless connection function, a vehicle-mounted device, and the like.
  • some examples of terminals are: mobile phone (mobile phone), tablet computer, notebook computer, PDA, mobile internet device (MID), wearable device, virtual reality (virtual reality, VR) device, augmented reality (augmented reality, AR) equipment, wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical surgery, and smart grids wireless terminal in transportation safety, wireless terminal in smart city, wireless terminal in smart home, cellular phone, cordless phone, session initiation protocol , SIP) telephones, wireless local loop (WLL) stations, personal digital assistants (PDAs), handheld devices with wireless communication capabilities, computing devices or other processing devices connected to wireless modems, automotive A device, a wearable device, a terminal device in a 5G network, or a terminal device in an evolved public land mobile network (Public Land Mobile Network, PLMN), etc., are not limited in
  • a wearable device may also be referred to as a wearable smart device, which is a general term for intelligently designing daily wearable devices and developing wearable devices using wearable technology, such as glasses, Gloves, watches, clothing and shoes, etc.
  • a wearable device is a portable device that is worn directly on the body or integrated into the user's clothing or accessories. Wearable device is not only a hardware device, but also realizes powerful functions through software support, data interaction, and cloud interaction.
  • wearable smart devices include full-featured, large-scale, complete or partial functions without relying on smart phones, such as smart watches or smart glasses, and only focus on a certain type of application function, which needs to cooperate with other devices such as smart phones.
  • the terminal device may also be a terminal device in an Internet of Things (IoT) system.
  • IoT Internet of Things
  • IoT is an important part of the future development of information technology, and its main technical feature is that items pass through communication technology Connect with the network, so as to realize the intelligent network of human-machine interconnection and interconnection of things.
  • the various terminal devices described above if they are located on the vehicle (for example, placed in the vehicle or installed in the vehicle), can be considered as on-board terminal equipment.
  • the on-board terminal equipment is also called on-board unit (OBU). ).
  • the terminal device may further include a relay (relay).
  • a relay relay
  • any device capable of data communication with the base station can be regarded as a terminal device.
  • the access network device in this embodiment of the present application may be a device used to communicate with a terminal device, and the access network device may also be referred to as an access device or a wireless access network device, and may be an evolved base station in an LTE system ( evolved NodeB, eNB or eNodeB), it can also be a wireless controller in a cloud radio access network (CRAN) scenario, or the access device can be a relay station, an access point, a vehicle-mounted device, or a wearable device.
  • the access equipment in the 5G network or the network equipment in the future evolved PLMN network, etc. can be an access point (access point, AP) in a WLAN, or a gNB in a new wireless system (new radio, NR) system.
  • the embodiments of the present application are not limited.
  • the access network device is a device in the RAN, or in other words, is a RAN node that accesses the terminal device to the wireless network.
  • an access network device it can be enumerated: gNB, transmission reception point (TRP), evolved Node B (evolved Node B, eNB), radio network controller (radio network controller) , RNC), Node B (Node B, NB), base station controller (base station controller, BSC), base transceiver station (base transceiver station, BTS), home base station (for example, home evolved NodeB, or home Node B, HNB ), base band unit (BBU), or wireless fidelity (wireless fidelity, Wifi) access point (access point, AP), etc.
  • a network device may include a centralized unit (CU) node, or a distributed unit (DU) node, or a RAN device including a CU node and a DU node, or a control plane CU node (CU).
  • CU centralized unit
  • DU distributed unit
  • RAN device including a CU node and a DU node, or a control plane CU node (CU).
  • CU-UP nodes user plane CU nodes
  • the access network equipment provides services for the cell, and the terminal equipment communicates with the access network equipment through the transmission resources (for example, frequency domain resources, or spectrum resources) used by the cell, and the cell may be the access network equipment (for example, the base station).
  • the cell can belong to the macro base station, or it can belong to the base station corresponding to the small cell (small cell), where the small cell can include: urban cell (metro cell), micro cell (micro cell), pico cell (pico cell) ), femto cells, etc.
  • These small cells have the characteristics of small coverage and low transmission power, and are suitable for providing high-speed data transmission services.
  • the access and mobility management function network element 130 and the session management function network element 140 belong to core network equipment.
  • the terminal device 110 may access the core network through the access network device 120, thereby implementing data transmission.
  • the access and mobility management function network element 130 may receive a request from an access network device to add the terminal device 110 to the multicast service, and request the session management function network element 140 to add the terminal device 110 to the multicast service.
  • the session management function network element 140 may create a corresponding multicast session tunnel for the terminal device 110 , add the terminal device 110 to the multicast service, and transmit the data stream of the multicast service to the terminal device 110 .
  • the foregoing system architecture 100 may be used to execute the method for transmitting a multicast service in the embodiment of the present application.
  • 5G system architecture Since the method for transmitting multicast services of the present application is mainly based on 5G mobile communication technology and other mobile communication technologies in the future, another system architecture of the embodiment of the present application, 5G system architecture, is introduced below with reference to FIG. 2 .
  • FIG. 2 is another system architecture 200 of an embodiment of the present application. As shown in FIG. 2, the system architecture 200 may specifically include the following network elements:
  • the (R)AN network element can manage wireless resources, provide access services for terminal equipment, and then complete the forwarding of control signals and user data between the terminal equipment and the core network.
  • (R)AN can also be understood as a base station in a traditional network. .
  • Access and mobility management function mainly used for mobility management and access management.
  • the AMF can be used to implement other functions other than session management among the functions of a mobility management entity (mobility management entity, MME), for example, functions such as legal interception, or access authorization (or authentication).
  • MME mobility management entity
  • functions such as legal interception, or access authorization (or authentication).
  • Session Management Function It is mainly used for session management, Internet Protocol (IP) address allocation and management of terminal devices, selection and management of user plane functions, policy control, or charging functions The endpoint of the interface and the downlink data notification, etc.
  • IP Internet Protocol
  • the terminal device 110 may be the UE in FIG. 2
  • the access network device 120 may be the RAN in FIG. 2
  • the access and mobility management function network element 130 may be the one in FIG. 2.
  • AMF; the session management function network element 140 may be the SMF in FIG. 2 , which is not limited.
  • system architecture 200 may further include:
  • User plane function It can also be called a user plane function network element, which is used for packet routing and forwarding, or quality of service (QoS) processing of user plane data.
  • UPF is specifically divided into intermediate-UPF (intermediate-UPF, I-UPF) and anchor UPF (PDU session anchor, PSA).
  • Data network A network used to provide data transmission, such as the Internet network.
  • the PSA accesses the remote DN, and the L-PSA can access the local DN.
  • AUSF Authentication server function
  • PCF Policy control function
  • Unified data management used to handle user identification, access authentication, registration, or mobility management, etc.
  • Application function mainly supports interaction with the 3rd generation partnership project (3GPP) core network to provide services, such as influencing data routing decisions, policy control functions, or providing services to the network side Provide some services of third parties.
  • 3GPP 3rd generation partnership project
  • It can be understood as a third-party server, such as an application server in the Internet, that provides relevant service information, including providing service quality requirement information corresponding to the service to the PCF, and sending user plane data information of the service to the PSA-UPF.
  • the AF may be a service provider (content provider, CP).
  • NSSF Network slice selection function
  • the N1 interface is the reference point between the terminal device and the AMF; the N2 interface is the reference point between the (R)AN and AMF, used for sending non-access stratum (NAS) messages etc.; N3 interface is the reference point between (R)AN and I-UPF, used to transmit user plane data, etc.; N4 interface is the reference point between SMF and I-UPF, used to transmit tunnels such as N3 connections Identification information, data buffer indication information, and downlink data notification messages; N5 interface is the reference point between PCF and AF; N6 interface is the reference point between UPF and DN, used to transmit user plane data, etc.; N7 The interface is the reference point between SMF and PCF; the N8 interface is the reference point between AMF and UDM; the N9 interface is the reference point between UPF; the N10 interface is the reference point between SMF and UDM; the N11 interface is the reference point between AMF and UDM. Reference point between SMF; N12 interface is the reference point between AMF and AUSF
  • system architecture 200 may further include:
  • Multicast control plane function or called multicast session management function (M-SMF) or multicast service session management function (MSF) -SMF) or multicast/broadcast session management function (MB-SMF), which is used to perform control plane related functions for multicast services, for example, MCF or M-SMF or MB-SMF with PCFs are interconnected to create resources for multicast services.
  • MCF multicast session management function
  • MSF multicast service session management function
  • MB-SMF multicast/broadcast session management function
  • multicast in this application is a broad concept, which may include multicast (multicast) or broadcast (broadcast), that is, the embodiments of this application can be applied to multicast service transmission, It can also be applied to broadcast service transmission. References to "multicast” in this application may be replaced by "multicast or broadcast”. Therefore, Multicast Control Plane Function (MCF), Multicast Session Management Function (M-SMF), Multicast Service Session Management Function (MS-SMF), and Multicast/Broadcast Session Management Function (MB-SMF) have the same meaning. , can be replaced with each other, which is not limited here.
  • MCF Multicast Control Plane Function
  • M-SMF Multicast Session Management Function
  • MS-SMF Multicast Service Session Management Function
  • M-SMF Multicast/Broadcast Session Management Function
  • Multicast user plane function also known as multicast user plane function (M-UPF), or multicast service user plane function (multicast service user plane function) , MS-UPF), or multicast/broadcast user plane function (MB-UPF), which is used to perform user plane-related functions on multicast services, such as transmitting multicast service data.
  • M-UPF multicast user plane function
  • MS-UPF multicast service user plane function
  • MB-UPF multicast/broadcast user plane function
  • multicast in this application is a broad concept, which may include multicast (multicast) or broadcast (broadcast), that is, the embodiments of this application can be applied to multicast service transmission, It can also be applied to broadcast service transmission. References to "multicast” in this application may be replaced by "multicast or broadcast”. Therefore, Multicast User Plane Function (MUF), Multicast User Plane Function (M-UPF), Multicast Service Session Management (MS-UPF), and Multicast/Broadcast Session Management (MB-UPF) have the same meaning and can be Mutual replacement, not limited here.
  • M-UPF Multicast User Plane Function
  • MS-UPF Multicast Service Session Management
  • MB-UPF Multicast/Broadcast Session Management
  • MCF or MS-SMF or MS-SMF or MB-SMF can be integrated into PCF (or SMF or NEF), MUF or M-UPF or MS-UPF or MB-UPF can be integrated into UPF, This embodiment of the present application does not limit this.
  • system architecture 200 applied to the embodiments of the present application is only a network architecture described from the perspective of the reference point architecture, and the network architecture applied to the embodiments of the present application is not limited thereto.
  • the network architectures of the functions of the elements are all applicable to the embodiments of the present application.
  • each network element such as SMF, AF, UPF, etc.
  • the above-mentioned network elements may also have other names, which are not specifically limited in this embodiment of the present application.
  • the 6th generation (the 6th generation, 6G) network some or all of the above network elements may use the terms in 5G, or may use other names, etc., which will be uniformly explained here, and will not be described below. Repeat.
  • the names of the messages (or signaling) transmitted between the above network elements are only an example, and do not constitute any limitation on the functions of the messages themselves.
  • Unicast It can be understood as "point to point” communication. Unicast contains multiple meanings, as follows:
  • unicast service means that the data of the service is sent to a specific terminal device.
  • unicast refers to a unicast tunnel between the source network element and the target network element (that is, the IP address of the target network element is a unicast IP address).
  • the air interface unicast mode means that the wireless access network sends service data to a single terminal device.
  • unicast refers to sending service data to terminal devices through a protocol data unit (PDU) session.
  • PDU protocol data unit
  • the unicast mode in the sending mode determined by the SMF refers to sending the data of the multicast service to the terminal device through the PDU session.
  • Multicast It can be called “multicast”, which can be understood as “point to multi-point” (PTM) communication. Multicast contains multiple meanings, as follows:
  • multicast service means that the data of the service is sent to multiple terminal devices.
  • multicast refers to a multicast tunnel between the source network element and the target network element (that is, the IP address of the target network element is the multicast IP address).
  • the air interface multicast mode refers to a piece of service data sent to the wireless access network, which can be received by multiple terminal devices at the same time and/or on the same frequency.
  • multicast refers to sending multicast service data to terminal devices through a multicast session, where a multicast session includes: unicast tunnels or multicast tunnels between network elements, and unicast mode air interface wireless Air interface radio bearer in bearer or multicast mode.
  • the multicast mode in the sending mode determined by the SMF refers to sending the data of the multicast service to the terminal device through the multicast session.
  • the multicast mode it is possible to transmit service data to all target nodes at one time, or to transmit service data only to specific objects. Therefore, in the multicast mode, a point-to-multipoint transmission between one sending node and multiple receiving nodes can be achieved. point transmission, thus solving the problem of low efficiency in unicast mode.
  • the broadcast service may be sent to the terminal device through a multicast session, which is not limited in this embodiment of the present application.
  • the "multicast” in the present application is a broad concept, which may include multicast (multicast) or broadcast (broadcast), that is, the embodiments of the present application can be applied to both multicast service transmission and broadcast service transmission. References to “multicast” in this application may be replaced by "multicast or broadcast”.
  • FIG. 3A is a schematic diagram of transmission of service data provided by an embodiment of the present application.
  • the schematic diagram shown in FIG. 3A can be used to transmit multicast service data (by unicast mode), and can also be used to transmit unicast service data.
  • each of the three UEs corresponds to a different PDU session.
  • the three different service data sent by the CP can be sent to the UE through their corresponding PDU sessions.
  • the service transmission path from the CP to the AN may include the transmission path between the CP and the UPF, and the transmission path between the UPF and the AN.
  • the transmission path between the UPF and the AN may be called a PDU session tunnel, and different PDU sessions have different PDU session tunnels.
  • the three PDU session tunnels in this schematic diagram correspond to three UEs respectively.
  • the AN can send service data to UE 1, UE 2 and UE 3 in a unicast mode, namely PTP mode.
  • the service data of each UE may be different (for example, the target addresses are the IP addresses of the UEs respectively), and the service data of each UE may be sent to each UE through their respective independent transmission paths.
  • FIG. 3B is a schematic diagram of another service data transmission provided by an embodiment of the present application.
  • the schematic diagram shown in FIG. 3B is used for transmitting multicast service data.
  • multicast service data can be sent from the CP to UE1, UE2 and UE3.
  • the transmission path of the multicast service from the CP to the AN may include the transmission path between the CP and the UPF, and the transmission path between the UPF and the AN.
  • the transmission path from the UPF to the AN may use a tunnel to transmit multicast service data, for example, a tunnel based on a general tunnel protocol (GTP).
  • GTP general tunnel protocol
  • the transmission path between the UPF and the AN can be called a multicast session tunnel, and the multicast session tunnel is shared by UE1, UE2, and UE3.
  • the AN can send the above-mentioned multicast service data to UE1, UE2 and UE3 through PTM, that is, only one piece of data needs to be sent, and all three UEs can receive it.
  • PTM Packet Transfer Protocol
  • only one copy of the multicast service data is sent on the transmission path from the CP to the UE, and multiple UEs can receive it at the same time.
  • both the multicast session tunnel and the PDU session tunnel are tunnels between a user plane network element (eg, UPF) and an access network AN (eg, a base station).
  • the multicast session tunnel can be used to transmit the multicast QoS flow of the multicast service
  • the PDU session tunnel can be used to transmit the unicast QoS flow of the unicast service, and can also be used to correspond to the multicast QoS flow of the multicast service.
  • unicast QoS flow unicast QoS flow.
  • the multicast QoS flow is transmitted between UPF and gNB 1; , Radio link control (radio link control, RLC) layer, media access control (media access control, MAC) layer, physical (physical, PHY) layer processing, the data received by each UE can be called multicast service data .
  • Radio link control radio link control, RLC
  • media access control media access control
  • PHY physical
  • Multicast service multicast service flow and multicast quality of service (QoS) flow
  • the multicast service may include one or more multicast service flows, which are represented by the information of the multicast service.
  • the information of the multicast service includes at least the description information of the multicast service
  • the description information of the multicast service may include the description information of one or more multicast service flows, wherein the description information of the multicast service flow includes at least one of the following :
  • the quality of service index (QoS flow identifier, QFI) that the multicast service flow should have the characteristic information of the multicast service flow (such as the multicast address, destination port number, source address, etc. of the multicast service), the multicast service flow QoS requirements (such as jitter, delay, packet loss rate, bandwidth, etc.).
  • a multicast session can include one or more multicast QoS flows.
  • the multicast service can be transmitted in the form of one or more multicast QoS flows in the multicast session tunnel where the multicast session is located.
  • the PDU session is at the UE level, and the multicast session is at the service level.
  • a PDU session of a UE can be associated with multiple multicast sessions, that is, the PDU session of the UE can join multiple multicast services, and a multicast service can be served by a multicast session.
  • the information of the multicast service may also include information of the terminal equipment, for example, may include the identifier of one or more terminal equipments that allow (or request) to join the multicast service, the terminal equipment Group ID, etc.
  • a multicast service can be assigned a globally unique multicast service identifier (multicast ID, MCID), and the MCID can uniquely identify the multicast service within the PLMN.
  • multicast ID multicast ID
  • MCID globally unique multicast service identifier
  • this application does not limit the English name MCID, and the MCID can also be replaced with other names, but its function is to uniquely identify the multicast service.
  • the MCF shown in FIG. 2 can obtain multicast service information from the CP, and then send the obtained multicast service information to the PCF, and the PCF can generate a policy and charging control (policy and charging) according to the multicast service information. control, PCC) rules. Wherein, if the multicast service information can be applied to all terminal devices, the generated PCC rule can also be applied to all terminal devices.
  • the generated PCC rules may be related to one or more terminal devices related to the multicast service.
  • the MCF allocates the MCID for the multicast service, and then the MCF can send the MCID together with the multicast service information to the PCF.
  • the PCC rule generated by the PCF for the multicast service may also include the MCID.
  • the MCF does not allocate the MCID for the multicast service, and the PCF allocates the MCID, and the PCF may send the MCID allocated for the multicast service to the MCF in the response message.
  • the fact that the access network device supports the multicast function can be understood as the fact that the access network device supports the PTM data transmission method to send multicast service data to the terminal device, and the access network device does not support the multicast function can be understood as the connection
  • the network access device does not support sending multicast service data to the terminal device in the PTM data sending mode.
  • the joined multicast service of the terminal device can be sent through the PDU session.
  • multicast service data can be received from the core network through a multicast session tunnel and sent to multiple terminal devices that join the multicast service.
  • the PDU session of the terminal device needs to be switched from the source access network device to the target access network device.
  • the PDU session can be called the PDU session of the switched terminal device.
  • the PDU session is associated with the multicast service, which can be understood as the context of the PDU session is associated with the multicast service.
  • the terminal device can apply to join the multicast service on the source access network device through the user plane or control plane of the PDU session.
  • PDU sessions are associated with multicast services. Exemplarily, if the terminal device joins to watch CCTV 1 through the user plane of the PDU session, then the PDU session is associated with a multicast service; if the terminal device joins to watch CCTV 10 again, then the PDU session is associated with a multicast service. .
  • the multicast service can be transmitted to the source through the multicast session tunnel in the form of a multicast QoS stream.
  • the access network device and the source access network device can send multicast service data to the terminal device in a point-to-point or point-to-multipoint air interface manner.
  • the multicast service is transmitted to the source access network through the PDU session tunnel in the form of a unicast QoS stream.
  • the network access device and the source access network device send multicast service data to the terminal device in a point-to-point manner over the air interface.
  • the multicast service data arrives at the RAN, it passes through the service data adaptation protocol (SDAP) layer of the RAN, the packet data convergence protocol (PDCP) layer, and the radio link control (radio link) layer. control, RLC) layer, media access control (media access control, MAC) layer, physical (physical, PHY) layer
  • SDAP service data adaptation protocol
  • PDCP packet data convergence protocol
  • RLC radio link control
  • media access control media access control
  • MAC physical (physical, PHY) layer
  • 3GPP has approved a project to study how to support the multicast broadcast function (ie, 5G multicast broadcast service, 5MBS) on the basis of the current 5G network architecture as a key research topic.
  • 5G multicast broadcast service 5MBS
  • 5G or future evolving networks access network equipment that supports multicast functions will be deployed.
  • the terminal equipment joins the multicast service for UE1, UE2, and UE3 as an example for description.
  • steps 401 to 410 describe the process of the UE1 joining the multicast service through the source gNB (source gNB, S-gNB) and the SMF1.
  • the transmission path of the multicast service includes the transmission path between the MUF and the UPF1, and the transmission path between the UPF1 and the S-gNB.
  • UE1 sends a request for joining the multicast service to SMF1, where the request includes relevant information of the multicast service.
  • the relevant information may be, for example, an identifier of a multicast service, or multicast IP address information.
  • SMF1 sends message #1 to MCF, where message #1 is used to notify MCF that UE1 joins the multicast service through S-gNB and SMF1.
  • the MCF sends a message #2 to the SMF1, where the message #2 is used to respond to the message #1 in step 402.
  • the SMF1 sends an N2 PDU session request (N2 PDU session request) to the S-gNB, which is used to request the S-gNB to allocate relevant air interface resources of the multicast service to the UE1.
  • N2 PDU session request N2 PDU session request
  • the S-gNB allocates the relevant air interface resources of the multicast service to the UE1, and generates its own tunnel identification information.
  • the S-gNB sends an N2 PDU session response (N2 PDU session response) to the SMF1, which carries the tunnel identification information of the S-gNB.
  • N2 PDU session response N2 PDU session response
  • SMF1 sends an N4 session establishment/modification request (N4 session establishment/modification request) to UPF1, which includes the tunnel identification information of the S-gNB and the tunnel identification information allocated by SMF1 for UPF1. After that, UPF1 sends N4 session establishment/modification response (N4 session establishment/modification response) to SMF1. Then, the multicast session tunnel between S-gNB and UPF1 is established.
  • N4 session establishment/modification request N4 session establishment/modification request
  • UPF1 sends N4 session establishment/modification response (N4 session establishment/modification response) to SMF1.
  • N4 session establishment/modification response N4 session establishment/modification response
  • the SMF1 sends a message #3 to the MCF, where the message #3 is used to request the establishment of a tunnel for transmitting multicast service data between the MUF and the UPF1.
  • message #3 may carry the tunnel identification information allocated by SMF1 to UPF1.
  • the MCF sends an N4 session establishment/modification request to the MUF, including the tunnel identification information allocated by the SMF1 for the UPF1, and also includes the tunnel identification information allocated by the MCF for the MUF.
  • the MUF sends an N4 session establishment/modification response to the MCF, and the MUF and the UPF1 The tunnel between them is established.
  • the MCF sends a message #4 to the SMF1, and the message #2 is used to respond to the message #3 in step 408.
  • a multicast service data transmission path from the multicast service source to the MUF to the UPF1 to the S-gNB is established.
  • the UE1 can receive the multicast service data through the multicast service data transmission path.
  • the UE2 can also join the multicast service through the S-gNB and the SMF1. For example, refer to steps 411 to 414 below.
  • UE2 sends a request for joining the multicast service to SMF1, where the request includes relevant information of the multicast service.
  • the request includes relevant information of the multicast service.
  • relevant information of the multicast service reference may be made to the description in step 401 .
  • SMF1 sends an N2 PDU session request (N2 PDU session request) to the S-gNB, which is used to request the S-gNB to allocate relevant air interface resources of the multicast service to UE2.
  • N2 PDU session request N2 PDU session request
  • UE2 also applies for joining the multicast service through S-gNB and SMF1
  • UE1 and UE2 apply for joining the multicast service through the same SMF (ie SMF1)
  • SMF1 only needs to request S-gNB to allocate multicast services to UE2
  • the air interface resources of the service that is, the S-gNB still receives the multicast service data through the multicast session tunnel between the UPF1 and the S-gNB, and sends the multicast service data to the UE2.
  • the S-gNB allocates the relevant air interface resources of the multicast service to the UE2.
  • the S-gNB sends an N2 PDU session response (N2 PDU session response) to the SMF1 for responding to step 412.
  • N2 PDU session response N2 PDU session response
  • a multicast service data transmission path from the multicast service source to the MUF to the UPF1 to the S-gNB is established.
  • UE2 can receive the multicast service data through the multicast service data transmission path.
  • UE3 can also join the multicast service. Different from UE1 and UE2 joining the multicast service, UE3 joins the multicast service through S-gNB and SMF2. Wherein, the transmission path of the multicast service includes the transmission path between the MUF and the UPF2, and the transmission path between the UPF2 and the S-gNB. For example, refer to steps 415 to 424 below.
  • UE3 sends a request for joining the multicast service to SMF2, where the request includes relevant information of the multicast service.
  • steps 416 to 424 need to be performed.
  • SMF2 SMF2
  • a multicast service data transmission path from the multicast service source to the MUF to the UPF2 to the S-gNB is established.
  • the UE3 may receive the multicast service data through the multicast service data transmission path.
  • the UE may be triggered to perform handover, eg, handover from an S-gNB to a target gNB (target gNB, T-gNB), causing the UE to withdraw from the multicast service joined by the source access network device.
  • handover eg, handover from an S-gNB to a target gNB (target gNB, T-gNB)
  • target gNB target gNB
  • T-gNB target gNB
  • UE1 switches and exits the multicast service joined by SMF1 and S-gNB.
  • UE2 switches and exits the multicast service joined by SMF1 and S-gNB.
  • UE3 switches and exits the multicast service joined by SMF2 and S-gNB.
  • the T-gNB may support the multicast function or not support the multicast function, which is not limited in this embodiment.
  • the terminal device When the terminal device is switched from the source access network device that supports the multicast function to the target access network device (the target access network device supports the multicast function or does not support the multicast function), in order to save the network resource overhead, how to release the source access network device?
  • the multicast session tunnel between the network access device and the core network device is an urgent problem to be solved.
  • the embodiments of the present application provide a communication method and apparatus, in which the source access network device or the session management function network element can learn that after the terminal device is switched from the source access network device to the target access network device, no There is another terminal device that receives the data of the multicast service through the source access network device, that is, the terminal device is the last terminal device that receives the data of the multicast service through the source access network device, and it is determined to release the source access network device. Multicast session tunnel with core network equipment.
  • the technical solution of the present application can be applied to a wireless communication system, for example, the communication system shown in FIG. 1 or the communication system shown in FIG. 2 .
  • Communication devices in a wireless communication system may have a wireless communication connection relationship.
  • One of the communication devices may be, for example, an access network device (such as a source access network device), or a chip configured in the access network device (such as a source access network device), and another device may be, for example, a session A management function network element, or a chip configured in the session management function network element. This embodiment of the present application does not limit this.
  • any access network device in the wireless communication system or a chip configured in the access network device can communicate based on the same method, and any session management function network element in the wireless communication system or configured in the The chips in the session management function network element can all communicate based on the same method. This application does not limit this.
  • UE2 is handed over from S-gNB to T-gNB1, and T-gNB1 supports the multicast function.
  • a multicast session tunnel and a PDU session tunnel exist between S-gNB and UPF1, and a multicast session tunnel and PDU session tunnel exist between T-gNB1 and UPF1.
  • a forwarding tunnel corresponding to the PDU session tunnel and a forwarding tunnel corresponding to the multicast session tunnel between the S-gNB and the T-gNB1.
  • UPF1 and UE2 in FIG. 5A may be UPF1 and UE2 in FIG. 4 .
  • FIG. 5A only takes the T-gNB1 supporting the multicast function as an example for description, but the embodiment of the present application is not limited to this.
  • the T-gNB1 may also not support the multicast function.
  • the T-gNB1 does not support the multicast function, there is no multicast session tunnel between the T-gNB1 and the UPF1, and there is no forwarding tunnel corresponding to the multicast session tunnel between the S-gNB and the T-gNB1.
  • the UE is handed over from the S-gNB to the T-gNB, and the T-gNB does not support the multicast function.
  • There is a multicast session tunnel between the S-gNB and the MUF a PDU session tunnel exists between the S-gNB and the UPF, and a PDU session tunnel exists between the T-gNB and the UPF.
  • a forwarding tunnel corresponding to the PDU session tunnel exists between the S-gNB and the T-gNB, and there is no forwarding tunnel corresponding to the multicast session tunnel.
  • FIG. 5B only takes the T-gNB not supporting the multicast function as an example for description, but the embodiment of the present application is not limited to this.
  • the T-gNB may also support multicast functionality.
  • a multicast session tunnel exists between the T-gNB and the MUF, and a forwarding tunnel corresponding to the multicast session tunnel exists between the S-gNB and the T-gNB.
  • the UE is switched from the S-gNB to the T-gNB, and the T-gNB does not support the multicast function.
  • There is a multicast session tunnel between the S-gNB and the MUF a PDU session tunnel exists between the S-gNB and the UPF, and a PDU session tunnel exists between the T-gNB and the UPF.
  • FIG. 5C only takes the T-gNB not supporting the multicast function as an example for description, but the embodiment of the present application is not limited to this.
  • the T-gNB may also support multicast functionality.
  • the T-gNB supports multicast session tunnels
  • there are multicast session tunnels between T-gNB and MUF and there are indirect multicast session tunnels between S-gNB and UPF, and between UPF and T-gNB.
  • the embodiments of this application can also be applied to the scenario where the T-gNB supports the multicast function.
  • FIG. 5A , FIG. 5B and FIG. 5C are special scenarios for the convenience of describing the technical solutions of the embodiments of the present application, and the technical solutions provided by the embodiments of the present application are not limited to FIG. 5A , FIG. 5B and Limitations of Figure 5C.
  • the technologies provided in the embodiments of the present application are also applicable to other unlisted scenarios.
  • other unlisted scenarios may include, for example, the following three situations.
  • Case 1 for the PDU session of the switched terminal device, during the switching process, the SMF and the anchor UPF serving the PDU session of the switched terminal device are unchanged.
  • the anchor point UPF is UPF1 in the figure, and for Figures 5B and 5C, it is UPF.
  • Case 2 For the multicast service associated with the source access network device of the PDU session of the switched terminal device, it is assumed that the control plane multicast network element serving the group service of the source access network device is MCF-1, and the user plane If the multicast network element is MUF-1, then MUF-1 can be connected to the anchor point UPF where the PDU session of the terminal device is located (that is, the MUF is connected to UPF1 in FIG. 5A ). Optionally, MUF-1 may also be connected to the source access network device. In addition, MUF-1 can also be connected to source access network equipment through other UPFs. That is to say, MUF-1 can also be connected to other UPFs other than the anchor UPF of the PDU session of the terminal device.
  • the network elements serving the multicast service may be MCF-1 and MUF-1, or may be are other MCFs and MUFs.
  • the MUF can be directly connected to the target access network device, or can be connected to the anchor UPF of the PDU session of the terminal device to be switched, or can be connected to the target access network device through other UPFs (ie, non-anchor UPFs). .
  • FIG. 6 shows a schematic flowchart of a communication method 600 provided by an embodiment of the present application from the perspective of device interaction. As shown in FIG. 6 , method 600 includes steps 610-630.
  • the session management function network element learns that after the first terminal device is switched from the first access network device to the second access network device, there is no terminal device that receives data of the first multicast service through the first access network device .
  • the first multicast service means that data of the service can be sent to multiple terminal devices.
  • the multicast service and multicast reference may be made to the above description, and details are not repeated here.
  • the first access network device may be referred to as a source access network device, and the second access network device may be referred to as a target access network device.
  • the session management function network element can determine that after the first terminal device is switched from the source access network device to the target access network device, there is no other terminal device receiving the first multicast service through the source access network device. data (that is, there is no other terminal device joining the first multicast service through the session management function network element and the source access network device).
  • the number of terminal devices that join the multicast service through the source access network device may include a multicast context (Multicast Context) corresponding to the multicast service associated with the PDU session of the first terminal device or Multicast session context (Multicast Session Context) or multicast group context (Multicast Group Context) or multicast service context (Multicast Service Context). That is to say, whether the session management network element still exists in the Multicast Context or Multicast Session Context or Multicast Group Context or Multicast Service Context Other terminal devices other than the terminal device receive the first multicast service to determine that there is no traffic through the first access network after the first terminal device switches from the first access network device to the second access network device A terminal device that receives data of the first multicast service.
  • Multicast Context Multicast context corresponding to the multicast service associated with the PDU session of the first terminal device
  • Multicast Session Context Multicast Session Context
  • Multicast Group Context Multicast Group Context
  • Multicast Service Context multicast service context
  • the session management function network element may further update the number of terminal devices that join the multicast service with the source access network device through the session management function network element.
  • the session management network element updates the multicast context (Multicast Context) or multicast session context (Multicast Session Context) or the corresponding multicast service associated with the PDU session of the first terminal device.
  • the number of terminal devices in the multicast group context (Multicast Group Context) or the multicast service context (Multicast Service Context) that join the multicast service through the session management function network element and the source access network device such as the number of terminal devices. Subtract 1 to obtain the number of terminal devices currently participating in the first multicast service through the network element with the session management function and the source access network device.
  • the session management function network element may, after the first terminal device is switched from the source access network device to the target access network device, update the saved session management function network element and the access network device and join the Before determining the number of terminal devices of the multicast service, it is determined whether other terminal devices receive data of the first multicast service through the source access network device. At this time, the session management function network element may determine that the first terminal device is the last terminal device that joins the first multicast service through the session management function network element and the source access network device, that is, through the session management function network element. When the number of terminal devices joining the first multicast service by the source access network device and the source access network device is 1 (that is, the first terminal device), it is known that no other terminal device receives the first multicast service through the source access network device. Multicast service data.
  • the session management function network element may be added to the session management function network element and the access network device after the first terminal device is switched from the source access network device to the target access network device, and after updating the saved session management function network element and the access network device.
  • the session management function network element After the number of terminal devices of the multicast service, it is determined whether there are other terminal devices that receive the data of the first multicast service through the source access network device.
  • the session management function network element may know that no other terminal device has passed through the session management function network element and the source access network device. The source access network device receives the data of the first multicast service.
  • the network element of the session management function notifies the user plane function to release the first tunnel.
  • the first tunnel is used to transmit the data of the first multicast service between the first access network device and the core network device.
  • the core network device may be a UPF.
  • the first tunnel may include a tunnel between the first access network device and the UPF for transmitting the first multicast service, that is, a multicast session tunnel for transmitting the first multicast service.
  • a multicast session tunnel for transmitting the first multicast service.
  • the session management function network element learns that after the first terminal device is switched from the first access network device to the second access network device, there is no other terminal device that receives the first multicast service through the first access network device After that, the user plane function can be notified to release the first tunnel.
  • the session management network element may send an N4 session update request to the first terminal device, which carries the first information for releasing the first tunnel.
  • the first information may include an indication (indication) to release the first tunnel, a request (request) to release the first tunnel, or a notification (notify or notification) to release the first tunnel.
  • the first information may also include information of the first tunnel and/or identification information of the first multicast service, which is not limited in this embodiment of the present application.
  • the first information may include an indication, a request, or a notification (notify or notification) for releasing the first tunnel, and may also include information of the first tunnel.
  • the first information may further include identification information of the first multicast service, which is not limited in this embodiment of the present application.
  • the first information may include an indication, a request, or a notification (notify or notification) for releasing the first tunnel, and may also include information about the first tunnel, and identification information of the first multicast service, This embodiment of the present application does not limit this.
  • the information of the first tunnel can be used to uniquely determine the first tunnel, for example, it can be a tunnel endpoint identifier (tunnel endpoint identifier, TEID) of the first tunnel, which is not limited here.
  • the identification information of the first multicast service can be used to uniquely determine a multicast service, for example, it can be the ID of the multicast service, or the name of the multicast service, or the multicast address, or the multicast group ID, etc., which are not limited here.
  • the user plane function releases the first tunnel.
  • the user plane function may release the first tunnel after receiving the N4 session update request (which carries the first information) sent by the network element of the session management function, for example, remove the first tunnel according to the tunnel identification information in the first information. Relevant resources of the first tunnel (eg, remove the tunnel endpoint identifier of the first tunnel).
  • the session management function network element may know that after the first terminal device is switched from the first access network device to the second access network device, there is no other terminal device through the first access network device.
  • an access network device receives the data of the first multicast service, it notifies the user plane function to release the first data between the source access network device and the core network device for transmitting the first multicast service tunnel, so as to realize the release of the multicast session tunnel between the access network device and the core network device, which helps to save the network resource overhead.
  • the core network device further includes AMF, MCF and MUF.
  • the MCF and MUF may not be included in the core network device, but the functions of the MCF are implemented by some functions or units in the SMF, and the functions or units in the UPF are implemented.
  • the function of the MUF is not limited in this embodiment of the present application.
  • FIG. 7 shows a schematic flowchart of another communication method 700 provided by an embodiment of the present application.
  • SMF1 determines whether the multicast session tunnel between S-gNB and UPF1 needs to be released.
  • the UE2 in FIG. 4 is used as an example for description, that is, the method 700 describes that, in step 426 in FIG. 4 , UE2 is handed over and exits through SMF1 and S - The process of SMF1 judging whether it is necessary to release the multicast session tunnel between S-gNB and UPF1 after the multicast service joined by gNB.
  • the method 700 may be applicable to the scenario shown in FIG. 5A .
  • the method 700 will be described in conjunction with the scenario in FIG. 5A.
  • method 700 may include steps 701 to 716 . It should be noted that this solution is also applicable to the scenario where the T-gNB1 does not support the multicast function, which is not limited here, and the scenario shown in FIG. 5A is only an example.
