WO2021164564A1 - 传输组播业务的方法和装置 - Google Patents

传输组播业务的方法和装置 Download PDF

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Publication number
WO2021164564A1
WO2021164564A1 PCT/CN2021/075259 CN2021075259W WO2021164564A1 WO 2021164564 A1 WO2021164564 A1 WO 2021164564A1 CN 2021075259 W CN2021075259 W CN 2021075259W WO 2021164564 A1 WO2021164564 A1 WO 2021164564A1
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WIPO (PCT)
Prior art keywords
multicast
network element
terminal device
access network
capability information
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PCT/CN2021/075259
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English (en)
French (fr)
Inventor
贾建鑫
吴问付
宗在峰
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华为技术有限公司
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Publication date
Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to EP21757924.2A priority Critical patent/EP4090039A4/en
Priority to CN202310251075.6A priority patent/CN116233564A/zh
Priority to CN202180000190.5A priority patent/CN113545098B/zh
Publication of WO2021164564A1 publication Critical patent/WO2021164564A1/zh
Priority to US17/892,119 priority patent/US20220408162A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/60—Network structure or processes for video distribution between server and client or between remote clients; Control signalling between clients, server and network components; Transmission of management data between server and client, e.g. sending from server to client commands for recording incoming content stream; Communication details between server and client 
    • H04N21/61—Network physical structure; Signal processing
    • H04N21/6106—Network physical structure; Signal processing specially adapted to the downstream path of the transmission network
    • H04N21/6131—Network physical structure; Signal processing specially adapted to the downstream path of the transmission network involving transmission via a mobile phone network
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/60—Network structure or processes for video distribution between server and client or between remote clients; Control signalling between clients, server and network components; Transmission of management data between server and client, e.g. sending from server to client commands for recording incoming content stream; Communication details between server and client 
    • H04N21/63—Control signaling related to video distribution between client, server and network components; Network processes for video distribution between server and clients or between remote clients, e.g. transmitting basic layer and enhancement layers over different transmission paths, setting up a peer-to-peer communication via Internet between remote STB's; Communication protocols; Addressing
    • H04N21/64—Addressing
    • H04N21/6405—Multicasting
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/20—Servers specifically adapted for the distribution of content, e.g. VOD servers; Operations thereof
    • H04N21/25—Management operations performed by the server for facilitating the content distribution or administrating data related to end-users or client devices, e.g. end-user or client device authentication, learning user preferences for recommending movies
    • H04N21/266—Channel or content management, e.g. generation and management of keys and entitlement messages in a conditional access system, merging a VOD unicast channel into a multicast channel
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N21/00—Selective content distribution, e.g. interactive television or video on demand [VOD]
    • H04N21/60—Network structure or processes for video distribution between server and client or between remote clients; Control signalling between clients, server and network components; Transmission of management data between server and client, e.g. sending from server to client commands for recording incoming content stream; Communication details between server and client 
    • H04N21/63—Control signaling related to video distribution between client, server and network components; Network processes for video distribution between server and clients or between remote clients, e.g. transmitting basic layer and enhancement layers over different transmission paths, setting up a peer-to-peer communication via Internet between remote STB's; Communication protocols; Addressing
    • H04N21/64—Addressing
    • H04N21/6408—Unicasting
    • 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
    • H04W76/00—Connection management
    • H04W76/10—Connection setup
    • H04W76/11—Allocation or use of connection identifiers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/10—Connection setup
    • H04W76/12—Setup of transport tunnels
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W76/00—Connection management
    • H04W76/40—Connection management for selective distribution or broadcast

Definitions

  • This application relates to the field of communications, and more specifically, to a method and device for transmitting multicast services in the field of communications.
  • the present application provides a method and device for transmitting multicast services, which can realize the transmission of multicast services regardless of whether there is a device supporting multicast in the system, thereby improving the flexibility and reliability of multicast service transmission.
  • a method for transmitting a multicast service including: a session management network element receives a first message or a second message, the first message is used to request a terminal device to join the multicast service, and the second The message is used to update the protocol data unit PDU session of the terminal device, and the PDU session is associated with a multicast service; the session management network element is based on the multicast capability information of the terminal device and/or the multicast of the access network device The capability information is used to determine the sending mode of the multicast service, the multicast capability information of the terminal device is used to indicate whether the terminal device supports multicast, and the multicast capability information of the access network device is used to indicate the Whether the access network device supports multicast, the access network device is the access network device currently accessed by the terminal device or the target access network device of the terminal device.
  • the support of multicast by the access network device means that the air interface of the access network device supports point-to-multipoint transmission.
  • the terminal device supporting multicast means that the terminal device supports receiving multicast services through an air interface multicast mode.
  • the session management network element may determine according to the multicast capability information of the terminal device and/or the multicast capability information of the access network device when the terminal device requests to join the multicast service or request to update the PDU session The way of sending multicast services, so as to more effectively deliver multicast services to terminal devices, and improve the flexibility and reliability of multicast service transmission.
  • the access and mobility management network element may send the above-mentioned first message to the session management network element to request the terminal device to join the multicast service.
  • the access and mobility management network element may send the above-mentioned second message to the session management network element for performing the PDU session renew. It should be understood that switching the terminal device from the source access network device to the target access network device essentially refers to switching the PDU session of the terminal device from the source access network device to the target access network device.
  • switching the PDU session of the terminal device means that when the terminal device moves from the source access network device to the target access network device, in order to maintain business continuity, the PDU session of the terminal device can be accessed from the source The network device switches to the target access network device.
  • the method when the sending mode is a unicast mode, the method further includes: the session management network element according to the multicast service quality of the multicast service QoS information, determining the unicast QoS flow corresponding to the service data flow (SDF) of the multicast service; the session management network element adds the unicast to the protocol data unit PDU session of the terminal device QoS flow, the unicast QoS flow is used to transmit the data of the multicast service.
  • SDF service data flow
  • the quality of service QOS information of the multicast service may include the QoS flow identification (QoS flow identification, QFI) of the multicast QoS flow of the multicast service, and the service data flow (Service data flow, SDF) corresponding to the multicast QoS flow.
  • QFI QoS flow identification
  • SDF Service data flow
  • the QoS parameters corresponding to the QFI of the multicast QoS flow for example, 5G QoS identifier (5G QoS identifier, 5QI) (representing a set of QoS parameters, including bandwidth, delay jitter, etc.), allocation retention priority (Allocation retention priority) , ARP), guaranteed bit rate (Guaranteed bit rate, GBR), maximum bit rate (Maximum bit rate, MBR), QoS notification control (QoS notification control, QNC), etc.
  • 5G QoS identifier 5G QoS identifier, 5QI
  • 5G QoS identifier, 5QI (representing a set of QoS parameters, including bandwidth, delay jitter, etc.), allocation retention priority (Allocation retention priority) , ARP), guaranteed bit rate (Guaranteed bit rate, GBR), maximum bit rate (Maximum bit rate, MBR), QoS notification control (QoS notification control, QNC), etc.
  • the session management network element can map the multicast QoS flow of the multicast service to the unicast QoS flow, thereby adding the unicast QoS flow to the PDU session, so that the terminal device can be downloaded in unicast mode later.
  • Send the multicast service Regarding the mapping of the multicast QoS flow of the multicast service to the unicast QoS flow, it is to establish the correspondence between the multicast QoS flow and the unicast QoS flow, so as to use the unicast QoS flow to deliver the multicast service.
  • the QFI of the unicast QoS flow determined by the session management network element cannot be the same as the QFI of the existing unicast QoS flow.
  • the process of determining the QFI of a unicast QoS flow according to the QFI of a multicast QoS flow can be called mapping.
  • the correspondence between the QFI of the multicast QoS flow and the QFI of the unicast QoS flow is called the first mapping. relation.
  • the method when the transmission mode is unicast, the method further includes: the session management network element: Select at least one unicast QoS flow from the unicast QoS flow of the PDU session of the terminal device, and the at least one unicast QoS flow is used to transmit the data of the multicast service; The element sends the correspondence between the packet detection rule of the multicast service and the identifier of the at least one unicast QoS flow.
  • the corresponding relationship is carried in an eighth message, and the eighth message is an N4 session modification request or a message forwarding control protocol PFCP session modification request.
  • the correspondence relationship may be that the eighth message also includes the packet detection rule (PDR, Packet Detection Rule) of the multicast service, and the at least one packet corresponding to the packet detection rule of the multicast service
  • PDR Packet Detection Rule
  • the identifier of the multicast QoS flow may be used to characterize the correspondence between the packet detection rule of the multicast service and the identifier of the at least one unicast QoS flow.
  • the session management network element adding the unicast QoS flow to the PDU session of the terminal device includes: The network element sends the information of the multicast service and the QFI of the unicast QoS flow; the session management network element determines the QoS parameters of the unicast QoS flow according to the QoS parameters of the multicast QoS flow; The session management network element sends the QFI of the unicast QoS flow and the QoS parameters of the unicast QoS flow to the access network device.
  • the multicast service information may include the destination address of the multicast service, and optionally, may also include at least one of a source address or a port number.
  • the multicast service is sent to the current user-plane network element through another user-plane network element, and the session management network element also includes the tunnel identifier of the other user-plane network element (for the convenience of the current user-plane network element).
  • the user plane network element connected to it) is sent to the current user plane network element.
  • the multicast service information may include the tunnel identifier of another user plane network element.