  • FIG. 7 shows the steps or operations of the communication method 700 provided by this embodiment of the present application, but these steps or operations are only examples, and this embodiment of the present application may also perform other operations or variations of the respective operations in FIG. 7 . Furthermore, the various steps in the figures may be performed in a different order than they are presented, and it is possible that not all operations in the figures are performed.
  • the S-gNB can learn the capability of the T-gNB1, that is, whether it supports the capability of the multicast function.
  • T-gNB1 can notify S-gNB of its own capability information through Xn interface, where Xn can be the connection between S-gNB and T-gNB Interface for Xn connection.
  • the T-gNB sends the indication information #1 to the S-gNB, where the indication information #1 is used to instruct the T-gNB1 to support the multicast function.
  • UE2 sends a measurement report (Measurement Report) to the S-gNB.
  • the S-gNB receives the measurement report and decides to switch UE2 to T-gNB1.
  • the S-gNB sends a handover request (Handover Request) to the T-gNB1.
  • the S-gNB can learn that the T-gNB1 supports the multicast function.
  • the handover request may include PDU session information of the UE2 to be handed over, wherein the PDU session information includes a PDU session identifier and QoS information corresponding to a unicast service included in the PDU session.
  • the PDU session information further includes QoS information corresponding to the associated multicast service.
  • the QoS information of the unicast service includes the identifier (QoS flow identifier, QFI) and QoS parameters of the unicast QoS flow corresponding to the unicast service
  • the QoS information of the multicast service includes the multicast QoS flow corresponding to the multicast service.
  • QoS flow identifier (QFI) and QoS parameters are examples of the multicast service.
  • the handover request may further include the QFI of the QoS flow that the S-gNB wishes to forward to the T-gNB1 and the forwarding tunnel endpoint identifier generated by the S-gNB.
  • the QoS flow that the S-gNB wishes to forward to the T-gNB1 may be a unicast QoS flow and/or a multicast QoS flow.
  • the handover request may include the QFI of the multicast QoS flow and the forwarding tunnel corresponding to the multicast session tunnel generated by the S-gNB. the endpoint identifier.
  • the handover request may include the QFI of the unicast QoS flow and the forwarding tunnel endpoint identifier corresponding to the unicast session tunnel generated by the S-gNB.
  • the handover request can include the QFI corresponding to the unicast QoS flow, and the S-gNB generates the QFI for the forwarding tunnel. the endpoint identifier. If the S-gNB expects a multicast QoS flow to be forwarded through the forwarding tunnel corresponding to the multicast session tunnel, the handover request may include the QFI corresponding to the multicast QoS flow and the endpoint identifier generated by the S-gNB for the forwarding tunnel .
  • step 704 the reason why the S-gNB needs to forward the service flow through the forwarding tunnel is because in step 704, that is, after the S-gNB issues the handover command to the UE2, the UE2 will be disconnected from the S-gNB. At this time, the UE2 is temporarily Data cannot be received through S-gNB, and UE2 has not accessed T-gNB1 at this time. That is to say, UE2 cannot receive the data within the period of step 704 and step 705 through the S-gNB.
  • the S-gNB needs to forward this part of the data to the T-gNB1 for buffering through the forwarding tunnel, until after step 705, that is, after the UE2 accesses the T-gNB1, the T-gNB1 delivers the part of the data to the UE2.
  • T-gNB1 sends a handover response (handover request ACK) to S-gNB.
  • handover request ACK handover response
  • the T-gNB1 prepares radio resources for the handover UE according to the QoS information of the unicast service and the QoS information of the multicast service received from the S-gNB.
  • T-gNB1 may determine the number of air interface radio data bearers (data radio bearers, DRB) and the mapping relationship between QFI and DRB according to the QoS parameter corresponding to the QFI of each service flow.
  • the T-gNB1 can also determine the configuration parameters corresponding to the DRB according to the QoS parameters corresponding to the QFI mapped by each DRB.
  • the configuration parameter corresponding to the DRB is, for example, whether the radio link control (radio link control, RLC) layer corresponding to the DRB adopts the confirmed mode or the non-confirmed mode.
  • RLC radio link control
  • T-gNB1 After T-gNB1 prepares radio resources, it sends a handover response to S-gNB.
  • the T-gNB1 may send the information that needs to be relayed to the UE2 by the S-gNB to the S-gNB.
  • T-gNB1 can send the radio bearer configuration information of T-gNB1 to UE2 through S-gNB, and the radio bearer configuration information can be used by UE2 to receive unicast service data sent by T-gNB1 after accessing T-gNB1 and/or multicast service data.
  • the T-gNB1 when the handover request in step 502 includes the QFI of the service flow that the S-gNB wishes to forward through the forwarding tunnel (including the QFI of the unicast QoS flow and/or the QFI of the multicast QoS flow) , and when the T-gNB1 supports data forwarding, the T-gNB1 allocates the endpoint identifier of the forwarding tunnel.
  • the S-gNB sends a handover command to UE2.
  • the S-gNB1 needs the S-gNB to relay the radio bearer configuration information required by the UE2 to receive service data at the T-gNB1 to the UE2, the S-gNB sends the radio bearer configuration information to the UE2. After the S-gNB issues the handover command to the UE2, the air interface connection between the UE2 and the S-gNB is temporarily disconnected.
  • the S-gNB replicates and forwards the multicast QoS flow received by the multicast session tunnel to T-gNB1.
  • the S-gNB After the air interface connection between the UE2 and the S-gNB is disconnected, the S-gNB stops delivering the service data included in the PDU session and the multicast service data associated with the PDU session to the switched UE2. Exemplarily, the S-gNB stops sending the service data contained in the PDU session to the switched UE2 through the PDU session tunnel, and stops forwarding the multicast service data to the switched UE2 through the multicast session tunnel.
  • the S-gNB also needs to do the following work for the QoS flow that needs to be forwarded by the handed UE2: For the unicast QoS flow that needs to be forwarded to the T-gNB2, the S-gNB forwards the unicast QoS flow through the forwarding tunnel corresponding to the PDU session tunnel. Sent to T-gNB1. After receiving the unicast QoS flow, the T-gNB1 buffers the unicast QoS flow.
  • the S-gNB For the multicast QoS flow that needs to be forwarded to T-gNB1, the S-gNB first copies the multicast QoS flow in the multicast session tunnel, and then copies the copied multicast QoS flow through the forwarding tunnel corresponding to the multicast session tunnel. The flow is forwarded to T-gNB1. After receiving the multicast QoS flow, the T-gNB1 buffers the multicast QoS flow.
  • UE2 accesses T-gNB1.
  • T-gNB1 After UE2 accesses T-gNB1, T-gNB1 sends the received and buffered unicast QoS flow and/or multicast QoS flow to UE2. UE2 receives corresponding service data according to the radio bearer configuration information sent by the S-gNB in step 704 .
  • T-gNB1 sends an N2 path switch request (N2 Path Switch Request) to the AMF.
  • N2 Path Switch Request N2 Path Switch Request
  • the request includes the QFIs of the unicast QoS flows in the PDU session of UE2 for which the handover succeeds and the handover fails, and/or the QFIs for the multicast QoS flows for which the handover succeeds and the handover fails in the PDU session.
  • these QFIs can be encapsulated in N2 SM messages.
  • the N2 path switching request may further include the endpoint identifier of the PDU session tunnel allocated by the T-gNB1 for the UE2.
  • the N2 path switching request may further include indication information #2, where the indication information #2 is used to indicate whether the multicast service associated with the PDU session of the switched UE2 is running in the T-gNB1 run.
  • the N2 path switching request may further include the endpoint identifier of the multicast session tunnel allocated by the T-gNB1, which is used to establish the multicast session tunnel between the T-gNB1 and the UPF.
  • the multicast service associated with the PDU session of the handed UE2 is running in T-gNB1, or when the multicast service is running in T-gNB1, it means that the T-gNB1 and the UPF are in the running state.
  • the multicast session tunnel for transmitting the multicast session between the two has been established, and at this time, the N2 path switching request may not include the endpoint identifier of the multicast session tunnel.
  • AMF sends a PDU session context update request (Nsmf_PDUSession_UpdateSMContext Request) to SMF1.
  • the PDU session context update request includes the information included in the N2 SM message in step 706.
  • AMF may collect capability information of gNB, including capability information of whether to support multicast function.
  • capability information of whether to support multicast function As an example, when the T-gNB1 is powered on, it can report whether it supports the multicast function to the AMF.
  • the PDU session context update request may further include capability information of the T-gNB1.
  • SMF1 receives the PDU session context update request. After that, SMF1 determines whether it is necessary to release the multicast session tunnel in the S-gNB where the multicast service associated with the PDU session of the handed UE2 is located (that is, the multicast channel between UPF1 and S-gNB for transmitting the multicast service). session tunnel, and assume that a multicast service is transmitted in a multicast session tunnel).
  • SMF1 may be based on whether there are other terminal devices receiving multicast service data through the S-gNB after UE2 switches from S-gNB to T-gNB, or whether UE2 joins with S-gNB through this SMF1. Whether the last UE in the multicast service, or UE2, after switching from S-gNB to T-gNB, whether the number of UEs joining the multicast service through SMF1 and S-gNB is 0. Exemplarily, the number of UEs joining the multicast service through the SMF1 and the S-gNB may be included in the context of the multicast service.
  • SMF1 can judge whether to release the multicast session tunnel where the multicast service is located by whether there are other UEs except UE2 requesting the multicast service in the S-gNB in the context of the multicast service.
  • the multicast service context may also be called a multicast session context.
  • UE1 and UE2 join the same multicast service through SMF1 and S-gNB, and in the following step 425, UE1 switches and exits the multicast service joined through SMF1 and S-gNB, and In step 426, UE2 switches and exits the multicast service joined by SMF1 and S-gNB. Therefore, after UE2 switches to T-gNB, there is no other terminal device to receive the data of the multicast service through the S-gNB, or UE2 is the last UE to join the multicast service through SMF1 and S-gNB, or through The number of UEs that SMF1 and S-gNB access the multicast service is 0. Based on this, the SMF1 can determine to release the multicast session tunnel where the multicast service is located.
  • the SMF may determine whether the multicast service associated with the PDU session of the handed UE2 is in T-gNB1 according to the indication information #2. running.
  • information #1 may be generated to instruct the S-gNB to release the multicast session tunnel where the multicast service is located.
  • Information #1 may be an example of the first information.
  • the information #1 may include an indication or notification or request to release the multicast session tunnel.
  • the information #1 may further include information of the multicast session tunnel (for example, the tunnel endpoint identifier TEID of the multicast session tunnel, used to confirm the multicast session tunnel) and/or the identification information of the multicast service.
  • the information #1 may include an indication, notification or request for releasing the multicast session tunnel, and may also include information about the multicast session tunnel.
  • the information #1 may further include identification information of the multicast service.
  • the information #1 may include an indication, notification or request for releasing the multicast session tunnel, and may also include information about the multicast session tunnel and identification information of the multicast service.
  • SMF1 and UPF1 perform N4 session update.
  • SMF1 may send an N4 session update request to UPF1, which carries the PDU session tunnel endpoint identifier of T-gNB1 and the PDU session tunnel endpoint identifier assigned to UPF1 by SMF1, for establishing a PDU between T-gNB1 and UPF1 Session Tunneling (N4 Session Modification).
  • the AMF also sends the multicast session tunnel endpoint identifier allocated by T-gNB1 to SMF1 (that is, the multicast service associated with the PDU session of the switched UE2 at this time) If the T-gNB1 is not running yet), the SMF1 also sends the multicast session tunnel endpoint identifier of the T-gNB1 to the UPF1.
  • this information #1 may be included in the N4 session update request.
  • the UPF1 can be used to notify the release of the tunnel between the UPF1 and the S-gNB for transmitting the above-mentioned multicast service.
  • SMF1 sends a first message to the MCF, which is used to notify to release the tunnel between MUF and UPF1 for transmitting the above-mentioned multicast service, that is, the tunnel from MUF to UPF1 .
  • the MCF and the MUF update the N4 session.
  • the MCF may release the tunnel identification information of the UPF1 allocated by the SMF1 (ie, the tunnel identification information of the UPF1 used for establishing the tunnel with the MUF).
  • the MCF sends a response to the first message to the SMF1.
  • SMF1 sends a PDU session context update response (Nsmf_PDUSession_UpdateSMContext Response) to the AMF.
  • the SMF1 may release the tunnel identification information of the MUF allocated by the MCF (ie, the tunnel identification information of the UPF1 used to establish the tunnel with the MUF).
  • the AMF sends an N2 path switch response (N2 Path Switch Request ACK) to the T-gNB1.
  • N2 Path Switch Request ACK N2 Path Switch Request ACK
  • T-gNB1 sends a UE context release request (UE Context Release) to S-gNB.
  • UE Context Release UE Context Release
  • SMF1 may notify UPF1 to release the S-gNB after judging that after UE2 switches from S-gNB to T-gNB2, no other terminal device receives the data of the multicast service through S-gNB.
  • the first tunnel between the gNB and the UPF1 is used for transmitting the multicast service, so as to realize the release of the multicast session tunnel between the S-gNB and the UPF1, which helps to save the network resource overhead.
  • FIG. 8 shows a schematic flowchart of a communication method 800 provided by an embodiment of the present application from the perspective of device interaction.
  • the method 800 may be applied to a scenario in which the first terminal device receives data of the first multicast service through the first access network device. As shown in FIG. 8, method 800 includes steps 810-830.
  • the first access network device learns (knows) that the first terminal device has passed the first access network device The last terminal device to receive the data of the first multicast service.
  • learning can also be replaced with perception, discovery, detection, etc., which is not limited.
  • the first access network device may learn in the handover preparation stage that after the first terminal device is switched to the second access network device, no other terminal device receives the first access network device through the first access network device.
  • Multicast service data It should be noted that when the terminal device receives the data of the first multicast service through the first access network device, it can be understood that the terminal device has joined the first multicast service through the first access network device. It can also be understood that when the first terminal is the last first terminal device that is known in the preparation stage to receive the data of the first multicast service through the first access network device, and subsequently the first terminal device switches to the second access network device. network equipment. It can also be understood that the first terminal device is the last first terminal device that receives data of the first multicast service through the first access network device, and the first terminal device is subsequently switched to the second access network device.
  • the first access network device may be referred to as a source access network device
  • the second access network device may be referred to as a target access network device.
  • the handover here may be Xn handover, or N2 handover.
  • the above handover preparation stage may refer to source access network equipment, target access network equipment or core network equipment (here, it may refer to AMF, SMF or UPF, etc., without limitation) as the first A stage in which the terminal equipment prepares to hand over the required resources.
  • the resources required for handover may include forwarding tunnels, or radio bearer configuration information required by the first terminal device to receive service data through the target access network device, air interface resources configured by the target access network device for the first terminal device, etc.
  • the application examples are not limited.
  • the handover preparation stage may refer to that the source access network device receives the measurement report of the first terminal device, and makes a handover decision on the first terminal device according to the measurement report and the decision result is handover, and the source access network device sends a handover to the first terminal device.
  • the process of sending the handover request by the target access network device and receiving the handover response sent by the target access network device for example, the processes of steps 901 to 903 in FIG. 9 below.
  • the handover preparation stage may refer to the source access network device receiving the measurement report from the first terminal device, and the source access network device sending the handover request (handover request) to the source access and mobility management function network element according to the measurement report. required), and the process of the source access and mobility management function network element receiving the create UE context response from the target access and mobility management network element, such as the process of steps 1001 to 1012 in FIG. 10 below.
  • the source access network device may learn at any time point in the handover preparation stage that the first terminal device is the last terminal device that receives data of the first multicast service through the first access network device.
  • the source access network device After receiving the measurement report of the first terminal device, the source access network device makes a handover decision on the first terminal device according to the measurement report, and the decision result is handover (for example, after step 901 in Figure 9 below) , or when the source access network device sends a handover request to the target access network device (for example, after step 902 in Figure 9 below), or when the source access network device receives a handover response from the target access network device (for example, Figure 9 below) After step 903 in ), it is learned that the first terminal device is the last terminal device that receives the data of the first multicast service through the first access network device.
  • the source access network device may receive a measurement report from the first terminal device (for example, after step 1001 in FIG. 10 below), or the source access network device may access and mobility to the source
  • the management function network element sends the handover request (for example, after step 1002 in FIG. 10 below), and learns that the first terminal device is the last terminal device that receives data of the first multicast service through the first access network device.
  • the first terminal device that joins the first multicast service sends a measurement report to the source access network device, and the source access network device performs a measurement report on the first terminal device according to the measurement report.
  • the source access network device may update the number of terminal devices that join the first multicast service through the source access network device, for example, decrement the number of terminal devices by 1. When the number of the terminal devices is 0, it can be known that the first terminal device is the last terminal device that receives the data of the first multicast service through the first access network device.
  • the source access network device may, after receiving the measurement report of the first terminal device and making a decision on handover (for example, after step 901 in FIG. 9 below), or after sending the handover to the target access network device.
  • the request for example, after step 902 in Figure 9 below
  • a handover response sent by the target access network device for example, after step 903 in Figure 9 below
  • the source access network device may, after receiving the measurement report of the first terminal device, before sending the handover request to the source access and mobility management function network element, or before sending the handover request to the source access and mobility management function network element.
  • the network element of the performance management function sends the switching requirement, the number of terminal devices that join the first multicast service through the source access network device is updated.
  • the source access network device may, after receiving the measurement report of the first terminal device (for example, after step 1001 in FIG. 10 below), or after the source access and mobility management function network After the element sending switching is required (for example, after step 1002 in FIG. 10 below), the number of terminal devices that join the first multicast service through the source access network device is updated. Then the source access network device may determine whether the first terminal device is the last terminal device that joins the first multicast service through the source access network device according to the updated number of the terminal devices.
  • the number of terminal devices that join the multicast service through the source access network device may include a multicast context (Multicast Context) corresponding to the multicast service associated with the PDU session of the first terminal device or Multicast session context (Multicast Session Context) or multicast group context (Multicast Group Context) or multicast service context (Multicast Service Context).
  • Multicast Context Multicast context
  • Multicast Session Context Multicast Session Context
  • Multicast Group Context Multicast Group Context
  • Multicast Service Context Multicast Service Context
  • the source access network passes the multicast context (Multicast Context) or multicast session context (Multicast Session Context) or multicast group context (Multicast Group Context) or multicast service context (Multicast Service Context) whether there is any Other terminal devices other than the terminal device receive the first multicast service to determine whether the first terminal device is the last terminal device that receives data of the first multicast service through the source access network device.
  • Multicast Context multicast context
  • Multicast Session Context Multicast Session Context
  • multicast group context Multicast Group Context
  • Multicast Service Context multicast Service Context
  • the first terminal device When the first terminal device is the last terminal in the multicast context (Multicast Context) or multicast session context (Multicast Session Context) or multicast group context (Multicast Group Context) or multicast service context (Multicast Service Context)
  • the terminal device leaves the source access network device, no other terminal device will receive the first multicast service under the source access network device.
  • the source access network device may learn that the first terminal device is the last terminal device that receives the data of the first multicast service through the source access network device.
  • one multicast service may correspond to one multicast session, and correspond to a multicast session tunnel between an access network device and a core network device (eg, MB-UPF or UPF). It should be noted here that one multicast service may also correspond to multiple multicast sessions, and correspond to multiple multicast session tunnels between multiple access network devices and core network devices.
  • a core network device eg, MB-UPF or UPF.
  • the first access network device sends the first information to the core network device.
  • the first information is used to release the first tunnel, and the first tunnel is used to transmit the data of the first multicast service between the first access network device and the core network device.
  • the core network device may be a multicast user plane functional network element, such as MUF, M-UPF, MS-UPF, or MB-UPF, etc., which are not limited.
  • the first tunnel may include a tunnel between the source access network device and a multicast user plane functional network element (for example, MUF or M-UPF, MS-UPF or MB-UPF) for transmitting the first multicast service A tunnel (such as the multicast session tunnel described above).
  • the core network device may be a user plane functional network element, such as a UPF.
  • the first tunnel may include a tunnel between the source access network device and the user plane functional network element (eg, UPF) for transmitting the first multicast service (for example, the tunnel is the multicast session described above). tunnel).
  • the user plane functional network element may include a function for performing user plane correlation for multicast services, that is, it can be considered that the user plane function is used for multicast services.
  • the functions for example, MUF, M-UPF, MS-UPF or MB-UPF
  • MUF, M-UPF, MS-UPF or MB-UPF related to the user plane of the service may be combined with the user plane functional network element to form a functional network element.
  • the session management function network element may include a function used to correlate the control plane of the multicast service, that is, the function used to correlate the control plane of the multicast service (for example, MCF, M-SMF, MS- SMF or MB-SMF) can be combined with the session management function network element as one function network element.
  • the function used to correlate the control plane of the multicast service for example, MCF, M-SMF, MS- SMF or MB-SMF
  • the first access network device may first send the above-mentioned first information to the multicast session management function network element, and then the multicast session management function network element The first information may be sent to the multicast user plane functional network element.
  • the first access network device sends the first information to the multicast session management function network element by other network devices (for example, the second access network device, AMF, SMF), and then the multicast session
  • the management function network element may send the first information to the multicast user plane function network element.
  • the multicast session management function network element may be a multicast service session management function network element, or a multicast control plane function network element, such as MB-SMF, MCF, etc., which is not limited in this embodiment of the present application.
  • the first access network device sends the first information to the multicast session management function network element by other core network devices (for example, AMF), and then the multicast session management function network element can send the multicast session management function network element to the multicast session management function network element.
  • the user plane function network element sends the first information.
  • the first access network device may directly send the above-mentioned first information to the network element of the multicast session management function, for example, through a notification message or a request message, which is not limited.
  • the first access network device may first send the above-mentioned first information to the session management function network element, and then the session management function network element may send the user plane function network element to the user plane function network element.
  • the element sends the first information.
  • the first access network device sends the first information to the session management function network element by other network devices (for example, the second access network device, AMF), and then the session management network element sends the first information to the session management function network element.
  • the information is sent to the user plane functional network element.
  • the first access network device sends the first information to the session management function network element by other core network devices (for example, AMF), and then the session management function network element sends the first information to the user plane. functional network element.
  • the first access network device may directly send the above-mentioned first information to the session management function network element, for example, through a notification message or a request message, which is not limited.
  • the first access network device may, after receiving the measurement report of the first terminal device and based on the measurement report, determine that the first handover to the second access network is required.
  • a network device is used, or when it is determined that a handover request is to be sent to the second access network device, it can be learned that the first terminal device is the last terminal device that joins the first multicast service through the first access network device.
  • the first access network device may send a handover request (for example, a handover request) to the second access network device, where the handover request includes the above-mentioned first information.
  • the handover request may be used to request that the first terminal device be handed over from the first access network device to the second access network device.
  • the second access network device may send a path switch request (for example, an N2 path switch request, N2 Path Switch Request), the path switching request includes the above-mentioned first information.
  • the access and mobility management function network element may send a PDU session context update request (eg, Nsmf_PDUSession_UpdateSMContext Request) to the session management function network element, where the PDU session context update request includes the first information.
  • the session management function network element may send the first message to the multicast session management function network element,
  • the first message includes first information.
  • the first message may be an N16 message.
  • the multicast session management function network element may send a fifth message to the multicast user plane function network element, and the fifth message may include the first information.
  • the fifth message may be an N4 session update request.
  • the multicast user plane function network element may obtain the first information according to the fifth message, and then execute step 830 .
  • the session management function network element may send an N4 session update request to the user plane function network element, and the N4 session update request may Include the first information.
  • the user plane function network element may obtain the first information according to the N4 session update request, and then perform step 830 .
  • the first access network device may, when receiving the measurement report of the first terminal device, or when determining to access the source and mobility management function
  • the network element sends the switching needs, it can be known that the first terminal device is the last terminal device that joins the first multicast service through the first access network device.
  • the first access network device may send a handover requirement (for example, handover required) to the first access and mobility management function network element, where the handover requirement includes the above-mentioned first information.
  • the first access and mobility management function network element may be a source access and mobility management function network element.
  • the first access and mobility management function network element may send a request for creating a UE context (for example, Namf_Communication_CreateUEContext Request) to the second access and mobility management function network element, the request for creating a UE context includes the first information.
  • the second access and mobility management function network element sends a PDU session update context request to the session management function network element, where the PDU session update context request may include the first information.
  • the second access and mobility management function network element may be referred to as a target access and mobility management function network element.
  • the session management function network element may send the first message to the multicast session management function network element,
  • the first message includes first information.
  • the first message may be an N16 message.
  • the multicast session management function network element may send a fifth message to the multicast user plane function network element, and the fifth message may include the first information.
  • the fifth message may be an N4 session update request.
  • the multicast user plane function network element may obtain the first information according to the fifth message, and then perform step 830 .
  • the session management function network element may send a session update request (for example, an N4 session update request) to the user plane function network element,
  • the session update request may include the first information.
  • the network element with the function of the multicast user plane may obtain the first information according to the session update request, and then perform step 830 .
  • the core network device in step 820 is a multicast user plane functional network element.
  • the first access network device can learn about the first access network device at any time point in the handover preparation stage.
  • a terminal device is the last terminal device that joins the first multicast service through the first access network device.
  • the first access network device The management function network element sends a third message, the third message may be an N2 message, and the third message carries the above-mentioned first information.
  • the third access and mobility management function network element may be the access and mobility selected by the first access network device for the first multicast service when the first terminal device joins the first multicast service.
  • the third access and mobility management function network element may send a fourth message to the multicast session management function network element, where the fourth message carries the first information.
  • the fourth message may be an N11 message.
  • the multicast session management function network element may send a fifth message to the multicast user plane function network element, which may carry the first information.
  • the fifth message may be an N4 session update request.
  • the multicast user plane function network element may obtain the first information according to the fifth message, and then perform step 830 .
  • the first access network device can obtain the identifier of the network element of the multicast session management function.
  • the first access network device can select the third access and mobility management function network element according to the identifier.
  • the first access network device may query a network repository function (NRF) according to the identifier to obtain a suitable third access and mobility management function network element.
  • NRF network repository function
  • the access and mobility management function network element related to the first terminal equipment may refer to the access and mobility services for the non-access stratum (non-access stratum, NAS) signaling service of the first terminal equipment
  • a mobility management function network element, the access and mobility management function network element not related to the first terminal device may refer to an access and mobility management function network element not serving the NAS signaling of the first terminal device.
  • the third access and mobility management function network element may be the same network element as the source access and mobility management function network element above, or the same as the target access and mobility management function network element above.
  • the network element is the same network element, which is not limited in this embodiment of the present application.
  • the third message such as the N2 message
  • the N2 message can be mainly used for the release of the multicast session tunnel.
  • the newly added N2 message may follow the naming method of the service interface signaling message, and its specific name is not limited, but the function is to notify the multicast user plane function network element to release the multicast session tunnel.
  • the fourth message such as the N11 message
  • the N11 message can be mainly used for the release of the multicast session tunnel.
  • the newly added N11 message may follow the naming method of the service interface signaling message, and its specific name is not limited, but the function is to notify the multicast user plane function network element of the release of the multicast session tunnel.
  • the first access network device may, at any time point in the handover preparation stage, learn that the first terminal device is the last device to join the first multicast service through the first access network device. a terminal device.
  • the first access network device learns that the first terminal device is the last terminal device that joined the first multicast service through the first access network device, or after a period of time, the first access network device may directly send The core network device sends the first information.
  • the first access network device in step 820 may directly send the first information to the multicast session management function network element, and then the multicast session management function
  • the network element sends the first information to the multicast user plane function network element (for example, carries the first information in the fifth message), and then performs step 830, which is not limited.
  • the first access network device in step 820 may directly send the first information to the session management function network element, and then the session management function network element sends the user plane function network element to the first information directly.
  • the network element sends the first information (for example, carries the first information in the N4 session update request), and then executes step 830, which is not limited.
  • the first access network device when the first access network device receives the measurement report of the first terminal device in the handover preparation stage, or the first access network device
  • the network device determines to send a handover request, or when a handover is required, it learns that the first terminal device is the last terminal device that joins the first multicast service through the first access network device, and the first access network device can
  • the signaling (for example, handover request or handover need) carries the first information, so that the first information is finally sent to the multicast user plane function network element, or the user plane function network element, thereby helping to save network resource overhead.
  • the first access network device after the first access network device receives the measurement report of the first terminal device in the handover preparation phase, it learns that the first terminal device is the last terminal device that joins the first multicast service through the first access network device, and immediately sends a third message to the third access and mobility management function network element after learning, or immediately sends a message to the multicast session management
  • the functional network element or the session management network element sends the first information, and the first access network device can know that the first terminal device is joining the first multicast through the first access network device at an earlier time point in the accurate handover phase
  • the last terminal device of the service can help the multicast user plane function network element or the user plane function network element to obtain the first information earlier.
  • the first access network device when the first access network device receives a handover request response in the handover accurate stage, it learns that the first terminal device has passed the An access network device joins the last terminal device of the first multicast service. Compared with learning that the first terminal device is the last terminal device at an earlier time point in the handover preparation phase, the first access network can more accurately know that the first terminal device is the last terminal device through the first access network. The device joins the last terminal device of the first multicast service, thereby helping to improve the reliability of multicast service transmission.
  • the first information may include an indication for releasing the first tunnel and information of the first tunnel.
  • the first information may include an indication for releasing the first tunnel and identification information of the first multicast service.
  • the first information may include an indication for releasing the first tunnel, identification information of the first multicast service, and information of the first tunnel.
  • the first information when the first information includes information of the first tunnel, the first information may include information of one, two or more first tunnels, which is not limited.
  • the first information when the first information includes identification information of the first multicast service, the first information may include one, two or more identification information of the first multicast service, which is not limited.
  • the information of the first tunnel can be used to uniquely determine the first tunnel, for example, it can be a tunnel endpoint identifier (tunnel endpoint identifier, TEID) of the first tunnel, or the ID of the first tunnel, which is not limited here.
  • the identification information of the first multicast service can be used to uniquely determine a multicast service, for example, it can be the ID of the multicast service, or the name of the multicast service, or the multicast address, or the multicast group ID, or the multicast/broadcast session ID. (MBS session ID), Temporary Mobile Group Identity (TMGI), etc., which are not limited here.
  • the first multicast service described herein may be one multicast service or multiple different multicast services, which is not limited.
  • the source access network device when the source access network device has two multicast sessions, corresponding to two multicast services, and corresponding to two multicast session tunnels, when the source access network device learns the switching terminal device in the handover preparation stage
  • the source access network device When the source access network device is the last terminal device that receives the data of the two multicast services through the source access network device, the source access network device can send the first information to the core network device.
  • the first tunnel for transmitting the data of the two multicast services between the source access network device and the core network device.
  • the first multicast service includes the two multicast services, and the first tunnel includes the two multicast services corresponding to tunnel.
  • the core network device releases the first tunnel according to the first information.
  • the multicast user plane function network element or the user plane function network element may release the first tunnel according to the first information, for example, remove the relevant resources of the first tunnel (for example, remove the tunnel endpoint identifier of the first tunnel). , such as TEID; or remove N4 session context information related to the first tunnel of the first multicast service (for example, including data detection rules (packet detection rule, PDR), forwarding action rule (forwarding action rule, FAR), etc.) .
  • PDR packet detection rule
  • FAR forwarding action rule
  • the multicast user plane function network element or the user plane function network element may release the first tunnel according to the indication for releasing the first tunnel. (indication) and the information of the first tunnel, release the first tunnel.
  • the information of the first tunnel in the first information is the TEID of the first tunnel
  • the multicast user plane function network element or the user plane function network element may release the TEID.
  • the multicast user plane function network element or the user plane function network element may determine the first tunnel according to the ID of the first tunnel , and then release the first tunnel according to the instruction for releasing the first tunnel, for example, remove related resources of the first tunnel, such as TEID, or N4 session context information related to the first tunnel of the first multicast service.
  • the multicast user plane function network element or the user plane function network element can correspond to the first tunnel (for example, it may be one first tunnel, or multiple first tunnels, without limitation) to release.
  • the multicast user plane function network element or the user plane function network element can The identification information of the service is used to determine the first multicast service, and then the first tunnel for transmitting the data of the first multicast service between the first access network device and the core network device is determined.
  • the multicast user plane function network element or the user plane function network element may determine one or more multicast sessions corresponding to the first multicast service and one or more multicast session tunnels corresponding to the one multicast session , or multiple multicast session tunnels corresponding to the multiple multicast sessions.
  • the determined multicast session tunnel is the tunnel (ie, the first tunnel) for transmitting the data of the first multicast service between the source access network device and the core network device.
  • the multicast user plane function network element or the user plane function network element may release the first tunnel according to the instruction for releasing the first tunnel, that is, release the above-mentioned resources related to the one multicast session tunnel or multiple multicast tunnels, for example TEID, or N4 session context information related to the first tunnel of the first multicast service.
  • the multicast session function network element or the session function network element can tunnel all the multicast sessions corresponding to the first multicast service indicated in the first information, that is, to be used between the source access network device and the core network device.
  • the first tunnel (eg, all first tunnels) transmitting the data of the first multicast service is released.
  • the multicast user plane function network element or the user plane function network element may The first multicast service is determined according to the identification information of the first multicast service. Then, the multicast user plane function network element or the user plane function network element determines a first tunnel for transmitting the data of the first multicast service between the first access network device and the core network device. Specifically, the multicast user plane function network element or the user plane function network element may determine one or more multicast sessions corresponding to the first multicast service and one or more multicast session tunnels corresponding to the one multicast session , or multiple multicast session tunnels corresponding to the multiple multicast sessions.
  • the multicast user plane function network element or the user plane function network element may further determine the first tunnel in the one or more multicast session tunnels according to the information of the first tunnel in the first information. Afterwards, the multicast user plane function network element or the user plane function network element may release the first tunnel according to the instruction for releasing the first tunnel, for example, remove the related resources of the first tunnel, such as TEID, or associate with the first tunnel. N4 session context information related to the first tunnel of the multicast service.
  • the multicast user plane function network element or the user plane function network element can release the first tunnel corresponding to the information of the first tunnel included in the first information.
  • the first tunnel is determined according to both the identification information of the first multicast service and the information of the first tunnel, it is only necessary to determine the first tunnel in one or more multicast session tunnels corresponding to the first multicast service.
  • a tunnel can help to determine the first tunnel more accurately and quickly, thereby helping to improve the efficiency of releasing the first tunnel.
  • the multicast user plane function network element or user The plane function network element may also determine the first tunnel to be released according to only one of the identification information of the first multicast service and the information of the first tunnel. For example, when the first tunnel is determined only according to the identification information of the first multicast service, the multicast user plane function network element or the user plane function network element may ignore the information of the first tunnel contained in the first information. For another example, when the first tunnel is determined only according to the information of the first tunnel, the multicast user plane function network element or the user plane function network element may ignore the identification information of the first multicast service contained in the first information.
  • the first access network device may learn that the first terminal device has passed the The last terminal device that the first access network device receives the data of the first multicast service, and sends the first information to release the first access network device for transmitting the first multicast service between the first access network device and the core network device
  • the first tunnel of data helps to save network resource overhead.
  • FIG. 9 and FIG. 10 description will be given by taking the network element of the multicast session management function as the MCF and the source access network device as the S-gNB as an example.
  • the network element of the multicast session management function as the MCF
  • the source access network device as the S-gNB
  • the chip in the MCF and the chip in the S-gNB reference may be made to the specific descriptions of the MCF and the S-gNB, and will not be repeated.
  • the core network device further includes AMF, SMF, UPF and MUF.
  • the MCF and MUF may not be included in the core network device, but the functions of the MCF are implemented by some functions or units in the SMF, and the functions or units in the UPF are implemented.
  • the function of the MUF is not limited in this embodiment of the present application.
  • FIG. 9 shows a schematic flowchart of another communication method 900 provided by an embodiment of the present application.
  • the handover type in method 900 is Xn handover.
  • the S-gNB determines whether the multicast session tunnel between the S-gNB and the MUF needs to be released.
  • Figure 9 takes the release of the multicast session tunnel between the S-gNB and the MUF as an example for description. This solution can also be applied to release the multicast session tunnel between the S-gNB and the UPF. It may be necessary to do Some simple adaptations are within the scope of protection of this application.
  • the PDU session of the UE is associated with the multicast service.
  • the method 900 may be applicable to the scenario shown in FIG. 5B .
  • the method 900 will be described in conjunction with the scenario in FIG. 5B.
  • method 900 may include steps 901 to 916 . It should be noted that this solution is also applicable to the scenario where the T-gNB supports the multicast function, which is not limited here, and the scenario shown in FIG. 5B is only an example.
  • FIG. 9 shows steps or operations of the communication method 900 provided by the embodiment of the present application, but these steps or operations are only examples, and the embodiment of the present application may also perform other operations or variations of the respective operations in FIG. 9 . Furthermore, the various steps in the figures may be performed in a different order than they are presented, and it is possible that not all operations in the figures are performed.
  • the S-gNB may learn the capability of the T-gNB, that is, the capability of supporting the multicast function.
  • the T-gNB can notify the S-gNB of its own capability information through the Xn interface, where Xn can be the connection between the S-gNB and the T-gNB Interface for Xn connection.
  • the T-gNB sends the indication information #1 to the S-gNB, where the indication information #1 is used to indicate that the T-gNB does not support the multicast function.
  • the indication information #1 may not be sent to the S-gNB.
  • the S-gNB does not receive the indication information #1, it can be considered that the T-gNB does not support the multicast function.
  • the handover preparation stage includes steps 901 to 903 of the flow shown in FIG. 9 .