  • the method when the sending mode is a multicast mode, the method further includes: the session management network element sending the group to the access network device The service identifier of the broadcast service.
  • the multicast service transmission mode is the multicast mode.
  • the session management network element may request the access network device to add the terminal device to the multicast service, so as to subsequently deliver the multicast service to the terminal device in a multicast manner.
  • the method further includes: the session management network element sending information of the multicast QoS flow of the multicast service to the access network device.
  • the method before the session management network element sends the service identifier of the multicast service to the access network device, the method further includes: the session The management network element determines that the multicast service exists on the access network device.
  • the session management network element may first determine whether the access network equipment has the multicast service. If the access network device has the multicast service, the session management network element requests the access network device to join the terminal device to the multicast service; if the access network device does not have the multicast service, the session The management network element may first request the access network device to create the multicast service, and after the creation of the multicast service is completed, the session management network element then requests the access network device to join the terminal device to the multicast service.
  • the session management network element may not make any judgments, and when requesting the access network device to join the terminal device to the multicast service, it sends the multicast service information to the access network device. Information about the multicast QoS flow. In this way, even if the multicast service does not exist on the access network device, the access network device can create the multicast service for the terminal device based on the information of the multicast QoS flow, and then join the terminal device to the group Broadcast business.
  • the session management network element may determine whether the access network device has the multicast service in a variety of ways, which is not limited in the embodiment of the present application.
  • the session management network element determining that the access network device has the multicast service includes: the session management network element receives data from a unified data management network Element’s fourth message, the fourth message is used to indicate that the access network device has the multicast service; the session management network element determines that the access network device has the Multicast business.
  • the session management network element may determine whether the access network device has the multicast service through the unified data management network element.
  • the unified data management network element may autonomously (for example, periodically) send the foregoing fourth message to the session management network element to inform the session management network element of the information about the multicast service existing on the access network device.
  • the session management network element may query the unified data management network element, that is, send a query message to the unified data management network element to query whether the multicast service requested by the current terminal device is in the access network that the terminal device accesses.
  • the session management network element receives the query result (that is, the foregoing fourth message) fed back by the unified data management network element, and according to the query result, it can be determined whether the access network device has the multicast service.
  • the session management network element sends a query message to the unified data management network element
  • the unified data management network element may not feed back the query result, and the session management network element defaults to the connection if the query result is not received within a period of time.
  • the network access device does not have the multicast service (or the access network device has the multicast service by default), but the embodiment of the present application does not limit this.
  • the method before the session management network element sends the service identifier of the multicast service to the access network device, the method further includes: the session The management network element determines that the access network device does not have the multicast service; the session management network element sends information about the multicast QoS flow of the multicast service to the access network device; the session management network The element receives the indication information from the access network device that is used to indicate that the multicast service corresponding to the multicast QoS flow is successfully created.
  • the session management network element may send information about the multicast QoS flow of the multicast service to the access network device, and the multicast QoS flow
  • the information may include the QFI of the multicast QoS flow and the QoS parameters of the multicast QoS flow.
  • the access network device can create a corresponding multicast service according to the information of the multicast QoS flow, so as to prepare for subsequent addition of terminal devices to the multicast service.
  • the method further includes: the session management network element sends a fifth message to the unified data management network element according to the instruction information, the fifth message It is used to indicate that the multicast service already exists in the access network device.
  • the session management network element may notify the unified data management network element of the multicast service already exists.
  • the foregoing fifth message may carry the identifier of the multicast service and the identifier of the access network device.
  • the method further includes: the session management network element determining the unicast QoS flow corresponding to the multicast QoS flow;
  • the access network device sends the first mapping relationship, where the first mapping relationship is used to indicate the correspondence between the QFI of the multicast QoS flow and the QFI of the unicast QoS flow.
  • the session management network element can also generate the mapping relationship between the QFI of the multicast QoS flow and the QFI of the unicast QoS flow, but there is no need to modify the PDU session (that is, there is no need to modify the PDU session).
  • the unicast QoS flow is added to the session).
  • the access network device that the terminal device accesses supports multicast that is, the multicast service is delivered through the multicast session tunnel, and the unicast service is delivered through the PDU session tunnel where the PDU session is located.
  • the terminal device has mobility, and the subsequent terminal device may move to another access network device, and the other access network device may not support multicast.
  • the session management network element can be stored in advance
  • the mapping relationship between the QFI of the above multicast QoS flow and the QFI of the unicast QoS flow, so that the session management network element notifies the user plane network when it knows that another access network device to which the terminal device will switch does not support multicast
  • the meta maps the multicast service to the PDU session tunnel where the PDU session is located and delivers it to the terminal device, thereby ensuring the continuity of the multicast service.
  • the method further includes: the session management network element receiving multicast capability information of the terminal device from the access and mobility management network element and/ Or the multicast capability information of the access network device.
  • the session management network element receives the multicast capability information of the terminal device from the access and mobility management network element and/or the access Before the multicast capability information of the network device, the method further includes: the session management network element sends a request message to the access and mobility management network element, and the request message is used to request multicast of the terminal device Capability information and/or multicast capability information of the access network device.
  • the method before the session management network element sends a request message to the access and mobility management network element, the method further includes: the session management network The element determines that the PDU session of the terminal device supports multicast.
  • the multicast capability information of the access network device may be sent by the session management network element requesting the access and mobility management network element. Further, optionally, the session management network element may request the access and mobility management network element to send the multicast capability information of the terminal device and/or the multicast capability of the access network device when the PDU session supports multicast information. Whether the PDU session supports multicast can be based on DNN (for example, multicast services can be accessed through the DNN), S-NSSAI (for example, EMBB slices may support access to multicast services), multicast service indication information (for example, PDU session At least one of the supported multicast service identifiers).
  • DNN for example, multicast services can be accessed through the DNN
  • S-NSSAI for example, EMBB slices may support access to multicast services
  • multicast service indication information for example, PDU session At least one of the supported multicast service identifiers.
  • the method further includes: the session management network element sends a subscription message to the access and mobility management network element, and the subscription message is used for all
  • the mobility management network element sends the multicast capability information of the terminal device and/or the access network element to the session management network element when the multicast capability of the terminal device and/or the access network device changes. Multicast capability information of network equipment.
  • the multicast capability information of the aforementioned terminal device and/or the multicast capability information of the aforementioned access network device may be acquired by the session management network element through subscription. That is, the session management network element sends a subscription message to the access and mobility management network element, and the subscription message is used by the mobility management network element to send the session management network element to the session management network element when the capability of the terminal device changes and/or the capability of the access network device changes. Send the multicast capability information of the terminal device and/or the multicast capability information of the access network device.
  • the access and mobility management network element receives the subscription message from the session management network element, and sends the multicast capability of the terminal device to the session management network element when the capabilities of the terminal device and/or the access network device change Information and/or multicast capability information of the access network equipment.
  • the access and mobility management network element may send the multicast capability information of the terminal device to the session management network element; when the capability of the access network device changes, the access and mobility management network element
  • the capability management network element can send the multicast capability information of the access network device to the session management network element; when the capabilities of the terminal device and the access network device are both changed, the access and mobility management network element can report to the session management network element.
  • the network element sends the multicast capability information of the terminal device and the multicast capability information of the access network device.
  • the session management network element receiving the first message includes: the session management network element receiving the first message from the access and mobility management network element Message; or, the session management network element receives the first message from the user plane network element.
  • another method for transmitting multicast services including: the access and mobility management network element obtains the multicast capability information of the terminal device and/or the multicast capability information of the access network device, and the terminal
  • the multicast capability information of the device is used to indicate whether the terminal device supports multicast
  • the multicast capability information of the access network device is used to indicate whether the access network device supports multicast
  • the access network device is The access network device currently accessed by the terminal device or the target access network device of the terminal device
  • the access and mobility management network element sends the multicast capability information of the terminal device to the session management network element and /Or the multicast capability information of the access network device.
  • the access and mobility management network element sends the multicast capability information of the terminal device and/or the access network element to the session management network element Before the multicast capability information of the device, the method further includes: the access and mobility management network element determines that the PDU session of the terminal device supports multicast.
  • the access and mobility management network element determining that the PDU session of the terminal device supports multicast includes: the access and mobility management network element receives from The reference information of the PDU session of the terminal device, where the reference information includes indication information for indicating whether the PDU session supports multicast, the data network name DNN of the PDU session, and the single network of the PDU session One or more of the slice selection auxiliary information S-NSSAI; the access and mobility management network element determines that the PDU session supports multicast according to the reference information.
  • the method further includes: the access and mobility management network element receiving a request message from the session management network element, the request message being used for Request the multicast capability information of the terminal device and/or the multicast capability information of the access network device.
  • the method further includes: the access and mobility management network element receives a subscription message from the session management network element, and the subscription request message is used When the mobility management network element sends the multicast capability information of the terminal device and/or the multicast capability information of the terminal device to the session management network element when the multicast capability of the terminal device and/or the access network device changes The multicast capability information of the access network device.
  • the multicast capability information of the access network device is carried in the next generation NG establishment request message.
  • the multicast capability information of the terminal device is carried in a PDU session establishment/modification request message.
  • another method for transmitting multicast services including: an access network device obtains multicast capability information of the access network device; and the access network device sends the group of the access network device Broadcast capability information, where the multicast capability information is used to indicate whether the access network device supports multicast.
  • the access network device sending the multicast capability information of the access network device includes: the access network device sends the access and mobility management information to the access network device.
  • the network element or the adjacent access network device of the access network device sends the multicast capability information.
  • the method further includes: the access network device receiving a handover request message from another access network device, the handover request message including the terminal device The identifier of the PDU session, the PDU session supports multicast; the access network device sends indication information to the core network device, and the indication information is used to indicate whether the access network device has the multicast service.
  • a device for transmitting a multicast service which is used to implement the foregoing aspects or the methods in any possible implementation manners of the aspects.
  • the device includes a unit for executing the foregoing aspects or methods in any possible implementation manners of the aspects.
  • the device may include modules that perform one-to-one correspondence of the methods/operations/steps/actions described in the above aspects.
  • the modules may be hardware circuits, software, or hardware circuits combined with software. accomplish.
  • the device is a communication chip
  • the communication chip may include an input circuit or interface for sending information or data, and an output circuit or interface for receiving information or data.
  • the device is a communication device, and the communication device may include a transmitter for sending information or data, and a receiver for receiving information or data.
  • the device is used to execute the above aspects or the methods in any possible implementation of each aspect.
  • the device can be configured in the above session management network element, or the device itself is the session management network element .
  • another device for transmitting multicast services includes a processor coupled with a memory, the memory is used to store a computer program, and the processor is used to call and run the computer from the memory.
  • the program enables the device to execute the method for transmitting the multicast service in the foregoing aspects or any possible implementation manners of the aspects.
  • processors there are one or more processors, and one or more memories.
  • the memory may be integrated with the processor, or the memory and the processor may be provided separately.
  • the device further includes a transmitter (transmitter) and a receiver (receiver).
  • the transmitter and the receiver can be set separately or integrated together, which is called a transceiver.
  • a system in a sixth aspect, includes a device for implementing the first aspect or any one of the possible methods of the first aspect, and a device for implementing any of the second or second aspects.
  • a computer program product includes: computer program code, which when the computer program code is run by a computer, causes the computer to execute the above-mentioned aspects or any of the above-mentioned aspects. The method in the implementation mode.
  • a computer-readable medium for storing instructions that, when the instructions run on a computer, cause the computer to execute the foregoing aspects or the methods in any possible implementation manners of the aspects Instructions.
  • an embodiment of the present application provides a chip system, which includes one or more processors, configured to call and execute instructions stored in the memory from the memory, so that the above aspects or any of the above aspects The methods in one possible implementation are executed.
  • the chip system can be composed of chips, or it can include chips and other discrete devices.
  • the chip system may include an input circuit or interface for sending information or data, and an output circuit or interface for receiving information or data.
  • 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 provided by an embodiment of the present application.
  • Fig. 3 is a schematic diagram of service data transmission provided by an embodiment of the present application.
  • Fig. 4 is a schematic diagram of another service data transmission provided by an embodiment of the present application.
  • Fig. 5 is a schematic flowchart of a method for transmitting a multicast service provided by an embodiment of the present application.
  • FIG. 6 is a schematic flowchart of another method for transmitting a multicast service according to an embodiment of the present application.
  • FIG. 7 is a schematic flowchart of another method for transmitting a multicast service according to an embodiment of the present application.
  • FIG. 8 is a schematic flowchart of another method for transmitting a multicast service according to an embodiment of the present application.
  • FIG. 9 is a schematic flowchart of another method for transmitting a multicast service according to an embodiment of the present application.
  • FIG. 10 is a schematic flowchart of another method for transmitting a multicast service according to an embodiment of the present application.
  • Fig. 11 is a schematic diagram of a tunnel for transmitting a multicast service provided by an embodiment of the present application.
  • Fig. 12 is a schematic diagram of another tunnel for transmitting a multicast service provided by an embodiment of the present application.
  • FIG. 13 is a schematic flowchart of another method for transmitting a multicast service according to an embodiment of the present application.
  • Fig. 14 is a schematic diagram of another tunnel for transmitting a multicast service provided by an embodiment of the present application.
  • Fig. 15 is a schematic diagram of another tunnel for transmitting a multicast service provided by an embodiment of the present application.
  • FIG. 16 is a schematic flowchart of another method for transmitting a multicast service according to an embodiment of the present application.
  • Fig. 17 is a schematic block diagram of an apparatus for transmitting a multicast service provided by an embodiment of the present application.
  • FIG. 18 is a schematic block diagram of another device for transmitting a multicast service according to an embodiment of the present application.
  • LTE long term evolution
  • FDD frequency division duplex
  • UMTS universal mobile telecommunication system
  • 5G fifth generation
  • NR new radio
  • the terminal equipment in the embodiments of this application may also be referred to as: user equipment (UE), mobile station (MS), 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.
  • UE user equipment
  • MS mobile station
  • 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, for example, a handheld device with a wireless connection function, a vehicle-mounted device, and so on.
  • a handheld device with a wireless connection function for example, a vehicle-mounted device, and so on.
  • some examples of terminals are: mobile phones (mobile phones), tablet computers, notebook computers, handheld computers, mobile internet devices (MID), wearable devices, virtual reality (VR) devices, and augmented reality.
  • Wireless terminals in transportation safety transportation safety
  • wireless terminals in smart city smart city
  • wireless terminals in smart home smart home
  • cellular phones cordless phones
  • session initiation protocol SIP
  • wireless local loop wireless local loop
  • WLL wireless local loop
  • PDA personal digital assistant
  • handheld device with wireless communication function computing device or other processing device connected to wireless modem
  • vehicle Devices wearable devices
  • terminal devices in a 5G network or terminal devices in a public land mobile network (PLMN) that will evolve in the future, etc., which are not limited in the embodiment of the present application.
  • PLMN public land mobile network
  • the terminal device may also be a wearable device.
  • Wearable devices can also be called wearable smart devices. It is a general term for using wearable technology to intelligently design everyday wear and develop wearable devices, such as glasses, gloves, watches, clothing and shoes.
  • a wearable device is a portable device that is directly worn on the body or integrated into the user's clothes or accessories. Wearable devices are not only a kind of hardware device, but also realize powerful functions through software support, data interaction, and cloud interaction.
  • wearable smart devices include full-featured, large-sized, complete or partial functions that can be achieved without relying on smart phones, such as smart watches or smart glasses, and only focus on a certain type of application function, and need to cooperate with other devices such as smart phones.
  • the terminal device may also be a terminal device in the Internet of Things (IoT) system.
  • IoT Internet of Things
  • Its main technical feature is to pass items through communication technology. Connect with the network to realize the intelligent network of human-machine interconnection and interconnection of things.
  • the access network device in the embodiment of the present application may be a transmission reception point (TRP), an evolved NodeB (eNB or eNodeB) in an LTE system, or a home base station ( For example, home evolved NodeB, or home Node B, HNB), baseband unit (BBU), or wireless controller in the cloud radio access network (CRAN) scenario, or the connection Network access devices can be relay stations, access points, in-vehicle devices, wearable devices, and access network devices in 5G networks, or access networks in the future evolution of public land mobile network (PLMN) networks
  • PLMN public land mobile network
  • the device, etc. may be an access point (access point, AP) in a WLAN, or a gNB in a new radio system (new radio, NR) system, which is not limited in the embodiment of the present application.
  • the access 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-CP node), user plane CU node (CU-UP node) and RAN equipment of DU node.
  • CU centralized unit
  • DU distributed unit
  • RAN device including a CU node and a DU node, or a control plane CU node (CU-CP node), user plane CU node (CU-UP node) and RAN equipment of DU node.
  • CU-CP node control plane CU node
  • CU-UP node user plane CU node
  • the terminal device or each network device includes a hardware layer, an operating system layer running on the hardware layer, and an application layer running on the operating system layer.
  • the hardware layer includes hardware such as a central processing unit (CPU), a memory management unit (MMU), and memory (also referred to as main memory).
  • the operating system can be any one or more computer operating systems that implement business processing through processes, for example, Linux operating systems, Unix operating systems, Android operating systems, iOS operating systems, or windows operating systems.
  • the application layer includes applications such as browsers, address books, word processing software, and instant messaging software.
  • the embodiments of the application do not specifically limit the specific structure of the execution body of the method provided in the embodiments of the application, as long as the program that records the codes of the methods provided in the embodiments of the application can be provided in accordance with the embodiments of the application.
  • the execution subject of the method provided in the embodiment of the present application may be a network device, or a functional module in the network device that can call and execute the program.
  • various aspects or features of the present application can be implemented as methods, devices, or products using standard programming and/or engineering techniques.
  • article of manufacture used in this application 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 (for example, hard disks, floppy disks or tapes, etc.), optical disks (for example, compact discs (CD), digital versatile discs (DVD)) Etc.), smart cards and flash memory devices (for example, erasable programmable read-only memory (EPROM), cards, sticks or key drives, etc.).
  • various storage media described herein may represent one or more devices and/or other machine-readable media for storing information.
  • 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 system architecture 100 includes: a terminal device 110, an access network device 120, an access and mobility management network element 130, and a session management network element 140.
  • the access and mobility management network element 130 and the session management 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 network element 140 to add the terminal device 110 to the multicast service.
  • the session management function network element 140 can create a corresponding multicast session tunnel for the terminal device 110, and add the terminal device 110 to the multicast service, so as to transmit the data stream of the multicast service to the terminal device 110.
  • the foregoing system architecture 100 may be used to implement the method for transmitting a multicast service in the embodiment of the present application.