  • the handover preparation stage it can be understood that the S-gNB and the T-gNB or core network equipment prepares the resources required for the handover (for example, it may include a forwarding tunnel, or the UE receives service data after accessing the T-gNB) required radio bearer configuration information, or air interface resources configured by the T-gNB for the handover UE, etc.).
  • the UE sends a measurement report (Measurement Report) to the S-gNB.
  • the S-gNB receives the measurement report and decides to switch the UE to the T-gNB.
  • the S-gNB may update the multicast service associated with the PDU session of the handover UE (that is, the multicast service that the UE joins in the S-gNB).
  • the Multicast Context (Multicast Context) corresponding to the service (Multicast Service) or the joined Multicast Group (Multicast Group)), or the Multicast Service Context (Multicast Service Context), or the Multicast Group Context (Multicast Group Context), or The number of UEs in the Multicast Session Context (for example, decrement the number of UEs by 1).
  • the S-gNB can know that the UE has passed the S-gNB - the last UE for which the gNB receives the data of the multicast service. At this point, the S-gNB may determine to release the multicast session tunnel between the S-gNB and the core network device (eg, MUF in FIG. 5B ).
  • the multicast service may be an example of the first multicast service in FIG. 8
  • the multicast session tunnel may be an example of the first tunnel in FIG. 8 .
  • the number of UEs joining the multicast service through the S-gNB may be included in the multicast session context (or called the multicast service context) of the multicast service. Or called the multicast context or called the multicast group context). That is to say, the S-gNB can determine whether to release the multicast session tunnel where the multicast service is located according to whether other UEs other than the UE receive the multicast service in the S-gNB in the above context.
  • one multicast service can correspond to one multicast session, that is, it can correspond to one base station (such as S-gNB) and core network equipment (such as , MUF or UPF) multicast session tunnel. It should be noted here that one multicast service may also correspond to multiple multicast/broadcast sessions, which is not limited here. This solution takes one-to-one as an example, and this solution is also applicable to one-to-many.
  • the S-gNB sends a handover request (Handover Request) to the T-gNB.
  • the S-gNB can learn that the T-gNB does not support the multicast function.
  • the handover request may include PDU session information of the UE to be handed over, wherein the PDU session identifier and the QoS information corresponding to the unicast service included in the PDU session.
  • PDU session information of the UE to be handed over
  • QoS information corresponding to the unicast service included in the PDU session.
  • the S-gNB can map the multicast QoS flow according to the mapping relationship between the multicast QoS flow QFI and the unicast QoS flow QFI. For unicast QoS flow. That is, at this time, the unicast QoS flow included in the PDU session also includes the unicast QoS flow to which the above-mentioned multicast QoS flow is mapped.
  • the handover request may also include a service flow identifier that the S-gNB wishes to forward through the forwarding tunnel corresponding to the PDU session tunnel.
  • the handover request may include the QFI of the unicast QoS flow corresponding to the multicast QoS flow.
  • the S-gNB may generate information #2 for releasing information between the S-gNB and the core network device (for example, , UPF or MUF, and MUF is taken as an example here) to transmit the multicast session tunnel of the above-mentioned multicast service data.
  • the information #2 may also be included in the handover request.
  • the S-gNB determines or can or decides to release the S-gNB and the MUF between the After tunneling the multicast session, the above information #2 can be generated.
  • information #2 may include an indication for releasing the multicast session tunnel and information about the multicast session tunnel; or, information #2 may include an indication for releasing the multicast session tunnel and identification information of the multicast service; or The information #2 may include an indication for releasing the multicast session tunnel, information about the multicast session tunnel, and identification information of the multicast service, which is not limited in this embodiment of the present application.
  • the T-gNB sends a handover request response (handover request ACK) to the S-gNB.
  • handover request ACK handover request response
  • the T-gNB prepares radio resources for the handover UE according to the QoS information of the unicast service (including the mapped unicast QoS flow) received from the S-gNB.
  • the T-gNB may determine the number of air interface radio data bearers (data radio bearers, DRB) and the mapping relationship between QFI and DRB according to the QoS parameter corresponding to the QFI of each service flow.
  • the T-gNB can also determine the configuration parameter corresponding to the DRB according to the QoS parameter corresponding to the QFI mapped by each DRB.
  • the configuration parameter corresponding to the DRB is, for example, whether the radio link control (radio link control, RLC) layer corresponding to the DRB adopts the confirmed mode or the non-confirmed mode. Finally, the T-gNB creates the corresponding DRB.
  • RLC radio link control
  • the T-gNB After preparing the radio resources, the T-gNB sends a handover request ACK (handover request ACK) to the S-gNB.
  • the T-gNB may send the information that needs to be relayed to the UE through the S-gNB to the S-gNB.
  • the T-gNB can send the radio bearer configuration information of the T-gNB to the UE through the S-gNB, and the radio bearer configuration information can be used for the UE to receive the unicast service data sent by the T-gNB after accessing the T-gNB and / or multicast service data.
  • the T-gNB when the handover request in step 902 includes the QFI of the service flow that the S-gNB wishes to forward through the forwarding tunnel (including the QFI of the unicast QoS flow and/or the QFI of the multicast QoS flow) , and when the T-gNB supports data forwarding, the T-gNB allocates the endpoint identifier of the forwarding tunnel.
  • the S-gNB can, after receiving the handover request response, , update the number of UEs in the multicast session context (or called multicast service context or called multicast context or called multicast group context) corresponding to the multicast service associated with the PDU session of the handover UE (for example, subtract the number of UEs from the number of UEs). 1) If the currently handed UE is the last UE in the context (that is, after the UE leaves, there is no other UE receiving the multicast service under the base station), then the S-gNB knows that the UE has passed through the S-gNB.
  • the S-gNB may determine to release the multicast session tunnel between the S-gNB and the core network device (eg, MUF in FIG. 5B ).
  • the number of UEs joining the multicast service through the S-gNB (which can also be understood as receiving the multicast service at the S-gNB) and/or the identification information of the UEs may be included in the multicast session context (or called a group). in the multicast service context or multicast context or multicast group context). That is to say, the S-gNB can check whether there are other UEs other than the UE in the multicast session context (or called the multicast service context or called the multicast context or called the multicast group context) at the S-gNB.
  • the multicast service is used to determine whether to release the multicast session tunnel where the multicast service is located.
  • the S-gNB may generate information #2.
  • the S-gNB can send the information #2 to the T-gNB, for example, through separate signaling, which is not limited here.
  • information #2 reference may be made to the above description, and details are not repeated here.
  • the S-gNB sends a handover command (handover command) to the UE.
  • the switching command may refer to the description in step 704 .
  • the S-gNB replicates, maps, and forwards the multicast QoS flow received by the multicast session tunnel to the T-gNB.
  • the S-gNB can first copy the multicast QoS flow in its own multicast session tunnel, and then map the multicast QoS flow to the unicast QoS flow according to the mapping relationship between the multicast QoS flow and the unicast QoS flow flow. Then, it is forwarded to the T-gNB through the forwarding tunnel corresponding to the PDU session tunnel between the S-gNB and the T-gNB. After receiving the unicast QoS flow through the forwarding tunnel, the T-gNB buffers the unicast QoS flow.
  • step 905 the UE accesses the T-gNB. Specifically, for step 905, reference may be made to the description in step 705, and details are not repeated here.
  • the T-gNB sends an N2 path switch request (N2 Path Switch Request) to the AMF.
  • N2 Path Switch Request N2 Path Switch Request
  • the request includes the QFIs of the unicast QoS flows (including the QFIs of the unicast QoS flows mapped by the multicast QoS flows) in the PDU session of the UE for which the handover is successful and the handover fails.
  • these QFIs can be encapsulated in N2 SM messages.
  • the N2 path switching request may further include the endpoint identifier of the PDU session tunnel allocated by the T-gNB for the UE.
  • the T-gNB if the T-gNB receives the information #2 sent by the S-gNB, the T-gNB further includes the above-mentioned information #2 in the "N2 path switching request".
  • the AMF sends a PDU session context update request (Nsmf_PDUSession_UpdateSMContext Request) to the SMF.
  • the PDU session context update request includes the information included in the N2SM message in step 906 .
  • the AMF may collect capability information of the gNB (for example, capability information including whether the multicast function is supported). As an example, when the T-gNB is powered on, it can report whether it supports the multicast function to the AMF. At this time, the PDU session context update request may further include capability information of the T-gNB.
  • the AMF if the AMF receives message #2 sent by the S-gNB in step 906 (ie, sent by the S-gNB to the T-gNB and then relayed by the T-gNB to the AMF), then the AMF will Information #2 may be included in the PDU session context update request.
  • N4 Session Modification N4 Session Modification
  • the SMF sends the first message to the MCF.
  • the first message may be an N16 message.
  • the SMF may include the information #2 in the first message sent to the MCF.
  • the MCF and the MUF perform N4 session modification (N4 Session Modification).
  • the MCF sends an N4 session update request to the MUF.
  • the MCF may include the information #2 in the N4 session update request.
  • the MUF releases the relevant multicast session tunnel.
  • the MUF may remove the relevant resources of the tunnel according to the corresponding tunnel identification information.
  • multicast/broadcast services generally only have downlink.
  • MUF configures the tunnel endpoint identifier TEID generated by S-gNB and the PDR configured by MCF to MUF, so that MUF can Send the data of the multicast service to the S-gNB. Therefore, the release here may be to remove the related TEID and remove the PDR related to the first multicast. It should be noted here that the multicast service data of the full text can be replaced with multicast/broadcast service data.
  • the MUF may release the first tunnel according to the indication and the information of the multicast session tunnel.
  • the MUF can release the TEID.
  • the MUF can determine the multicast session tunnel according to the ID of the multicast session tunnel, and then release the group according to the instruction in information #2.
  • the multicast session tunnel for example, remove the related resources of the multicast session tunnel, such as TEID, or remove the PDR related to the first multicast.
  • the MUF may determine the multicast service according to the identification information of the multicast service, and then determine A multicast session tunnel for transmitting the data of the multicast service between the S-gNB and the MUF. Specifically, the MUF may determine one or more multicast sessions corresponding to the multicast service, one or more multicast session tunnels corresponding to the one multicast session, or multiple multicast sessions corresponding to the multiple multicast sessions session tunnel.
  • the MUF may release the multicast session tunnel according to the indication in the message #2, that is, release the above-mentioned resources related to the one or more multicast tunnels, such as TEID, or remove the first multicast-related resources. PDR.
  • the MUF can determine the group according to the identification information of the multicast service. broadcast business. Then, according to the information of the multicast session tunnel in the information #2, the multicast session tunnel of the data of the multicast service is transmitted between the S-gNB and the MUF. Specifically, the MUF may determine one or more multicast sessions corresponding to the first multicast service, and one or more multicast session tunnels corresponding to the one multicast session, or multiple multicast sessions corresponding to the multiple multicast sessions. Multicast session tunnel.
  • the MUF may further determine the multicast session tunnel in the one or more multicast session tunnels according to the information of the multicast session tunnel in the information #2.
  • the multicast user plane function network element or the user plane function network element may release the multicast session tunnel according to the instruction in information #2, for example, remove the relevant resources of the multicast session tunnel, such as TEID, or remove the The first multicast related PDR.
  • the MUF may send an N4 session update response to the MCF.
  • the MCF sends a response to the first message to the SMF.
  • the response to the first message may include response information for information #2.
  • the response message may not be sent.
  • steps 908 to 911 reference may be made to the descriptions of steps 708 to 711, which will not be repeated here.
  • the SMF sends a PDU session context update response (Nsmf_PDUSession_UpdateSMContext Response) to the AMF.
  • Nsmf_PDUSession_UpdateSMContext Response a PDU session context update response
  • the SMF receives a response information element related to the release of the multicast session tunnel, for example, the response information of message #2 , then optionally, the response information element may also be included in the PDU session context update response.
  • the AMF sends an N2 path switch response (N2 Path Switch Request ACK) to the T-gNB.
  • N2 Path Switch Request ACK N2 Path Switch Request ACK
  • the response cell may also be included in the N2 path switching response.
  • the T-gNB sends a UE context release request (UE Context Release) to the S-gNB.
  • UE Context Release UE Context Release
  • the signaling includes response information elements related to the release of the multicast session tunnel in step 913, such as the response information of information #2, it is optional. Yes, the response information element is also included in the N2 path switching response.
  • the T-gNB does not support the multicast function as an example for description, but the embodiment of the present application is not limited to this.
  • the T-gNB can also support the multicast function.
  • the S-gNB needs to copy and forward the multicast QoS flow received by the multicast session tunnel to the T-gNB, that is, it does not need to map the multicast QoS flow to the unicast QoS
  • the S-gNB needs to copy and forward the multicast QoS flow received by the multicast session tunnel to the T-gNB, that is, it does not need to map the multicast QoS flow to the unicast QoS
  • the information #2 is included in the existing signaling as a cell and brought to the MCF, but the embodiment of the present application is not limited to this.
  • the S-gNB may also perform step 915, that is, the S-gNB directly sends a notification message to the MCF, where the notification message is used to notify the MCF to release the multicast session tunnel where the multicast service is located, that is, the S-gNB - The multicast session tunnel between the gNB and the MUF to transmit the multicast service.
  • the messages in steps 902, 906, 907, 909, and 910 may not include information #2, that is, the S-gNB does not include information #2 as a cell in the existing signaling, but uses a separate Signal the MCF to release the multicast session tunnel.
  • the signaling may include an indication for releasing the multicast session tunnel and information about the multicast session tunnel; or, the signaling may include an indication for releasing the multicast session tunnel and the identification information of the multicast service; Alternatively, the signaling may include an indication for releasing the multicast session tunnel, information of the multicast session tunnel, and identification information of the multicast service, which is not limited in this embodiment of the present application.
  • step 915 may be performed after the S-gNB determines to release the multicast session tunnel used for transmitting multicast services between the S-gNB and the MUF, for example, between steps 901 and 914, Or after step 914, this embodiment of the present application does not limit this.
  • the S-gNB and the MCF release the multicast session tunnel.
  • the MCF can send the signaling to the MUF, and the MUF can, according to the signaling, tunnel the multicast session between the S-gNB and the MUF for transmitting the multicast service. to release.
  • the MCF may also subscribe to the S-gNB for the notification of the release of the multicast session tunnel when the UE joins the multicast service. That is, when the S-gNB determines that the multicast session tunnel between the S-gNB and the core network device (eg, MUF or UPF) needs to be released during the handover process, it can send a release notification to the MCF. At this time, the signaling in the above steps 901 to 914 can be performed according to the existing normal handover procedure without including additional information, such as information #2.
  • the core network device eg, MUF or UPF
  • the S-gNB when the S-gNB judges or determines or can release the multicast session tunnel of the S-gNB in the handover preparation stage (the specific method is as described in steps 901 to 903, which will not be described here) , the S-gNB may also perform steps 917 to 919 .
  • the S-gNB sends a third message to the AMF, the third message may be an N2 message, and the third message carries information #2.
  • the AMF in step 917 may be the same AMF as the AMF in the handover process in FIG. 9 (ie, the AMF serving the handover UE), or may be another AMF, which is not limited.
  • the N2 message may be an existing N2 message (that is, carrying information #2), or a newly added N2 message (for example, it is mainly used for the release of multicast session tunnels, and the newly added N2 message follows the service-oriented approach)
  • the naming method of the interface signaling message the specific name of which is not limited, but the function is to notify the release of the MUF multicast session tunnel), which is not limited in this embodiment of the present application.
  • the AMF sends a fourth message to the MCF, where the fourth message may be an N11 message, and the fourth message carries the foregoing information #2.
  • the N11 message may be an existing N11 message (that is, carrying information #2), or may be a newly added N11 message (for example, mainly used for the release of multicast session tunnels, and the newly added N11 message follows the service
  • the naming method of the interface signaling message, the specific name is not limited, but the function is to notify the MUF of the release of the multicast session tunnel).
  • the MCF and the MUF perform N4 Session Modification.
  • the MCF sends a fifth message to the MUF, the fifth message may be an N4 session update request, the fifth message carries information #2, and the MUF releases the multicast session tunnel according to the information #2.
  • the MUF sends a response to the fifth message to the MCF, which may be, for example, an N4 session update response.
  • the S-gNB uses steps 917 to 919 to notify the MUF to release the multicast session tunnel, then in the handover process shown in Figure 9, when the S-gNB judges or decides or can After releasing the multicast session tunnel of the source base station, the S-gNB executes steps 917 to 919 to notify the MUF to release the multicast session tunnel, that is, the handover process (for example, in steps 906 to 914 ) no longer carries information #2 and for Response of the associated multicast session tunnel release.
  • the S-gNB may judge the multicast session context (or multicast service context or multicast context or multicast group context or multicast group context or When there is no other UE in the multicast session context), when the S-gNB receives the multicast service, it notifies the core network device (for example, MUF or UPF) to release the communication between the S-gNB and the core network device for transmitting the multicast service.
  • the multicast session tunnel of the multicast service for example, can release the tunnel through existing signaling or through separate signaling notification, so as to realize the multicast session between the S-gNB and the core network device (eg, MUF or UPF) The release of the tunnel helps to save network resource overhead.
  • FIG. 10 is a schematic flowchart of another communication method 1000 provided by an embodiment of the present application.
  • the handover in method 1000 is an N2 handover.
  • the S-gNB determines whether the multicast session tunnel between the S-gNB and the MUF needs to be released.
  • Figure 10 takes the release of the multicast session tunnel between the S-gNB and the MUF as an example. This solution can also be applied to release the multicast session tunnel between the S-gNB and the UPF. It may be necessary to do Some simple adaptations are within the scope of protection of this application.
  • the PDU session of the UE is associated with the multicast service.
  • the method 1000 may be applicable to the scenario shown in FIG. 5C .
  • the method 1000 will be described in conjunction with the scenario in FIG. 5C.
  • method 1000 may include steps 1001 to 1017 . It should be noted that this solution is also applicable to the scenario where the T-gNB supports the multicast function, which is not limited here, and the scenario shown in FIG. 5C is only an example.
  • FIG. 10 shows steps or operations of the communication method 1000 provided by this embodiment of the present application, but these steps or operations are only examples, and this embodiment of the present application may also perform other operations or variations of the respective operations in FIG. 10 . Furthermore, the various steps in the figures may be performed in a different order than they are presented, and it is possible that not all operations in the figures are performed.
  • the S-gNB may learn the capability of the T-gNB, that is, the capability of supporting the multicast function.
  • the T-gNB can notify the S-gNB of its own capability information through the Xn interface, where Xn can be the connection between the S-gNB and the T-gNB Interface for Xn connection.
  • the T-gNB2 sends the indication information #1 to the S-gNB, where the indication information #1 is used to indicate that the T-gNB does not support the multicast function.
  • the indication information #1 may not be sent to the S-gNB.
  • the S-gNB does not receive the indication information #1, it can be considered that the T-gNB does not support the multicast function.
  • the handover preparation stage includes steps 1001 to 1012 of the flow shown in FIG. 10 .
  • the S-gNB and the T-gNB or the core network equipment prepares the resources required for the handover for the handover UE (for example, the information of the forwarding tunnel may be included, and the UE receives the service after accessing the T-gNB).
  • the UE sends a measurement report (Measurement Report) to the S-gNB.
  • the S-gNB receives the measurement report and decides to switch the UE to the T-gNB.
  • the S-gNB may update the multicast session context (or multicast service context) corresponding to the multicast service associated with the PDU session of the handover UE or the number of UEs in the multicast context or multicast group context) (eg, reduce the number of UEs by 1). If the currently switched UE is the last UE in the above context (that is, after the UE leaves, there is no other UE receiving the multicast service under the base station), the S-gNB can know that the UE has passed the S-gNB The last UE to receive the data of the multicast service. At this time, the S-gNB may determine to release the multicast session tunnel between the S-gNB and the core network device (eg, MUF in FIG. 5C ).
  • the core network device eg, MUF in FIG. 5C
  • the multicast service may be an example of the first multicast service in FIG. 8
  • the multicast session tunnel may be an example of the first tunnel in FIG. 8 .
  • the number of UEs joining the multicast service through the S-gNB (which can also be understood as receiving the multicast service at the S-gNB) and/or the identification information of the UEs may be included in the multicast session context (or the multicast session context). service context or multicast context or multicast group context). That is to say, the S-gNB can check whether there are other UEs other than the UE in the multicast session context (or multicast service context or multicast context or multicast group context) to receive the multicast at the S-gNB service to determine whether to release the multicast session tunnel where the multicast service is located.
  • one multicast service may correspond to one multicast session, that is, it may correspond to one base station (such as S-gNB) and core network equipment (such as , MUF or UPF) multicast session tunnel. It should be noted here that one multicast service may also correspond to multiple multicast/broadcast sessions, which is not limited here. This solution takes one-to-one as an example, and this solution is also applicable to one-to-many.
  • the S-gNB sends a handover required (Handover Required) to the S-AMF.
  • the "handover requirement" includes the PDU session information of the UE to be handed over and the associated multicast service information (including the associated multicast service identifier), and the PDU session information includes the PDU session identifier and the PDU session information contained in the PDU session.
  • QoS information corresponding to the unicast service flow includes QFI and QoS parameters. If the PDU session of the currently switched UE is associated with a multicast service, the S-gNB maps the multicast QoS flow to a unicast QoS flow according to the mapping relationship between the multicast QoS flow QFI and the unicast QoS flow QFI.
  • "Handover Required” may also contain SMN2 information. If there is no direct forwarding tunnel between S-gNB and T-gNB indicated in the S-gNB information, it means that an indirect forwarding tunnel can be established between S-gNB and T-gNB. At this time, the S-gNB information can include S-gNB allocation Indirect forwarding tunnel information.
  • the "handover requirement" may also include the service flow identifier that the S-gNB wishes to forward through the forwarding tunnel. If the multicast QoS flow needs to be forwarded through the forwarding tunnel, the handover request includes the QFI of the unicast QoS flow corresponding to the multicast QoS flow.
  • the S-gNB may generate information #2 for releasing information between the S-gNB and the core network device (for example, , UPF or MUF, and MCF is taken as an example here) to transmit the multicast session tunnel of the above-mentioned multicast service data.
  • the information #2 may be included in the handover requirement. Specifically, for information #2, reference may be made to the description in step 902 in FIG. 9 , and details are not repeated here.
  • the S-AMF selects a target AMF (ie, Target-AMF, T-AMF) according to the target cell ID, and the T-AMF is connected to the T-gNB.
  • a target AMF ie, Target-AMF, T-AMF
  • the S-AMF sends a request for creating a UE context (Namf_Communication_CreateUEContext Request) to the T-AMF, and the request may include the UE context information stored by the S-AMF for the handover, and may also include the information sent by the S-gNB to the S in step 1002. -AMF information.
  • step 1004 the S-AMF sends the message #2 to the T-AMF.
  • the T-AMF sends a PDU session context update request (Nsmf_PDUSession_UpdateSMContext Request) to the SMF, which includes the information sent by the S-gNB to the S-AMF in step 1002.
  • a PDU session context update request (Nsmf_PDUSession_UpdateSMContext Request)
  • the SMF sends a PDU session context update request (Nsmf_PDUSession_UpdateSMContext Request) to the SMF, which includes the information sent by the S-gNB to the S-AMF in step 1002.
  • the information #2 is included in step 1004, the information #2 is also carried in the PDU session context update request.
  • N4 Session Modification N4 Session Modification
  • the SMF sends an N4 session update request to the UPF.
  • the N4 session update request carries the indirect forwarding tunnel information allocated by the S-gNB.
  • UPF replies N4 session update response to SMF.
  • the N4 session update response includes the indirect forwarding tunnel information allocated by the UPF, which is used to establish the indirect forwarding tunnel between the S-gNB and the T-gNB as shown in FIG. 5C .
  • the SMF sends a PDU session context update response (Nsmf_PDUSession_UpdateSMContext Response) to the T-AMF.
  • the message may include QoS information for the unicast QoS flow of the PDU session.
  • the QoS information includes QFI and corresponding QoS parameters.
  • the unicast QoS flow includes the unicast QoS flow mapped by the multicast QoS flow.
  • the T-AMF sends a handover request (Handover Request) to the T-gNB.
  • the message may include the QoS information of the unicast QoS flow included in the PDU session (the QoS information of the unicast QoS flow including the multicast QoS flow mapping).
  • the T-gNB allocates radio resources for the unicast QoS flow based on the QoS information of the above-mentioned QoS flow.
  • the handover request includes the indirect forwarding tunnel information allocated by the S-gNB and the indirect forwarding tunnel information of the UPF.
  • the T-gNB sends a handover request response (Handover Request ACK) to the T-AMF.
  • Handover Request ACK handover request response
  • the handover request response may include the QFI of the unicast QoS flow for which the handover succeeds and/or the handover fails (for example, the T-gNB resource is insufficient and cannot allocate radio resources for the unicast QoS flow, resulting in the handover failure); UE access The radio bearer configuration required by the T-gNB to receive service data, etc.
  • the T-gNB since an indirect forwarding tunnel exists between the S-gNB and the T-gNB, the T-gNB also includes the information of the indirect forwarding tunnel in the handover request response (that is, for establishing the forwarding tunnel with the UPF). Then, the tunnel information is brought to the UPF through steps 1009 to 1018).
  • the T-AMF sends a PDU session context update request (Nsmf_PDUSession_UpdateSMContext Request) to the SMF, which contains the relevant information contained in the handover request response in step 1009.
  • Nsmf_PDUSession_UpdateSMContext Request a PDU session context update request
  • the SMF sends a PDU session context update response (Nsmf_PDUSession_UpdateSMContext Response) to the T-AMF.
  • the response also includes indirect forwarding tunnel information of the UPF.
  • the T-AMF sends a create UE context response (Nsmf_PDUSession_UpdateSMContext Response) to the S-AMF, including the information of step 1011.
  • a create UE context response Nsmf_PDUSession_UpdateSMContext Response
  • the S-AMF sends a handover command (Handover Command) to the S-gNB, including the information of step 1012.
  • a handover command Handover Command
  • step 1001 that is, the S-gNB does not generate information #2 after receiving the signaling in step 1001, that is, from the signaling in steps 1001 to 1005) Does not carry information #2
  • the S-gNB can update the number of UEs in the multicast session context corresponding to the multicast service associated with the PDU session of the handover UE (for example, the UE's Quantity minus 1).
  • the S-gNB learns that the UE is the last UE to receive the data of the multicast service through the S-gNB. At this time, the S-gNB may determine to release the multicast session tunnel between the S-gNB and the core network device (eg, MUF in FIG. 5C ).
  • the core network device eg, MUF in FIG. 5C
  • the number of UEs joining the multicast service through the S-gNB may be included in the multicast session context (or multicast service context) of the multicast service. or multicast context or multicast group context). That is to say, the S-gNB can use the multicast session context (or multicast service context or multicast context or multicast group context) whether there are other UEs other than the UE in the S-gNB to receive the multicast
  • the data of the service is used to determine whether to release the multicast session tunnel where the multicast service is located.
  • the S-gNB may generate information #2 for requesting or instructing or notifying the core network device (for example, MCF or MUF, where MUF is used here). For example) release the multicast session tunnel where the multicast service is located.
  • the S-gNB can carry the information #2 in the signaling and send it to the session management function network element.
  • the S-gNB sends a handover command (Handover Command) to the UE, including the radio bearer configuration information required by the UE to access the target base station (the radio bearer configuration information here includes the radio bearer configuration information required for the unicast QoS flow and the Radio bearer configuration information for unicast QoS flows mapped by multicast QoS flows).
  • Handover Command a handover command
  • the radio bearer configuration information here includes the radio bearer configuration information required for the unicast QoS flow and the Radio bearer configuration information for unicast QoS flows mapped by multicast QoS flows.
  • the S-gNB replicates and maps the multicast QoS flow received by the multicast session tunnel, and forwards it to the T-gNB through the indirect forwarding tunnel.
  • the UE accesses the T-gNB.
  • the T-gNB sends the received and buffered unicast QoS flow and/or the multicast QoS flow to the UE.
  • the UE receives corresponding service data according to the radio bearer configuration information sent by the S-gNB in step 1014 .
  • the T-gNB sends a handover notification (Handover Notify) to the T-AMF, where the notification indicates that the UE is successfully handed over to the T-gNB.
  • a handover notification Handover Notify
  • the T-AMF sends a PDU session context update request (Nsmf_PDUSession_UpdateSMContext) to the SMF, which carries the information of the PDU session tunnel allocated by the T-gNB.
  • Nsmf_PDUSession_UpdateSMContext a PDU session context update request
  • the SMF which carries the information of the PDU session tunnel allocated by the T-gNB.
  • the information of the indirect forwarding tunnel generated by the T-gNB is also carried.
  • the SMF sends the first message to the MCF.
  • the first message may be an N16 message.
  • the SMF may include the information #2 in the first message sent to the MCF.
  • Steps 1019 to 1021 are similar to the descriptions of steps 910 to 912, and are not repeated here.
  • the T-gNB does not support the multicast function as an example for description, but the embodiment of the present application is not limited to this.
  • the T-gNB can also support the multicast function.
  • the S-gNB needs to copy and forward the multicast QoS flow received by the multicast session tunnel to the T-gNB, that is, it does not need to map the multicast QoS flow to the unicast QoS
  • the S-gNB needs to copy and forward the multicast QoS flow received by the multicast session tunnel to the T-gNB, that is, it does not need to map the multicast QoS flow to the unicast QoS
  • the S-gNB includes information #2 in The existing signaling is brought to the MCF, and the MCF is further brought to the MUF through step 1019, but the embodiment of the present application is not limited to this.
  • the S-gNB may also perform step 1023, that is, the S-gNB directly sends a notification message to the MCF, where the notification message is used to notify the MCF to release the multicast session tunnel where the multicast service is located, that is, the S-gNB - The multicast session tunnel between the gNB and the MUF to transmit the multicast service.
  • the message in steps (1002, 1004, 1005, 1007, 1008, 1016, 1017, 1018, 1019) may not include information #2, that is, the S-gNB does not take the relevant indication information for releasing the multicast session tunnel as The information element is included in the existing signaling, but the MCF is notified to release the multicast session tunnel through a separate signaling.
  • the signaling may include an instruction for releasing the multicast session tunnel and information about the multicast session tunnel; or, the signaling may include an instruction for releasing the multicast session tunnel and the identification information of the multicast service. ; or the signaling may include an indication for releasing the multicast session tunnel, information of the multicast session tunnel, and identification information of the multicast service, which is not limited in this embodiment of the present application.
  • step 1023 may be performed after the S-gNB determines to release the multicast session tunnel used for transmitting multicast services between the S-gNB and the MUF, for example, between steps 1001 and 1022, Or after step 1022, this embodiment of the present application does not limit this.
  • the S-gNB and the MCF release the multicast session tunnel.
  • the MCF can send the signaling to the MUF, and the MUF can, according to the signaling, tunnel the multicast session between the S-gNB and the MUF for transmitting the multicast service. to release.
  • the MCF may also subscribe to the S-gNB for the notification of the release of the multicast session tunnel when the UE joins the multicast service. That is, when the S-gNB determines that the multicast session tunnel between the S-gNB and the core network device (eg, MUF or UPF) needs to be released during the handover process, it can send a release notification to the MCF. At this time, in the signaling of the above steps 1001 to 1022, it can be performed according to the existing normal handover process, and it is not necessary to include additional information, such as information #2.
  • the core network device eg, MUF or UPF
  • the S-gNB when the S-gNB judges or determines or can release the multicast session tunnel of the S-gNB in the handover preparation stage (the specific method is as described in steps 1001 to 1012, which will not be described here) , the S-gNB may also perform steps 1025 to 1027 .
  • the S-gNB sends a third message to the S-AMF, the third message may be an N2 message, and the third message carries information #2.
  • the S-AMF in step 1025 may be the same AMF as the S-AMF in the handover process in FIG. 10 (that is, the S-AMF serving the handover UE), or may be another AMF, Not limited.
  • the N2 message may be an existing N2 message (that is, carrying information #2), or a newly added N2 message (for example, it is mainly used for the release of the multicast session tunnel, and the newly added N2 message follows the service-oriented The naming method of the interface signaling message, the specific name of which is not limited, but the function is to notify the release of the MUF multicast session tunnel), which is not limited in this embodiment of the present application.
  • the S-AMF sends a fourth message to the MCF, where the fourth message may be an N11 message, and the N11 message carries the foregoing information #2.
  • the N11 message may be an existing N11 message (that is, carrying information #2), or may be a newly added N11 message (for example, mainly used for the release of multicast session tunnels, and the newly added N11 message follows the service
  • the naming method of the interface signaling message, the specific name is not limited, but the function is to notify the MUF of the release of the multicast session tunnel).
  • the MCF and the MUF perform N4 session modification (N4 Session Modification).
  • N4 Session Modification For example, the MCF sends the fifth message to the MUF, the fifth message may be an N4 session update request, the fifth message carries information #2, the MUF releases the multicast session tunnel according to the information #2, and then the MUF sends a response to the fifth message to the MCF , for example, could be an N4 session update response.
  • the S-gNB uses steps 1025 to 1027 to notify the MUF to release the multicast session tunnel, then in the handover process shown in Figure 10, when the S-gNB judges or decides or After the multicast session tunnel of the source base station can be released, the S-gNB executes steps 1025 to 1027 to notify the MUF to release the multicast session tunnel, that is, the handover process no longer carries the information #2 and the response to the release of the relevant multicast session tunnel.
  • the S-gNB may judge the multicast session context (or multicast service context or multicast context or multicast group context) during the handover preparation stage of the UE switching from S-gNB to T-gNB.
  • the core network device for example, MUF or UPF
  • the release of the tunnel can be notified through existing signaling or through separate signaling, so as to realize the release of the multicast session tunnel between the S-gNB and the core network device (for example, MUF or UPF), Helps to save network resource overhead.
  • FIG. 11 is a schematic diagram of an apparatus 1100 for wireless communication provided by an embodiment of the present application.
  • the apparatus 1100 may be an access network device, or may be a chip or a circuit, for example, a chip or a circuit that may be provided in the access network device.
  • the apparatus 1100 may be an access and mobility management function network element, or may be a chip or circuit, for example, a chip or circuit that may be provided in the access and mobility management function network element.
  • the apparatus 1100 may be a session management function network element, or may be a chip or circuit, for example, a chip or circuit that may be provided in a session management function network element.
  • the apparatus 1100 may be a network element with a multicast session management function, or may be a chip or a circuit, for example, a chip or circuit that can be provided in the network element with a multicast session management function.
  • the apparatus 1100 may be a multicast user plane functional network element, and may also be a chip or circuit, for example, a chip or circuit that may be provided in a multicast user plane functional network element.
  • the apparatus 1100 may include a processing unit 1110 (ie, an example of a processor) and a transceiver unit 1130 .
  • a processing unit 1110 ie, an example of a processor
  • a transceiver unit 1130 ie, an example of a transceiver
  • the transceiver unit 1130 may be implemented by a transceiver or a transceiver-related circuit or an interface circuit.
  • the apparatus 1100 may further include a storage unit 1120 .
  • the storage unit 1120 is used to store instructions.
  • the storage unit 1120 may also be used to store data or information.
  • the storage unit 1120 may be implemented by a memory.
  • the processing unit 1110 may be configured to execute the instructions stored in the storage unit 1120, so that the apparatus 1100 implements the steps performed by the access network device in the above method.
  • the processing unit 1110, the storage unit 1120, and the transceiver unit 1130 can communicate with each other through an internal connection path to transmit control and/or data signals.
  • the storage unit 1120 is used to store a computer program, and the processing unit 1110 can be used to call and run the computer program from the storage unit 1120 to control the transceiver unit 1130 to receive signals and/or send signals, and complete the above method. Steps of an access network device or an access and mobility management function network element or a session management function network element or a multicast session management function network element or a multicast user plane function network element.
  • the storage unit 1120 may be integrated in the processing unit 1110, or may be provided separately from the processing unit 1110.
  • the transceiver unit 1130 may include a receiver and a transmitter.
  • the receiver and the transmitter may be the same or different physical entities. When they are the same physical entity, they can be collectively referred to as transceivers.
  • the transceiver unit 1130 may include an input interface and an output interface.
  • the function of the transceiver unit 1130 can be considered to be implemented by a transceiver circuit or a dedicated chip for transceiver.
  • the processing unit 1110 can be considered to be implemented by a dedicated processing chip, a processing circuit, a processing unit or a general-purpose chip.
  • a general-purpose computer may be used to implement the communication device provided in the embodiments of the present application (for example, an access network device or an access and mobility management function network element or a session management function network element or a multicast network element). session management function network element or multicast user plane function network element).
  • the program codes that will implement the functions of the processing unit 1110 and the transceiver unit 1130 are stored in the storage unit 1120 , and the general-purpose processing unit implements the functions of the processing unit 1110 and the transceiver unit 1130 by executing the codes in the storage unit 1120 .
  • the apparatus 1100 when the apparatus 1100 is the first access network device, or can be provided in a chip or circuit of the first access network device,
  • the processing unit 1110 is configured to, in the handover preparation stage of the handover of the first terminal device from the first access network device to the second access network device, learn that the first terminal device is to receive through the first access network device The last terminal device of the data of the first multicast service;
  • the transceiver unit 1130 is configured to send first information, where the first information is used to release a first tunnel, and the first tunnel is used to transmit the first group between the first access network device and the core network device broadcast service data.
  • the transceiver unit 1130 is specifically configured to: send a handover request to the second access network device, where the handover request is used to request to handover the first terminal device from the first access network device To the second access network device, the handover request includes the first information.