  • FIG. 2 is another system architecture 200 according to an embodiment of the present application. As shown in FIG. 2, the system architecture 200 may specifically include the following network elements:
  • Radio access network (R)AN): It is used to provide network access functions for authorized users in a specific area, and can use transmission tunnels of different quality according to the user's level and service requirements.
  • (R)AN network element can manage wireless resources, provide access services for terminal equipment, and complete the forwarding of control signals and user data between terminal equipment and 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. Specifically, AMF can be used to implement other functions in addition to session management in the functions of a mobility management entity (MME), for example, functions such as lawful interception, or access authorization (or authentication).
  • MME mobility management entity
  • functions such as lawful interception, or access authorization (or authentication).
  • Session Management Function SMF
  • Session Management Function SMF
  • SMF Session Management Function
  • IP Internet Protocol
  • the source session management network element 110, the anchor session management network element 120, and the target session management network element 190 in FIG. 1 may all be SMFs.
  • the access network device 120 may be the RAN in FIG. 2; the access and mobility management network element 130 may be the AMF in FIG. 2; the session management network element 140 may be the RAN in FIG.
  • the SMF is not restricted.
  • system architecture 200 may further include:
  • User plane function also called user plane function or user plane network element or user plane function network element, used for packet routing and forwarding, or the quality of service of user plane data , QoS) processing and so on.
  • UPF is specifically divided into intermediate-UPF (intermediate-UPF, I-UPF) and anchor point UPF (anchor-UPF, A-UPF).
  • I-UPF intermediate-UPF
  • anchor-UPF anchor-UPF
  • the I-UPF is connected to the access network RAN
  • the A-UPF is the UPF of the session anchor
  • the A-UPF may also be referred to as the PDU session anchor (PSA).
  • PSA PDU session anchor
  • Data network A network used to provide data transmission, such as an Internet network.
  • the PSA is connected to the remote DN, and the L-PSA can be connected to the local DN.
  • Authentication server function (authentication server function, AUSF): mainly used for user authentication, etc.
  • PCF Policy control function
  • Unified data management used to process user identification, access authentication, registration, or mobility management, etc.
  • Application function It mainly supports interaction with the 3rd generation partnership project (3rd generation partnership project, 3GPP) core network to provide services, such as influencing data routing decisions, policy control functions, or to the network side Provide some third-party services.
  • 3rd generation partnership project 3rd generation partnership project, 3GPP
  • 3GPP 3rd generation partnership project
  • the AF may be a service provider (content provider, CP).
  • Network slice selection function (network slice selection function, NSSF): used to select network slices.
  • 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, and is used to send 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 connection 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
  • system architecture 200 may further include:
  • Multicast control plane function used to control multicast services, MCF and service provider (content provider, CP) docking, in order to receive multicast service related information (such as multicast services Description), MCF and PCF are connected to create resources for multicast services.
  • MCF multicast control plane function
  • service provider content provider, CP
  • Multicast user plane function used to deliver multicast service-related data, that is, to send multicast data received from the CP to the UPF. It should be noted here that in a 5G network, the aforementioned MUF network element may also have other names, which implement the user plane function of the multicast service.
  • MCF can be integrated into PCF (or SMF), and MUF can be integrated into UPF, which is not limited in the embodiment of the present application.
  • the name of the interface between the various network elements in FIG. 2 is only an example, and the name of the interface in a specific implementation may be another name, which is not specifically limited in the embodiment of the present application.
  • the names of the various network elements are only an example, and do not limit the functions of the network elements themselves.
  • the aforementioned network elements may also have other names, which are not specifically limited in the embodiment of the present application.
  • some or all of the above-mentioned network elements may use the terminology in 5G, or may adopt other names, etc., which are uniformly explained here and will not be repeated in the following.
  • the name of the message (or signaling) transmitted between the various network elements described above is only an example, and does not constitute any limitation on the function of the message itself.
  • Unicast can be understood as "point to point” (point to point) communication. Unicast has 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 refers to the wireless access network sending service data to a single terminal device.
  • unicast refers to sending service data to terminal devices through PDU sessions.
  • 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” and can be understood as “point to multi-point” (PTM) communication. Multicast has multiple meanings, as follows:
  • the 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 a multicast IP address).
  • the air interface multicast mode refers to a piece of service data sent to the wireless access network, and multiple terminal devices can receive it at the same time and/or at the same frequency.
  • multicast refers to sending multicast service data to terminal devices through a multicast session.
  • the multicast session includes: unicast tunnels or multicast tunnels between network elements, and air interface wireless in unicast mode. Air interface wireless 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 method can be used to transmit service data to all target nodes at one time, or only to specific objects. Therefore, in the multicast method, one sending node and multiple receiving nodes can achieve point-to-many Point transmission, thus solving the problem of low efficiency in unicast mode.
  • the broadcast service can be sent to the terminal device through a multicast session, which is not limited in the embodiment of the present application.
  • Multicast in this application is a broad concept, and can include multicast or broadcast, that is, the embodiments of this application can be applied to both multicast service transmission and broadcast service transmission.
  • the "multicast” mentioned in this application can be replaced with “multicast or broadcast”.
  • Fig. 3 is a schematic diagram of service data transmission provided by an embodiment of the present application.
  • the schematic diagram shown in Figure 3 is used to transmit multicast service data.
  • multicast service data can be sent from the CP to UE1, UE2, and UE3.
  • the multicast service transmission path from CP to AN may include the transmission path between CP and UPF and the transmission path between UPF and 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 (general tunnel protocol, GTP). Therefore, 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.
  • GTP general tunnel protocol
  • the AN can send the above multicast service data to UE 1, UE 2, and UE 3 through PTM, that is, only one copy of the data needs to be sent, and all 3 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.
  • Fig. 4 is a schematic diagram of another service data transmission provided by an embodiment of the present application.
  • the schematic diagram shown in FIG. 4 can be used to transmit multicast service data (through unicast), 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 UPF and AN can 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 UE1, UE2, and UE3 in unicast mode, that is, PTP mode.
  • the service data of each UE may be different (for example, the target address is the IP address of each UE), and the service data of each UE may be sent to each UE through its independent transmission path.
  • the multicast session tunnel and the PDU session tunnel are both tunnels from a user plane network element (for example, UPF) to an access network AN (for example, 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; it passes through the service data adaptation protocol (SDAP) layer and packet data convergence protocol (PDCP) layer of gNB 1 , Radio link control (RLC) layer, media access control (MAC) layer, physical (PHY) layer processing, the data received by each UE can be called multicast service data .
  • SDAP service data adaptation protocol
  • PDCP packet data convergence protocol
  • RLC Radio link control
  • MAC 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 streams, 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 streams.
  • the description information of the multicast service stream 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 of the multicast service, the destination port number, the source address, etc.), and the multicast service flow QoS requirements (eg, jitter, delay, packet loss rate, bandwidth, etc.).
  • QFI quality of service index
  • a multicast session can include one or more multicast QoS streams.
  • the multicast service can be transmitted in one or more multicast QoS streams in the multicast session tunnel where the multicast session is located.
  • 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, a multicast service can be served by one multicast session, and a multicast session includes slaves The unicast or multicast tunnel from the data network to the core network and then to the wireless access network, and the unicast or multicast air interface resources allocated by the wireless access network for sending the multicast service.
  • the information of the multicast service may also contain the information of the terminal device. For example, it may include the identification of one or more terminal devices and the terminal device that allow (or request) to join the multicast service. The identity of the group, 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 in the PLMN.
  • multicast ID multicast ID
  • MCID globally unique multicast service identifier
  • this application does not limit the English name MCID, and MCID can also be replaced with other names, but its function is to uniquely identify multicast services.
  • the MCF shown in Figure 2 can obtain multicast service information from the CP, and then send the obtained multicast service information to the PCF.
  • the PCF can generate policy and charging control based on the multicast service information. control, PCC) rules. Among them, if the multicast service information can be applied to all terminal devices, the generated PCC rules can also be applied to all terminal devices.
  • the generated PCC rule may be related to one or more terminal devices related to the multicast service.
  • the MCF may send the MCID and the multicast service information to the PCF together.
  • 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 embodiment of the application proposes A method for transmitting multicast services can realize the transmission of multicast services regardless of whether there is a device supporting multicast in the system, thereby improving the reliability of multicast service transmission.
  • the user plane function may also be referred to as a user plane function or a user plane network element or a user plane function network element, and the four names can be replaced with each other.
  • FIG. 5 shows a schematic flowchart of a method 500 for transmitting a multicast service according to an embodiment of the present application.
  • the method 500 may be applied to the system architecture 100 shown in FIG. 1 and may also be applied to the system architecture 200 shown in FIG. 2, and the embodiment of the present application is not limited thereto.
  • S510 The session management network element receives the first message.
  • the first message is used to request the terminal device to join the multicast service.
  • the first message may come from an access and mobility management network element or a user plane function network element (for example, UPF).
  • UPF user plane function network element
  • the session management network element determines the sending mode of the multicast service according to the multicast capability information of the terminal device and/or the multicast capability information of the access network device accessed by the terminal device.
  • the sending mode is a unicast mode or a multicast mode.
  • the multicast capability information of the terminal device refers to whether the terminal device supports multicast, and the multicast capability information of the access network device is used to indicate whether the access network device supports multicast.
  • the access network device supports multicast means that the air interface of the access network device supports point-to-multipoint transmission.
  • the terminal device supporting multicast means that the terminal device supports receiving multicast services through an air interface multicast mode.
  • the session management network element may, when a terminal device requests to join a multicast service, according to the multicast capability information of the terminal device and/or the multicast capability information of the access network device that the terminal device accesses , The terminal equipment is added to the multicast service, thereby more effectively delivering the multicast service to the terminal equipment, reducing the delay of the terminal equipment requesting to join the multicast service, thereby improving the flexibility and reliability of the multicast service transmission.
  • the session management network element in S520 may not refer to the multicast capability information of the aforementioned terminal devices, but only refer to the multicast capability information of the access network devices, that is, Determine whether the access network device accessed by the terminal device supports multicast.
  • the session management network element in S520 may not refer to the multicast capability information of the above-mentioned access network devices, but only refer to the multicast capability information of the terminal device, that is, judge Whether the terminal device supports multicast.
  • the session management network element may refer to the foregoing multicast capability information of the terminal device and the multicast capability information of the access network device.
  • step S520 can be divided into the following two situations:
  • the multicast capability information of the terminal device indicates that the terminal device does not support multicast, and/or the multicast capability information of the access network device indicates that the access network device does not support multicast.
  • step S520 includes: when the transmission mode is unicast, the method further includes: the session management network element according to the multicast service quality of the multicast service QoS information to determine the unicast QoS flow corresponding to the multicast service; the session management network element adds the unicast QoS flow to the protocol data unit PDU session of the terminal device, and the unicast QoS flow is used for transmission The data of the multicast service.
  • adding the unicast QoS flow to the PDU session of the terminal device by the session management network element may include: the session management network element is from a multicast/broadcast session management function network element Obtain the QoS information of the multicast service, including the QFI of the multicast QoS flow of the multicast service, the service data flow (SDF) corresponding to the multicast QoS flow, and the QoS parameters corresponding to the QFI of the multicast QoS flow,
  • QoS parameters may include: 5QI, ARP, GBR, MBR, QNC (QoS notification control), etc.
  • the QoS parameters corresponding to the unicast QoS flow with the same value can be found according to the QoS information corresponding to the multicast QoS flow of the multicast service, and then it is determined that the unicast QoS flow is the determined unicast QoS flow.
  • the session management network element adds the unicast QoS flow to the PDU session of the terminal device, including: the session management network element sends a filter for identifying the multicast service to the user plane network element Device information (for example, packet detection rule (PDR)) and the QFI of the unicast QoS flow; the session management network element determines the QoS parameters of the unicast QoS flow according to the QoS parameters of the multicast QoS flow ; The session management network element sends the QFI of the unicast QoS flow and the QoS parameters of the unicast QoS flow to the target access network device.
  • PDR packet detection rule
  • the session management network element adds the unicast QoS flow to the PDU session of the terminal device, including: the session management network element sends an N4 session modification request (N4 session modification request) to the user plane network element ) Or a Packet Forwarding Control Protocol (PFCP) session modification request (PFCP session modification request), and a filter for filtering the multicast/broadcast service data is added to the mapped unicast QoS flow. That is, based on the technical solution, the mapped unicast QoS flow has been used to transmit the service data in the PDU session before.
  • N4 session modification request N4 session modification request
  • PFCP Packet Forwarding Control Protocol
  • PFCP session modification request Packet Forwarding Control Protocol session modification request
  • the packet detection rule may be a filter of the multicast service, and the filter is a five-tuple including a source address, a destination address, a source port number, and a destination port Number, protocol number, can be used to identify the data of the multicast service.
  • the session management network element maps the multicast QoS flow of the multicast service to the unicast QoS flow, thereby adding the unicast QoS flow to the PDU session for subsequent unicast delivery to the terminal device The multicast service.
  • mapping of the multicast QoS flow of the multicast service to the unicast QoS flow it may refer to the establishment of a correspondence between the multicast QoS flow and the unicast QoS flow, so that the unicast QoS flow is used to deliver the multicast service.
  • the QFI of the unicast QoS flow determined by the session management network element is different from the QFI of the existing unicast QoS flow.
  • the available value of QFI of a unicast QoS flow is (10-64)
  • mapping The process of determining the QFI of a unicast QoS flow according to the QFI of a multicast QoS flow can be called mapping.
  • mapping the correspondence between the QFI of the multicast QoS flow and the QFI of the unicast QoS flow is called the first mapping. relation.
  • one multicast QoS flow can be mapped to one unicast QoS flow, or multiple multicast QoS flows can be mapped to one unicast QoS flow, and the embodiment of the present application does not limit how to map.
  • adding the unicast QoS flow to the PDU session of the terminal device by the session management network element may include: the session management network element is from a multicast/broadcast session management function network element Obtain the QoS information of the service data flow (SDF) of the multicast service.
  • the QoS information may include: 5QI, ARP, GBR, MBR, QNC (QoS notification control), etc.
  • the QoS parameters corresponding to the unicast QoS flow with the same value can be found according to the QoS information corresponding to the service data flow SDF of the multicast service, and then it is determined that the unicast QoS flow is the determined unicast QoS flow.
  • the session management network element sends to the user plane network element filter information used to identify the multicast service (for example, packet detection rule (PDR)), as well as information about the multicast service and the The QFI of the unicast QoS flow; the session management network element determines the QoS parameters of the unicast QoS flow according to the QoS parameters of the multicast QoS flow; the session management network element sends all the QoS parameters to the access network device The QFI of the unicast QoS flow and the QoS parameters of the unicast QoS flow.
  • PDR packet detection rule
  • the packet detection rule may be a filter of the multicast service, and the filter is a five-tuple including a source address, a destination address, a source port number, and a destination port Number, protocol number, can be used to identify the data of the multicast service.
  • the session management network element adds the unicast QoS flow to the PDU session of the terminal device, including:
  • the session management network element selects at least one unicast QoS flow from the unicast QoS flow of the PDU session of the terminal device according to the QoS information of the multicast service, and the at least one unicast QoS flow is used to transmit the Multicast service data, where the unicast QoS flow is an existing QoS flow; the session management network element sends the multicast service data packet detection rule and the at least one unicast service to the user plane function network element Correspondence between QoS flow identifiers.
  • the corresponding relationship may be carried in the eighth message, where the eighth message is an N4 session modification request (N4 session modification request) message or a PFCP session modification request (PFCP session modification request).
  • N4 session modification request N4 session modification request
  • PFCP session modification request PFCP session modification request
  • the correspondence relationship may be that the eighth message also includes the packet detection rule of the multicast service, and the identification of the at least one unicast QoS flow corresponding to the packet detection rule of the multicast service , Can be used to characterize the correspondence between the packet detection rule of the multicast service and the identifier of the at least one unicast QoS flow.
  • the session management network element sends an N4 session modification request (N4 Session Modification Request) or a PFCP session modification request (PFCP session modification request) to the user plane network element.
  • the N4 session modification request (N4 session modification request) or PFCP session modification request message also includes the packet detection rule of the multicast service, and the at least one unicast corresponding to the packet detection rule of the multicast service
  • the identifier of the QoS flow may be used to characterize the correspondence between the packet detection rule of the multicast service and the identifier of the at least one unicast QoS flow.
  • the data packet detection rule may be a filter of the multicast service.
  • the filter is a five-tuple, including a source address, a destination address, a source port number, a destination port number, and a protocol number. To identify the data of the multicast service.
  • the information of the multicast service refers to the information of the multicast service corresponding to the multicast QoS flow mapped to the unicast QoS flow.
  • the session management network element may determine according to the QoS parameters of all multicast QoS flows mapped to the unicast QoS flow, but this embodiment of the application does not limit this .
  • the session management network element may also instruct the user plane network element to send the data packet of the multicast service through the PDU session tunnel.
  • the user plane network element can identify the data packet of the multicast service according to the information of the multicast service, and send the data packet of the multicast service to the downstream node (for example, the radio access network) through the PDU session tunnel.
  • the user plane network element can determine the QFI corresponding to the data packet according to the information of the multicast service and the QFI of the unicast QoS flow, and carry the unicast corresponding to the data packet when sending the data packet to the downstream node. The QFI of the QoS flow.
  • the QFI corresponding to the foregoing data packet may be determined by the session management network element according to the QoS requirements of the multicast service.
  • the SMF may obtain the QoS requirements related to the multicast service (for example, bandwidth, delay, jitter, etc.) from the PCF.
  • the SMF may determine the QFI according to the QoS requirements. For example, the SMF may determine the QFI of the picture included in the multicast service as 1, and the QFI of the voice included in the multicast service as 3.
  • the QFI of the unicast QoS flow may be included in the packet header of the general packet radio service tunneling protocol-user plane (general packet radio service tunneling protocol-user, GTP-U) as a field of the GTP-U packet header .
  • general packet radio service tunneling protocol-user plane general packet radio service tunneling protocol-user, GTP-U
  • the multicast service information may include the destination address of the multicast service, and further, may also include at least one of a source address or a port number.
  • the multicast service is sent to the current user-plane network element through another user-plane network element, and the session management network element also includes the tunnel identifier of the other user-plane network element (for the convenience of the current user-plane network element).
  • the user plane network element connected to it) is sent to the current user plane network element.
  • the information of the multicast service may include the tunnel identifier of the other user plane network element.
  • the multicast capability information of the access network device indicates that the access network device supports multicast.