  • the transceiver unit 1130 is specifically configured to: send a handover requirement to the first access and mobility management function network element, where the handover requirement includes the first information.
  • the transceiver unit 1130 is specifically configured to: the first access network device sends a third message to a third access and mobility management function network element, where the third message includes the first information,
  • the third access and mobility management function network element is the first terminal device to join the first multicast service, the access network device selected by the first access network device for the first multicast service. Access and mobility management function network elements.
  • processing unit 1110 is further configured to: update the number of terminal devices that join the first multicast service through the first access network device.
  • the first information includes an indication for releasing the first tunnel and information about the first tunnel;
  • the first information includes an indication for releasing the first tunnel and identification information of the first multicast service
  • the first information includes an indication for releasing the first tunnel, identification information of the first multicast service, and information of the first tunnel.
  • the core network device includes a multicast user plane function network element or a user plane function network element.
  • modules or units in the apparatus 1100 listed above are only exemplary descriptions.
  • the modules or units in the apparatus 1100 can be used for Perform each action or processing procedure performed by the first access network device in the above method.
  • the apparatus 1100 when the apparatus 1100 is the second access network device, or can be provided in a chip or circuit of the second access network device,
  • the transceiver unit 1130 is configured to receive a handover request from the first access network device, where the handover request is used to request to switch the first terminal device from the first access network device to the second access network device , the handover request includes first information, and the first information is used to release the first tunnel, and the first tunnel is used to transmit the first multicast between the first access network device and the core network device business data;
  • the transceiver unit 1130 is further configured to send a path switching request to the access and mobility management function network element, where the path switching request includes the first information.
  • modules or units in the apparatus 1100 listed above are only exemplary descriptions.
  • the modules or units in the apparatus 1100 can be used for Perform each action or processing process performed by the second access network device in the above method.
  • the device 1100 when the device 1100 is an access and mobility management function network element, or can be configured in a chip or circuit of the access and mobility management function network element,
  • the transceiver unit 1130 is used for the access and mobility management function network element to receive a path switching request from the second access network device, where the path switching request includes first information, and the first information is used to release the first tunnel , the first tunnel is used to transmit data of the first multicast service between the first access network device and the core network device;
  • the transceiver unit 1130 is further configured to send a protocol data unit PDU session context update request to the session management function network element, where the PDU session context update request includes the first information.
  • modules or units in the apparatus 1100 listed above are only illustrative.
  • the modules or units in the apparatus 1100 It can be used to execute each action or process performed by the access and mobility management function network element in the above method.
  • the apparatus 1100 when the apparatus 1100 is a session management function network element, or can be provided in a chip or circuit of the session management function network element,
  • a transceiver unit 1130 configured to receive a protocol data unit PDU session context update request from an access and mobility management function network element, where the PDU session context update request includes first information, and the first information is used to release the first tunnel , the first tunnel is used to transmit data of the first multicast service between the first access network device and the core network device;
  • the transceiver unit 1130 is further configured to send a first message to the network element of the multicast session management function, where the first message includes the first information.
  • the first message may be an N16 message.
  • the apparatus 1100 when the apparatus 1100 is a session management function network element, or can be provided in a chip or circuit of the session management function network element,
  • a transceiver unit 1130 configured to receive a protocol data unit PDU session context update request from an access and mobility management function network element, where the PDU session context update request includes first information, and the first information is used to release the first tunnel , the first tunnel is used to transmit data of the first multicast service between the first access network device and the core network device;
  • the transceiver unit 1130 is further configured to send a session update request to the user plane function network element, where the session update request includes the first information.
  • modules or units in the device 1100 listed above are only exemplary descriptions.
  • the modules or units in the device 1100 can be used to execute Each action or processing process performed by the session management function network element in the above method.
  • the apparatus 1100 when the apparatus 1100 is a multicast session management function network element, or can be provided in a chip or circuit of the multicast session management function network element,
  • the transceiver unit 1130 is configured to receive a first message from the session management function network element, where the first message includes first information, and the first information is used to release the first tunnel, and the first tunnel is used to 1.
  • the data of the first multicast service is transmitted between the access network equipment and the core network equipment;
  • the transceiver unit 1130 is further configured to send a fifth message to the multicast user plane function network element, where the fifth message includes the first information.
  • the first message is an N16 message.
  • the fifth message is an N4 session update request.
  • each module or unit in the device 1100 can use Each action or process performed by the network element of the multicast session management function in the above method is performed.
  • the apparatus 1100 when the apparatus 1100 is the first access and mobility management function network element, or can be provided in a chip or circuit of the first access and mobility management function network element,
  • the transceiver unit 1130 is configured to receive a handover requirement from a first access network device, where the handover requirement includes first information, and the first information is used to release a first tunnel, and the first tunnel is used to transmitting the data of the first multicast service between the first access network device and the core network device;
  • the transceiver unit 1130 is further configured to send a request for creating a user equipment UE context to the second access and mobility management function network element, where the request for creating a UE context includes the first information.
  • the functions and actions of the modules or units in the device 1100 listed above are only exemplary descriptions.
  • the modules in the device 1100 The OR unit may be configured to perform each action or processing procedure performed by the first access and mobility management function network element in the above method.
  • the apparatus 1100 when the apparatus 1100 is the second access and mobility management function network element, or can be provided in a chip or circuit of the second access and mobility management function network element,
  • the transceiver unit 1130 is configured to receive a request for creating a user equipment UE context from the first access and mobility management function network element, where the request for creating a UE context includes first information, and the first information is used to release the first tunnel , the first tunnel is used to transmit data of the first multicast service between the first access network device and the core network device;
  • the transceiver unit 1130 is further configured to send a protocol data unit PDU session context update request to the session management function network element, where the PDU session context update request includes the first information.
  • the functions and actions of the modules or units in the device 1100 listed above are only exemplary descriptions.
  • the modules in the device 1100 The OR unit may be configured to execute each action or processing procedure performed by the second access and mobility management function network element in the above method.
  • the device 1100 when the device 1100 is the third access and mobility management function network element, or can be configured in a chip or circuit of the third access and mobility management function network element,
  • the transceiver unit 1130 is configured to receive a third message from the first access network device, where the third message includes first information, and the first information is used to release the first tunnel, and the first tunnel is used to
  • the data of the first multicast service is transmitted between the first access network device and the core network device, and the third access and mobility management function network element is the first terminal device to join the first multicast service, the access and mobility management function network element selected by the first access network device for the first multicast service;
  • the transceiver unit 1130 is further configured to send a fourth message to the multicast session management function network element, where the fourth message includes the first information.
  • the third message is an N2 message.
  • the fourth message is an N11 message.
  • the functions and actions of the modules or units in the apparatus 1100 listed above are only exemplary descriptions.
  • the modules in the apparatus 1100 The OR unit may be configured to execute each action or processing procedure performed by the third access and mobility management function network element in the above method.
  • the apparatus 1100 when the apparatus 1100 is a multicast session management function network element, or can be provided in a chip or circuit of the multicast session management function network element,
  • the transceiver unit 1130 is configured to receive a fourth message from a third access and mobility management function network element, where the fourth message includes first information, and the first information is used to release the first tunnel, and the first information is used to release the first tunnel.
  • a tunnel is used to transmit the data of the first multicast service between the first access network device and the core network device, and the third access and mobility management function network element is used for adding the first terminal device to the In the case of the first multicast service, the access and mobility management function network element selected by the first access network device for the first multicast service;
  • the transceiver unit 1130 is further configured to send a fifth message to the multicast user plane function network element, where the fifth message includes the first information.
  • the fifth message is an N4 session update request.
  • the fourth message is an N11 message.
  • each module or unit in the device 1100 can use Each action or process performed by the network element of the multicast session management function in the above method is performed.
  • the apparatus 1100 when the apparatus 1100 is a multicast user plane functional network element, or can be provided in a chip or circuit of the multicast user plane functional network element,
  • the transceiver unit 1130 is configured to receive a fifth message from the network element of the multicast session management function, where the fifth message includes first information, and the first information is used to release the first tunnel, and the first tunnel is used for transmitting data of the first multicast service between the first access network device and the core network device;
  • the transceiver unit 1130 is further configured to release the first tunnel according to the first information.
  • the transceiver unit 1130 is specifically configured to receive a fifth message from the network element of the multicast session management function, where the fifth message includes the first information.
  • the fifth message is an N4 session update request.
  • each module or unit in the apparatus 1100 can use Each action or processing process performed by the multicast user plane function network element in the execution of the above method.
  • the apparatus 1100 when the apparatus 1100 is a user plane functional network element, or can be provided in a chip or circuit of the user plane functional network element,
  • the transceiver unit 1130 is configured to receive a session update request from a session management network element, where the session update request includes first information, and the first information is used to release a first tunnel, and the first tunnel is used to The data of the first multicast service is transmitted between the access network equipment and the core network equipment;
  • the transceiver unit 1130 is further configured for the user plane function network element to release the first tunnel according to the first information.
  • Each unit in the above embodiments may also be referred to as a module or a circuit or a component.
  • FIG. 12 is a schematic structural diagram of a network device 1200 according to an embodiment of the application, which can be used to implement the functions of the access network device (for example, the first access network device or the second access network device) in the above method .
  • the network device 1200 includes one or more radio frequency units, such as a remote radio unit (RRU) 1210 and one or more baseband units (BBU) (also referred to as digital units, digital units, DUs) 1220.
  • RRU 1210 may be referred to as a transceiver unit, a transceiver, a transceiver circuit, or a transceiver, etc., and may include at least one antenna 1211 and a radio frequency unit 1212 .
  • the RRU1210 part is mainly used for receiving and sending radio frequency signals and converting radio frequency signals to baseband signals, for example, for sending the signaling messages described in the above embodiments to terminal equipment.
  • the part of the BBU1220 is mainly used to perform baseband processing and control the base station.
  • the RRU 1210 and the BBU 1220 may be physically set together, or may be physically separated, that is, a distributed base station.
  • the BBU1220 is the control center of the base station, which can also be called a processing unit, and is mainly used to complete baseband processing functions, such as channel coding, multiplexing, modulation, and spread spectrum.
  • the BBU (processing unit) 1220 may be used to control the access network device to execute the operation flow of the access network device in the foregoing method embodiments.
  • the BBU1220 may be composed of one or more single boards, and the multiple single boards may jointly support a wireless access network of a single access standard (such as an LTE system or a 5G system), or may support different access modes respectively. into the standard wireless access network.
  • the BBU 1220 also includes a memory 1221 and a processor 1222 .
  • the memory 1221 is used to store necessary instructions and data.
  • the processor 1222 is configured to control the access network device to perform necessary actions, for example, to control the access network device to perform the operation flow of the access network device in the foregoing method embodiments.
  • the memory 1221 and the processor 1222 may serve one or more single boards. That is to say, the memory and processor can be provided separately on each single board. It can also be that multiple boards share the same memory and processor. In addition, necessary circuits may also be provided on each single board.
  • SoC system-on-chip
  • all or part of the functions of part 1220 and part 1210 can be implemented by SoC technology, for example, a base station function chip Implementation, the base station function chip integrates a processor, a memory, an antenna interface and other devices, the program of the base station related functions is stored in the memory, and the processor executes the program to realize the related functions of the base station.
  • the base station function chip can also read the external memory of the chip to realize the related functions of the base station.
  • FIG. 12 the structure of the network device illustrated in FIG. 12 is only a possible form, and should not constitute any limitation to the embodiments of the present application. This application does not exclude the possibility of other forms of base station structures that may appear in the future.
  • processor in the embodiments of the present application may be a central processing unit (central processing unit, CPU), and the processor may also be other general-purpose processors, digital signal processors (digital signal processors, DSP), application-specific integrated circuits (application specific integrated circuit, ASIC), off-the-shelf programmable gate array (field programmable gate array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.
  • a general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
  • the memory in the embodiments of the present application may be volatile memory or non-volatile memory, or may include both volatile and non-volatile memory.
  • the non-volatile memory may be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically programmable Erase programmable read-only memory (electrically EPROM, EEPROM) or flash memory.
  • Volatile memory may be random access memory (RAM), which acts as an external cache.
  • RAM random access memory
  • SRAM static random access memory
  • DRAM dynamic random access memory
  • DRAM synchronous dynamic random access memory
  • SDRAM synchronous dynamic random access memory
  • DDR SDRAM double data rate synchronous dynamic random access memory
  • enhanced SDRAM enhanced synchronous dynamic random access memory
  • SLDRAM synchronous connection dynamic random access memory Fetch memory
  • direct memory bus random access memory direct rambus RAM, DR RAM
  • the above embodiments may be implemented in whole or in part by software, hardware, firmware or any other combination.
  • the above-described embodiments may be implemented in whole or in part in the form of a computer program product.
  • the computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of the present application are generated.
  • the computer may be a general purpose computer, special purpose computer, computer network, or other programmable device.
  • the computer instructions may be stored in or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions may be downloaded from a website site, computer, server, or data center Transmission to another website site, computer, server or data center by wire (eg, infrared, wireless, microwave, etc.).
  • the computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, a data center, or the like that contains one or more sets of available media.
  • the usable media may be magnetic media (eg, floppy disks, hard disks, magnetic tapes), optical media (eg, DVDs), or semiconductor media.