  • the multicast capability information of the terminal device indicates that the terminal device supports multicast
  • the multicast capability information of the access network device indicates that the access network The device supports multicast.
  • step S520 includes: when the sending mode is a multicast mode, the method further includes: the session management network element sends a third message to the access network device , The third message is used to request the terminal device to join the multicast service.
  • the third message may include the service identification of the foregoing multicast service, and may also be referred to as the identification information of the multicast service.
  • the identification information of the multicast service may be any of the following, or may be a combination of one or more of the following, without limitation:
  • TMGI temporary mobile group identity
  • the service identifier of the multicast service can also be carried in other messages, for example, in N1N2 information transfer (Namf_Communication_N1N2Message Transfer), specifically, through S806 and/or S814 in FIG. 8 and S906 and S906 in FIG. 9 /Or the N1N2 information shown in S914 is transferred and sent to the AMF, and the AMF sends the service identifier of the multicast service to the access network device through other messages.
  • the other message may also be an N2 message.
  • the N2 message may be N2 PDU session request (N2 PDU session request), PDU session resource setup request (PDU session resource establishment request), or PDU session resource modify request (PDU session resource modification) ),Wait.
  • the access network device receives the third message from the session management network element. If the current air interface resources are sufficient, the access network device can issue corresponding radio bearer configuration information for the terminal device, and the terminal device can configure according to the radio bearer configuration. After the information is configured for receiving at the access layer, it can receive the data of the multicast service, that is, the terminal device successfully joins the multicast service; if the air interface resources are tight and the wireless bearer cannot be configured, the access network device cannot issue the wireless for the terminal device. Bearer configuration information, that is, the terminal device cannot join the multicast service. It should be understood that the so-called radio bearer configuration may be identified by a data radio bear (DRB) ID, which corresponds to a complete set of radio access layer configurations.
  • DRB data radio bear
  • radio bearer configuration information can be replaced with the configuration information of radio resources, and the radio bearer configuration can be replaced with the configuration of radio resources.
  • the radio resource may include a radio bearer
  • the configuration information of the radio resource may include radio bearer configuration information, which is not limited.
  • the multicast service transmission mode is a multicast mode.
  • the session management network element may request the access network device to add the terminal device to the multicast service, so as to subsequently deliver the multicast service to the terminal device in a multicast manner.
  • the method further includes: the session management network element determines the access network The device has the multicast service.
  • the access network device has established a multicast session of the multicast service, or the access network device has participated in the transmission of the multicast service, or the access network device has joined the multicast service.
  • the multicast session of the multicast service may refer to the multicast session used to transmit the multicast service.
  • the session management network element may first determine whether the access network device has the multicast service. If the access network device has the multicast service, the session management network element sends a third message to request the access network device to join the terminal device to the multicast service; if the access network device does not have the multicast service Service, the session management network element may first request the access network device to create a multicast session for the multicast service, and after the multicast session is created, the session management network element sends a third message, that is, to request the access The network device joins the terminal device to the multicast service.
  • the session management network element may not perform any judgment on the presence of the multicast service on the access network device, but is requesting the access network device to join the terminal device Simultaneously with the multicast service, the information of the multicast QoS flow of the multicast service is sent to the access network device.
  • the access network device can create a multicast session of the multicast service for the terminal device according to the information of the multicast QoS flow, and then, The terminal device joins the multicast service.
  • the session management network element can determine whether the access network device has the multicast service in a variety of ways, which is not limited.
  • the determination by the session management network element that the multicast service exists on the access network device includes: the session management network element receives a fourth message from the unified data management network element, and The fourth message is used to indicate that the access network device has the multicast service; the session management network element determines that the access network device has the multicast service according to the fourth message.
  • the unified data management network element may autonomously (e.g., periodically) send the aforementioned third message to the session management network element to inform the session management network element of the information about the multicast service existing on the access network device.
  • the session management network element may query the unified data management network element, that is, send a query message to the unified data management network element to query whether the multicast service requested by the current terminal device is in the access network that the terminal device accesses.
  • the session management network element receives the query result (that is, the foregoing fourth message) fed back by the unified data management network element, and according to the query result, it can be determined whether the access network device has the multicast service.
  • the session management network element sends a query message to the unified data management network element
  • the unified data management network element may not feed back the query result, and the session management network element defaults to the connection if the query result is not received within a period of time.
  • the network access device does not have the multicast service (or the access network device has the multicast service by default), but the embodiment of the present application does not limit this.
  • the method further includes: the session management network element determines the access network The device does not have the multicast service; the session management network element sends information about the multicast QoS flow of the multicast service to the access network device; the session management network element receives information from the access network device The indication information used to indicate that the radio bearer corresponding to the multicast QoS flow is successfully created.
  • the session management network element may send the information of the multicast QoS flow of the multicast service to the access network device, and the information of the multicast QoS flow
  • the information may include the QFI of the multicast QoS flow and the QoS parameters of the multicast QoS flow.
  • the access network device can create a corresponding multicast service according to the information of the multicast QoS flow, so as to prepare for subsequent addition of terminal devices to the multicast service.
  • the method further includes: the session management network element sends a fifth message to the unified data management network element according to the instruction information, where the fifth message is used to instruct the access network The multicast service already exists in the device.
  • the session management network element may notify the unified data management network element
  • the above-mentioned access network equipment already has the multicast service.
  • the foregoing fifth message may carry the identifier of the multicast service and the identifier of the access network device.
  • the method may further include: the session management network element determines the unicast QoS flow corresponding to the multicast QoS flow; and the session management network element sends the first session to the access network device A mapping relationship, where the first mapping relationship is used to indicate the corresponding relationship between the QFI of the multicast QoS flow and the QFI of the unicast QoS flow.
  • the session management network element can also generate the mapping relationship between the QFI of the multicast QoS flow and the QFI of the unicast QoS flow, but there is no need to modify the PDU session ( That is, there is no need to add the unicast QoS flow in the PDU session).
  • the access network device that the terminal device accesses supports multicast that is, the multicast service is delivered through the multicast session tunnel, and the unicast service is delivered through the PDU session tunnel where the PDU session is located.
  • the terminal device has mobility, and the subsequent terminal device may move to another access network device, and the other access network device may not support multicast.
  • the session management network element can be stored in advance
  • the mapping relationship between the QFI of the above multicast QoS flow and the QFI of the unicast QoS flow, so that the session management network element notifies the user plane network when it knows that another access network device to which the terminal device will switch does not support multicast
  • the meta maps the multicast service to the PDU session tunnel where the PDU session is located and delivers it to the terminal device, thereby ensuring the continuity of the multicast service.
  • the session management network element determines the sending mode of the multicast service according to the multicast capability information of the terminal device and/or the multicast capability information of the access network device that the terminal device accesses, the session management network element needs to obtain this The multicast capability information of the terminal device and/or the multicast capability information of the access network device.
  • the session management network element may obtain the multicast capability information of the terminal device and/or the multicast capability information of the access network device in a variety of ways, which may specifically include the following multiple implementation manners.
  • the method may further include: the access and mobility management network element sends the multicast capability information of the terminal device and/or the access network to the session management network element Information about the multicast capability of the device.
  • the session management network element receives the multicast capability information of the terminal device and/or the multicast capability information of the access network device from the access and mobility management network element.
  • the above method may further include: the access and mobility management network element determines whether the protocol data unit PDU session of the terminal device supports multicast, and the PDU session supports multicast In the case of, the access and mobility management network element sends the multicast capability information of the terminal device and/or the multicast capability information of the access network device to the session management network element.
  • the session management network element receives the multicast capability information of the terminal device and/or the multicast capability information of the access network device from the access and mobility management network element.
  • the determining by the access and mobility management network element that the PDU session of the terminal device supports multicast includes: the access and mobility management network element receives reference information of the PDU session from the terminal device
  • the reference information includes one of the indication information used to indicate whether the PDU session supports multicast, the data network name DNN of the PDU session, the single network slice selection auxiliary information S-NSSAI of the PDU session, or Multiple items; the access and mobility management network element determines that the PDU session supports multicast according to the reference information.
  • the method may further include: the session management network element sending a request message to the access and mobility management network element, the request message being used to request the terminal device Multicast capability information and/or multicast capability information of the access network device.
  • the access and mobility management network element receives the request message from the session management network element, and sends the multicast capability information of the terminal device and/or the connection to the session management network element according to the request message. Multicast capability information of the connected device.
  • the method further includes: the session management network element sends a subscription message to the access and mobility management network element, where the subscription message is used for the mobility management network element
  • the access and mobility management network element receives the subscription message from the session management network element, and sends the multicast capability of the terminal device to the session management network element when the capabilities of the terminal device and/or the access network device change Information or multicast capability information of the access network equipment.
  • the multicast capability information of the aforementioned terminal device and/or the multicast capability information of the aforementioned access network device may be acquired by the session management network element through subscription. That is, the session management network element sends a subscription message to the access and mobility management network element, and the subscription message is used by the mobility management network element to send a subscription message when the multicast capability of the terminal device changes and/or the multicast capability of the access network device changes.
  • the session management network element sends the multicast capability information of the terminal device or the multicast capability information of the access network device.
  • the access and mobility management network element may send the multicast capability information of the terminal device to the session management network element; when the capability of the access network device changes, the access and mobility management network element The capability management network element can send the multicast capability information of the access network device to the session management network element; when the capabilities of the access network device and the terminal device are both changed, the access and mobility management network element can report to the session management The network element sends the multicast capability information of the access network equipment and the multicast capability information of the terminal equipment.
  • the session management network element may only obtain the multicast capability information of the terminal device.
  • the session management The network element may only obtain the multicast capability information of the access network device.
  • the session management network element may simultaneously obtain the group of the aforementioned terminal devices.
  • the multicast capability information of the access network device and the multicast capability information of the access network device may also be obtained separately for the foregoing terminal device multicast capability information and the multicast capability information of the access network device, which is not limited in this embodiment of the application.
  • the multicast capability information of the terminal device may be actively sent by the access and mobility management network element to the session management network element, and the multicast capability information of the access network device may be the session management network element requesting access. Incoming and Mobility Management Network Element.
  • the multicast capability information of the access network device may be actively sent by the access and mobility management network element to the session management network element, and the multicast capability information of the terminal device may be a request from the session management network element. Sent by the access and mobility management network element.
  • FIG. 6 shows a schematic flowchart of a method 600 for transmitting a multicast service according to an embodiment of the present application.
  • the method 600 may be applied to the system architecture 100 shown in FIG. 1 and may also be applied to the system architecture 200 shown in FIG. 2, and the embodiment of the present application is not limited thereto.
  • the access and mobility management network element sends a second message to the session management network element; correspondingly, the session management network element receives the second message from the access and mobility management network element.
  • the second message is used to update the PDU session of the terminal device, and the PDU session is associated with a multicast service.
  • the second message may specifically be an Nsmf_PDUSession_UpdateSMContext Request message.
  • the session management network element determines the sending mode of the multicast service according to the multicast capability information of the terminal device and/or the multicast capability information of the target access network device of the terminal device.
  • the sending mode is a unicast mode or a multicast mode.
  • the multicast capability information of the terminal device is used to indicate whether the terminal device supports multicast, and the multicast capability information of the target access network device is used to indicate whether the target access network device supports multicast.
  • the access and mobility management network element may send the above-mentioned second message to the session management network element for performing the PDU session renew.
  • switching the terminal device from the source access network device to the target access network device may refer to switching the PDU session of the terminal device from the source access network device to the target access network device.
  • switching the PDU session of the terminal device means that when the terminal device moves from the source access network device to the target access network device, in order to maintain business continuity, the PDU session of the terminal device is from the source access network device. The device switches to the target access network 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 through the user plane or the control plane of the PDU session at the source access network device.
  • the PDU can be stored in the PDU session context by storing the multicast service identifier
  • the session is associated with the multicast service. Exemplarily, if a terminal device joins to watch CCTV 1 through the user plane of a PDU session, then the PDU session is associated with a multicast service. If the terminal device joins to watch CCTV 10, then the PDU session is associated with a multicast service. .
  • the session management network element may determine the terminal device according to the multicast capability information of the target access network device when the terminal device is switched from the source access network device supporting the multicast function to the target access network device Regardless of whether the target access network device supports multicast or not, the multicast service and unicast service of the terminal device on the source access network device can not be interrupted due to the switching of the multicast service delivery method after switching, ensuring the terminal device’s reliability. Service continuity, and can reduce packet loss during the handover process, and reduce the handover delay.
  • the multicast service associated with the PDU session can be transmitted to the terminal device through a multicast tunnel, that is, the multicast service is sent in a group If the terminal device does not support multicast or the source access network device does not support multicast, the multicast QoS flow of the multicast service associated with the PDU session can be mapped into the unicast QoS flow of the PDU session and pass the PDU The session tunnel is sent to the terminal device, that is, the sending mode of the multicast service is unicast.
  • the session management network element may re-determine the sending mode of the multicast service according to the multicast capability information of the terminal device and/or the multicast capability information of the target access network device. Therefore, the method for determining the sending mode of the multicast service in the embodiment of the present application is similar to the foregoing method 500, and the access network device in the foregoing method 500 can be replaced with the target access network device. For details, please refer to the foregoing method 500. I won't repeat it here.
  • the above method further includes: when the PDU session is switched from the source access network device to the target access network device, the session management network element may determine the unicast QoS according to the multicast QoS flow of the multicast service
  • the unicast QoS flow is added to the above-mentioned PDU session, and the unicast QoS flow is sent through the PDU session tunnel, that is, after the PDU session is switched to the target access network device, the unicast method is used to send the PDU session-associated Multicast business.
  • the session management network element adds a description of the unicast QoS flow in the PDU session. You can refer to the description in S520 about the session management network element adding the unicast QoS flow to the PDU session of the terminal device. For brevity, this application is here. No longer.
  • the session management network element sends the corresponding relationship between the packet detection rule of the multicast service and the identifier of the at least one unicast QoS flow to the user plane function network element.
  • the corresponding relationship is carried in the eighth message, where the eighth message is an N4 session modification request message or a PFCP session modification request.
  • the correspondence relationship may be that the eighth message also includes the packet detection rule of the multicast service, and the identifier of the at least one unicast QoS flow corresponding to the packet detection rule of the multicast service may be used for Characterizing the correspondence between the packet detection rule of the multicast service and the identifier of the at least one unicast QoS flow.
  • the session management network element sends an N4 session modification request or a PFCP session modification request to the user plane network element.
  • the N4 session modification request or the PFCP session modification request message also includes the packet detection rule of the multicast service, and the identification of the at least one unicast QoS flow corresponding to the packet detection rule of the multicast service may be The corresponding relationship between the data packet detection rule used to characterize the multicast service and the identifier of the at least one unicast QoS flow.
  • the data packet detection rule for example, may be a filter of the multicast service.
  • the filter is a five-tuple, including a source address, a destination address, a source port number, a destination port number, and a protocol number.
  • the session management network element may determine that the switched PDU session is associated with the multicast service according to the second message, and then determine the QoS requirement of the multicast service according to the identifier of the multicast service, thereby Determine the multicast QoS flow of the multicast service, and then obtain the unicast QoS flow corresponding to the multicast QoS flow.
  • adding the unicast QoS flow to the PDU session of the terminal device by the session management network element includes: the session management network element sends the multicast service to a user plane network element Information (for example, packet detection rule (PDR)) and the QFI of the unicast QoS flow; the session management network element determines the QoS parameters of the multicast QoS flow The QoS parameters of the unicast QoS flow; the session management network element sends the QFI of the unicast QoS flow and the QoS parameters of the unicast QoS flow to the target access network device.
  • PDR packet detection rule
  • the session management network element adds the unicast QoS flow to the PDU session of the terminal device, including: the session management network element sends an N4 session modification request or a PFCP session modification request to the user plane network element , Add a filter for filtering the multicast/broadcast service to the mapped unicast QoS flow. That is, based on the technical solution, the mapped unicast QoS flow has been used to transmit the service data in the PDU session before.
  • the information of the multicast service refers to the information of the multicast service corresponding to the multicast QoS flow mapped to the unicast QoS flow.
  • the unicast QoS flow it is based on all the multicast QoS flows mapped to the unicast QoS flow. QoS parameters.
  • the method further includes: the session management network element determines that the terminal device does not support group And/or the target access network device does not support multicast.
  • the session management network element may map the multicast QoS flow to the unicast QoS flow when the terminal device does not support multicast and/or the target access network device does not support multicast, or it may directly Mapping the multicast QoS flow to the unicast QoS flow, after the terminal device accesses the target access network device, the session management network element then based on the multicast capability information of the terminal device and/or the multicast capability information of the target access network device Make judgments.
  • the session management network element can restore the multicast QoS flow mapped to the unicast QoS flow to a multicast QoS flow, and deliver it through the multicast session tunnel of the target access network device;
  • the session management network element may still deliver the unicast QoS flow corresponding to the multicast QoS flow to the terminal device through the PDU session tunnel of the target access network device in a unicast manner.
  • the session management network element first maps the multicast QoS flow to the unicast QoS flow. This is because the terminal device requests both the unicast service and the multicast service when accessing the source access network device.
  • the broadcast service is transmitted in the PDU session tunnel, and the multicast service is transmitted in the multicast session tunnel.
  • the service continuity of the terminal equipment can be guaranteed.
  • the so-called service continuity includes the continuity of unicast services and the continuity of multicast services.
  • the terminal device switches from the source access network device to the target access network device, if the multicast QoS flow in the multicast session tunnel of the source access network device is not mapped into the source access network device’s PDU session first, For the unicast QoS flow in the PDU session tunnel, if the target access network device does not support multicast (that is, the multicast session tunnel cannot be established) after the handover, the multicast service of the terminal device will be interrupted and service continuity cannot be maintained. Therefore, in order to ensure the service continuity of the terminal equipment, the multicast QoS flow can be mapped to the unicast QoS flow at the source access network equipment (that is, before the terminal equipment is switched to the target access network equipment), and the unicast switching is performed.
  • the session management network element knows the multicast capability information of the target access network device in the handover process, it can operate according to whether the target access network device supports multicast, so as to connect to the target access network device in an appropriate manner. Add terminal equipment to the multicast service.
  • the session management network element does not make a judgment before the handover, and directly maps the multicast QoS flow to the unicast QoS flow, then after the terminal device accesses the target access network device, the session management network element The judgment can be made based on the multicast capability information of the terminal device and/or the multicast capability information of the target access network device.
  • the method further includes: the session management network element sends a sixth message to the user plane network element, and the sixth message is used Instructing to delete the unicast QoS flow in the PDU session; the session management network element sends a seventh message to the target access network device, and the seventh message is used to instruct to release the unicast QoS flow Corresponding radio bearer.