  • the semiconductor medium may be a solid state drive.
  • Embodiments of the present application further provide a computer-readable medium on which a computer program is stored, and when the computer program is executed by a computer, implements the access network device or the access and mobility management function network element in any of the foregoing embodiments Or the steps performed by the session management function network element or the multicast session management function network element or the multicast user plane function network element.
  • Embodiments of the present application further provide a computer program product, which, when executed by a computer, implements the access network device or the access and mobility management function network element or the session management function network element or the The steps performed by the multicast session management function network element or the multicast user plane function network element.
  • An embodiment of the present application also provides a system chip, where the system chip includes: a communication unit and a processing unit.
  • the processing unit may, for example, be a processor.
  • the communication unit may be, for example, an input/output interface, a pin or a circuit, or the like.
  • the processing unit can execute computer instructions, so that the chip in the communication device executes the access network equipment or the access and mobility management function network element or the session management function network element or the multicast session management function provided by the above embodiments of the present application The steps performed by the network element or the network element with the function of the multicast user plane.
  • the computer instructions are stored in a storage unit.
  • various aspects or features of the present application may be implemented as a method, apparatus, or article of manufacture using standard programming and/or engineering techniques.
  • article of manufacture encompasses a computer program accessible from any computer readable device, carrier or medium.
  • computer readable media may include, but are not limited to: magnetic storage devices (eg, hard disks, floppy disks, or magnetic tapes, etc.), optical disks (eg, compact discs (CDs), digital versatile discs (DVDs) etc.), smart cards and flash memory devices (eg, erasable programmable read-only memory (EPROM), card, stick or key drives, etc.).
  • various storage media described herein can represent one or more devices and/or other machine-readable media for storing information.
  • the term "machine-readable medium” may include, but is not limited to, wireless channels and various other media capable of storing, containing, and/or carrying instructions and/or data.
  • the size of the sequence numbers of the above-mentioned processes does not mean the sequence of execution, and the execution sequence of each process should be determined by its functions and internal logic, and should not be dealt with in the embodiments of the present application. implementation constitutes any limitation.
  • the first and the second are only for the convenience of distinguishing different objects, and should not constitute any limitation to the present application.
  • different access network devices, different access and mobility management function network elements, etc. are distinguished.
  • the disclosed system, apparatus and method may be implemented in other manners.
  • the apparatus embodiments described above are only illustrative.
  • the division of the units is only a logical function division. In actual implementation, there may be other division methods.
  • multiple units or components may be combined or Can be integrated into another system, or some features can be ignored, or not implemented.
  • the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, and may be in electrical, mechanical or other forms.
  • the units described as separate components may or may not be physically separated, and components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.
  • each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit.
  • the functions, if implemented in the form of software functional units and sold or used as independent products, may be stored in a computer-readable storage medium.
  • the technical solution of the present application can be embodied in the form of a software product in essence, or the part that contributes to the prior art or the part of the technical solution, and the computer software product is stored in a storage medium, including Several instructions are used to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application.
  • the aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disk and other media that can store program codes .

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Abstract

本申请提供一种通信方法和装置，能够实现对接入网设备与核心网设备之间的传输组播业务的数据的隧道的释放，有助于节省网络资源开销。该方法包括：第一接入网设备在第一终端设备从第一接入网设备向第二接入网设备切换的切换准备阶段，获知第一终端设备为通过该第一接入网设备接收第一组播业务的数据的最后一个终端设备；第一接入网设备发送第一信息，该第一信息用于释放第一隧道，该第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据。

Description

通信方法和通信装置
本申请要求于2020年07月13日提交中国专利局、申请号为202010671517.9、申请名称为“通信方法和通信装置”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信领域，并且更具体的，涉及通信方法和通信装置。
背景技术
随着移动互联网的发展，移动高清视频业务呈现井喷态势。用户已经逐渐从传统的通过固定电视收看热点节目的方式转变为通过手机等移动终端收看热点节目。因此，视频业务对移动互联网的冲击愈发强烈。如果可以通过空口组播的方式优化视频业务的传输，将会大幅减少视频流量对移动网络的冲击。
在前几代移动通信技术中，例如第3代(the 3rd generation，3G)移动通信技术和第4代(the 4th generation，4G)移动通信技术中，组播方案的推广遇到了较大的困难。例如，前几代移动通信技术中组播方案需要在现有的通信架构基础上添加支持组播的专有网元和接口，并且还需要专有的组播信道支持。这不但增加了运营商角的开销，还提高了终端的复杂度。
为克服上述困难，在第5代(the 5th generation，5G)移动通信网络架构的基础上如何支持组播/广播功能(5G Multicast Broadcast Service，5MBS)成为一个关键研究课题。其中，5MBS研究课题的一个关键研究问题(key issue)是组播业务会话管理(MBS(multicast/broadcast service)session management)。针对该研究问题，组播会话隧道如何释放是一个亟待解决的问题。
发明内容
本申请实施例提供一种用于组播业务的通信方法和装置，能够实现对接入网设备与核心网设备之间的传输组播业务的数据的隧道的释放，有助于节省网络资源开销。
第一方面，提供了一种通信方法，该方法包括：
第一接入网设备在第一终端设备从所述第一接入网设备向第二接入网设备切换的切换准备阶段，获知所述第一终端设备为通过所述第一接入网设备接收第一组播业务的数据的最后一个终端设备；
所述第一接入网设备发送第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在所述第一接入网设备与核心网设备之间传输所述第一组播业务的数据。
因此，本申请实施例中，第一接入网设备可以在第一终端设备在从第一接入网设备切换至第二接入网设备的切换准备阶段，获知该第一终端设备为通过该第一接入网设备接收第一组播业务的数据的最后一个终端设备，并发送第一信息以释放用于在该第一接入网设 备与核心网设备之间传输该第一组播业务的数据的第一隧道，有助于节省网络资源开销。
示例性的，第一接入网设备可以为源接入网设备，第二接入网设备为目标接入网设备。
其中，上述第一组播业务可以是一个组播业务或者是多个不同的组播业务，不做限定。
本申请的一个示例中，第一信息可以包括用于释放第一隧道的指示(indication)和该第一隧道的信息。
本申请的另一个示例中，第一信息可以包括用于释放第一隧道的指示(indication)和第一组播业务的标识信息。
本申请的另一个示例中，第一信息可以包括用于释放第一隧道的指示(indication)、第一组播业务的标识信息和该第一隧道的信息。
其中，第一隧道的信息可用于唯一确定该第一隧道，例如可以是第一隧道的隧道端点标识(tunnel endpoint identifier，TEID)，或第一隧道的ID，此处不限定。第一组播业务的标识信息可用于唯一确定一个组播业务，例如可以是组播业务的ID，或组播业务的名称，或组播地址，或组播组ID等，此处不限定。
本申请实施例中，切换准备阶段，可以指的是源接入网设备、目标接入网设备或者核心网设备(此处，可以指的是AMF，SMF或UPF等，不予限制)为第一终端设备准备切换所需资源的阶段。其中，切换所需资源可以包括转发隧道，或者第一终端设备通过目标接入网设备接收业务数据所需的无线承载配置信息，目标接入网设备为第一终端设备配置的空口资源等，本申请实施例不作限定。
作为一个示例，在Xn切换场景中，切换准备阶段可以指源接入网设备接收到第一终端设备的测量报告，并依据测量报告对第一终端设备进行切换判决且判决结果为切换，源接入网设备向目标接入网设备发送切换请求，以及接收目标接入网设备发送切换请求响应的过程。
作为一个示例，在N2切换中，切换准备阶段可以指源接入网设备接收到第一终端设备的测量报告、源接入网设备根据该测量报告向源接入与移动性管理功能网元发送切换需要(handover required)，以及源接入与移动性管理功能网元从目标接入与移动性管理网元接收创建UE上下文响应的过程。
源接入网设备可以在切换准备阶段的任意一个时间点，获知第一终端设备为通过该第一接入网设备接收第一组播业务的数据的最后一个终端设备。
在一些可选的实施例中，在切换准备阶段，在加入第一组播业务的第一终端设备向源接入网设备发送测量报告，源接入网设备依据测量报告对第一终端设备进行切换判决且判决结果为切换的情况下，源接入网设备可以更新通过源接入网设备加入该第一组播业务的终端设备的数量，例如将该终端设备的数量减1。当该终端设备的数量为0时，源接入网设备可以获知第一终端设备为通过该第一接入网设备接收第一组播业务的数据的最后一个终端设备。
在一些可选的实施例中，通过源接入网设备加入组播业务的终端设备的数量可以包括在该第一终端设备的PDU会话关联的组播业务对应的组播上下文(Multicast Context)或组播会话上下文(Multicast Session Context)或组播组上下文(Multicast Group Context)或组播业务上下文(Multicast Service Context)中。
示例性的，核心网设备可以为组播用户面功能网元，例如可以是MUF、M-UPF、MS- UPF或MB-UPF等，不作限定。此时，第一隧道可以包括源接入网设备与组播用户面功能网元(例如MUF或M-UPF、MS-UPF或MB-UPF)之间的用于传输该第一组播业务的隧道。
示例性的，核心网设备可以为用户面功能网元，例如可以是UPF。此时，第一隧道可以包括源接入网设备与用户面功能网元(例如UPF)之间的用于传输该第一组播业务的隧道。
需要说明的是，在核心网设备为用户面功能网元的情况下，该用户面功能网元中可以包括用于对组播业务进行用户面相关的功能，即可以认为该用于对组播业务进行用户面相关的功能(例如MUF、M-UPF、MS-UPF或MB-UPF)可以与用户面功能网元合设为一个功能网元。对应的，此时会话管理功能网元中可以包括用于对组播业务进行控制面相关的功能，即该用于对组播业务进行控制面相关的功能(例如MCF、M-SMF、MS-SMF或MB-SMF)可以与会话管理功能网元合设为一个功能网元。
结合第一方面，在第一方面的某些实现方式中，例如Xn切换场景中，所述第一接入网设备发送第一信息，包括：
所述第一接入网设备向所述第二接入网设备发送切换请求，所述切换请求用于请求将所述第一终端设备从所述第一接入网设备切换至所述第二接入网设备，所述切换请求中包括所述第一信息。
示例性的，第一接入网设备可以在接收到第一终端设备的测量报告且依据该测量报告，判决需要第切换到第二接入网设备时，或者在确定要向第二接入网设备发送切换请求时，可以获知第一终端设备为通过该第一接入网设备加入第一组播业务的最后一个终端设备。此时，第一接入网设备向第二接入网设备发送的切换请求中可以携带第一信息。
相应地，第二接入网设备接收来自第一接入网设备切换请求之后，可以向接入与移动性管理功能网元(例如，AMF)发送路径切换请求(例如N2路径切换请求，N2 Path Switch Request)，该径切换请求中包括上述第一信息。之后，接入与移动性管理功能网元可以向会话管理功能网元发送PDU会话上下文更新请求(例如，Nsmf_PDUSession_UpdateSMContext Request)，该PDU会话上下文更新请求中包括该第一信息。
进一步地，在上述核心网设备为组播用户面功能网元的情况下，会话管理功能网元接收PDU会话上下文更新请求后，可以向组播会话管理功能网元发送第一消息，第一消息中包括第一信息。示例性的，第一消息可以为N16消息。组播会话管理功能网元接收第一消息后，可以向组播用户面功能网元发送第五消息，第五消息中可以包括该第一信息。示例性的，第五消息可以为N4会话更新请求。组播用户面功能网元可以根据该第五消息，获得第一信息，进而释放第一隧道。
在上述核心网设备为用户面功能网元的情况下，会话管理功能网元接收PDU会话上下文更新请求后，可以向用户面功能网元发送N4会话更新请求，N4会话更新请求中可以包括该第一信息。用户面功能网元可以根据该N4会话更新请求，获得第一信息，进而释放第一隧道。
因此，本申请实施例在Xn切换场景中，通过在第一接入网设备向第二接入网设备发送的切换请求中携带该第一信息，从而将第一信息传输至核心网设备，使得核心网设备可以根据该第一信息，对第一隧道进行释放。因此本申请实施例能够实现在Xn切换场景中 对接入网设备与核心网设备之间的传输第一组播业务的数据的第一隧道的释放，有助于节省网络资源开销。
另外，在Xn切换场景中，第一接入网设备能够通过目前已有的信令(例如切换请求)携带该第一信息，使得该第一信息最终发送至组播用户面功能网元，或用户面功能网元，有助于进一步节省网络资源开销。
结合第一方面，在第一方面的某些实现方式中，例如在N2切换场景中，所述第一接入网设备发送第一信息，包括：
所述第一接入网设备向第一接入与移动性管理功能网元发送切换需要(例如handover required)，所述切换需要中包括所述第一信息。
示例性的，第一接入网设备可以在接收到第一终端设备的测量报告时，或者在确定要向第一接入与移动性管理功能网元发送切换需要时，可以获知第一终端设备为通过该第一接入网设备加入第一组播业务的最后一个终端设备。此时，第一接入网设备向第一接入与移动性管理功能网元发送的切换需要中可以包括上述第一信息。示例性的，第一接入与移动性管理功能网元可以为源接入与移动性管理功能网元。
相应地，第一接入与移动性管理功能网元接收到切换需要后，可以向第二接入与移动性管理功能网元发送创建UE上下文请求(例如，Namf_Communication_CreateUEContext Request)，该创建UE上下文请求中包括第一信息。之后，第二接入与移动性管理功能网元向会话管理功能网元发送PDU会话更新上下文请求，该PDU会话更新上下文请求中可以包括该第一信息。其中，第二接入与移动性管理功能网元可以称为目标接入与移动性管理功能网元。
进一步地，在上述核心网设备为组播用户面功能网元的情况下，会话管理功能网元接收PDU会话上下文更新请求后，可以向组播会话管理功能网元发送第一消息，第一消息中包括第一信息。示例性的，第一消息可以为N16消息。组播会话管理功能网元接收第一消息后，可以向组播用户面功能网元发送第五消息，第五消息中可以包括该第一信息。示例性的，第五消息可以为N4会话更新请求。对应的，组播用户面功能网元可以根据该第五消息，获得第一信息，进而释放第一隧道。组播用户面功能网元也可以根据该第五消息，释放第一隧道。
在上述核心网设备为用户面功能网元的情况下，会话管理功能网元接收PDU会话上下文更新请求后，可以向用户面功能网元发送会话更新请求(例如N4会话更新请求)，会话更新请求中可以包括该第一信息。对应的，组播用户面功能网元可以根据该会话更新请求，获得第一信息，进而释放第一隧道。
因此，本申请实施例在N2切换场景中，通过在第一接入网设备向第一接入与移动性管理功能网元发送的切换需要中携带该第一信息，从而将第一信息传输至核心网设备，使得核心网设备可以根据该第一信息，对第一隧道进行释放。因此本申请实施例能够实现在N2切换场景中对接入网设备与核心网设备之间的传输第一组播业务的数据的第一隧道的释放，有助于节省网络资源开销。
另外，在N2切换场景中，第一接入网设备能够通过目前已有的信令(例如切换需要)携带该第一信息，使得该第一信息最终发送至组播用户面功能网元，或用户面功能网元，有助于进一步节省网络资源开销。
结合第一方面，在第一方面的某些实现方式中，所述第一接入网设备发送第一信息，包括：
所述第一接入网设备向第三接入与移动性管理功能网元发送第三消息，所述第三消息包括所述第一信息，所述第三接入与移动性管理功能网元为所述第一终端设备加入所述第一组播业务时，由所述第一接入网设备为所述第一组播业务服务选择的接入与移动性管理功能网元。
示例性的，第一接入网设备可以在切换准备阶段的任意一个时间点，获知第一终端设备为通过该第一接入网设备加入第一组播业务的最后一个终端设备。在获知第一终端设备为通过该第一接入网设备加入第一组播业务的最后一个终端设备的同时，或一段时间的之后，第一接入网设备可以向第三接入与移动性管理功能网元发送上述第三消息，本申请对此不作限定。
对应的，第三接入与移动性管理功能网元接收到第三消息。之后，第三接入与移动性管理功能网元可以向组播会话管理功能网元发送第四消息，第四消息携带第一信息。示例性的，第四消息可以是N11消息。组播会话管理功能网元收到第四消息后，可以向组播用户面功能网元发送第五消息，携带第一信息。示例性的，第五消息可以为N4会话更新请求。对应的，组播用户面功能网元可以根据该第五消息，获得第一信息，进而释放第一隧道。
在一些可选的实施例中，第三接入与移动性管理功能网元还可以是其它的与该第一终端设备有关，或者无关的接入与移动性管理功能网元。示例性的，所述与第一终端设备有关的接入与移动性管理功能网元可以是指为该第一终端设备的非接入层(non-access stratum,NAS)信令服务的接入与移动性管理功能网元，所述与第一终端设备无关的接入与移动性管理功能网元可以是指不是为该第一终端设备的NAS信令服务的接入与移动性管理功能网元。
在一些可选的实施例中，第三接入与移动性管理功能网元可以与上文中的源接入与移动性管理功能网元为同一个网元，或者与上文中的目标接入与移动性管理功能网元为同一个网元，本申请实施例对此不作限定。
因此，本申请实施例，通过在第一接入网设备向第三接入与移动性管理功能网元发送的第三消息中携带该第一信息，从而将第一信息传输至核心网设备，使得核心网设备可以根据该第一信息，对第一隧道进行释放。因此本申请实施例能够实现对接入网设备与核心网设备之间的传输第一组播业务的数据的第一隧道的释放，有助于节省网络资源开销。
第二方面，提供了一种通信方法，该方法包括：
第二接入网设备接收来自所述第一接入网设备的切换请求，所述切换请求用于请求将所述第一终端设备从第一接入网设备切换至所述第二接入网设备，所述切换请求中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在所述第一接入网设备与核心网设备之间传输第一组播业务的数据；
所述第二接入网设备向接入与移动性管理功能网元发送路径切换请求，所述路径切换请求中包含所述第一信息。
第三方面，提供了一种通信方法，所述方法包括：
接入与移动性管理功能网元接收来自第二接入网设备的路径切换请求，所述路径切换 请求中包含第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
所述接入与移动性管理功能网元向会话管理功能网元发送协议数据单元PDU会话上下文更新请求，所述PDU会话上下文更新请求包括所述第一信息。
第四方面，提供了一种通信方法，所述方法包括：
会话管理功能网元接收来自接入与移动性管理功能网元的协议数据单元PDU会话上下文更新请求，所述PDU会话上下文更新请求包含第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
所述会话管理功能网元向组播会话管理功能网元发送第一消息，所述第一消息中包括所述第一信息。
结合第四方面，在第四方面的一些可能的实现方式中，所述第一消息为N16消息。
第五方面，提供了一种通信方法，所述方法包括：
会话管理功能网元接收来自接入与移动性管理功能网元的协议数据单元PDU会话上下文更新请求，所述PDU会话上下文更新请求包含第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
所述会话管理功能网元向用户面功能网元发送会话更新请求，所述会话更新请求中包括所述第一信息。
第六方面，提供了一种通信方法，所述方法包括：
组播会话管理功能网元接收来自会话管理功能网元的第一消息，所述第一消息中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
所述组播会话管理功能网元向组播用户面功能网元发送第五消息，所述第五消息中包括所述第一信息。
结合第六方面，在第六方面的一些可能的实现方式中，所述第一消息为N16消息。
结合第六方面，在第六方面的一些可能的实现方式中，所述第五消息为N4会话更新请求。
第七方面，提供了一种通信方法，所述方法包括：
第一接入与移动性管理功能网元接收来自第一接入网设备的切换需要，所述切换需要中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在所述第一接入网设备与核心网设备之间传输所述第一组播业务的数据；
所述第一接入与移动性管理功能网元向第二接入与移动性管理功能网元发送创建用户设备UE上下文请求，所述创建UE上下文请求中包含所述第一信息。
第八方面，提供了一种通信方法，所述方法包括：
第二接入与移动性管理功能网元接收来自第一接入与移动性管理功能网元的创建用户设备UE上下文请求，所述创建UE上下文请求中包含第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
所述第二接入与移动性管理功能网元向会话管理功能网元发送协议数据单元PDU会话上下文更新请求，所述PDU会话上下文更新请求包括所述第一信息。
第九方面，提供了一种通信方法，包括：
第三接入与移动性管理功能网元接收来自第一接入网设备的第三消息，所述第三消息包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在所述第一接入网设备与核心网设备之间传输第一组播业务的数据，所述第三接入与移动性管理功能网元为在所述第一终端设备加入所述第一组播业务时，由所述第一接入网设备为所述第一组播业务选择的接入与移动性管理功能网元；
所述第三接入与移动性管理功能网元向组播会话管理功能网元发送第四消息，所述第四消息中包括所述第一信息。
结合第九方面，在第九方面的一些可能的实现方式中，所述第三消息为N2消息。
第十方面，提供了一种通信方法，包括：
组播会话管理功能网元接收来自第三接入与移动性管理功能网元的第四消息，所述第四消息中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据，所述第三接入与移动性管理功能网元为在所述第一终端设备加入所述第一组播业务时，所述第一接入网设备为所述第一组播业务选择的接入与移动性管理功能网元；
所述组播会话管理功能网元向组播用户面功能网元发送第五消息，所述第五消息包括所述第一信息。
结合第十方面，在第十方面的一些可能的实现方式中，所述第五消息为N4会话更新请求。
结合第九方面或第十方面，在第九方面或第十方面的一些可能的实现方式中，所述第四消息为N11消息。
第十一方面，提供了一种通信方法，所述方法包括：
组播用户面功能网元接收来自组播会话管理功能网元的第五消息，所述第五消息中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
所述组播用户面功能网元根据所述第一信息，释放所述第一隧道。
第十二方面，提供了一种通信方法，所述方法包括：
用户面功能网元接收来自会话管理网元的会话更新请求，所述会话更新请求中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
所述用户面功能网元根据所述第一信息，释放所述第一隧道。
结合第十一方面或第十二方面，在第十一方面或十二方面的一些可能的实现方式中，可以通过移除第一隧道的相关资源，例如隧道端点标识，来释放第一隧道。
结合第十一方面或第十二方面，在第十一方面或十二方面的一些可能的实现方式中，所述第一信息包括用于释放所述第一隧道的指示和所述第一隧道的信息，
其中，所述释放所述第一隧道包括根据所述用于释放所述第一隧道的指示和所述第一隧道的信息，释放所述第一隧道。
这样，组播用户面功能网元或用户面功能网元能够对该第一信息所包含的第一隧道的信息对应的第一隧道(例如可以为一个第一隧道，或多个第一隧道，不作限定)进行释放。
结合第十一方面或第十二方面，在第十一方面或十二方面的一些可能的实现方式中，所述第一信息包括用于释放所述第一隧道的指示和所述第一组播业务的标识信息；
其中，所述释放所述第一隧道包括：
根据所述第一组播业务的标识信息，确定所述第一组播业务；
确定在所述第一接入网设备与所述核心网设备之间传输所述第一组播业务的数据的第一隧道；
根据所述用于释放所述第一隧道的指示，释放所述第一隧道。
这样，组播会话功能网元或会话功能网元可以将第一信息中所指示的第一组播业务对应的所有组播会话隧道，即用于在源接入网设备与核心网设备之间传输该第一组播业务的数据的第一隧道(例如所有第一隧道)释放。
结合第十一方面或第十二方面，在第十一方面或十二方面的一些可能的实现方式中，所述第一信息包括用于释放所述第一隧道的指示、所述第一组播业务的标识信息和所述第一隧道的信息；
其中，所述释放所述第一隧道包括：
根据所述第一组播业务的标识信息，确定所述第一组播业务；
根据所述第一隧道的信息，在所述第一接入网设备与所述核心网设备之间传输所述第一组播业务的数据的隧道中确定所述第一隧道；
根据所述用于释放所述第一隧道的指示，释放所述第一隧道。
这样，组播用户面功能网元或用户面功能网元能够对该第一信息所包含的第一隧道的信息对应的第一隧道进行释放。并且，当根据第一组播业务的标识信息和第一隧道的信息二者来确定第一隧道时，只需要在第一组播业务对应的一个或多个组播会话隧道中来确定该第一隧道，能够有助于更准确、快速的确定该第一隧道，从而有助于提高释放第一隧道的效率。
应理解，本申请的第二方面至第十二方面及对应的实现方式所取得的有益效果参见本申请的第一方面及对应的实现方式所取得的有益效果，不再赘述。
第十三方面，提供了一种通信装置，该装置包括用于执行第一方面至第十二方面中任一方面，或任一方面的任意一种可能的实现方式中的通信方法的模块或单元。
第十四方面，提供了一种通信装置，该装置包括处理器，所述处理器用于从存储器中调用并运行计算机程序，以执行如第一方面至第十二方面中任一方面，或任一方面的任意一种可能的实现方式中的通信方法。
可选的，该通信装置还可以包括存储器，存储器用于存储处理器执行的程序。
该通信装置的示例可以为接入网设备、接入与移动性管理功能网元、会话管理功能网元、组播会话管理功能网元或组播用户面功能网元等。
第十五方面，提供了一种芯片，芯片包括处理器和通信接口，该通信接口用于与外部器件或内部器件进行通信，该处理器用于实现上述第一方面至第十二方面中任一方面，或任一方面的任意一种可能的实现方式中的方法。
可选地，该芯片还可以包括存储器，该存储器中存储有指令，处理器用于执行存储器中存储的指令或源于其他的指令。当该指令被执行时，处理器用于实现上述第一方面至第十二方面中任一方面，或任一方面的任意一种可能的实现方式中的方法。
可选地，该芯片可以集成在接入网设备、接入与移动性管理功能网元、会话管理功能网元、组播会话管理功能网元或组播用户面功能网元上。
第十六方面，提供一种计算机可读存储介质，该计算机可读存储介质存储用于同步的装置执行的程序代码，该程序代码包括用于实现第一方面至第十二方面中任一方面，或任一方面的任意一种可能的实现方式中的方法的指令。
第十七方面，提供一种包含指令的计算机程序产品，当该计算机程序产品在计算机上运行时，使得该计算机执行第一方面至第十二方面中任一方面，或任一方面的任意一种可能的实现方式中的方法。
第十八方面，提供了一种通信系统，包括用于执行第一方面或第一方面的任一种可能的实现方式中的方法的装置，用于执行第二方面、第三方面和第四方面中的方法的装置，以及第十一方面或第十一方面的任一种可能的实现方式中的方法的装置。
第十九方面，提供了一种通信系统，包括用于执行第一方面或第一方面的任一种可能的实现方式中的方法的装置，用于执行第二方面、第三方面、第五方面和第六方面中的方法的装置，以及第十二方面或第十二方面的任一种可能的实现方式中的方法的装置。
第二十方面，提供了一种通信系统，包括用于执行第一方面或第一方面的任一种可能的实现方式中的方法的装置，用于执行第七方面、第八方面和第四方面中的方法的装置，以及第十一方面或第十一方面的任一种可能的实现方式中的方法的装置。
第二十一方面，提供了一种通信系统，包括用于执行第一方面或第一方面的任一种可能的实现方式中的方法的装置，用于执行第七方面、第八方面、第五方面中和第六方面的方法的装置，以及第十二方面或第十二方面的任一种可能的实现方式中的方法的装置。
第二十二方面，提供了一种通信系统，包括用于执行第一方面或第一方面的任一种可能的实现方式中的方法的装置，用于执行第九方面和第十方面中的方法的装置，以及第十一方面或第十一方面的任一种可能的实现方式中的方法的装置。
附图说明
图1是本申请实施例提供的系统架构的示意图。
图2是本申请实施例的另一个系统架构的示意图。
图3A是本申请实施例提供的一种业务数据的传输示意图。
图3B是本申请实施例提供的另一种业务数据的传输示意图。
图4是终端设备加入组播业务的一个示意性流程图。
图5A示出了适用于本申请实施例的方案的一种应用场景的示意图。
图5B示出了适用于本申请实施例的方案的一种应用场景的示意图。
图5C示出了适用于本申请实施例的方案的一种应用场景的示意图。
图6示出了本申请实施例提供的一种通信方法的示意性流程图。
图7是本申请实施例提供的一种通信方法的具体的例子。
图8示出了本申请实施例提供的另一种通信方法的示意性流程图。
图9是本申请实施例提供的另一种通信方法的具体的例子。
图10是本申请实施例提供的另一种通信方法的具体的例子。
图11是本申请实施例提供的一种无线通信设备的结构示意图。
图12是本申请实施例提供的一种网络设备的结构示意图。
具体实施方式
下面将结合附图，对本申请中的技术方案进行描述。
本申请实施例的技术方案可以应用于各种通信系统，例如：例如：全球移动通信(global system formobile communications，GSM)系统、码分多址(code division multiple access，CDMA)系统、宽带码分多址(wideband code division multiple access，WCDMA)系统、通用分组无线业务(general packet radio service，GPRS)、长期演进(long term evolution，LTE)系统、系统架构演进(system architecture evolved，SAE)系统、LTE频分双工(frequency division duplex，FDD)系统、LTE时分双工(time division duplex，TDD)、通用移动通信系统(universal mobile telecommunication system，UMTS)、全球互联微波接入(worldwide interoperability for microwave access，WiMAX)通信系统、第五代(5th generation，5G)系统或新无线(new radio，NR)，以及后续演进通信系统等。
图1示出了本申请实施例的一种通信系统的示意图。在图1中包括接入网设备、核心网设备以及终端设备。其中，终端设备与接入网设备连接，接入网设备与核心网设备连接，使得终端设备能够通过接入网设备与核心网设备进行通信。
其中，本申请实施例中的终端设备也可以称为：用户设备(user equipment，UE)、移动台(mobile station，MS)、移动终端(mobile terminal，MT)、接入终端、用户单元、用户站、移动站、移动台、远方站、远程终端、移动设备、用户终端、终端、无线通信设备、用户代理或用户装置等。
终端设备可以是一种向用户提供语音/数据连通性的设备，例如，具有无线连接功能的手持式设备、车载设备等。目前，一些终端的举例为：手机(mobile phone)、平板电脑、笔记本电脑、掌上电脑、移动互联网设备(mobile internet device，MID)、可穿戴设备，虚拟现实(virtual reality，VR)设备、增强现实(augmented reality，AR)设备、工业控制(industrial control)中的无线终端、无人驾驶(self driving)中的无线终端、远程手术(remote medical surgery)中的无线终端、智能电网(smart grid)中的无线终端、运输安全(transportation safety)中的无线终端、智慧城市(smart city)中的无线终端、智慧家庭(smart home)中的无线终端、蜂窝电话、无绳电话、会话启动协议(session initiation protocol，SIP)电话、无线本地环路(wireless local loop，WLL)站、个人数字助理(personal digital assistant，PDA)、具有无线通信功能的手持设备、计算设备或连接到无线调制解调器的其它处理设备、车载设备、可穿戴设备，5G网络中的终端设备或者演进的公用陆地移动通信网络(public land mobile network，PLMN)中的终端设备等，本申请实施例对此并不限定。
作为示例而非限定，在本申请实施例中，可穿戴设备也可以称为穿戴式智能设备，是应用穿戴式技术对日常穿戴进行智能化设计、开发出可以穿戴的设备的总称，如眼镜、手套、手表、服饰及鞋等。可穿戴设备即直接穿在身上，或是整合到用户的衣服或配件的一种便携式设备。可穿戴设备不仅仅是一种硬件设备，更是通过软件支持以及数据交互、云端交互来实现强大的功能。广义穿戴式智能设备包括功能全、尺寸大、可不依赖智能手机实现完整或者部分的功能，例如：智能手表或智能眼镜等，以及只专注于某一类应用功能，需要和其它设备如智能手机配合使用，如各类进行体征监测的智能手环、智能首饰等。
此外，在本申请实施例中，终端设备还可以是物联网(internet of things，IoT)系统中的终端设备，IoT是未来信息技术发展的重要组成部分，其主要技术特点是将物品通过通信技术与网络连接，从而实现人机互连，物物互连的智能化网络。
而如上介绍的各种终端设备，如果位于车辆上(例如放置在车辆内或安装在车辆内)，都可以认为是车载终端设备，车载终端设备例如也称为车载单元(on-board unit，OBU)。
本申请实施例中，终端设备还可以包括中继(relay)。或者理解为，能够与基站进行数据通信的都可以看作终端设备。
本申请实施例中的接入网设备可以是用于与终端设备通信的设备，该接入网设备也可以称为接入设备或无线接入网设备，可以是LTE系统中的演进型基站(evolved NodeB，eNB或eNodeB)，还可以是云无线接入网络(cloud radio access network，CRAN)场景下的无线控制器，或者该接入设备可以为中继站、接入点、车载设备、可穿戴设备以及5G网络中的接入设备或者未来演进的PLMN网络中的网络设备等，可以是WLAN中的接入点(access point，AP),可以是新型无线系统(new radio，NR)系统中的gNB本申请实施例并不限定。
另外，在本申请实施例中，接入网设备是RAN中的设备，或者说，是将终端设备接入到无线网络的RAN节点。例如，作为示例而非限定，作为接入网设备，可以列举：gNB、传输接收点(transmission reception point，TRP)、演进型节点B(evolved Node B，eNB)、无线网络控制器(radio network controller，RNC)、节点B(Node B，NB)、基站控制器(base station controller，BSC)、基站收发台(base transceiver station，BTS)、家庭基站(例如，home evolved NodeB，或home Node B，HNB)、基带单元(base band unit，BBU)，或无线保真(wireless fidelity，Wifi)接入点(access point，AP)等。在一种网络结构中，网络设备可以包括集中单元(centralized unit，CU)节点、或分布单元(distributed unit，DU)节点、或包括CU节点和DU节点的RAN设备、或者控制面CU节点(CU-CP节点)和用户面CU节点(CU-UP节点)以及DU节点的RAN设备。
接入网设备为小区提供服务，终端设备通过该小区使用的传输资源(例如，频域资源，或者说，频谱资源)与接入网设备进行通信，该小区可以是接入网设备(例如基站)对应的小区，小区可以属于宏基站，也可以属于小小区(small cell)对应的基站，这里的小小区可以包括：城市小区(metro cell)、微小区(micro cell)、微微小区(pico cell)、毫微微小区(femto cell)等，这些小小区具有覆盖范围小、发射功率低的特点，适用于提供高速率的数据传输服务。
为了便于理解本申请实施例，首先结合图1对适用于本申请实施例的系统架构进行详细说明。如图1所示，该系统架构100包括：终端设备110、接入网设备120、接入与移动性管理功能网元130以及会话管理功能网元140。
其中，接入与移动性管理功能网元130和会话管理功能网元140属于核心网设备。示例性地，终端设备110可以通过接入网设备120接入核心网，从而实现数据传输。接入与移动性管理功能网元130可以接收来自接入网设备的将终端设备110加入组播业务的请求，并请求会话管理功能网元140将终端设备110加入组播业务。会话管理功能网元140可以为终端设备110创建相应的组播会话隧道，将终端设备110加入组播业务，从而将组播业务的数据流传输给终端设备110。
上述系统架构100可以用于执行本申请实施例中的传输组播业务的方法。
由于本申请的传输组播业务的方法主要基于5G移动通信技术以及未来的其他移动通信技术，下面结合图2介绍本申请实施例的另一个系统架构——5G系统架构。
需要说明的是，本申请中针对组播业务的方案可应用于广播业务。
图2是本申请实施例的另一个系统架构200。如图2所示，该系统架构200具体可以包括下列网元：
1、用户设备UE。
2、(无线)接入网(radio access network，(R)AN)：用于为特定区域的授权用户提供入网功能，并能够根据用户的级别，业务的需求等使用不同质量的传输隧道。(R)AN网元能够管理无线资源，为终端设备提供接入服务，进而完成控制信号和用户数据在终端设备和核心网之间的转发，(R)AN也可以理解为传统网络中的基站。
3、接入和移动性管理功能(access and mobility management function，AMF)：主要用于移动性管理和接入管理等。具体地，AMF可以用于实现移动性管理实体(mobility management entity，MME)的功能中除会话管理之外的其它功能，例如，合法监听、或接入授权(或鉴权)等功能。
4、会话管理功能(Session Management Function，SMF)：主要用于会话管理、终端设备的网络互连协议(Internet Protocol，IP)地址分配和管理、选择可管理用户平面功能、策略控制、或收费功能接口的终结点以及下行数据通知等。
应理解，在上述系统架构100中，终端设备110可以为图2中的UE，接入网设备120可以为图2中的RAN；接入与移动性管理功能网元130可以为图2中的AMF；会话管理功能网元140可以为图2中的SMF，不予限制。
可选地，该系统架构200还可以包括：
5、用户平面功能(user plane function，UPF)：也可以称为用户面功能网元，用于分组路由和转发、或用户面数据的服务质量(quality of service，QoS)处理等。UPF具体分为中间-UPF(intermediate-UPF，I-UPF)和锚点UPF(PDU session anchor，PSA)。
6、数据网络(data network，DN)：用于提供传输数据的网络，例如，Internet网络等。在本申请实施例的架构中，PSA接入远端DN，L-PSA可以接入本地DN。
7、认证服务功能(authentication server function，AUSF)：主要用于用户鉴权等。
8、策略控制功能(policy control function，PCF)：用于指导网络行为的统一策略框架，为控制平面功能网元(例如AMF、SMF网元等)提供策略规则信息等。
9、统一数据管理(unified data management，UDM)：用于处理用户标识、接入鉴权、注册、或移动性管理等。
10、应用功能(application function，AF)：主要支持与第三代合作伙伴计划(3rd generation partnership project，3GPP)核心网交互来提供服务，例如，影响数据路由决策、策略控制功能、或者向网络侧提供第三方的一些服务。可理解为第三方服务器，例如，Internet中的应用服务器，提供相关业务信息，包括向PCF提供业务对应的服务质量需求信息，以及向PSA-UPF发送业务的用户面数据信息。AF可以是服务提供商(content provider，CP)。
11、网络切片选择功能(network slice selection function，NSSF)：用于进行网络切片 的选择。
在该系统架构200中，N1接口为终端设备与AMF之间的参考点；N2接口为(R)AN和AMF的参考点，用于非接入层(non-access stratum，NAS)消息的发送等；N3接口为(R)AN和I-UPF之间的参考点，用于传输用户面的数据等；N4接口为SMF和I-UPF之间的参考点，用于传输例如N3连接的隧道标识信息、数据缓存指示信息、以及下行数据通知消息等信息；N5接口为PCF与AF之间的参考点；N6接口为UPF和DN之间的参考点，用于传输用户面的数据等；N7接口为SMF和PCF之间的参考点；N8接口为AMF和UDM之间的参考点；N9接口为UPF之间的参考点；N10接口为SMF与UDM之间的参考点；N11接口为AMF与SMF之间的参考点；N12接口为AMF与AUSF之间的参考点；N22接口为AMF与NSSF之间的参考点。
可选地，该系统架构200还可以包括：
12、组播控制面功能(multicast control plane function，MCF)：或称为组播会话管理功能(multicast session management function，M-SMF)或称为组播业务会话管理功能(multicast service session mangementfunction，MS-SMF)或组播/广播会话管理功能(multicast/broadcast session management function，MB-SMF)，其用于对组播业务进行控制面相关的功能，例如，MCF或M-SMF或MB-SMF与PCF对接，以便为组播业务创建资源。此处应注意，在5G网络中，上述MCF或MS-SMF或MS-SMF网元或MB-SMF还可以是其它名称，其实现的是组播业务的控制面功能。此处应注意，如前文所述，本申请的“组播”是广义上的概念，可以包括组播(multicast)或广播(broadcast)，即本申请实施例既可以应用于组播业务传输，也可以应用于广播业务传输。本申请中提及的“组播”可以替换为“组播或广播”。因此，组播控制面功能(MCF)、组播会话管理功能(M-SMF)、组播业务会话管理功能(MS-SMF)、组播/广播会话管理功能(MB-SMF)四者意思相同，可以相互替换，此处不限定。
13、组播用户面功能(multicast user plane function，MUF)：或称为组播用户面功能(multicast user plane function，M-UPF)，或称为组播业务用户面功能(multicast service user plane function,MS-UPF)，或称为组播/广播用户面功能(multicast/broadcast user plane Function,MB-UPF)，其用于对组播业务进行用户面相关的功能，例如，传递组播业务数据。此处应注意，在5G网络中，上述MUF或M-UPF或MS-UPF或MB-UPF网元还可以是其它名称，其实现的是组播业务的用户面功能。此处应注意，如前文所述，本申请的“组播”是广义上的概念，可以包括组播(multicast)或广播(broadcast)，即本申请实施例既可以应用于组播业务传输，也可以应用于广播业务传输。本申请中提及的“组播”可以替换为“组播或广播”。因此，组播用户面功能(MUF)、组播用户面功能(M-UPF)、组播业务会话管理(MS-UPF)、组播/广播会话管理(MB-UPF)四者意思相同，可以相互替换，此处不限定。
上述系统架构200中，MCF或MS-SMF或MS-SMF或MB-SMF可以集成到PCF(或SMF或NEF)中，MUF或M-UPF或MS-UPF或MB-UPF可集成到UPF中，本申请实施例对此不作限定。
应理解，上述应用于本申请实施例的系统架构200仅是举例说明的从参考点架构的角度描述的网络架构，适用本申请实施例的网络架构并不局限于此，任何能够实现上述各个网元的功能的网络架构都适用于本申请实施例。
需要说明的是，图2中的各个网元之间的接口名称只是一个示例，具体实现中接口的名称可能为其他的名称，本申请实施例对此不作具体限定。
需要说明的是，图2中包括的各个网元(比如SMF、AF、UPF等)的名称也仅是一个示例，对网元本身的功能不构成限定。在5G网络以及未来其它的网络中，上述各个网元也可以是其他的名称，本申请实施例对此不作具体限定。例如，在第6代(the 6th generation，6G)网络中，上述各个网元中的部分或全部可以沿用5G中的术语，也可能采用其他名称，等等，在此进行统一说明，以下不再赘述。此外，应理解，上述各个网元之间的所传输的消息(或信令)的名称也仅仅是一个示例，对消息本身的功能不构成任何限定。
为便于理解本申请实施例，首先对本申请中涉及到的术语作简单说明。
1、组播和单播
单播：可以理解为“点对点”(point to point)通信。单播包含多层含义，具体如下：
在业务层面，单播业务是指该业务的数据是发送给一个特定终端设备的。
针对网元间的单播，单播是指源网元与目标网元之间为单播隧道(即，目标网元的IP地址为单播IP地址)。
对于空口而言，空口单播模式是指无线接入网向单个终端设备发送业务数据。
在核心网业务层面，单播是指通过协议数据单元(protocol data unit，PDU)会话向终端设备发送业务数据。
在本申请文件中，SMF所确定的发送方式中的单播方式是指通过PDU会话向终端设备发送组播业务的数据。
组播：可以称为“多播”，可以理解为“点对多点”(point to multi-point，PTM)通信。组播包含多层含义，具体如下：
在业务层面，组播业务是指该业务的数据发送给多个终端设备。
针对网元间的组播，组播是指源网元与目标网元之间为组播隧道(即，目标网元的IP地址为组播IP地址)。
对于空口而言，空口组播模式是指针对无线接入网发送的一份业务数据，多个终端设备可同时和/或同频接收。
在核心网业务层面，组播是指通过组播会话向终端设备发送组播业务的数据，其中，组播会话包括：网元间的单播隧道或组播隧道、以及单播模式的空口无线承载或组播模式的空口无线承载。
在本申请实施例中，SMF所确定的发送方式中的组播方式是指通过组播会话向终端设备发送组播业务的数据。
采用组播方式，既可以实现一次向所有目标节点传输业务数据，也可以只对特定对象传送业务数据，因此，在组播方式中，一个发送节点和多个接收节点之间可以实现点到多点的传输，从而解决了单播方式效率低的问题。
需要说明的是，广播业务可以通过组播会话向终端设备发送，本申请实施例对此不作限定。本申请的“组播”是广义上的概念，可以包括组播(multicast)或广播(broadcast)，即本申请实施例既可以应用于组播业务传输，也可以应用于广播业务传输。本申请中提及的“组播”可以替换为“组播或广播”。
图3A是本申请实施例提供的一种业务数据的传输示意图。图3A所示的示意图既可 以用于传输组播业务数据(通过单播的方式)，也可以用于传输单播业务数据。在图3A中，3个UE中的每个UE分别对应一个不同的PDU会话。CP发送的三份不同的业务数据可以通过各自对应的PDU会话发送给UE。具体地，从CP至AN的业务传输路径可以包含CP与UPF之间的传输路径、以及UPF与AN之间的传输路径。UPF与AN之间的传输路径可以称为PDU会话隧道，不同的PDU会话具有不同的PDU会话隧道。本示意图中的3条PDU会话隧道分别对应3个UE。在空口上，AN可以以单播的方式，即PTP方式，分别向UE 1、UE 2和UE 3发送业务数据。在该示意图中，每个UE的业务数据可以均不相同(例如，目标地址分别为各UE的IP地址)，且各个UE的业务数据可以通过各个UE各自独立的传输路径分别发送给各UE。
图3B是本申请实施例提供的另一种业务数据的传输示意图。图3B所示的示意图用于传输组播业务数据。在图3B中，组播业务数据可以从CP发送至UE 1、UE 2和UE 3。其中，从CP至AN的组播业务传输路径可以包含CP与UPF之间的传输路径、以及UPF与AN之间的传输路径。UPF到AN的传输路径可以采用隧道传送组播业务数据，例如，采用基于通用隧道协议(general tunnel protocol，GTP)的隧道。因此，UPF与AN之间的传输路径可以称为组播会话隧道，该组播会话隧道是UE 1、UE 2和UE 3共享的。在空口上，AN可以通过PTM方式向UE 1、UE 2和UE3发送上述组播业务数据，即只需要发送一份数据，3个UE均可接收。在该示意图中，组播业务数据在从CP一直到UE的传输路径上均只发送一份，多个UE可同时接收。
在本申请中，组播会话隧道和PDU会话隧道都是用户面网元(例如UPF)至接入网AN(例如基站)之间的隧道。其中，组播会话隧道可以用于传输组播业务的组播QoS流，PDU会话隧道可以用于传输单播业务的单播QoS流，还可以用于与传输组播业务的组播QoS流对应的单播QoS流。
应理解，组播QoS流是在UPF和gNB 1之间传输的；经过gNB 1的服务数据适配协议(service data adaptation protocol，SDAP)层、分组数据汇聚协议(packet data convergence protocol，PDCP)层、无线链路控制(radio link control，RLC)层、媒体接入控制(media access control，MAC)层、物理(physical，PHY)层的处理，各个UE接收到的数据可以称为组播业务数据。
2、组播业务、组播业务流以及组播服务质量(quality of service，QoS)流
组播业务可以包括一个或多个组播业务流，通过组播业务的信息表示。组播业务的信息至少包括组播业务的描述信息，该组播业务的描述信息中可以包括一个或多个组播业务流的描述信息，其中，组播业务流的描述信息包括下列至少一项：该组播业务流应该具备的服务质量索引(QoS flow identifier，QFI)、组播业务流的特征信息(如组播业务的组播地址、目的端口号、源地址等)、组播业务流的QoS需求(如，抖动、时延、丢包率、带宽等)。组播业务流的QoS需求用于建立组播QoS流。一个组播会话可以包括一个或多个组播QoS流。换句话说，组播业务可以在组播会话所在的组播会话隧道中以一条或多条组播QoS流的方式进行传输。
需要理解的是，PDU会话是UE级别的，组播会话是业务级别的。一个UE的一个PDU会话可以与多个组播会话关联，即，该UE的该PDU会话可以加入多个组播业务，一个组播业务可以由一个组播会话提供服务，一个组播会话包括从数据网络到核心网再到无线接 入网的单播或组播隧道、以及无线接入网分配的用于发送该组播业务的单播或组播空口资源。
除了组播业务的描述信息之外，组播业务的信息中还可以包含终端设备的信息，例如，可以包括允许(或请求)加入该组播业务的一个或多个终端设备的标识、终端设备组的标识等。
一个组播业务可以被分配全球唯一的组播业务标识(multicast ID，MCID)，该MCID可以在该PLMN内唯一标识该组播业务。应理解，本申请对英文名称MCID不进行限定，MCID还可以替换为其它名称，但是其功能都是唯一对组播业务进行标识。示例性地，图2所示的MCF可以从CP获得组播业务信息，再将所获得的组播业务信息发送至PCF，PCF可以根据该组播业务信息生成策略与计费控制(policy and charging control，PCC)规则。其中，若组播业务信息可以应用于所有终端设备，则所生成的PCC规则也可以应用于所有终端设备。否则，所生成的PCC规则可以与组播业务相关的一个或多个终端设备相关。可选地，MCF为组播业务分配了MCID，则MCF可以将MCID和组播业务信息一起发送给PCF。相应地，该PCF为该组播业务生成的PCC规则中也可以包括MCID。或者，MCF没有为组播业务分配MCID，由PCF分配MCID，PCF可以在响应消息中将为该组播业务分配的MCID发送给MCF。
3、接入网设备的组播能力
根据上述单播与组播的相关介绍。在本申请实施例中，接入网设备支持组播功能可以理解为接入网设备支持PTM的数据发送方式向终端设备发送组播业务数据，接入网设备不支持组播功能可以理解为接入网设备不支持以PTM的数据发送方式向终端设备发送组播业务数据。对于不支持组播功能的接入网设备，可以通过PDU会话发送终端设备的加入的组播业务。对于支持组播功能的接入网设备，可以通过组播会话隧道从核心网接收组播业务数据并发送给加入该组播业务的多个终端设备。
4、切换的终端设备的PDU会话
当终端设备由源接入网设备切换至目标接入网设备时，终端设备的PDU会话需要从源接入网设备切换到目标接入网设备。此时，可以称该PDU会话为切换的终端设备的PDU会话。
在本申请实施例中，PDU会话关联组播业务，可以理解为PDU会话的上下文与组播业务进行了关联。具体来说，终端设备可以在源接入网设备通过PDU会话的用户面或者控制面申请加入组播业务，可选地，可以通过将组播业务标识信息存储至PDU会话上下文中的方式，将PDU会话与组播业务进行关联。示例性地，若终端设备通过PDU会话的用户面加入观看CCTV 1，那么该PDU会话就关联了一个组播业务，若终端设备又加入观看CCTV 10，那么该PDU会话又关联了一个组播业务。对于支持组播功能的源接入网设备，当终端设备通过PDU会话的用户面或控制面加入组播业务后，组播业务可以是以组播QoS流的方式通过组播会话隧道传输至源接入网设备，源接入网设备可以采用空口点对点或者空口点对多点的方式向终端设备发送组播业务数据。对于不支持组播功能的源接入网设备，当终端设备通过PDU会话的用户面或控制面加入组播业务后，组播业务是以单播QoS流的方式通过PDU会话隧道传输至源接入网设备，源接入网设备采用空口点对点的方式向终端设备发送组播业务数据。
应理解，组播业务数据到达RAN之后，经过RAN的服务数据适配协议(service data adaptation protocol，SDAP)层、分组数据汇聚协议(packet data convergence protocol，PDCP)层、无线链路控制(radio link control，RLC)层、媒体接入控制(media access control，MAC)层、物理(physical，PHY)层的处理，发送给每个接收组播业务数据的UE。
目前，3GPP已通过立项，将如何在当前5G网络架构的基础上支持组播广播功能(即，5G multicast broadcast service，5MBS)作为关键研究课题进行研究。在5G或未来演进的网络中，将部署支持组播功能的接入网设备。
下面结合图4，对终端设备加入组播业务的流程进行描述。示例性的，图4中以终端设备为UE1、UE2、UE3加入组播业务为例进行描述。
如图4所示，步骤401至步骤410描述的是UE1通过源gNB(sourcegNB，S-gNB)和SMF1加入组播业务的过程。其中，该组播业务的传输路径包含MUF与UPF1之间的传输路径，以及UPF1与S-gNB之间的传输路径。
401，UE1发送加入组播业务的请求至SMF1，该请求包含组播业务的相关信息。该相关信息例如可以是组播业务的标识，或者，组播IP地址信息。
402，SMF1向MCF发送消息#1，消息#1用于向MCF通知UE1通过S-gNB和SMF1加入组播业务。
403，MCF向SMF1发送消息#2，消息#2用于响应步骤402中的消息#1。
404，SMF1向S-gNB发送N2 PDU会话请求(N2 PDU session request)，用于请求S-gNB为UE1分配组播业务的相关空口资源。
405，S-gNB为UE1分配组播业务的相关空口资源，并生成自身的隧道标识信息。
406，S-gNB向SMF1发送N2 PDU会话响应(N2 PDU session response)，其中携带S-gNB的隧道标识信息。
407，SMF1与UPF1之间进行N4会话建立/修改(N4 session establishment/modification)。
示例性的，SMF1向UPF1发送N4会话建立/修改请求(N4 session establishment/modification request)，其中包含S-gNB的隧道标识信息和SMF1为UPF1分配的隧道标识信息。之后，UPF1向SMF1发送N4会话建立/修改响应(N4 session establishment/modification response)。然后，S-gNB与UPF1之间的组播会话隧道建立。
408，SMF1向MCF发送消息#3，消息#3用于请求建立MUF与UPF1之间传输组播业务数据的隧道。示例性的，消息#3中可以携带SMF1为UPF1分配的隧道标识信息。
409，MCF向MUF发送N4会话建立/修改请求，包含SMF1为UPF1分配的隧道标识信息，还包含MCF为MUF分配的隧道标识信息，之后，MUF向MCF发送N4会话建立/修改响应，MUF与UPF1之间的隧道建立。
410，MCF向SMF1发送消息#4，消息#2用于响应步骤408中的消息#3。
步骤410之后，由组播业务源到MUF到UPF1到S-gNB的组播业务数据传输路径建立。UE1可以通过该组播业务数据传输路径接收到组播业务数据。
继续参见图4，在UE1通过S-gNB和SMF1加入组播业务之后，UE2还可以通过该S-gNB和SMF1加入组播业务。示例性的，可以参见下面的步骤411至414。
411，UE2发送加入组播业务的请求至SMF1，该请求包含组播业务的相关信息。这里， 组播业务的相关信息可以参见步骤401中的描述。
412，SMF1向S-gNB发送N2 PDU会话请求(N2 PDU session request)，用于请求S-gNB为UE2分配组播业务的相关空口资源。
由于UE2也是通过S-gNB和SMF1申请加入组播业务，也即，UE1与UE2都是通过同一个SMF(即SMF1)申请加入组播业务，因此SMF1只需要请求S-gNB为UE2分配组播业务的空口资源，也即，S-gNB还是通过UPF1与S-gNB之间的组播会话隧道接收组播业务数据，并将该组播业务数据发送给UE2。
413，S-gNB为UE2分配组播业务的相关空口资源。
需要说明的是，由于通过同一个SMF加入组播业务的UE都共享一条由UPF到S-gNB之间的组播会话隧道，即，UE1与UE2共享UPF1与S-gNB之间的组播会话隧道，因此在步骤410中，S-gNB不需要生成隧道标识信息。
414，S-gNB向SMF1发送N2 PDU会话响应(N2 PDU session response)，用于响应步骤412。
步骤414之后，由组播业务源到MUF到UPF1到S-gNB的组播业务数据传输路径建立。UE2可以通过该组播业务数据传输路径接收到组播业务数据。
继续参见图4，UE3还可以加入组播业务。与UE1和UE2加入组播业务不同的是，UE3是通过S-gNB和SMF2加入组播业务的。其中，该组播业务的传输路径包含MUF与UPF2之间的传输路径，以及UPF2与S-gNB之间的传输路径。示例性的，可以参见下面的步骤415至424。
415，UE3发送加入组播业务的请求至SMF2，该请求包含组播业务的相关信息。
由于UE3是通过另一个SMF(即SMF2)申请加入组播业务，因此，需要执行后续步骤416至步骤424。步骤416至步骤424的描述与步骤402至步骤410类似，可以参考上文中的描述，此处不再阐述。
步骤424之后，由组播业务源到MUF到UPF2到S-gNB的组播业务数据传输路径建立。UE3可以通过该组播业务数据传输路径接收到组播业务数据。
一些实施例中，由于UE的移动性，可能触发UE发生切换，例如从S-gNB切换至目标gNB(targetgNB，T-gNB)，导致UE退出在源接入网设备加入的组播业务。示例性的，可以参见步骤425至步骤427。
425，UE1发生切换，退出通过SMF1和S-gNB加入的组播业务。
426，UE2发生切换，退出通过SMF1和S-gNB加入的组播业务。
427，UE3发生切换，退出通过SMF2和S-gNB加入的组播业务。
其中，T-gNB可以支持组播功能或者不支持组播功能，本身实施例对此不作限定。
当终端设备由支持组播功能的源接入网设备切换至目标接入网设备(目标接入网设备支持组播功能或者不支持组播功能)时，为节省网络资源开销，如何释放源接入网设备与核心网设备之间的组播会话隧道是亟待解决的问题。
有鉴于此，本申请实施例提供了一种通信方法和装置，其中源接入网设备或会话管理功能网元能够获知在终端设备从源接入网设备切换至目标接入网设备后，不存在其它终端设备通过该源接入网设备接收组播业务的数据，即该终端设备为最后一个通过源接入网设备接收该组播业务的数据的终端设备，并确定释放源接入网设备与核心网设备之间的组播 会话隧道。
下面将结合附图详细说明本申请实施例。
本申请的技术方案可以应用于无线通信系统中，例如，图1中所示的通信系统，或图2中所示的通信系统。处于无线通信系统中的通信装置之间可具有无线通信连接关系。该通信装置中的一个装置例如可以为接入网设备(比如源接入网设备)，或者配置于该接入网设备(比如源接入网设备)中的芯片，另一个装置例如可以为会话管理功能网元，或者配置于该会话管理功能网元中的芯片。本申请实施例对此不做限定。
以下，不失一般性，首先以一个终端设备的通信过程为例详细说明本申请实施例。可以理解，处于无线通信系统中的任意一个接入网设备或者配置于接入网设备中的芯片均可以基于相同的方法进行通信，处于无线通信系统中的任意一个会话管理功能网元或者配置于会话管理功能网元中的芯片均可以基于相同的方法进行通信。本申请对此不做限定。
下面结合图5A、图5B和图5C来描述应用本申请实施例的方案的场景的示例。
在图5A中，UE2由S-gNB切换至T-gNB1，T-gNB1支持组播功能。S-gNB与UPF1之间存在组播会话隧道和PDU会话隧道，T-gNB1与UPF1之间存在组播会话隧道和PDU会话隧道。此时，S-gNB与T-gNB1之间既存在PDU会话隧道对应的转发隧道，又存在组播会话隧道对应的转发隧道。示例性的，图5A中的UPF1、UE2可以为图4中的UPF1、UE2。
需要说明的是，图5A仅以T-gNB1支持组播功能为例进行描述，但是本申请实施例并不限于此。在其他实施例中，T-gNB1还可以不支持组播功能。在T-gNB1不支持组播功能的情况下，T-gNB1与UPF1之间不存在组播会话隧道，S-gNB与T-gNB1之间也不存在组播会话隧道对应的转发隧道。
在图5B中，UE由S-gNB切换至T-gNB，T-gNB不支持组播功能。S-gNB与MUF之间存在组播会话隧道，与UPF之间存在PDU会话隧道，T-gNB与UPF之间存在PDU会话隧道。此时，S-gNB与T-gNB之间存在PDU会话隧道对应的转发隧道，不存在组播会话隧道对应的转发隧道。
需要说明的是，图5B仅以T-gNB不支持组播功能为例进行描述，但是本申请实施例并不限于此。在其他实施例中，T-gNB还可以支持组播功能。在T-gNB支持组播功能的情况下，T-gNB与MUF之间存在组播会话隧道，S-gNB与T-gNB之间存在组播会话隧道对应的转发隧道。
在图5C中，UE由S-gNB切换至T-gNB，T-gNB不支持组播功能。S-gNB与MUF之间存在组播会话隧道，与UPF之间存在PDU会话隧道，T-gNB与UPF之间存在PDU会话隧道。此时，S-gNB与UPF之间，以及UPF与T-gNB之间存在PDU会话隧道对应的间接转发隧道。也就是说，S-gNB要将需要发送给T-gNB的PDU会话通过该间接转发隧道发送给UPF，UPF再将该PDU会话通过该间接转发隧道发送给T-gNB。
需要说明的是，图5C仅以T-gNB不支持组播功能为例进行描述，但是本申请实施例并不限于此。在其他实施例中，T-gNB还可以支持组播功能。在T-gNB支持组播会话隧道的情况下，T-gNB与MUF之间存在组播会话隧道，S-gNB与UPF之间，以及UPF与T-gNB之间存在组播会话隧道对应的间接转发隧道，本申请实施例还可以应用于T-gNB支持组播功能的场景。
还需要说明的是，图5A、图5B以及图5C的场景是为了方便描述本申请实施例的技术方案的特殊场景，本申请实施例所提供的技术方案并不限制于图5A、图5B以及图5C的限制。换而言之，本申请实施例所提供的技术同样适用于其他未列举的场景。作为示例，其他未列举的场景例如可以包括以下三种情况。
情况1，对于切换的终端设备的PDU会话，在切换过程中，为该切换的终端设备的PDU会话服务的SMF与锚点UPF是不变的。例如，对于图5A中的场景而言，锚点UPF为图中的UPF1，图5B与5C而言，为UPF。
情况2，对于切换的终端设备的PDU会话在源接入网设备所关联的组播业务，假设为源接入网设备的组别业务服务的控制面组播网元为MCF-1，用户面组播网元为MUF-1，则MUF-1可以与为终端设备的PDU会话所在的锚点UPF相连(即图5A中MUF与UPF1连接)。可选的，MUF-1也可以与源接入网设备相连。此外，MUF-1还可以通过其他的UPF与源接入网设备相连。也就是说，MUF-1还可以与终端设备的PDU会话的锚点UPF之外的其他UPF相连。
情况3，对于目标接入网设备而言，与该切换的终端设备的PDU会话所关联的该组播业务，为该组播业务服务的网元可能是MCF-1与MUF-1，也可能是其他的MCF和MUF。其中，该MUF可以与目标接入网设备直接相连，也可以与该切换的终端设备的PDU会话的锚点UPF相连，也可以通过其他UPF(即非锚点UPF)与目标接入网设备相连。
下面结合图6至图10来描述本申请实施例提供的通信方法。
图6从设备交互的角度示出了本申请实施例提供的通信方法600的示意性流程图。如图6所示，方法600包括步骤610至630。
610，会话管理功能网元获知在第一终端设备从第一接入网设备切换至第二接入网设备后不存在通过该第一接入网设备接收第一组播业务的数据的终端设备。
示例性的，在业务层面，第一组播业务是指该业务的数据可以发送给多个终端设备。具体的，组播业务、组播可以参见上文中的描述，不再赘述。
其中，第一接入网设备可以称为源接入网设备，第二接入网设备可以称为目标接入网设备。
作为示例，在第一终端设备从源接入网设备切换至目标接入网设备之后，当通过该会话管理功能网元与源接入网设备加入到该第一组播业务的终端设备的数量为0时，会话管理功能网元可以确定在第一终端设备从源接入网设备切换至目标接入网设备后，不存在其它终端设备通过该源接入网设备接收第一组播业务的数据(即不存在其他终端设备通过该会话管理功能网元和源接入网设备加入该第一组播业务)。
在一些可选的实施例中，通过源接入网设备加入组播业务的终端设备的数量可以包括在该第一终端设备的PDU会话关联的组播业务对应的组播上下文(Multicast Context)或组播会话上下文(Multicast Session Context)或组播组上下文(Multicast Group Context)或组播业务上下文(Multicast Service Context)中。也就是说，会话管理网元通过组播上下文(Multicast Context)或组播会话上下文(Multicast Session Context)或组播组上下文(Multicast Group Context)或组播业务上下文(Multicast Service Context)中是否还有除该终端设备之外的其他终端设备接收该第一组播业务，来判断在第一终端设备从第一接入网设备切换至第二接入网设备后不存在通过该第一接入网设备接收第一组播业务的数据的终端设备。
在一些可选的实施例中，会话管理功能网元还可以更新通过该会话管理功能网元与源接入网设备加入组播业务的终端设备的数量。
例如，会话管理网元在接收到PDU会话上下文更新请求之后，更新该第一终端设备的PDU会话关联的组播业务对应的组播上下文(Multicast Context)或组播会话上下文(Multicast Session Context)或组播组上下文(Multicast Group Context)或组播业务上下文(Multicast Service Context)中的通过该会话管理功能网元与源接入网设备加入组播业务的终端设备的数量，例如将终端设备的数量减1，得到当前通过该会话管理功能网元和源接入网设备加入到第一组播业务的终端设备的数量。
作为一个示例，会话管理功能网元可以在第一终端设备从源接入网设备切换至目标接入网设备之后，且在更新保存的通过该会话管理功能网元和接入网设备加入到第一组播业务的终端设备的数量之前，确定是否存在其它终端设备通过该源接入网设备接收该第一组播业务的数据。此时，会话管理功能网元可以在确定第一终端设备是通过该会话管理功能网元和源接入网设备加入第一组播业务的终端设备中的最后一个，即通过该会话管理功能网元与源接入网设备加入该第一组播业务的终端设备的数量为1(即该第一终端设备)的情况下，获知不存在其它终端设备通过该源接入网设备接收该第一组播业务的数据。
作为另一个示例，会话管理功能网元可以在第一终端设备从源接入网设备切换至目标接入网设备之后，以及在更新保存的通过该会话管理功能网元和接入网设备加入到组播业务的终端设备的数量之后，确定是否存在其它终端设备通过该源接入网设备接收该第一组播业务的数据。此时，会话管理功能网元可以在确定通过该会话管理功能网元和源接入网设备加入该第一组播业务的终端设备的数量为0的情况下，获知不存在其它终端设备通过该源接入网设备接收该第一组播业务的数据。
620，会话管理功能网元通知用户平面功能释放第一隧道。
其中，所述第一隧道用于在所述第一接入网设备与核心网设备之间传输上述第一组播业务的数据。其中，核心网设备可以是UPF。
示例性的，第一隧道可以包括第一接入网设备与UPF之间的用于传输该第一组播业务的隧道，即用于传输第一组播业务的组播会话隧道。具体的，组播会话隧道可以参见上文中的描述，不再赘述。
也就是说，会话管理功能网元获知在第一终端设备从第一接入网设备切换至第二接入网设备后不存在其它终端设备通过该第一接入网设备接收第一组播业务的数据之后，可以向用户平面功能通知释放该第一隧道。例如，会话管理网元可以向第一终端设备发送N4会话更新请求，其中携带第一信息，用于释放第一隧道。
示例性的，第一信息可以包括释放第一隧道的指示(indication)或者释放第一隧道的请求(request)或者释放第一隧道的通知(notify或notification)。可选的，第一信息也可以包含第一隧道的信息和/或第一组播业务的标识信息，本申请实施例对此不作限定。
示例性的，第一信息可以包括释放第一隧道的指示(indication)或请求(request)或通知(notify或notification)，还可以包括第一隧道的信息。可选的，第一信息还可以包括第一组播业务的标识信息，本申请实施例对此不作限定。
示例性的，第一信息可以包括释放第一隧道的指示(indication)或请求(request)或通知(notify或notification)，还可以包括第一隧道的信息，以及第一组播业务的标识信息，本 申请实施例对此不作限定。
其中，第一隧道的信息可用于唯一确定该第一隧道，例如可以是第一隧道的隧道端点标识(tunnel endpoint identifier，TEID)，此处不限定。第一组播业务的标识信息可用于唯一确定一个组播业务，例如可以是组播业务的ID，或组播业务的名称，或组播地址，或组播组ID等，此处不限定。
630、用户平面功能释放第一隧道。
示例性的，用户平面功能可以在接收到会话管理功能网元发送的N4会话更新请求(其中携带第一信息)之后，释放第一隧道，例如根据第一信息中的隧道标识信息，移除该第一隧道的相关资源(比如移除第一隧道的隧道端点标识)。
因此，本申请实施例中，会话管理功能网元可以在获知在所述第一终端设备从所述第一接入网设备切换至第二接入网设备后不存在其它终端设备通过所述第一接入网设备接收所述第一组播业务的数据的情况下，通知该用户平面功能释放该源接入网设备与核心网设备之间的用于传输该第一组播业务的第一隧道，从而实现对接入网设备与核心网设备之间的组播会话隧道的释放，有助于节省网络资源开销。
下面，将结合图7，描述本申请实施例提供的一种通信方法的具体的例子。在下面的实施例中，将以会话管理功能网元为SMF，源接入网设备为S-gNB，用户平面功能为UPF为例进行描述。对于SMF中的芯片、S-gNB中的芯片、UPF中的芯片的实现方法，可以参考SMF、S-gNB和UPF的具体说明，不作重复介绍。
可选的，在图7中，核心网设备中还包括AMF、MCF和MUF。或者，在一些可选的实施例中，核心网设备中可以不包括MCF和MUF，而是由SMF中的某些功能或单元来实现MCF的功能，由UPF中的某些功能或单元来实现MUF的功能，本申请实施例对此不作限定。
图7示出了本申请实施例提供的另一种通信方法700的示意性流程图。在方法700中，由SMF1来判断是否需要释放S-gNB与UPF1之间的组播会话隧道。
需要说明的是，在图7中，以切换的UE为图4中的UE2为例进行说明，即方法700中描述的是，在图4中的步骤426，UE2发生切换，退出通过SMF1和S-gNB加入的组播业务之后，SMF1判断是否需要释放S-gNB与UPF1之间的组播会话隧道的过程。
在一些实施例中，当UE2切换到的T-gNB1支持组播功能时，方法700可以适用于图5A所示的场景。下面，将结合图5A中的场景，对方法700进行描述。如图7所示，方法700可以包括步骤701至716。应注意的是，该方案同样可以适用于T-gNB1不支持组播功能的场景，这里不限定，图5A所示的场景仅为举例。
应理解，图7示出了本申请实施例提供的通信方法700的步骤或操作，但这些步骤或操作仅是示例，本申请实施例还可以执行其他操作或者图7中的各个操作的变形。此外，图中的各个步骤可以按照与其呈现的不同的顺序来执行，并且有可能并非要执行图中的全部操作。
可选的，在步骤701之前，S-gNB可以获知T-gNB1的能力，即是否支持组播功能的能力。作为示例，当T-gNB1与S-gNB之间存在Xn连接时，T-gNB1可以通过Xn接口将自身的能力信息通知S-gNB，其中Xn即可即为S-gNB与T-gNB之间Xn连接的接口。例如，当T-gNB1支持组播功能时，T-gNB向S-gNB发送指示信息#1，该指示信息#1用于指 示T-gNB1支持组播功能。
701，UE2向S-gNB发送测量报告(Measurement Report)。
对应的，S-gNB接收该测量报告，并决定将UE2切换至T-gNB1。
702，S-gNB向T-gNB1发送切换请求(Handover Request)。这里，S-gNB可以获知T-gNB1支持组播功能。
示例性的，该切换请求中可以包含待切换的UE2的PDU会话信息，其中，PDU会话信息包含PDU会话标识和PDU会话中所包含的单播业务对应的QoS信息。如果切换的UE的PDU会话还关联组播业务，则PDU会话信息中还包括所关联的组播业务对应的QoS信息。作为示例，单播业务的QoS信息包括该单播业务对应的单播QoS流的标识(QoS flow identifier,QFI)和QoS参数，组播业务的QoS信息包括该组播业务对应的组播QoS流的标识(QoS flow identifier,QFI)和QoS参数。
另外，该切换请求中还可以包括S-gNB希望转发给T-gNB1的QoS流的QFI的和S-gNB生成的转发隧道端点标识。作为示例，S-gNB希望转发给T-gNB1的QoS流可以为单播QoS流和/或组播QoS流。
示例性的，当S-gNB希望转发给T-gNB1的业务流包含组播QoS流时，切换请求中可以包括该组播QoS流的QFI和S-gNB生成的组播会话隧道对应的转发隧道的端点标识。当S-gNB希望转发给T-gNB1的业务流包含单播QoS流时，切换请求中可以包含该单播QoS流的QFI和S-gNB生成的单播会话隧道对应的转发隧道端点标识。
换句话说，如果S-gNB希望某个单播QoS流通过PDU会话隧道对应的转发隧道转发，则切换请求中可以包含该单播QoS流所对应的QFI，以及S-gNB为该转发隧道生成的端点标识。如果S-gNB希望某个组播QoS流通过组播会话隧道对应的转发隧道转发，则切换请求中可以包含该组播QoS流所对应的QFI，以及S-gNB为该转发隧道生成的端点标识。
需要说明的是，S-gNB之所以要通过转发隧道进行业务流转发，是因为在步骤704，即S-gNB下发切换命令给UE2之后，UE2会与S-gNB断开，此时UE2暂时无法通过S-gNB接收数据，并且此时UE2还没有接入T-gNB1。也就是说，UE2无法通过S-gNB接收在步骤704和步骤705这段时间内的数据。因此，S-gNB需要通过转发隧道将这部分数据转发至T-gNB1进行缓存，直到步骤705后，即UE2接入T-gNB1之后，由T-gNB1将这部分数据下发给UE2。
703，T-gNB1向S-gNB发送切换响应(handover request ACK)。
作为示例，T-gNB1根据从S-gNB收到的单播业务的QoS信息和组播业务的QoS信息，为切换的UE准备无线资源。示例性的，T-gNB1可以根据每个业务流的QFI所对应的QoS参数确定空口无线数据承载(data radio bearer，DRB)的数量，以及QFI到DRB的映射关系。此外，T-gNB1还可以根据每个DRB所映射的QFI所对应的QoS参数，确定该DRB对应的配置参数。DRB对应的配置参数例如为DRB所对应的无线链路控制(radio link control，RLC)层采用确认模式还是非确认模式等。最后，T-gNB1创建相应的DRB。
T-gNB1在准备好无线资源之后，向S-gNB发送切换响应。在一些可选的实施例中，T-gNB1可以将需要通过S-gNB中继给UE2的信息发送给S-gNB。例如，T-gNB1可以通过S-gNB将T-gNB1的无线承载配置信息发送给UE2，该无线承载配置信息可以用于UE2 在接入T-gNB1后接收T-gNB1下发的单播业务数据和/或组播业务数据。
在一些可选的实施例中，当在步骤502中的切换请求中包含S-gNB希望通过转发隧道转发的业务流的QFI(包括单播QoS流的QFI和/或组播QoS流的QFI)，并且T-gNB1支持数据转发时，T-gNB1分配转发隧道的端点标识。
704，S-gNB向UE2发切换命令(handover command)。
如果T-gNB1需要S-gNB将UE2在T-gNB1接收业务数据所需的无线承载配置信息中继给UE2，则S-gNB将该无线承载配置信息发送给UE2。在S-gNB下发切换命令给UE2后，UE2与S-gNB之间的空口连接暂时断开。
之后，S-gNB将组播会话隧道收到的组播QoS流复制转发至T-gNB1。
在UE2与S-gNB之间的空口连接断开之后，S-gNB停止向切换的UE2下发PDU会话包含的业务数据与PDU会话关联的组播业务数据。示例性的，S-gNB停止通过PDU会话隧道向该切换的UE2发送PDU会话包含的业务数据，并且停止通过组播会话隧道向该切换的UE2转发组播业务数据。
针对切换的UE2需要支持转发的QoS流，S-gNB还需做以下工作：对于需要转发给T-gNB2的单播QoS流，S-gNB通过PDU会话隧道对应的转发隧道将该单播QoS流转发至T-gNB1。T-gNB1在收到该单播QoS流之后，缓存该单播QoS流。
对于需要转发给T-gNB1的组播QoS流，S-gNB先对该组播会话隧道中的组播QoS流进行复制，然后通过组播会话隧道对应的转发隧道将该复制得到的组播QoS流转发至T-gNB1。T-gNB1在收到该组播QoS流之后，缓存该组播QoS流。
705，UE2接入T-gNB1。
示例性的，UE2接入T-gNB1后。在UE2接入T-gNB1之后，T-gNB1将接收并缓存的单播QoS流，和/或组播QoS流发送给UE2。UE2根据步骤704中S-gNB发送的无线承载配置信息接收相应的业务数据。
706，T-gNB1向AMF发N2路径切换请求(N2 Path Switch Request)。
示例性的，该请求中包含UE2的该PDU会话中切换成功以及切换失败的单播QoS流的QFI，和/或该PDU会话中切换成功以及切换失败的组播QoS流的QFI。作为示例，这些QFI可以封装在N2 SM消息中。
在一些可选的实施例中，该N2路径切换请求中还可以包括T-gNB1为该UE2分配的PDU会话隧道的端点标识。
在一些可选的实施例中，该N2路径切换请求中还可以包括指示信息#2，该指示信息#2用于指示该切换的UE2的PDU会话所关联的组播业务在T-gNB1是否正在运行。
一种可能的情况，当该切换的UE2的PDU会话所关联的组播业务在T-gNB1没有运行，表示T-gNB1与UPF之间的用于传输该组播会话的组播会话隧道还没有建立，那么该N2路径切换请求中还可以包括T-gNB1分配的组播会话隧道的端点标识，用于建立T-gNB1与UPF之间的组播会话隧道。
另一种可能的情况，当该切换的UE2的PDU会话所关联的组播业务在T-gNB1正在运行，或该组播业务在T-gNB1处于正在运行状态时，表示T-gNB1与UPF之间的用于传输该组播会话的组播会话隧道已经建立，此时，该N2路径切换请求中可以不包括该组播会话隧道的端点标识。
707，AMF向SMF1发送PDU会话上下文更新请求(Nsmf_PDUSession_UpdateSMContext Request)。
示例性的，该PDU会话上下文更新请求中包含步骤706中的N2 SM消息所包含的信息。
一些实施例中，在UE2向T-gNB1切换之前，AMF可以收集了gNB的能力信息，包括是否支持组播功能的能力信息。作为示例，T-gNB1在上电时，可以将自身是否支持组播功能上报至AMF。此时，PDU会话上下文更新请求中还可以包括T-gNB1的能力信息。
对应的，SMF1接收该PDU会话上下文更新请求。之后，SMF1判断是否需要释放S-gNB中与切换的UE2的PDU会话所关联的组播业务所在的组播会话隧道(即UPF1与S-gNB之间的用于传输该组播业务的组播会话隧道，并假设一种组播业务在一个组播会话隧道中传输)。
一些实施例中，SMF1可以根据UE2在从S-gNB切换至T-gNB之后，是否存在其他终端设备通过该S-gNB接收组播业务的数据，或者UE2是否是通过该SMF1与S-gNB加入组播业务的UE中的最后一个，或者UE2在从S-gNB切换至T-gNB之后，通过SMF1与S-gNB加入该组播业务的UE的数量是否为0。示例性的，通过SMF1与S-gNB加入组播业务的UE的数量可以包括在该组播业务的上下文中。也就是说，SMF1可以通过该组播业务上下文中是否还有除UE2之外的其他UE在S-gNB请求该组播业务，来判断是否释放该组播业务所在的组播会话隧道。其中，组播业务上下文，也可以叫做组播会话上下文(multicast session context)。
作为示例，继续参考图4，UE1和UE2通过SMF1和S-gNB加入同一个组播业务，并在之后的步骤425中，UE1发生切换，退出通过SMF1和S-gNB加入的组播业务，以及步骤426中，UE2发生切换，退出通过SMF1和S-gNB加入的组播业务。因此，在UE2切换到T-gNB之后，不存在其他终端设备通过该S-gNB接收组播业务的数据，或者UE2是通过SMF1与S-gNB加入组播业务的UE中的最后一个，或者通过SMF1与S-gNB接入该组播业务的UE的数量为0。基于此，SMF1可以确定释放该组播业务所在的组播会话隧道。
在一些可选的实施例中，当PDU会话上下文更新请求中包括指示信息#2时，SMF可以根据该指示信息#2，确定该切换的UE2的PDU会话关联的组播业务在T-gNB1是否正在运行。
在一些可选的实施例中，在SMF1确定释放该组播业务所在的组播会话隧道之后，可以生成信息#1，用于指示S-gNB释放该组播业务所在的组播会话隧道。信息#1可以为第一信息的一个示例。
示例性的，信息#1可以包括释放组播会话隧道的指示或通知或请求。可选的，信息#1还可以包括该组播会话隧道的信息(例如，组播会话隧道的隧道端点标识TEID，用于确认组播会话隧道)和/或组播业务的标识信息。
示例性的，信息#1可以包括释放组播会话隧道的指示或通知或请求，还可以包括该组播会话隧道的信息。可选的，信息#1还可以包括组播业务的标识信息。
示例性的，信息#1可以包括释放组播会话隧道的指示或通知或请求，还可以包括该组播会话隧道的信息，以及组播业务的标识信息。
708，SMF1与UPF1进行N4会话更新。
示例性的，SMF1可以向UPF1发送N4会话更新请求，其中携带T-gNB1的PDU会话隧道端点标识，以及SMF1分配给UPF1的PDU会话隧道端点标识，用于建立T-gNB1与UPF1之间的PDU会话隧道(N4 Session Modification)。
在一些可选的实施例中，若在步骤707中，AMF还向SMF1发送了T-gNB1分配的组播会话隧道端点标识(即，此时与切换的UE2的PDU会话所关联的组播业务在T-gNB1还没有运行)，则SMF1还将T-gNB1的组播会话隧道端点标识发送给UPF1。
在一些实施例中，如果在步骤707中，SMF1生成了信息#1，则在该N4会话更新请求中可以包含该信息#1。UPF1可以根据该信令#1，用于通知释放UPF1到S-gNB之间的用于传输上述组播业务的隧道。
709，SMF1向MCF发送第一消息，用于通知释放MUF到UPF1之间的用于传输上述组播业务的隧道，即MUF至UPF1的这段隧道。
710，MCF与MUF进行N4会话更新。示例性的，MCF可以释放SMF1分配的UPF1的隧道标识信息(即，用于与MUF建立隧道的UPF1的隧道标识信息)。
711，MCF向SMF1发送第一消息的响应。
712，SMF1向AMF发送PDU会话上下文更新响应(Nsmf_PDUSession_UpdateSMContext Response)。
示例性的，SMF1可以释放MCF分配的MUF的隧道标识信息(即，用于与MUF建立隧道的UPF1的隧道标识信息)。
713，AMF向T-gNB1发送N2路径切换响应(N2 Path Switch Request ACK)。
714，T-gNB1向S-gNB发送释放UE上下文请求(UE Context Release)。
因此，本申请实施例中，SMF1可以在判断UE2在从S-gNB切换至T-gNB2之后，不存在其他终端设备通过S-gNB接收该组播业务的数据的情况下，通知UPF1释放S-gNB与UPF1之间的用于传输该组播业务的第一隧道，从而实现对S-gNB与UPF1之间的组播会话隧道的释放，有助于节省网络资源开销。
图8从设备交互的角度示出了本申请实施例提供的通信方法800的示意性流程图。方法800可以应用于第一终端设备通过第一接入网设备接收第一组播业务的数据的场景。如图8所示，方法800包括步骤810至830。
810，第一接入网设备在第一终端设备从第一接入网设备向第二接入网设备切换的切换准备阶段，获知(know)第一终端设备为通过该第一接入网设备接收第一组播业务的数据的最后一个终端设备。这里，获知也可以替换为感知(perceice)、发现(find)或检测(detect)等，不作限定。
也就是说，第一接入网设备可以在该切换准备阶段，获知在该第一终端设备切换至第二接入网设备之后，不存在其他终端设备通过该第一接入网设备接收第一组播业务的数据。需要指出的是，终端设备通过第一接入网设备接收第一组播业务的数据，可以理解为终端设备通过该第一接入网设备加入了该第一组播业务。也可以理解为，当第一终端是准备阶段获知的通过第一接入网设备接收第一组播业务的数据的最后一个第一终端设备，并且后续该第一终端设备切换到了第二接入网设备。也可以理解为，第一终端设备是通过第一接入网设备接收第一组播业务的数据的最后一个第一终端设备，并且后续该第一终端设备切 换到了第二接入网设备。
示例性的，第一接入网设备可以称为源接入网设备，第二接入网设备可以称为目标接入网设备。
作为示例，这里的切换可以为Xn切换，或者N2切换。
需要说明的是，上述切换准备阶段，可以指的是源接入网设备、目标接入网设备或者核心网设备(此处，可以指的是AMF，SMF或UPF等，不予限制)为第一终端设备准备切换所需资源的阶段。其中，切换所需资源可以包括转发隧道，或者第一终端设备通过目标接入网设备接收业务数据所需的无线承载配置信息，目标接入网设备为第一终端设备配置的空口资源等，本申请实施例不作限定。
在Xn切换场景中，切换准备阶段可以指源接入网设备接收到第一终端设备的测量报告，并依据测量报告对第一终端设备进行切换判决且判决结果为切换，源接入网设备向目标接入网设备发送切换请求，以及接收目标接入网设备发送切换响应的过程，例如下文图9中的步骤901至903的过程。
在N2切换中，切换准备阶段可以指源接入网设备接收到第一终端设备的测量报告、源接入网设备根据该测量报告向源接入与移动性管理功能网元发送切换需要(handover required)，以及源接入与移动性管理功能网元从目标接入与移动性管理网元接收创建UE上下文响应的过程，例如下文图10中的步骤1001至步骤1012的过程。
源接入网设备可以在切换准备阶段的任意一个时间点，获知第一终端设备为通过该第一接入网设备接收第一组播业务的数据的最后一个终端设备。
例如，在Xn切换场景，在接收到第一终端设备的测量报告，源接入网设备依据测量报告对第一终端设备进行切换判决且判决结果为切换时(例如下文图9的步骤901之后)，或者源接入网设备向目标接入网设备发送切换请求时(例如下文图9中的步骤902之后)，或者源接入网设备接收目标接入网设备的切换响应时(例如下文图9中的步骤903之后)，获知第一终端设备为通过该第一接入网设备接收第一组播业务的数据的最后一个终端设备。
又例如，在N2切换场景，源接入网设备可以在接收到第一终端设备的测量报告时(例如下文图10的步骤1001之后)，或者源接入网设备在向源接入与移动性管理功能网元发送切换需要(例如下文图10中的步骤1002之后)，获知第一终端设备为通过该第一接入网设备接收第一组播业务的数据的最后一个终端设备。
在一些可选的实施例中，在切换准备阶段，在加入第一组播业务的第一终端设备向源接入网设备发送测量报告，源接入网设备依据测量报告对第一终端设备进行切换判决且判决结果为切换的情况下，源接入网设备可以更新通过源接入网设备加入该第一组播业务的终端设备的数量，例如将该终端设备的数量减1。当该终端设备的数量为0时，可以获知第一终端设备为通过该第一接入网设备接收第一组播业务的数据的最后一个终端设备。
示例性的，在Xn切换中，源接入网设备可以在接收到第一终端设备的测量报告且判决切换之后(例如下文图9中步骤901之后)，或者在向目标接入网设备发送切换请求之后(例如下文图9中步骤902之后)，或者在接收目标接入网设备发送的切换响应之后(例如下文图9中步骤903之后)，更新通过源接入网设备加入第一组播业务的终端设备的数量。然后源接入网设备可以根据更新后的该终端设备的数量，确定第一终端设备是否为通 过该源接入网设备加入第一组播业务的最后一个终端设备。
示例性的，在N2切换中，源接入网设备可以在接收第一终端设备的测量报告之后，向源接入与移动性管理功能网元发送切换需要之前，或者在向源接入与移动性管理功能网元发送切换需要之后，更新通过源接入网设备加入第一组播业务的终端设备的数量。
示例性的，在N2切换中，源接入网设备可以在接收到第一终端设备的测量报告之后(例如下文图10中的步骤1001之后)，或者在向源接入与移动性管理功能网元发送切换需要之后(例如下文图10中的步骤1002之后)，更新通过源接入网设备加入第一组播业务的终端设备的数量。然后源接入网设备可以根据更新后的该终端设备的数量，确定第一终端设备是否为通过该源接入网设备加入第一组播业务的最后一个终端设备。
在一些可选的实施例中，通过源接入网设备加入组播业务的终端设备的数量可以包括在该第一终端设备的PDU会话关联的组播业务对应的组播上下文(Multicast Context)或组播会话上下文(Multicast Session Context)或组播组上下文(Multicast Group Context)或组播业务上下文(Multicast Service Context)中。也就是说，源接入网通过组播上下文(Multicast Context)或组播会话上下文(Multicast Session Context)或组播组上下文(Multicast Group Context)或组播业务上下文(Multicast Service Context)中是否还有除该终端设备之外的其他终端设备接收该第一组播业务，来判断第一终端设备是否为通过该源接入网设备接收第一组播业务的数据的最后一个终端设备。
当该第一终端设备为该组播上下文(Multicast Context)或组播会话上下文(Multicast Session Context)或组播组上下文(Multicast Group Context)或组播业务上下文(Multicast Service Context)中的最后一个终端设备时，该终端设备离开源接入网设备后，将不存在其他终端设备在该源接入网设备下接收该第一组播业务。此时，源接入网设备可以获知第一终端设备为通过该源接入网设备接收第一组播业务的数据的最后一个终端设备。
需要说明的是，本申请实施例中，一个组播业务可以对应一个组播会话，对应一个接入网设备与核心网设备(例如，MB-UPF或UPF)之间的组播会话隧道。此处应注意，一个组播业务也可以对应多个组播会话，对应多个接入网设备与核心网设备之间的组播会话隧道。
820，第一接入网设备向核心网设备发送第一信息。其中，该第一信息用于释放第一隧道，第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据。
一些实施例中，核心网设备可以为组播用户面功能网元，例如可以是MUF、M-UPF、MS-UPF或MB-UPF等，不作限定。此时，第一隧道可以包括源接入网设备与组播用户面功能网元(例如MUF或M-UPF、MS-UPF或MB-UPF)之间的用于传输该第一组播业务的隧道(该隧道例如为上文中所述的组播会话隧道)。
一些实施例中，核心网设备可以为用户面功能网元，例如可以是UPF。此时，第一隧道可以包括源接入网设备与用户面功能网元(例如UPF)之间的用于传输该第一组播业务的隧道(该隧道例如为上文中所述的组播会话隧道)。
需要说明的是，在核心网设备为用户面功能网元的情况下，该用户面功能网元中可以包括用于对组播业务进行用户面相关的功能，即可以认为该用于对组播业务进行用户面相关的功能(例如MUF、M-UPF、MS-UPF或MB-UPF)可以与用户面功能网元合设为一个功能网元。对应的，此时会话管理功能网元中可以包括用于对组播业务进行控制面相关的 功能，即该用于对组播业务进行控制面相关的功能(例如MCF、M-SMF、MS-SMF或MB-SMF)可以与会话管理功能网元合设为一个功能网元。
一些实施例中，当核心网设备为组播用户面功能网元时，第一接入网设备可以先向组播会话管理功能网元发送上述第一信息，然后，组播会话管理功能网元可以向组播用户面功能网元发送该第一信息。
一种可能的实现方式，第一接入网设备通过由其它网络设备(例如，第二接入网设备，AMF，SMF)将第一信息发送给组播会话管理功能网元，然后组播会话管理功能网元可以向组播用户面功能网元发送该第一信息。示例性的，组播会话管理功能网元可以为组播业务会话管理功能网元，或组播控制面功能网元，例如MB-SMF、MCF等，本申请实施例对此不作限定。一种可能的实现方式，第一接入网设备通过由其他核心网设备(例如，AMF)将第一信息发送给组播会话管理功能网元，然后组播会话管理功能网元可以向组播用户面功能网元发送该第一信息。另一种可能的实现方式，第一接入网设备可以直接向组播会话管理功能网元发送上述第一信息，例如通过一个通知消息或请求消息，不作限定。
一些实施例中，当核心网设备为用户面功能网元时，第一接入网设备可以先向会话管理功能网元发送上述第一信息，然后，会话管理功能网元可以向用户面功能网元发送该第一信息。
一种可能的实现方式，第一接入网设备通过由其它网络设备(例如，第二接入网设备，AMF)将第一信息发送给会话管理功能网元，然后会话管理网元将第一信息发送给用户面功能网元。一种可能的实现方式，第一接入网设备通过由其它核心网设备(例如，AMF)将第一信息发送给会话管理功能网元，然后会话管理功能网元将第一信息发送给用户面功能网元。另一种可能的实现方式，第一接入网设备可以直接向会话管理功能网元发送上述第一信息，例如通过一个通知消息或请求消息，不作限定。
在第一种可选的实施场景中，例如在Xn切换场景中，第一接入网设备可以在接收到第一终端设备的测量报告且依据该测量报告，判决需要第切换到第二接入网设备时，或者在确定要向第二接入网设备发送切换请求时，可以获知第一终端设备为通过该第一接入网设备加入第一组播业务的最后一个终端设备。此时，第一接入网设备可以向第二接入网设备发送切换请求(例如，handover request)，该切换请求中包括上述第一信息。其中，该切换请求可以用于请求将第一终端设备从第一接入网设备切换至第二接入网设备。
相应地，第二接入网设备接收来自第一接入网设备切换请求之后，可以向接入与移动性管理功能网元(例如，AMF)发送路径切换请求(例如N2路径切换请求，N2 Path Switch Request)，该径切换请求中包括上述第一信息。之后，接入与移动性管理功能网元可以向会话管理功能网元发送PDU会话上下文更新请求(例如，Nsmf_PDUSession_UpdateSMContext Request)，该PDU会话上下文更新请求中包括该第一信息。
进一步地，在步骤820中的核心网设备为组播用户面功能网元的情况下，会话管理功能网元接收PDU会话上下文更新请求后，可以向组播会话管理功能网元发送第一消息，第一消息中包括第一信息。示例性的，第一消息可以为N16消息。组播会话管理功能网元接收第一消息后，可以向组播用户面功能网元发送第五消息，第五消息中可以包括该第一信息。示例性的，第五消息可以为N4会话更新请求。组播用户面功能网元可以根据该第五消息，获得第一信息，进而执行步骤830。
在步骤820中的核心网设备为用户面功能网元的情况下，会话管理功能网元接收PDU会话上下文更新请求后，可以向用户面功能网元发送N4会话更新请求，N4会话更新请求中可以包括该第一信息。用户面功能网元可以根据该N4会话更新请求，获得第一信息，进而执行步骤830。
在第二种可选的实施场景中，例如在N2切换场景中，第一接入网设备可以在接收到第一终端设备的测量报告时，或者在确定要向源接入与移动性管理功能网元发送切换需要时，可以获知第一终端设备为通过该第一接入网设备加入第一组播业务的最后一个终端设备。此时，第一接入网设备可以向第一接入与移动性管理功能网元发送切换需要(例如，handover required)，该切换需要中包括上述第一信息。示例性的，第一接入与移动性管理功能网元可以为源接入与移动性管理功能网元。
相应地，第一接入与移动性管理功能网元接收到切换需要后，可以向第二接入与移动性管理功能网元发送创建UE上下文请求(例如，Namf_Communication_CreateUEContext Request)，该创建UE上下文请求中包括第一信息。之后，第二接入与移动性管理功能网元向会话管理功能网元发送PDU会话更新上下文请求，该PDU会话更新上下文请求中可以包括该第一信息。其中，第二接入与移动性管理功能网元可以称为目标接入与移动性管理功能网元。
进一步地，在步骤820中的核心网设备为组播用户面功能网元的情况下，会话管理功能网元接收PDU会话上下文更新请求后，可以向组播会话管理功能网元发送第一消息，第一消息中包括第一信息。示例性的，第一消息可以为N16消息。组播会话管理功能网元接收第一消息后，可以向组播用户面功能网元发送第五消息，第五消息中可以包括该第一信息。示例性的，第五消息可以为N4会话更新请求。对应的，组播用户面功能网元可以根据该第五消息，获得第一信息，进而执行步骤830。
在步骤820中的核心网设备为用户面功能网元的情况下，会话管理功能网元接收PDU会话上下文更新请求后，可以向用户面功能网元发送会话更新请求(例如N4会话更新请求)，会话更新请求中可以包括该第一信息。对应的，组播用户面功能网元可以根据该会话更新请求，获得第一信息，进而执行步骤830。
在第三种可选的实施场景中，在步骤820中的核心网设备为组播用户面功能网元，此时，第一接入网设备可以在切换准备阶段的任意一个时间点，获知第一终端设备为通过该第一接入网设备加入第一组播业务的最后一个终端设备。在获知第一终端设备为通过该第一接入网设备加入第一组播业务的最后一个终端设备的同时，或一段时间的之后，第一接入网设备可以向第三接入与移动性管理功能网元发送第三消息，第三消息可以是N2消息，第三消息携带上述第一信息。示例性的，第三接入与移动性管理功能网元可以是第一终端设备加入第一组播业务时，由第一接入网设备为该第一组播业务选择的接入与移动性管理功能网元，或者是其它的与该第一终端设备有关，或者无关的接入与移动性管理功能网元。
进一步地，第三接入与移动性管理功能网元接收到第三消息之后，可以向组播会话管理功能网元发送第四消息，第四消息携带第一信息。示例性的，第四消息可以是N11消息。组播会话管理功能网元收到第四消息后，可以向组播用户面功能网元发送第五消息，可以携带第一信息。示例性的，第五消息可以为N4会话更新请求。对应的，组播用户面功能网元可以根据该第五消息，获得第一信息，进而执行步骤830。
示例性的，第一终端设备加入组播业务或广播业务时，第一接入网设备可以获得组播会话管理功能网元的标识。这样，第一接入网设备可以根据该标识选择第三接入与移动性管理功能网元。例如，第一接入网设备可以根据该标识去网络存储功能(network repository function，NRF)查询，以获得合适的第三接入与移动性管理功能网元。
其中，所述与第一终端设备有关的接入与移动性管理功能网元可以是指为该第一终端设备的非接入层(non-access stratum,NAS)信令服务的接入与移动性管理功能网元，所述与第一终端设备无关的接入与移动性管理功能网元可以是指不是为该第一终端设备的NAS信令服务的接入与移动性管理功能网元。
需要指出的是，第三接入与移动性管理功能网元可以与上文中的源接入与移动性管理功能网元为同一个网元，或者与上文中的目标接入与移动性管理功能网元为同一个网元，本申请实施例对此不作限定。
需要说明的是，该第三消息，比如N2消息可以是已有的N2消息(即在该已有的N2消息中额外携带第一信息)，也可以是新增的N2消息，该新增的N2消息可以主要用于组播会话隧道的释放。其中，新增的N2消息可遵循服务化接口信令消息的命名方式，其具体名称不限定，但功能是用于通知组播用户面功能网元进行组播会话隧道的释放。
需要说明的是，该第四消息，比如N11消息可以是已有的N11消息(即在该已有的N11消息中额外携带第一信息)，也可以是新增的N11消息，该新增的N11消息可以主要用于组播会话隧道的释放。其中，新增的N11消息可遵循服务化接口信令消息的命名方式，其具体名称不限定，但功能是用于通知组播用户面功能网元组播会话隧道的释放。
在第四种可选的实施场景中，第一接入网设备可以在切换准备阶段的任意一个时间点，获知第一终端设备为通过该第一接入网设备加入第一组播业务的最后一个终端设备。在第一接入网设备获知第一终端设备为通过该第一接入网设备加入第一组播业务的最后一个终端设备的同时，或一段时间的之后，第一接入网设备可以直接向核心网设备发送该第一信息。
例如，在步骤820中的核心网设备为组播用户面功能网元的情况下，第一接入网设备可以直接向组播会话管理功能网元发送该第一信息，然后组播会话管理功能网元向组播用户面功能网元发送该第一信息(例如将第一信息携带在第五消息中)，进而执行步骤830，不作限定。
例如，在步骤820中的核心网设备为用户面功能网元的情况下，第一接入网设备可以直接向会话管理功能网元发送该第一信息，然后会话管理功能网元向用户面功能网元发送该第一信息(例如将第一信息携带在N4会话更新请求中)，进而执行步骤830，不作限定。
在上述第一种可选的实施场景或第二种可选的实施场景中，当第一接入网设备在切换准备阶段中的接收到第一终端设备的测量报告之后，或者第一接入网设备在确定发送切换请求，或切换需要时，获知第一终端设备为通过该第一接入网设备加入第一组播业务的最后一个终端设备，第一接入网设备能够通过目前已有的信令(例如切换请求，或切换需要)携带该第一信息，使得该第一信息最终发送至组播用户面功能网元，或用户面功能网元，从而有助于节省网络资源开销。
在上述第三种可选的实施场景或第四种可选的实施场景中，当第一接入网设备在切换 准备阶段中的接收到第一终端设备的测量报告之后，获知第一终端设备为通过该第一接入网设备加入第一组播业务的最后一个终端设备，并且在获知之后即刻向第三接入与移动性管理功能网元发送第三消息，或者即刻向组播会话管理功能网元或会话管理网元发送第一信息，第一接入网设备能够在切换准确阶段中的一个较早的时间点获知第一终端设备为通过第一接入网设备加入第一组播业务的最后一个终端设备，从而能够有助于组播用户面功能网元或用户面功能网元较早的获取第一信息。
当在该第三种可选的实施场景或第四种可选的实施场景中，第一接入网设备在切换准确阶段中的接收到切换请求响应时，获知第一终端设备为通过该第一接入网设备加入第一组播业务的最后一个终端设备。相对于上述在切换准备阶段的一个较早的时间点获知第一终端设备为该最后一个终端设备而言，这里第一接入网能够更准确的获知第一终端设备为通过第一接入网设备加入第一组播业务的最后一个终端设备，进而有助于提高组播业务传输的可靠性。
本申请的一个示例中，第一信息可以包括用于释放第一隧道的指示(indication)和该第一隧道的信息。
本申请的另一个示例中，第一信息可以包括用于释放第一隧道的指示(indication)和第一组播业务的标识信息。
本申请的另一个示例中，第一信息可以包括用于释放第一隧道的指示(indication)、第一组播业务的标识信息和该第一隧道的信息。
需要说明的是，当第一信息包含第一隧道的信息时，第一信息中可以包含一个，两个或多个第一隧道的信息，不作限定。当第一信息包含第一组播业务的标识信息时，第一信息中可以包含一个，两个或多个第一组播业务的标识信息，不作限定。
其中，第一隧道的信息可用于唯一确定该第一隧道，例如可以是第一隧道的隧道端点标识(tunnel endpoint identifier，TEID)，或第一隧道的ID，此处不限定。第一组播业务的标识信息可用于唯一确定一个组播业务，例如可以是组播业务的ID，或组播业务的名称，或组播地址，或组播组ID，组播/广播会话ID(MBS session ID),临时移动组标识(Temporary Mobile Group Identity,TMGI),等，此处不限定。
需要说明的是，本文所述的第一组播业务可以是一个组播业务或者是多个不同的组播业务，不做限定。举例来说，在源接入网设备存在两个组播会话，对应两个组播业务，对应两个组播会话隧道的情况下，当源接入网设备在切换准备阶段获知切换的终端设备为通过源接入网设备接收该两个组播业务的数据的最后一个终端设备时，源接入网设备可以向核心网设备发送第一信息，那么此时第一信息用于释放用于在源接入网设备与核心网设备之间传输这两个组播业务的数据的第一隧道，第一组播业务包含这两个组播业务，第一隧道包含这两个组播业务分别对应的隧道。
830，核心网设备根据第一信息，释放第一隧道。
示例性的，组播用户面功能网元或用户面功能网元可以根据该第一信息，释放第一隧道，例如移除该第一隧道的相关资源(比如移除第一隧道的隧道端点标识，例如TEID；或移除与第一组播业务的第一隧道相关的N4会话上下文信息(例如，包含数据检测规则(packet dection rule，PDR)、转发动作规则(forwarding action rule，FAR)等)。
例如，当第一信息包括用于释放第一隧道的指示(indication)和第一隧道的信息时，组 播用户面功能网元或用户面功能网元可以根据该用于释放第一隧道的指示(indication)和该第一隧道的信息，释放第一隧道。作为一个示例，当第一信息中的第一隧道的信息为该第一隧道的TEID时，组播用户面功能网元或用户面功能网元可以释放该TEID。另一个示例，当第一信息中的第一隧道的信息为第一隧道的ID时，组播用户面功能网元或用户面功能网元可以根据该第一隧道的ID，确定该第一隧道，然后根据该用于释放第一隧道的指示，释放第一隧道，例如移除该第一隧道的相关资源，例如TEID，或与第一组播业务的第一隧道相关的N4会话上下文信息。
这样，组播用户面功能网元或用户面功能网元能够对该第一信息所包含的第一隧道的信息对应的第一隧道(例如可以为一个第一隧道，或多个第一隧道，不作限定)进行释放。
再例如，当第一信息包括用于释放第一隧道的指示(indication)和第一组播业务的标识信息时，组播用户面功能网元或用户面功能网元可以根据该第一组播业务的标识信息，确定该第一组播业务，然后确定在第一接入网设备与核心网设备之间传输该第一组播业务的数据的第一隧道。具体的，组播用户面功能网元或用户面功能网元可以确定该第一组播业务对应的一个或多个组播会话，以及该一个组播会话对应的一个或多个组播会话隧道，或该多个组播会话对应的多个组播会话隧道。这里，确定的该组播会话隧道即为源接入网设备与核心网设备之间的传输该第一组播业务的数据的隧道(即第一隧道)。之后，组播用户面功能网元或用户面功能网元可以根据用于释放第一隧道的指示，释放第一隧道，即释放上述一个组播会话隧道或多个组播隧道的相关资源，例如TEID，或与第一组播业务的第一隧道相关的N4会话上下文信息。
这样，组播会话功能网元或会话功能网元可以将第一信息中所指示的第一组播业务对应的所有组播会话隧道，即用于在源接入网设备与核心网设备之间传输该第一组播业务的数据的第一隧道(例如所有第一隧道)释放。
再例如，当第一信息包括用于释放第一隧道的指示(indication)、第一组播业务的标识信息和第一隧道的信息时，组播用户面功能网元或用户面功能网元可以根据该第一组播业务的标识信息，确定该第一组播业务。然后，组播用户面功能网元或用户面功能网元确定在第一接入网设备与所述核心网设备之间传输所述第一组播业务的数据的第一隧道。具体的，组播用户面功能网元或用户面功能网元可以确定该第一组播业务对应的一个或多个组播会话，以及该一个组播会话对应的一个或多个组播会话隧道，或该多个组播会话对应的多个组播会话隧道。之后，组播用户面功能网元或用户面功能网元可以进一步根据第一信息中的第一隧道的信息，在该一个或多个组播会话隧道中确定第一隧道。之后，组播用户面功能网元或用户面功能网元可以根据用于释放第一隧道的指示，释放该第一隧道，例如移除该第一隧道的相关资源，例如TEID，或与第一组播业务的第一隧道相关的N4会话上下文信息。
这样，组播用户面功能网元或用户面功能网元能够对该第一信息所包含的第一隧道的信息对应的第一隧道进行释放。并且，当根据第一组播业务的标识信息和第一隧道的信息二者来确定第一隧道时，只需要在第一组播业务对应的一个或多个组播会话隧道中来确定该第一隧道，能够有助于更准确、快速的确定该第一隧道，从而有助于提高释放第一隧道的效率。
需要说明的是，在第一信息包括用于释放第一隧道的指示(indication)、第一组播业务 的标识信息和该第一隧道的信息的情况下，组播用户面功能网元或用户面功能网元还可以只根据第一组播业务的标识信息和该第一隧道的信息中的其中一种信息，来确定需要释放的第一隧道。例如，当只根据第一组播业务的标识信息来确定第一隧道时，组播用户面功能网元或用户面功能网元可以忽略第一信息中包含的该第一隧道的信息。又例如，当只根据第一隧道的信息来确定第一隧道时，组播用户面功能网元或用户面功能网元可以忽略第一信息中包含的该第一组播业务的标识信息。
因此，本申请实施例中，第一接入网设备可以在第一终端设备在从第一接入网设备切换至第二接入网设备的切换准备阶段，获知该第一终端设备为通过该第一接入网设备接收第一组播业务的数据的最后一个终端设备，并发送第一信息以释放用于在该第一接入网设备与核心网设备之间传输该第一组播业务的数据的第一隧道，有助于节省网络资源开销。
下面，将结合图9和图10，描述本申请实施例提供的通信方法的具体的例子。在图9和图10中，将以组播会话管理功能网元为MCF，源接入网设备为S-gNB为例进行描述。对于MCF中的芯片、S-gNB中的芯片的实现方法，可以参考MCF和S-gNB的具体说明，不作重复介绍。
可选的，在图9或图10中，核心网设备中还包括AMF、SMF、UPF和MUF。或者，在一些可选的实施例中，核心网设备中可以不包括MCF和MUF，而是由SMF中的某些功能或单元来实现MCF的功能，由UPF中的某些功能或单元来实现MUF的功能，本申请实施例对此不作限定。
图9示出了本申请实施例提供的另一种通信方法900的示意性流程图。方法900中的切换类型为Xn切换。其中，由S-gNB来判断是否需要释放S-gNB与MUF之间的组播会话隧道。
需要说明的是，图9中以释放S-gNB与MUF之间的组播会话隧道为例进行描述，该方案也可以适用于释放S-gNB与UPF之间的组播会话隧道，可能需要做一些简单的适配，都在本申请的保护范围之内。
在一些实施例中，当UE在S-gNB接收组播业务数据(或称作UE在S-gNB加入了组播业务)，该UE的PDU会话与组播业务关联。
当UE切换到的T-gNB不支持组播功能时，方法900可以适用于图5B所示的场景。下面，将结合图5B中的场景，对方法900进行描述。如图9所示，方法900可以包括步骤901至916。应注意的是，该方案同样可以适用于T-gNB支持组播功能的场景，这里不限定，图5B所示的场景仅为举例。
应理解，图9示出了本申请实施例提供的通信方法900的步骤或操作，但这些步骤或操作仅是示例，本申请实施例还可以执行其他操作或者图9中的各个操作的变形。此外，图中的各个步骤可以按照与其呈现的不同的顺序来执行，并且有可能并非要执行图中的全部操作。
可选的，在步骤901之前，S-gNB可以获知T-gNB的能力，即是否支持组播功能的能力。作为示例，当T-gNB与S-gNB之间存在Xn连接时，T-gNB可以通过Xn接口将自身的能力信息通知S-gNB，其中Xn即可即为S-gNB与T-gNB之间Xn连接的接口。例如，当T-gNB不支持组播功能时，T-gNB向S-gNB发送指示信息#1，该指示信息#1用于指示T-gNB不支持组播功能。或者在一些实施例中，当T-gNB不支持组播功能时，可以不向S- gNB发送指示信息#1。对应的，若S-gNB没有接收到该指示信息#1时，可以认为T-gNB不支持组播功能。
这里，首先根据3GPP技术规范(techinicalspecification,TS)38.300对Xn切换的切换准备阶段的定义，切换准备阶段包含图9所示流程的步骤901～步骤903。该切换准备阶段，可以理解为，S-gNB与T-gNB或者核心网设备之间为切换的UE准备切换所需资源(例如，可包括转发隧道，或UE接入T-gNB后接收业务数据所需的无线承载配置信息，或T-gNB为切换的UE配置的空口资源等)的阶段。
901，UE向S-gNB发送测量报告(Measurement Report)。对应的，S-gNB接收该测量报告，并决定将UE切换至T-gNB。
在一些可选的实施例中，S-gNB在收到UE发送的测量报告之后，S-gNB可更新与切换UE的PDU会话关联的组播业务(即，UE在S-gNB加入的组播业务(Multicast Service)或叫做加入的组播组(Multicast Group))对应的组播上下文(Multicast Context)，或组播业务上下文(Multicast Service Context)，或组播组上下文(Multicast Group Context)，或组播会话上下文(Multicast Session Context)中UE的数量(例如，将UE的数量减1)。若当前切换的UE为上述上下文中最后一个UE(也即，该UE离开后，不存在其它UE在该S-gNB下接收该组播业务)，则S-gNB可以获知该UE为通过该S-gNB接收该组播业务的数据的最后一个UE。此时，S-gNB可以确定释放S-gNB与核心网设备(例如，图5B中的MUF)之间的组播会话隧道。
这里，该组播业务可以为图8中第一组播业务的一个示例，该组播会话隧道可以为图8中第一隧道的一个示例。
示例性的，通过S-gNB加入组播业务(也可理解为在S-gNB接收该组播业务)的UE的数量可以包括在该组播业务的组播会话上下文(或叫做组播业务上下文或叫做组播上下文或叫做组播组上下文)中。也就是说，S-gNB可以通过上述上下文中是否还有除该UE之外的其他UE在S-gNB接收该组播业务，来判断是否释放该组播业务所在的组播会话隧道。
这里应注意的是，以基站为粒度(也即，以基站为单位)，一个组播业务可以对应一个组播会话，也即，可以对应一个基站(比如S-gNB)与核心网设备(例如，MUF或UPF)之间的组播会话隧道。此处应注意，一个组播业务也可以对应多个组播/广播会话，此处不限定，该方案以一对一为例，该方案也适用于一对多。
902，S-gNB向T-gNB发送切换请求(Handover Request)。这里，S-gNB可以获知T-gNB不支持组播功能。
示例性的，该切换请求中可以包含待切换的UE的PDU会话信息，其中，PDU会话标识和PDU会话中所包含的单播业务对应的QoS信息。具体的，可以参考步骤702中的描述，为了简洁，这里不再赘述。
需要说明的是，在步骤902中，如果当前切换的UE的PDU会话关联组播业务，则S-gNB可以根据组播QoS流QFI与单播QoS流QFI的映射关系，将组播QoS流映射为单播QoS流。即，此时PDU会话中包含的单播QoS流还包含上述组播QoS流所映射的单播QoS流。
另外，该切换请求中还可以包括S-gNB希望通过PDU会话隧道所对应的转发隧道进行转发的业务流标识。具体而言，对应于图5B中的场景，由于T-gNB不支持组播功能， 因此S-gNB和T-gNB之间只能建立PDU会话隧道对应的转发隧道。此时，如果组播QoS流需要通过该转发隧道转发，则在切换请求中可以包含该组播QoS流所对应的单播QoS流的QFI。
在一些可选的实施例中，若在步骤901中，S-gNB确定释放组播会话隧道，则S-gNB可以生成信息#2，用于释放用于在S-gNB与核心网设备(例如，UPF或MUF，这里以MUF为例)之间传输上述组播业务的数据的组播会话隧道。此时，切换请求中还可以包括该信息#2。
作为一个具体的示例，对于下行(即MUF向S-gNB发送)方向的组播会话隧道，S-gNB在确定(determine)或能(can)或decide(决定)释放S-gNB与MUF之间的组播会话隧道之后，可以生成上述信息#2。
作为示例，信息#2可以包括用于释放组播会话隧道的指示和组播会话隧道的信息；或者，信息#2可以包括用于释放组播会话隧道的指示和组播业务的标识信息；或者信息#2可以包括用于释放组播会话隧道的指示、组播会话隧道的信息和组播业务的标识信息，本申请实施例对此不作限定。
903，T-gNB向S-gNB发送切换请求响应(handover request ACK)。
作为示例，T-gNB根据从S-gNB收到的单播业务的QoS信息(包括映射后的单播QoS流)，为切换的UE准备无线资源。示例性的，T-gNB可以根据每个业务流的QFI所对应的QoS参数确定空口无线数据承载(data radio bearer，DRB)的数量，以及QFI到DRB的映射关系。此外，T-gNB还可以根据每个DRB所映射的QFI所对应的QoS参数，确定该DRB对应的配置参数。DRB对应的配置参数例如为DRB所对应的无线链路控制(radio link control，RLC)层采用确认模式还是非确认模式等。最后，T-gNB创建相应的DRB。
T-gNB在准备好无线资源之后，向S-gNB发送切换请求响应(handover request ACK)。在一些可选的实施例中，T-gNB可以将需要通过S-gNB中继给UE的信息发送给S-gNB。例如，T-gNB可以通过S-gNB将T-gNB的无线承载配置信息发送给UE，该无线承载配置信息可以用于UE在接入T-gNB后接收T-gNB发送的单播业务数据和/或组播业务数据。
在一些可选的实施例中，当在步骤902中的切换请求中包含S-gNB希望通过转发隧道转发的业务流的QFI(包括单播QoS流的QFI和/或组播QoS流的QFI)，并且T-gNB支持数据转发时，T-gNB分配转发隧道的端点标识。
在一些可选的实施例中，若在步骤901，即收到UE发送的测量报告之后，S-gNB没有进行组播会话隧道是否释放的判断，则S-gNB可以在收到切换请求响应后，更新与切换UE的PDU会话关联的组播业务对应的组播会话上下文(或叫做组播业务上下文或叫做组播上下文或叫做组播组上下文)中UE的数量(例如，将UE的数量减1)，若当前切换的UE为该上下文中最后一个UE(也即，该UE离开后，不存在其它UE在该基站下接收该组播业务)，则S-gNB获知该UE为通过该S-gNB接收该组播业务的数据的最后一个UE。此时，S-gNB可以确定释放S-gNB与核心网设备(例如，图5B中的MUF)之间的组播会话隧道。
示例性的，通过S-gNB加入组播业务(也可理解为在S-gNB接收该组播业务)的UE的数量和/或UE的标识信息可以包括在该组播会话上下文(或叫做组播业务上下文或叫做组播上下文或叫做组播组上下文)中。也就是说，S-gNB可以通过该组播会话上下文(或叫做 组播业务上下文或叫做组播上下文或叫做组播组上下文)中是否还有除该UE之外的其他UE在S-gNB接收该组播业务，来判断是否释放该组播业务所在的组播会话隧道。
示例性的，若S-gNB在收到切换请求响应后确定释放组播会话隧道，则S-gNB可以生成信息#2。此时，S-gNB可以将该信息#2发送给T-gNB，例如，可以通过单独的信令，此处不限定。具体的，信息#2可以参见上文中的描述，不再赘述。
904，S-gNB向UE发送切换命令(handover command)。这里，切换命令可以参见步骤704中的描述。
之后，S-gNB将组播会话隧道收到的组播QoS流复制、映射、并转发至T-gNB。
与图7中的“S-gNB将组播会话隧道收到的组播QoS流复制转发至T-gNB1”不同的是，由于本流程中的T-gNB不支持组播功能，对于需要转发的组播QoS流，S-gNB可以先将自身组播会话隧道中的组播QoS流进行复制，然后根据组播QoS流与单播QoS流的映射关系，将组播QoS流映射为单播QoS流。之后通过S-gNB与T-gNB之间的PDU会话隧道对应的转发隧道转发至T-gNB。T-gNB在通过该转发隧道收到该单播QoS流之后，缓存该单播QoS流。
905，UE接入T-gNB。具体的，步骤905可以参考步骤705中的描述，不再赘述。
906，T-gNB向AMF发送N2路径切换请求(N2 Path Switch Request)。
示例性的，该请求中包含UE的该PDU会话中切换成功以及切换失败的单播QoS流的QFI(其中包括由组播QoS流所映射的单播QoS流的QFI)。作为示例，这些QFI可以封装在N2 SM消息中。
在一些可选的实施例中，该N2路径切换请求中还可以包括T-gNB为该UE分配的PDU会话隧道的端点标识。
在一些可选的实施例中，如果T-gNB收到了S-gNB发送的信息#2，那么T-gNB在“N2路径切换请求”中还包含上述信息#2。
907，AMF向SMF发送PDU会话上下文更新请求(Nsmf_PDUSession_UpdateSMContext Request)。
示例性的，该PDU会话上下文更新请求中包含步骤906中的N2SM消息所包含的信息。
一些可选的实施例中，在UE向T-gNB切换之前，AMF可以收集gNB的能力信息(例如包括是否支持组播功能的能力信息)。作为示例，T-gNB在上电时，可以将自身是否支持组播功能上报至AMF。此时，PDU会话上下文更新请求中还可以包括T-gNB的能力信息。
在一些实施例中，如果AMF在步骤906中收到了S-gNB发送的信息#2(即，由S-gNB发送给T-gNB，然后由T-gNB中继给AMF的)，那么AMF在PDU会话上下文更新请求中可以包含信息#2。
908，SMF与UPF进行N4会话更新(N4 Session Modification)。
909，SMF向MCF发送第一消息。示例性的，该第一消息可以是N16消息。
在一些实施例中，如果SMF在步骤907收到了S-gNB发送的信息#2，那么SMF在向MCF发送的第一消息中可以包含信息#2。
910，MCF与MUF进行N4会话更新(N4 Session Modification)。
示例性的，MCF向MUF发送N4会话更新请求。在一些实施例中，如果MCF在步骤 909中收到S-gNB发送的信息#2，那么MCF在N4会话更新请求中可以包含信息#2。MUF收到信息#2后，释放相关组播会话隧道。示例性的，MUF可以根据相应的隧道标识信息，移除该隧道的相关资源。
例如，组播/广播业务一般只有下行，在建立S-gNB与MUF之间的共享隧道时，MUF配置了由S-gNB生成的隧道端点标识TEID和MCF配置给MUF的PDR，这样MUF就可以将组播业务的数据发送给S-gNB。因此，这里的释放可以是移除相关的TEID，移除与第一组播相关的PDR。这里应注意，全文的组播业务数据可以替换为组播/广播业务数据。
作为一个示例，当信息#2包括用于释放组播会话隧道的指示(indication)和该组播会话隧道的信息时，MUF可以根据该指示和该组播会话隧道的信息，释放第一隧道。例如，当信息#2中的组播会话隧道的信息为该组播会话隧道的TEID时，MUF可以释放该TEID。又例如，当组播会话隧道的信息为组播会话隧道的ID时，MUF可以根据该组播会话隧道的ID，确定该组播会话隧道，然后根据信息#2中的该指示，释放该组播会话隧道，例如移除该组播会话隧道的相关资源，例如TEID，或移除与第一组播相关的PDR。
作为另一个示例，当信息#2包括用于释放组播会话隧道的指示(indication)和组播业务的标识信息时，MUF可以根据该组播业务的标识信息，确定该组播业务，然后确定在S-gNB与MUF之间传输该组播业务的数据的组播会话隧道。具体的，MUF可以确定该组播业务对应的一个或多个组播会话，以及该一个组播会话对应的一个或多个组播会话隧道，或该多个组播会话对应的多个组播会话隧道。之后，MUF可以根据信息#2中的该指示，释放组播会话隧道，即释放上述一个组播会话隧道或多个组播隧道的相关资源，例如TEID，或移除与第一组播相关的PDR。
再例如，当信息#2包括用于释放组播会话隧道的指示(indication)、组播业务的标识信息和组播会话隧道的信息时，MUF可以根据该组播业务的标识信息，确定该组播业务。然后，根据信息#2中的组播会话隧道的信息，在S-gNB与所述MUF之间传输该组播业务的数据的组播会话隧道。具体的，MUF可以确定该第一组播业务对应的一个或多个组播会话，以及该一个组播会话对应的一个或多个组播会话隧道，或该多个组播会话对应的多个组播会话隧道。之后，MUF可以进一步根据信息#2中的组播会话隧道的信息，在该一个或多个组播会话隧道中确定组播会话隧道。之后，组播用户面功能网元或用户面功能网元可以根据信息#2中的指示，释放该组播会话隧道，例如移除该组播会话隧道的相关资源，例如TEID，或移除与第一组播相关的PDR。
之后，MUF可以向MCF发送N4会话更新响应。
911，MCF向SMF发送第一消息的响应。可选的，该第一消息的响应中可包含针对信息#2的响应信息。另外，需要说明的是，这里并不限定一定有响应消息，即也可以不发送该响应消息。
具体的，步骤908至步骤911可以参考步骤708至步骤711的描述，这里不再赘述。
912，SMF向AMF发送PDU会话上下文更新响应(Nsmf_PDUSession_UpdateSMContext Response)。
在一些实施例中，该信令中除包含已有协议规定的信元外，如果在步骤911中，SMF收到了与组播会话隧道释放相关的响应信元，例如，信息#2的响应信息，则可选的，在该PDU会话上下文更新响应中还可以包含该响应信元。
913，AMF向T-gNB发送N2路径切换响应(N2 Path Switch Request ACK)。
在一些实施例中，该信令中除包含已有协议规定的信元外，如果在步骤912中包含与组播会话隧道释放相关的响应信元，例如，信息#2的响应信息，则可选的，在该N2路径切换响中还可以包含该响应信元。
914，T-gNB向S-gNB发送释放UE上下文请求(UE Context Release)。
在一些实施例中，该信令中除包含已有协议规定的信元外，如果在步骤913中包含与组播会话隧道释放相关的响应信元，例如信息#2的响应信息，则可选的，在该N2路径切换响应中还包含该响应信元。
需要说明的是，在图9所示的实施例中，以T-gNB不支持组播功能为例进行描述，但是本申请实施例并不限于此。例如，T-gNB还可以支持组播功能，此时S-gNB需要将组播会话隧道收到的组播QoS流复制转发至T-gNB，即不需要将组播QoS流映射为单播QoS流，具体的可以参考图7中的描述，不再赘述。
在上述步骤906、907、909中，将信息#2作为信元包含于已有信令中带给MCF，但是本申请实施例并不限于此。
在一些可选的实施例中，S-gNB还可以执行步骤915，即S-gNB直接向MCF发送通知消息，该通知消息用于通知MCF释放上述组播业务所在的组播会话隧道，即S-gNB与MUF之间的传输该组播业务的组播会话隧道。此时，步骤902、906、907、909、910中的消息中可以不包括信息#2，即S-gNB不将信息#2作为信元包含于已有的信令中，而是通过单独的信令通知MCF释放组播会话隧道。
示例性的，该信令可以包含用于释放组播会话隧道的指示和组播会话隧道的信息；或者，该信令可以包括用于释放组播会话隧道的指示和组播业务的标识信息；或者该信令可以包括用于释放组播会话隧道的指示、组播会话隧道的信息和组播业务的标识信息，本申请实施例对此不作限定。
作为一种可能的实现方式，步骤915可以在S-gNB确定释放S-gNB与MUF之间的用于传输组播业务的组播会话隧道之后执行，例如可以在步骤901与步骤914之间，或者在步骤914之后，本申请实施例对此不作限定。
916，S-gNB与MCF释放组播会话隧道。
示例性的，MCF收到步骤915中的信令后，可以将该信令发送给MUF，MUF可以根据该信令，对S-gNB与MUF之间的传输该组播业务的组播会话隧道进行释放。
另外，在另一些可选的实施例中，MCF也可以在UE加入组播业务时，向S-gNB订阅组播会话隧道释放的通知。也就是说，当切换过程中S-gNB判断需要释放S-gNB与核心网设备(例如，MUF或UPF)之间的组播会话隧道时，可以向MCF发送释放通知。此时，在上述步骤901至步骤914的信令中，可以按照现有的正常切换流程进行，而不需要包括额外的信息，例如信息#2。
在一些可选的实施例中，当S-gNB在切换准备阶段判断或者确定或者能释放S-gNB的组播会话隧道时(具体方式如步骤901～步骤903所述，此处不再撰述)，S-gNB还可以执行步骤917至919。
917，S-gNB向AMF发送第三消息，第三消息可以是N2消息，第三消息携带信息#2。
这里应注意的是，步骤917中的该AMF可以是与图9中切换流程的AMF是同一个 AMF(即，为切换UE服务的AMF)，也可以是其它的AMF，不作限定。另外，N2消息可以是已有的N2消息(即，携带信息#2)，也可以是新增的N2消息(例如，其主要用于组播会话隧道的释放，新增的N2消息遵循服务化接口信令消息的命名方式，其具体名称不限定，但功能是用于通知MUF组播会话隧道的释放)，本申请实施例对此不作限定。
918，AMF向MCF发送第四消息，第四消息可以是N11消息，第四消息携带上述信息#2。示例性的，N11消息可以是已有的N11消息(即，携带信息#2)，也可以是新增的N11消息(例如，主要用于组播会话隧道的释放，新增的N11消息遵循服务化接口信令消息的命名方式，其具体名称不限定，但功能是用于通知MUF组播会话隧道的释放)。
919，MCF与MUF进行N4会话更新(N4 Session Modification)。例如，MCF向MUF发送第五消息，第五消息可以是N4会话更新请求，第五消息携带信息#2，MUF根据信息#2释放组播会话隧道。之后，MUF向MCF发送第五消息的响应，例如，可以是N4会话更新响应。
还需注意的是，如果S-gNB采用步骤917～步骤919的方式通知MUF释放组播会话隧道，那么在图9所示的切换流程中，当S-gNB在切换准备阶段判断或决定或能释放源基站的组播会话隧道后，S-gNB执行步骤917～步骤919来通知MUF释放组播会话隧道，也即切换流程(例如，在步骤906～步骤914)不再携带信息#2以及针对相关组播会话隧道释放的响应。
因此，本申请实施例中，S-gNB可以在UE从S-gNB切换至T-gNB的切换准备阶段，在判断组播会话上下文(或组播业务上下文或组播上下文或组播组上下文或组播会话上下文)中不存在其它UE在S-gNB接收该组播业务的情况下，通知核心网设备(例如，MUF或UPF)释放S-gNB与该核心网设备之间的用于传输该组播业务的组播会话隧道，例如可以通过已有信令，或者通过单独的信令通知释放隧道，从而实现对S-gNB与核心网设备(例如，MUF或UPF)之间的组播会话隧道的释放，有助于节省网络资源开销。
图10出了本申请实施例提供的另一种通信方法1000的示意性流程图。方法1000中的切换为N2切换。其中，由S-gNB来判断是否需要释放S-gNB与MUF之间的组播会话隧道。
需要说明的是，图10中以释放S-gNB与MUF之间的组播会话隧道为例进行描述，该方案也可以适用于释放S-gNB与UPF之间的组播会话隧道，可能需要做一些简单的适配，都在本申请的保护范围之内。
在一些实施例中，当UE在S-gNB接收组播业务数据(或称作UE在S-gNB加入了组播业务)，该UE的PDU会话与组播业务关联。
当UE切换到的T-gNB不支持组播功能时，方法1000可以适用于图5C所示的场景。下面，将结合图5C中的场景，对方法1000进行描述。如图10所示，方法1000可以包括步骤1001至1017。应注意的是，该方案同样可以适用于T-gNB支持组播功能的场景，这里不限定，图5C所示的场景仅为举例。
应理解，图10示出了本申请实施例提供的通信方法1000的步骤或操作，但这些步骤或操作仅是示例，本申请实施例还可以执行其他操作或者图10中的各个操作的变形。此外，图中的各个步骤可以按照与其呈现的不同的顺序来执行，并且有可能并非要执行图中的全部操作。
可选的，在步骤1001之前，S-gNB可以获知T-gNB的能力，即是否支持组播功能的能力。作为示例，当T-gNB与S-gNB之间存在Xn连接时，T-gNB可以通过Xn接口将自身的能力信息通知S-gNB，其中Xn即可即为S-gNB与T-gNB之间Xn连接的接口。例如，当T-gNB不支持组播功能时，T-gNB2向S-gNB发送指示信息#1，该指示信息#1用于指示T-gNB不支持组播功能。或者在一些实施例中，当T-gNB不支持组播功能时，可以不向S-gNB发送指示信息#1。对应的，若S-gNB没有接收到该指示信息#1时，可以认为T-gNB不支持组播功能。
这里，首先根据3GPP技术规范(techinicalspecification,TS)23.502对N2切换的切换准备阶段的定义，切换准备阶段包含图10所示流程的步骤1001～步骤1012。该切换准备阶段，可以理解为，S-gNB与T-gNB或者核心网设备之间为切换的UE准备切换所需资源(例如，可包括转发隧道的信息，UE接入T-gNB后接收业务数据所需的无线承载配置信息，T-gNB为切换的终端设备配置的空口资源等)的阶段。
1001，UE向S-gNB发送测量报告(Measurement Report)。对应的，S-gNB接收该测量报告，并决定将UE切换至T-gNB。
在一些可选的实施例中，S-gNB在收到UE发送的测量报告之后，S-gNB可更新与切换UE的PDU会话关联的组播业务对应的组播会话上下文(或组播业务上下文或组播上下文或组播组上下文)中UE的数量(例如，将UE的数量减1)。若当前切换的UE为上述上下文中最后一个UE(也即，该UE离开后，不存在其它UE在该基站下接收该组播业务)，则S-gNB可以获知该UE为通过该S-gNB接收该组播业务的数据的最后一个UE。此时，S-gNB可以确定释放S-gNB与核心网设备(例如，图5C中的MUF)之间的组播会话隧道。
这里，该组播业务可以为图8中第一组播业务的一个示例，该组播会话隧道可以为图8中第一隧道的一个示例。
示例性的，通过S-gNB加入组播业务(也可理解为在S-gNB接收该组播业务)的UE的数量和/或UE的标识信息可以包括在该组播会话上下文(或组播业务上下文或组播上下文或组播组上下文)中。也就是说，S-gNB可以通过该组播会话上下文(或组播业务上下文或组播上下文或组播组上下文)中是否还有除该UE之外的其他UE在S-gNB接收该组播业务，来判断是否释放该组播业务所在的组播会话隧道。
这里应注意的是，以基站为粒度(也即，以基站为单位)，一个组播业务可以对应一个组播会话，也即，可以对应一个基站(比如S-gNB)与核心网设备(例如，MUF或UPF)之间的组播会话隧道。此处应注意，一个组播业务也可以对应多个组播/广播会话，此处不限定，该方案以一对一为例，该方案也适用于一对多。
1002，S-gNB向S-AMF发送切换需要(Handover Required)。
示例性的，“切换需要”中包含待切换的UE的PDU会话信息以及所关联的组播业务信息(包括关联的组播业务标识)，PDU会话信息包含PDU会话标识和PDU会话中所包含的单播业务流对应的QoS信息。其中，单播业务流的QoS信息包括QFI和QoS参数。若当前切换的UE的PDU会话关联组播业务，则S-gNB根据组播QoS流QFI与单播QoS流QFI的映射关系将组播QoS流映射为单播QoS流。
此外，“切换需要”还可以包含SM N2信息。若SM N2信息中的指示S-gNB与T-gNB之间不存在直接转发隧道，则表示S-gNB与T-gNB之间可建立间接转发隧道，此时 SM N2信息可包含S-gNB分配的间接转发隧道信息。
在“切换需要”中还可以包括S-gNB希望通过转发隧道转发的业务流标识。若组播QoS流需要通过转发隧道转发，则在切换请求中包含该组播QoS流所对应的单播QoS流的QFI。
在一些可选的实施例中，若在步骤1001中，S-gNB确定释放组播会话隧道，则S-gNB可以生成信息#2，用于释放用于在S-gNB与核心网设备(例如，UPF或MUF，这里以MCF为例)之间传输上述组播业务的数据的组播会话隧道。此时，切换需要中可以包括该信息#2。具体的，信息#2可以参见图9中步骤902中的描述，不再赘述。
1003，S-AMF根据目标小区ID选择目标AMF(即，Target-AMF，T-AMF)，T-AMF与T-gNB相连。
1004，S-AMF向T-AMF发送创建UE上下文请求(Namf_Communication_CreateUEContext Request)，在该请求中可以包含S-AMF存储的发生切换的UE上下文信息，还可以包含步骤1002中由S-gNB发送给S-AMF的信息。
可选的，若在步骤1002中S-gNB将信息#2发送给了S-AMF，则在步骤1004中，S-AMF将信息#2发送给T-AMF。
1005，T-AMF向SMF发送PDU会话上下文更新请求(Nsmf_PDUSession_UpdateSMContext Request)，其中包含步骤1002中由S-gNB发送给S-AMF的信息。可选的，若在步骤1004中包含了信息#2，则在PDU会话上下文更新请求中还携带信息#2。
1006，SMF与UPF进行N4会话更新(N4 Session Modification)。
示例性的，SMF向UPF发送N4会话更新请求。可选的，N4会话更新请求携带S-gNB分配的间接转发隧道信息。之后，UPF向SMF回复N4会话更新响应。可选的，N4会话更新响应包含UPF分配的间接转发隧道信息，用于建立如图5C中所示的S-gNB与T-gNB之间的间接转发隧道。
1007，SMF向T-AMF发送PDU会话上下文更新响应(Nsmf_PDUSession_UpdateSMContext Response)。该消息可包括PDU会话的单播QoS流的QoS信息。其中，QoS信息包括QFI和对应的QoS参数。所述单播QoS流包含由组播QoS流所映射来的单播QoS流。
1008，T-AMF向T-gNB发送切换请求(Handover Request)。该消息可包括PDU会话所包含的单播QoS流的QoS信息(包含组播QoS流映射的单播QoS流的QoS信息)。T-gNB基于上述QoS流的QoS信息为单播QoS流分配无线资源。可选的，若S-gNB支持间接转发隧道的建立，则在切换请求包含S-gNB分配的间接转发隧道信息以及UPF的间接转发隧道信息。
1009，T-gNB向T-AMF发送切换请求响应(Handover Request ACK)。
示例性的，切换请求响应中可包含切换成功和/或切换失败的单播QoS流的QFI(例如，T-gNB资源紧张无法为该单播QoS流分配无线资源导致切换失败)；UE接入T-gNB接收业务数据所需的无线承载配置等。此外，由于S-gNB与T-gNB之间存在间接转发隧道，因此T-gNB还在切换请求响应中包含该间接转发隧道的信息(即，用于与UPF建立转发隧道)。然后，通过步骤1009～1018将该隧道信息带给UPF)。
1010，T-AMF向SMF发送PDU会话上下文更新请求 (Nsmf_PDUSession_UpdateSMContext Request)，其中包含步骤1009中切换请求响应中包含的相关的信息。
1011，SMF向T-AMF发送PDU会话上下文更新响应(Nsmf_PDUSession_UpdateSMContext Response)。可选的，该响应中还包含UPF的间接转发隧道信息。
1012，T-AMF向S-AMF发送创建UE上下文响应(Nsmf_PDUSession_UpdateSMContext Response)，包含步骤1011的信息。
1013，S-AMF向S-gNB发送切换命令(Handover Command)，包含步骤1012的信息。
可选的，若在步骤1001中没有生成信息#2(也即，S-gNB没有在收到步骤1001的信令后，生成信息#2，也即，从步骤1001～步骤1005的信令中不携带信息#2)，则S-gNB在收到切换命令后，S-gNB可更新与切换UE的PDU会话关联的组播业务对应的组播会话上下文中UE的数量(例如，将UE的数量减1)。若当前切换的UE为该组播会话上下文(或组播业务上下文或组播上下文或组播组上下文)中最后一个UE(也即，该UE离开后，不存在其它UE在该基站下接收该组播业务)，则S-gNB获知该UE为通过该S-gNB接收该组播业务的数据的最后一个UE。此时，S-gNB可以确定释放S-gNB与核心网设备(例如，图5C中的MUF)之间的组播会话隧道。
示例性的，通过S-gNB加入组播业务(也可理解为在S-gNB接收该组播业务数据)的UE的数量可以包括在该组播业务的组播会话上下文(或组播业务上下文或组播上下文或组播组上下文)中。也就是说，S-gNB可以通过该组播会话上下文(或组播业务上下文或组播上下文或组播组上下文)中是否还有除该UE之外的其他UE在S-gNB接收该组播业务的数据，来判断是否释放该组播业务所在的组播会话隧道。
示例性的，若S-gNB收到切换命令后确定释放组播会话隧道，则S-gNB可以生成信息#2，用于请求或指示或通知核心网设备(例如，MCF或MUF，这里以MUF为例)释放该组播业务所在的组播会话隧道。具体的，信息#2可以参见上文中的描述，不再赘述。然后，S-gNB可以将该信息#2携带在信令中发送给会话管理功能网元。
1014，S-gNB向UE发送切换命令(Handover Command)，包含UE接入目标基站所需的无线承载配置信息(这里的无线承载配置信息包括针对单播QoS流所需的无线承载配置信息以及由组播QoS流映射的单播QoS流的无线承载配置信息)。
之后，S-gNB将组播会话隧道收到的组播QoS流复制、映射、并通过间接转发隧道转发至T-gNB。
1015，UE接入T-gNB。T-gNB将接收并缓存的单播QoS流，和/或组播QoS流发送给UE。UE根据步骤1014中S-gNB发送的无线承载配置信息接收相应的业务数据。
1016，T-gNB向T-AMF发送切换通知(Handover Notify)，该通知指示UE成功的切换至T-gNB。
1017，T-AMF向SMF发送PDU会话上下文更新请求(Nsmf_PDUSession_UpdateSMContext)，携带T-gNB分配的PDU会话隧道的信息。可选的，还携带T-gNB生成的间接转发隧道的信息。
1018，SMF向MCF发送第一消息。示例性的，第一消息可以是N16消息。
在一些实施例中，如果SMF在步骤1005收到了S-gNB发送的信息#2，那么SMF在 向MCF发送的第一消息中可以包含信息#2。
步骤1019至步骤1021与步骤910～步骤912描述相似，此处不再赘述。
1022，继续按照3GPP技术规范规定的N2切换流程执行后续的切换流程。
需要说明的是，在图10所示的实施例中，以T-gNB不支持组播功能为例进行描述，但是本申请实施例并不限于此。例如，T-gNB还可以支持组播功能，此时S-gNB需要将组播会话隧道收到的组播QoS流复制转发至T-gNB，即不需要将组播QoS流映射为单播QoS流，具体的可以参考图7中的描述，不再赘述。
在上述步骤(步骤1002、步骤1004、步骤1005、步骤1007、步骤1008、步骤1016、步骤1017、步骤1019)或(步骤1016、步骤1017、步骤1018)中，S-gNB将信息#2包含于已有信令中带给MCF，MCF进一步通过步骤1019带给MUF，但是本申请实施例并不限于此。
在一些可选的实施例中，S-gNB还可以执行步骤1023，即S-gNB直接向MCF发送通知消息，该通知消息用于通知MCF释放上述组播业务所在的组播会话隧道，即S-gNB与MUF之间的传输该组播业务的组播会话隧道。此时，步骤(1002、1004、1005、1007、1008、1016、1017、1018，1019)中的消息中可以不包括信息#2，即S-gNB不将释放组播会话隧道的相关指示信息作为信元包含于已有的信令中，而是通过单独的信令通知MCF释放组播会话隧道。
示例性的，该信令中可以包含用于释放组播会话隧道的指示和组播会话隧道的信息；或者，该信令可以包括用于释放组播会话隧道的指示和组播业务的标识信息；或者该信令可以包括用于释放组播会话隧道的指示、组播会话隧道的信息和组播业务的标识信息，本申请实施例对此不作限定。
作为一种可能的实现方式，步骤1023可以在S-gNB确定释放S-gNB与MUF之间的用于传输组播业务的组播会话隧道之后执行，例如可以在步骤1001与步骤1022之间，或者在步骤1022之后，本申请实施例对此不作限定。
1024，S-gNB与MCF释放组播会话隧道。
示例性的，MCF收到步骤1023中的信令后，可以将该信令发送给MUF，MUF可以根据该信令，对S-gNB与MUF之间的传输该组播业务的组播会话隧道进行释放。
另外，在另一些可选的实施例中，MCF也可以在UE加入组播业务时，向S-gNB订阅组播会话隧道释放的通知。也就是说，当切换过程中S-gNB判断需要释放S-gNB与核心网设备(例如，MUF或UPF)之间的组播会话隧道时，可以向MCF发送释放通知。此时，在上述步骤1001至步骤1022的信令中，可以按照现有的正常切换流程进行，而不需要包括额外的信息，例如信息#2。
在一些可选的实施例中，当S-gNB在切换准备阶段判断或者确定或者能释放S-gNB的组播会话隧道时(具体方式如步骤1001～步骤1012所述，此处不再撰述)，S-gNB还可以执行步骤1025至1027。
1025，S-gNB向S-AMF发送是第三消息，第三消息可以是N2消息，第三消息携带信息#2。
这里应注意的是，步骤1025中的该S-AMF可以是与图10中切换流程的S-AMF是同一个AMF(即，为切换UE服务的S-AMF)，也可以是其它的AMF，不作限定。另外，N2 消息可以是已有的N2消息(即，携带信息#2)，也可以是新增的N2消息(例如，其主要用于组播会话隧道的释放，新增的N2消息遵循服务化接口信令消息的命名方式，其具体名称不限定，但功能是用于通知MUF组播会话隧道的释放)，本申请实施例对此不作限定。
1026，S-AMF向MCF发送第四消息，第四消息可以是N11消息，N11消息携带上述信息#2。示例性的，N11消息可以是已有的N11消息(即，携带信息#2)，也可以是新增的N11消息(例如，主要用于组播会话隧道的释放，新增的N11消息遵循服务化接口信令消息的命名方式，其具体名称不限定，但功能是用于通知MUF组播会话隧道的释放)。
1027，MCF与MUF进行N4会话更新(N4 Session Modification)。例如，MCF向MUF发送第五消息，第五消息可以是N4会话更新请求，第五消息携带信息#2，MUF根据信息#2释放组播会话隧道，之后，MUF向MCF发送第五消息的响应，例如，可以是N4会话更新响应。
这里还需注意的是，如果S-gNB采用步骤1025～步骤1027的方式通知MUF释放组播会话隧道，那么在图10所示的切换流程中，当S-gNB在切换准备阶段判断或决定或能释放源基站的组播会话隧道后，S-gNB执行步骤1025～步骤1027来通知MUF释放组播会话隧道，也即切换流程不再携带信息#2以及针对相关组播会话隧道释放的响应。
因此，本申请实施例中，S-gNB可以在UE从S-gNB切换至T-gNB的切换准备阶段，在判断组播会话上下文(或组播业务上下文或组播上下文或组播组上下文)中不存在其它UE在S-gNB接收该组播业务的情况下，通知核心网设备(例如，MUF或UPF)释放S-gNB与该核心网设备之间的用于传输该组播业务的组播会话隧道，例如可以通过已有信令中，或者通过单独的信令通知释放隧道，从而实现对S-gNB与核心网设备(例如，MUF或UPF)之间的组播会话隧道的释放，有助于节省网络资源开销。
根据前述方法，图11为本申请实施例提供的无线通信的装置1100的示意图。
其中，该装置1100可以为接入网设备，也可以为芯片或电路，比如可设置于接入网设备的芯片或电路。
或者，该装置1100可以为接入与移动性管理功能网元，也可以为芯片或电路，比如可设置于接入与移动性管理功能网元的芯片或电路。
或者，该装置1100可以为会话管理功能网元，也可以为芯片或电路，比如可设置于会话管理功能网元的芯片或电路。
或者，该装置1100可以为组播会话管理功能网元，也可以为芯片或电路，比如可设置于组播会话管理功能网元的芯片或电路。
或者，该装置1100可以为组播用户面功能网元，也可以为芯片或电路，比如可设置于组播用户面功能网元的芯片或电路。
该装置1100可以包括处理单元1110(即，处理器的一例)和收发单元1130。
可选的，收发单元1130可以通过收发器或者收发器相关电路或者接口电路实现。
可选的，该装置1100还可以包括存储单元1120。一种可能的方式中，该存储单元1120用于存储指令。可选的，该存储单元1120也可以用于存储数据或者信息。存储单元1120可以通过存储器实现。
一种可能的设计中，该处理单元1110可以用于执行该存储单元1120存储的指令，以使装置1100实现如上述方法中接入网设备执行的步骤。
进一步的，该处理单元1110、存储单元1120、收发单元1130可以通过内部连接通路互相通信，传递控制和/或数据信号。例如，该存储单元1120用于存储计算机程序，该处理单元1110可以用于从该存储单元1120中调用并运行该计算计程序，以控制收发单元1130接收信号和/或发送信号，完成上述方法中接入网设备或接入与移动性管理功能网元或会话管理功能网元或组播会话管理功能网元或组播用户面功能网元的步骤。该存储单元1120可以集成在处理单元1110中，也可以与处理单元1110分开设置。
可选地，若该装置1100为通信设备，该收发单元1130可以包括接收器和发送器。其中，接收器和发送器可以为相同或者不同的物理实体。为相同的物理实体时，可以统称为收发器。
可选地，若该装置1100为芯片或电路，该收发单元1130可以包括输入接口和输出接口。
作为一种实现方式，收发单元1130的功能可以考虑通过收发电路或者收发的专用芯片实现。处理单元1110可以考虑通过专用处理芯片、处理电路、处理单元或者通用芯片实现。
作为另一种实现方式，可以考虑使用通用计算机的方式来实现本申请实施例提供的通信设备(例如，接入网设备或接入与移动性管理功能网元或会话管理功能网元或组播会话管理功能网元或组播用户面功能网元)。即将实现处理单元1110、收发单元1130功能的程序代码存储在存储单元1120中，通用处理单元通过执行存储单元1120中的代码来实现处理单元1110、收发单元1130的功能。
在一些实施例中，当装置1100为第一接入网设备，或可设置于第一接入网设备的芯片或电路时，
处理单元1110用于在第一终端设备从所述第一接入网设备向第二接入网设备切换的切换准备阶段，获知所述第一终端设备为通过所述第一接入网设备接收第一组播业务的数据的最后一个终端设备；
收发单元1130用于发送第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在所述第一接入网设备与核心网设备之间传输所述第一组播业务的数据。
可选的，所述收发单元1130具体用于：向所述第二接入网设备发送切换请求，所述切换请求用于请求将所述第一终端设备从所述第一接入网设备切换至所述第二接入网设备，所述切换请求中包括所述第一信息。
可选的，所述收发单元1130具体用于：向第一接入与移动性管理功能网元发送切换需要，所述切换需要中包括所述第一信息。
可选的，所述收发单元1130具体用于：所述第一接入网设备向第三接入与移动性管理功能网元发送第三消息，所述第三消息包括所述第一信息，所述第三接入与移动性管理功能网元为所述第一终端设备加入所述第一组播业务时，由所述第一接入网设备为所述第一组播业务选择的接入与移动性管理功能网元。
可选的，所述处理单元1110还用于：更新通过所述第一接入网设备加入所述第一组播业务的终端设备的数量。
可选的，所述第一信息包括用于释放所述第一隧道的指示和所述第一隧道的信息；或者
所述第一信息包括用于释放所述第一隧道的指示和所述第一组播业务的标识信息；或者
所述第一信息包括用于释放所述第一隧道的指示、所述第一组播业务的标识信息和所述第一隧道的信息。
可选的，所述核心网设备包括组播用户面功能网元或用户面功能网元。
其中，以上列举的装置1100中各模块或单元的功能和动作仅为示例性说明，当该装置1100配置在或本身即为第一接入网设备时，装置1100中各模块或单元可以用于执行上述方法中第一接入网设备所执行的各动作或处理过程。
在一些实施例中，当装置1100为第二接入网设备，或可设置于第二接入网设备的芯片或电路时，
所述收发单元1130用于接收来自第一接入网设备的切换请求，所述切换请求用于请求将第一终端设备从所述第一接入网设备切换至所述第二接入网设备，所述切换请求中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在所述第一接入网设备与核心网设备之间传输第一组播业务的数据；
所述收发单元1130还用于向接入与移动性管理功能网元发送路径切换请求，所述路径切换请求中包含所述第一信息。
其中，以上列举的装置1100中各模块或单元的功能和动作仅为示例性说明，当该装置1100配置在或本身即为第二接入网设备时，装置1100中各模块或单元可以用于执行上述方法中第二接入网设备所执行的各动作或处理过程。
在一些实施例中，当装置1100为接入与移动性管理功能网元，或可设置于接入与移动性管理功能网元的芯片或电路时，
收发单元1130，用于接入与移动性管理功能网元接收来自第二接入网设备的路径切换请求，所述路径切换请求中包含第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
所述收发单元1130还用于向会话管理功能网元发送协议数据单元PDU会话上下文更新请求，所述PDU会话上下文更新请求包括所述第一信息。
其中，以上列举的装置1100中各模块或单元的功能和动作仅为示例性说明，当该装置1100配置在或本身即为接入与移动性管理功能网元时，装置1100中各模块或单元可以用于执行上述方法中接入与移动性管理功能网元所执行的各动作或处理过程。
在一些实施例中，当装置1100为会话管理功能网元，或可设置于会话管理功能网元的芯片或电路时，
收发单元1130，用于接收来自接入与移动性管理功能网元的协议数据单元PDU会话上下文更新请求，所述PDU会话上下文更新请求包含第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
收发单元1130还用于向组播会话管理功能网元发送第一消息，所述第一消息中包括所述第一信息。
可选的，该第一消息可以为N16消息。
在一些实施例中，当装置1100为会话管理功能网元，或可设置于会话管理功能网元的芯片或电路时，
收发单元1130，用于接收来自接入与移动性管理功能网元的协议数据单元PDU会话上下文更新请求，所述PDU会话上下文更新请求包含第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
收发单元1130还用于向用户面功能网元发送会话更新请求，所述会话更新请求中包括所述第一信息。
其中，以上列举的装置1100中各模块或单元的功能和动作仅为示例性说明，当该装置1100配置在或本身即为会话管理功能网元时，装置1100中各模块或单元可以用于执行上述方法中会话管理功能网元所执行的各动作或处理过程。
在一些实施例中，当装置1100为组播会话管理功能网元，或可设置于组播会话管理功能网元的芯片或电路时，
收发单元1130，用于接收来自会话管理功能网元的第一消息，所述第一消息中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
收发单元1130还用于向组播用户面功能网元发送第五消息，所述第五消息中包括所述第一信息。
可选的，所述第一消息为N16消息。
可选的，所述第五消息为N4会话更新请求。
其中，以上列举的装置1100中各模块或单元的功能和动作仅为示例性说明，当该装置1100配置在或本身即为组播会话管理功能网元时，装置1100中各模块或单元可以用于执行上述方法中组播会话管理功能网元所执行的各动作或处理过程。
在一些实施例中，当装置1100为第一接入与移动性管理功能网元，或可设置于第一接入与移动性管理功能网元的芯片或电路时，
收发单元1130，用于接收来自第一接入网设备的切换需要，所述切换需要中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在所述第一接入网设备与核心网设备之间传输所述第一组播业务的数据；
收发单元1130还用于向第二接入与移动性管理功能网元发送创建用户设备UE上下文请求，所述创建UE上下文请求中包含所述第一信息。
其中，以上列举的装置1100中各模块或单元的功能和动作仅为示例性说明，当该装置1100配置在或本身即为第一接入与移动性管理功能网元时，装置1100中各模块或单元可以用于执行上述方法中第一接入与移动性管理功能网元所执行的各动作或处理过程。
在一些实施例中，当装置1100为第二接入与移动性管理功能网元，或可设置于第二接入与移动性管理功能网元的芯片或电路时，
收发单元1130，用于接收来自第一接入与移动性管理功能网元的创建用户设备UE上下文请求，所述创建UE上下文请求中包含第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
收发单元1130还用于向会话管理功能网元发送协议数据单元PDU会话上下文更新请求，所述PDU会话上下文更新请求包括所述第一信息。
其中，以上列举的装置1100中各模块或单元的功能和动作仅为示例性说明，当该装置1100配置在或本身即为第二接入与移动性管理功能网元时，装置1100中各模块或单元可 以用于执行上述方法中第二接入与移动性管理功能网元所执行的各动作或处理过程。
在一些实施例中，当装置1100为第三接入与移动性管理功能网元，或可设置于第三接入与移动性管理功能网元的芯片或电路时，
收发单元1130，用于接收来自第一接入网设备的第三消息，所述第三消息包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在所述第一接入网设备与核心网设备之间传输第一组播业务的数据，所述第三接入与移动性管理功能网元为在所述第一终端设备加入所述第一组播业务时，由所述第一接入网设备为所述第一组播业务选择的接入与移动性管理功能网元；
收发单元1130还用于向组播会话管理功能网元发送第四消息，所述第四消息中包括所述第一信息。
可选的，所述第三消息为N2消息。
可选的，所述第四消息为N11消息。
其中，以上列举的装置1100中各模块或单元的功能和动作仅为示例性说明，当该装置1100配置在或本身即为第三接入与移动性管理功能网元时，装置1100中各模块或单元可以用于执行上述方法中第三接入与移动性管理功能网元所执行的各动作或处理过程。
在一些实施例中，当装置1100为组播会话管理功能网元，或可设置于组播会话管理功能网元的芯片或电路时，
收发单元1130，用于接收来自第三接入与移动性管理功能网元的第四消息，所述第四消息中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据，所述第三接入与移动性管理功能网元为在所述第一终端设备加入所述第一组播业务时，所述第一接入网设备为所述第一组播业务选择的接入与移动性管理功能网元；
收发单元1130还用于向组播用户面功能网元发送第五消息，所述第五消息包括所述第一信息。
可选的，所述第五消息为N4会话更新请求。
可选的，所述第四消息为N11消息。
其中，以上列举的装置1100中各模块或单元的功能和动作仅为示例性说明，当该装置1100配置在或本身即为组播会话管理功能网元时，装置1100中各模块或单元可以用于执行上述方法中组播会话管理功能网元所执行的各动作或处理过程。
在一些实施例中，当装置1100为组播用户面功能网元，或可设置于组播用户面功能网元的芯片或电路时，
收发单元1130，用于接收来自组播会话管理功能网元的第五消息，所述第五消息中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
收发单元1130还用于根据所述第一信息，释放所述第一隧道。
可选的，所述收发单元1130具体用于从组播会话管理功能网元接收第五消息，所述第五消息中包括所述第一信息。
可选的，所述第五消息为N4会话更新请求。
其中，以上列举的装置1100中各模块或单元的功能和动作仅为示例性说明，当该装置 1100配置在或本身即为组播用户面功能网元时，装置1100中各模块或单元可以用于执行上述方法中组播用户面功能网元所执行的各动作或处理过程。
在一些实施例中，当装置1100为用户面功能网元，或可设置于用户面功能网元的芯片或电路时，
收发单元1130，用于接收来自会话管理网元的会话更新请求，所述会话更新请求中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
收发单元1130还用于所述用户面功能网元根据所述第一信息，释放所述第一隧道。
上述实施例中的各个单元也可以称为模块或者电路或者部件。
该装置1100所涉及的与本申请实施例提供的技术方案相关的概念，解释和详细说明及其他步骤请参见前述方法或其他实施例中关于这些内容的描述，此处不做赘述。
图12为本申请实施例提供的一种网络设备1200的结构示意图，可以用于实现上述方法中的接入网设备(例如，第一接入网设备，或者第二接入网设备)的功能。网络设备1200包括一个或多个射频单元，如远端射频单元(remote radio unit,RRU)1210和一个或多个基带单元(baseband unit，BBU)(也可称为数字单元，digital unit，DU)1220。所述RRU1210可以称为收发单元、收发机、收发电路、或者收发器等等，其可以包括至少一个天线1211和射频单元1212。所述RRU1210部分主要用于射频信号的收发以及射频信号与基带信号的转换，例如用于向终端设备发送上述实施例中所述的信令消息。所述BBU1220部分主要用于进行基带处理，对基站进行控制等。所述RRU1210与BBU1220可以是物理上设置在一起，也可以物理上分离设置的，即分布式基站。
所述BBU1220为基站的控制中心，也可以称为处理单元，主要用于完成基带处理功能，如信道编码，复用，调制，扩频等等。例如该BBU(处理单元)1220可以用于控制接入网设备执行上述方法实施例中关于接入网设备的操作流程。
在一个示例中，所述BBU1220可以由一个或多个单板构成，多个单板可以共同支持单一接入制式的无线接入网(如LTE系统，或5G系统)，也可以分别支持不同接入制式的无线接入网。所述BBU1220还包括存储器1221和处理器1222。所述存储器1221用以存储必要的指令和数据。所述处理器1222用于控制接入网设备进行必要的动作，例如用于控制接入网设备执行上述方法实施例中关于接入网设备的操作流程。所述存储器1221和处理器1222可以服务于一个或多个单板。也就是说，可以每个单板上单独设置存储器和处理器。也可以是多个单板共用相同的存储器和处理器。此外每个单板上还可以设置有必要的电路。
在一种可能的实施方式中，随着片上系统(system-on-chip，SoC)技术的发展，可以将1220部分和1210部分的全部或者部分功能由SoC技术实现，例如由一颗基站功能芯片实现，该基站功能芯片集成了处理器、存储器、天线接口等器件，基站相关功能的程序存储在存储器中，由处理器执行程序以实现基站的相关功能。可选的，该基站功能芯片也能够读取该芯片外部的存储器以实现基站的相关功能。
应理解，图12示例的网络设备的结构仅为一种可能的形态，而不应对本申请实施例构成任何限定。本申请并不排除未来可能出现的其他形态的基站结构的可能。
应理解，本申请实施例中的处理器可以为中央处理单元(central processing unit，CPU)， 该处理器还可以是其他通用处理器、数字信号处理器(digital signal processor，DSP)、专用集成电路(application specific integrated circuit，ASIC)、现成可编程门阵列(field programmable gate array，FPGA)或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件等。通用处理器可以是微处理器或者该处理器也可以是任何常规的处理器等。
还应理解，本申请实施例中的存储器可以是易失性存储器或非易失性存储器，或可包括易失性和非易失性存储器两者。其中，非易失性存储器可以是只读存储器(read-only memory，ROM)、可编程只读存储器(programmable ROM，PROM)、可擦除可编程只读存储器(erasable PROM，EPROM)、电可擦除可编程只读存储器(electrically EPROM，EEPROM)或闪存。易失性存储器可以是随机存取存储器(random access memory，RAM)，其用作外部高速缓存。通过示例性但不是限制性说明，许多形式的随机存取存储器(random access memory，RAM)可用，例如静态随机存取存储器(static RAM，SRAM)、动态随机存取存储器(DRAM)、同步动态随机存取存储器(synchronous DRAM，SDRAM)、双倍数据速率同步动态随机存取存储器(double data rate SDRAM，DDR SDRAM)、增强型同步动态随机存取存储器(enhanced SDRAM，ESDRAM)、同步连接动态随机存取存储器(synchlink DRAM，SLDRAM)和直接内存总线随机存取存储器(direct rambus RAM，DR RAM)。
上述实施例，可以全部或部分地通过软件、硬件、固件或其他任意组合来实现。当使用软件实现时，上述实施例可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括一个或多个计算机指令或计算机程序。在计算机上加载或执行所述计算机指令或计算机程序时，全部或部分地产生按照本申请实施例所述的流程或功能。所述计算机可以为通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含一个或多个可用介质集合的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质(例如，软盘、硬盘、磁带)、光介质(例如，DVD)、或者半导体介质。半导体介质可以是固态硬盘。
本申请实施例还提供了一种计算机可读介质，其上存储有计算机程序，该计算机程序被计算机执行时实现上述任一实施例中的接入网设备或接入与移动性管理功能网元或会话管理功能网元或组播会话管理功能网元或组播用户面功能网元执行的步骤。
本申请实施例还提供了一种计算机程序产品，该计算机程序产品被计算机执行时实现上述任一实施例中的接入网设备或接入与移动性管理功能网元或会话管理功能网元或组播会话管理功能网元或组播用户面功能网元执行的步骤。
本申请实施例还提供了一种系统芯片，该系统芯片包括：通信单元和处理单元。该处理单元，例如可以是处理器。该通信单元例如可以是输入/输出接口、管脚或电路等。该处理单元可执行计算机指令，以使该通信装置内的芯片执行上述本申请实施例提供的接入网设备或接入与移动性管理功能网元或会话管理功能网元或组播会话管理功能网元或组播用户面功能网元执行的步骤。
可选地，该计算机指令被存储在存储单元中。
本申请中的各个实施例可以独立的使用，也可以进行联合的使用，这里不做限定。
另外，本申请的各个方面或特征可以实现成方法、装置或使用标准编程和/或工程技术的制品。本申请中使用的术语“制品”涵盖可从任何计算机可读器件、载体或介质访问的计算机程序。例如，计算机可读介质可以包括，但不限于:磁存储器件(例如，硬盘、软盘或磁带等)，光盘(例如，压缩盘(compact disc，CD)、数字通用盘(digital versatile disc，DVD)等)，智能卡和闪存器件(例如，可擦写可编程只读存储器(erasable programmable read-only memory，EPROM)、卡、棒或钥匙驱动器等)。另外，本文描述的各种存储介质可代表用于存储信息的一个或多个设备和/或其它机器可读介质。术语“机器可读介质”可包括但不限于，无线信道和能够存储、包含和/或承载指令和/或数据的各种其它介质。
应理解，在本申请的各种实施例中，上述各过程的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定，而不应对本申请实施例的实施过程构成任何限定。
还应理解，在上文示出的实施例中，第一、第二仅为便于区分不同的对象，而不应对本申请构成任何限定。例如，区分不同的接入网设备，不同的接入与移动性管理功能网元等。
还应理解，“和/或”，描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。字符“/”一般表示前后关联对象是一种“或”的关系。“至少一个”是指一个或一个以上；“A和B中的至少一个”，类似于“A和/或B”，描述关联对象的关联关系，表示可以存在三种关系，例如，A和B中的至少一个，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的系统、装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
在本申请所提供的几个实施例中，应该理解到，所揭露的系统、装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。
所述功能如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本申请的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的部分可以以软件产品的形式体现出来，该计算机软件产品存储在一个存储介质中，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)执行本申请各个实施例所述方法的全部或部分步骤。而前述的存储介质包括：U盘、移动硬盘、只读存储器(Read-Only Memory，ROM)、随机存取存储器(Random Access Memory，RAM)、磁碟或者光盘等各种可以存储程序代码的介质。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (26)

  1. 一种通信方法，其特征在于，所述方法包括：
    第一接入网设备在第一终端设备从所述第一接入网设备向第二接入网设备切换的切换准备阶段，获知所述第一终端设备为通过所述第一接入网设备接收第一组播业务的数据的最后一个终端设备；
    所述第一接入网设备发送第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在所述第一接入网设备与核心网设备之间传输所述第一组播业务的数据。
  2. 根据权利要求1所述的方法，其特征在于，所述第一接入网设备发送第一信息，包括：
    所述第一接入网设备向所述第二接入网设备发送切换请求，所述切换请求用于请求将所述第一终端设备从所述第一接入网设备切换至所述第二接入网设备，所述切换请求中包括所述第一信息。
  3. 根据权利要求1所述的方法，其特征在于，所述第一接入网设备发送第一信息，包括：
    所述第一接入网设备向第一接入与移动性管理功能网元发送切换需要，所述切换需要中包括所述第一信息。
  4. 根据权利要求1所述的方法，其特征在于，所述第一接入网设备发送第一信息，包括：
    所述第一接入网设备向第三接入与移动性管理功能网元发送第三消息，所述第三消息包括所述第一信息。
  5. 根据权利要求1-4任一项所述的方法，其特征在于，还包括：
    所述第一接入网设备更新通过所述第一接入网设备加入所述第一组播业务的终端设备的数量。
  6. 根据权利要求1-5任一所述的方法，其特征在于，所述第一信息包括用于释放所述第一隧道的指示和所述第一隧道的信息；或者
    所述第一信息包括用于释放所述第一隧道的指示和所述第一组播业务的标识信息；或者
    所述第一信息包括用于释放所述第一隧道的指示、所述第一组播业务的标识信息和所述第一隧道的信息。
  7. 根据权利要求1-6任一项所述的方法，其特征在于，所述核心网设备包括组播用户面功能网元或用户面功能网元。
  8. 一种通信方法，其特征在于，所述方法包括：
    第二接入网设备接收来自第一接入网设备的切换请求，所述切换请求用于请求将第一终端设备从所述第一接入网设备切换至所述第二接入网设备，所述切换请求中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在所述第一接入网设备与核心网设备之间传输第一组播业务的数据；
    所述第二接入网设备向接入与移动性管理功能网元发送路径切换请求，所述路径切换请求中包含所述第一信息。
  9. 一种通信方法，其特征在于，所述方法包括：
    接入与移动性管理功能网元接收来自第二接入网设备的路径切换请求，所述路径切换请求中包含第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
    所述接入与移动性管理功能网元向会话管理功能网元发送协议数据单元PDU会话上下文更新请求，所述PDU会话上下文更新请求包括所述第一信息。
  10. 一种通信方法，其特征在于，所述方法包括：
    会话管理功能网元接收来自接入与移动性管理功能网元的协议数据单元PDU会话上下文更新请求，所述PDU会话上下文更新请求包含第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
    所述会话管理功能网元向组播会话管理功能网元发送第一消息，所述第一消息中包括所述第一信息。
  11. 一种通信方法，其特征在于，所述方法包括：
    会话管理功能网元接收来自接入与移动性管理功能网元的协议数据单元PDU会话上下文更新请求，所述PDU会话上下文更新请求包含第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
    所述会话管理功能网元向用户面功能网元发送会话更新请求，所述会话更新请求中包括所述第一信息。
  12. 一种通信方法，其特征在于，所述方法包括：
    组播会话管理功能网元接收来自会话管理功能网元的第一消息，所述第一消息中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
    所述组播会话管理功能网元向组播用户面功能网元发送第五消息，所述第五消息中包括所述第一信息。
  13. 一种通信方法，其特征在于，所述方法包括：
    第一接入与移动性管理功能网元接收来自第一接入网设备的切换需要，所述切换需要中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在所述第一接入网设备与核心网设备之间传输所述第一组播业务的数据；
    所述第一接入与移动性管理功能网元向第二接入与移动性管理功能网元发送创建用户设备UE上下文请求，所述创建UE上下文请求中包含所述第一信息。
  14. 一种通信方法，其特征在于，所述方法包括：
    第二接入与移动性管理功能网元接收来自第一接入与移动性管理功能网元的创建用户设备UE上下文请求，所述创建UE上下文请求中包含第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
    所述第二接入与移动性管理功能网元向会话管理功能网元发送协议数据单元PDU会话上下文更新请求，所述PDU会话上下文更新请求包括所述第一信息。
  15. 一种通信方法，其特征在于，所述方法包括：
    第三接入与移动性管理功能网元接收来自第一接入网设备的第三消息，所述第三消息包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在所述第一接入网设 备与核心网设备之间传输第一组播业务的数据；
    所述第三接入与移动性管理功能网元向组播会话管理功能网元发送第四消息，所述第四消息中包括所述第一信息。
  16. 一种通信方法，其特征在于，所述方法包括：
    组播会话管理功能网元接收来自第三接入与移动性管理功能网元的第四消息，所述第四消息中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
    所述组播会话管理功能网元向组播用户面功能网元发送第五消息，所述第五消息包括所述第一信息。
  17. 一种通信方法，其特征在于，所述方法包括：
    组播用户面功能网元接收来自组播会话管理功能网元的第五消息，所述第五消息中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
    所述组播用户面功能网元根据所述第一信息，释放所述第一隧道。
  18. 一种通信方法，其特征在于，所述方法包括：
    用户面功能网元接收来自会话管理网元的会话更新请求，所述会话更新请求中包括第一信息，所述第一信息用于释放第一隧道，所述第一隧道用于在第一接入网设备与核心网设备之间传输第一组播业务的数据；
    所述用户面功能网元根据所述第一信息，释放所述第一隧道。
  19. 根据权利要求17或18所述的方法，其特征在于，所述第一信息包括用于释放所述第一隧道的指示和所述第一隧道的信息，
    其中，所述释放所述第一隧道包括：
    根据所述用于释放所述第一隧道的指示和所述第一隧道的信息，释放所述第一隧道。
  20. 根据权利要求17或18所述的方法，其特征在于，所述第一信息包括用于释放所述第一隧道的指示和所述第一组播业务的标识信息；
    其中，所述释放所述第一隧道包括：
    根据所述第一组播业务的标识信息，确定所述第一组播业务；
    确定在所述第一接入网设备与所述核心网设备之间传输所述第一组播业务的数据的第一隧道；
    根据所述用于释放所述第一隧道的指示，释放所述第一隧道。
  21. 根据权利要求17或18所述的方法，其特征在于，所述第一信息包括用于释放所述第一隧道的指示、所述第一组播业务的标识信息和所述第一隧道的信息；
    其中，所述释放所述第一隧道包括：
    根据所述第一组播业务的标识信息，确定所述第一组播业务；
    根据所述第一隧道的信息，在所述第一接入网设备与所述核心网设备之间传输所述第一组播业务的数据的隧道中确定所述第一隧道；
    根据所述用于释放所述第一隧道的指示，释放所述第一隧道。
  22. 一种无线通信的装置，其特征在于，包括用于执行权利要求1-21任一项所述的方法的单元。
  23. 一种通信装置，其特征在于，包括：处理器，所述处理器用于从存储器中调用并运行计算机程序，以执行如权利要求1-21任一项所述的方法。
  24. 根据权利要求23所述的通信装置，其特征在于，还包括：所述存储器。
  25. 一种通信芯片，其特征在于，所述芯片包括：
    处理器和通信接口，所述处理器用于从所述通信接口调用并运行指令，当所述处理器执行所述指令时，实现如权利要求1-21中任一项所述的方法。
  26. 一种通信系统，其特征在于，包括：
    用于执行如权利要求1-7任一项所述的方法的装置、用于执行如权利要求8、9和10所述的方法的装置、用于执行如权利要求17或19或20或21任一项所述的方法的装置；或者
    用于执行如权利要求1-7任一项所述的方法的装置、用于执行如权利要求8、9、11和12所述的方法的装置、用于执行如权利要求18-21任一项所述的方法的装置；或者
    用于执行如权利要求1-7任一项所述的方法的装置、用于执行如权利要求13、14和10所述的方法的装置、用于执行如权利要求17或19或20或21任一项所述的方法的装置；或者
    用于执行如权利要求1-7任一项所述的方法的装置、用于执行如权利要求13、14、11和12所述的方法的装置、用于执行如权利要求18-21任一项所述的方法的装置；或者
    用于执行如权利要求1-7任一项所述的方法的装置、用于执行如权利要求15和16所述的方法的装置、用于执行如权利要求17或19或20或21任一项所述的方法的装置。
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