  • the user plane network element receives the sixth message and deletes the unicast QoS flow in the aforementioned PDU session.
  • the target access network device receives the seventh message and releases the radio bearer corresponding to the unicast QoS flow.
  • the unicast QoS flow refers to the unicast QoS flow to which the multicast QoS flow is mapped.
  • the multicast service can be delivered to the terminal device through the multicast session tunnel, and the session management network element can restore the multicast QoS flow mapped to the unicast QoS flow to the multicast QoS flow. That is, delete the unicast QoS flow and the corresponding radio bearer.
  • the method 600 of the present application is only different from the foregoing method 500 in the scenario, regarding the session management network element determining the sending mode of the multicast service, requesting the terminal device to join the multicast service, and obtaining the multicast capability of the terminal device
  • the information and/or the multicast capability information of the access network equipment are similar.
  • the access network equipment in the above method 500 can be replaced with the target access network equipment. For details, please refer to the above method 500. Go into details again.
  • the second message may carry the multicast capability information of the terminal device and/or the multicast capability information of the target access network device, but the embodiment of the present application does not limit this.
  • the above method further includes: the target access network device sends the multicast/broadcast capability information of the target access network device to the AMF.
  • the target access network device may send the multicast/broadcast capability information of the target access network device to the AMF through an N2 path switch request (N2 path switch request)/path switch request (path switch request).
  • N2 path switch request N2 path switch request
  • path switch request path switch request
  • the target access device after receiving a handover confirmation (handover confirmation) from the UE, the target access device sends an N2 path switch request/path switch request.
  • the N2 path switch request/path switch request carries the multicast/broadcast capability information of the target access network device.
  • the target access device can obtain the capability information of the target access network device locally, and send the multicast/broadcast capability information of the target access network device to the AMF.
  • the target access network device can obtain the capability information of the target access network device from operation administration and maintenance (OAM), and send the target access network device's information to the AMF Multicast/broadcast capability information.
  • OAM operation administration and maintenance
  • FIG. 7 shows a schematic flowchart of a method 700 for transmitting a multicast service according to an embodiment of the present application.
  • the method 700 may be applied to the system architecture 100 shown in FIG. 1 and may also be applied to the system architecture 200 shown in FIG. 2, and the embodiment of the present application is not limited thereto.
  • the access network device obtains multicast capability information of the access network device.
  • the access network device sends the multicast capability information of the access network device, where the multicast capability information of the access network device is used to indicate whether the access network device supports multicast.
  • that the access network device supports multicast means that the access network device supports the establishment of a multicast session tunnel between itself and the UPF, and the access network device supports PTM transmission on the air interface.
  • the access network device can send its own multicast capability information to the access and mobility management network element, and correspondingly, the access and mobility management network element can receive the access network device’s information Multicast capability information.
  • the access network device may include its own multicast capability information as an information element in the next generation (NG) establishment request message, and report it to the access and mobility management network element.
  • NG next generation
  • the NG establishment request message here is a piece of signaling, which is used when the access network device is powered on, the access network device requests to establish a connection with the access and mobility management network element, and the signaling may include One or more cells.
  • the access network device includes its own multicast capability information as an information element in the NG establishment request message, which refers to the existing information contained in the current NG establishment request message by the access network device.
  • its own multicast capability information is added as a new information element to the NG establishment request message.
  • the access network device may also send multicast capability information to the access and mobility management network element through other messages, which is not limited in the embodiment of the present application.
  • the access and mobility management network element can collect the multicast capability information of the access network equipment (which may include the access network equipment shown in Figures 1 and 2 and multiple other access network equipment).
  • the above-mentioned NG establishment process is a process in an existing protocol, which can be used to collect information related to the access network device by the access and mobility management network element after the access network device is powered on. Therefore, the NG establishment process involved in the embodiments of the present application can be improved based on the existing process, is backward compatible, and is easy to implement.
  • the access and mobility management network element may send the multicast capability information of the access network device to the session management network element, so that the session management network element can according to the group of the access network device Broadcast capability information to determine whether the access network device supports multicast.
  • the access network device may send its own multicast capability information to adjacent access network devices of the access network device.
  • the terminal device can switch from the source access network device to the target access network device.
  • the target access network device may send the multicast capability information to the source access network device, and when the target access network device does not support multicast At this time, the target access network device may not send any information. If the source access network device does not receive the information, the target access network device does not support multicast by default.
  • the method further includes: the access network device receives a handover request message from another access network device, where the handover request message includes an identifier of a protocol data unit PDU session of the terminal device, The PDU session is associated with a multicast service; the access network device sends indication information to a core network device, where the indication information is used to indicate whether the access network device has the multicast service.
  • the above-mentioned access network device can be used as the target access network device in the handover scenario. If the terminal device switches from the source access network device to the target access network device, the target access network device can send instruction information to the core network device, indicating Whether the target access network device has the multicast service that the terminal device requests to access. In this embodiment, the core network device can determine whether the multicast service exists through the target access network device, and there is no need to query the unified data management network element.
  • the above method further includes: the terminal device obtains the multicast capability information of the terminal device; the terminal device sends the multicast capability information of the terminal device, and the multicast capability information of the terminal device is used Yu indicates whether the terminal device supports multicast.
  • the terminal device supporting multicast means that the terminal device supports receiving multicast services through a multicast session, or the terminal device supports air interface multicast mode to receive multicast services.
  • a terminal device can send its own multicast capability information, and correspondingly, the access and mobility management network element can receive a non-access stratum (NAS) message sent by the terminal device .
  • NAS non-access stratum
  • the multicast capability information of the terminal device may be carried in a PDU session establishment/modification request message, and the PDU session establishment/modification request message is sent by the terminal device to the access and mobility management network element.
  • the terminal device may include its own multicast capability information as an information element in the information element 5GSM Core Network Capability (5GSM Core Network Capability) of the PDU session establishment/modification request (for example, PDU Session Establishment Request) message, and report it Manage network elements for access and mobility.
  • 5GSM Core Network Capability 5GSM Core Network Capability
  • the PDU session establishment/modification request message here is a piece of NAS signaling, which is used when the terminal device requests to establish/modify the PDU session, which is sent to the session management by the terminal device through the access and mobility management network element.
  • Network element the signaling may include one or more cells.
  • 5GSM Core Network Capability is one cell, and the cell contains some sub-cells.
  • the terminal equipment includes its own multicast capability information as information elements in the information element 5GSM Core Network Capability of the PDU session establishment request message, which means that the terminal equipment includes the current 5GSM Core Network Capability
  • the terminal device adds its own multicast capability information as a new sub cell to the cell.
  • the terminal device may also send the multicast capability information of the terminal device to the access and mobility management network element through other messages, which is not limited in the embodiment of the present application.
  • the access and mobility management network element may report the multicast capability information of the terminal device to the session Manage network elements.
  • the access and mobility management network element can send the capability information of the terminal device through a create context request message (for example, Nsmf_PDUSession_CreateSMContext Request), which is an access and mobility management network element After receiving the PDU session establishment/modification request message, it is sent to the session management network element.
  • a create context request message for example, Nsmf_PDUSession_CreateSMContext Request
  • the create context request message is a piece of signaling, and the signaling may include one or more cells.
  • 5GSM Core Network Capability is one cell, and the cell contains some sub-cells.
  • the multicast capability information of the terminal device can still be included in the 5GSM Core Network Capability.
  • the access and mobility management network element may also send the multicast capability information of the terminal device to the session management network element through other messages, which is not limited in the embodiment of the present application.
  • FIG. 8 is a schematic flowchart of another method 800 for transmitting a multicast service according to an embodiment of the present application.
  • the method 800 can be applied to the system architecture 200 shown in FIG. 2.
  • the MCF has obtained multicast service information from the CP.
  • S801 The UE sends a message requesting to join the multicast service to the AMF, and correspondingly, the AMF receives the message.
  • the UE may send a request to join the multicast service to the AMF through a non-access stratum (NAS) message.
  • NAS non-access stratum
  • the UE has obtained the MCID of the multicast service (for example, the CP can deliver multicast service information through the application layer, including the MCID of the multicast service), then the UE can send the multicast service
  • the MCID is used to identify the multicast service.
  • the UE may send the multicast address and optional source address information of the multicast service to identify the multicast service (for example, the CP may deliver the multicast service information through the application layer, where Including the multicast address and optional source address of the multicast service).
  • the message requesting to join the multicast service sent by the UE includes an indication that the UE supports the multicast capability.
  • the AMF After receiving the message requesting to join the multicast service sent by the UE, the AMF sends the multicast capability information of the UE and the multicast capability information of the gNB accessed by the UE to the SMF.
  • the AMF also sends a message that the UE requests to join the multicast service to the SMF.
  • the AMF obtains the multicast capability information of the gNB accessed by the UE.
  • the multicast capability information of the gNB is reported by the gNB to the AMF when the gNB is powered on. For details, refer to method 700.
  • S803 The SMF obtains PCC rules related to the multicast service.
  • the SMF does not need to send the request message to the PCF. If the SMF does not have the multicast service information locally, the SMF can send the request message to the PCF and obtain the multicast through the PCF. PCC rules for the business.
  • the message requesting to join the multicast service sent by the UE carries the MCID of the multicast service, and the SMF can send the MCID to the PCF so that the PCF can obtain the multicast service location according to the MCID.
  • the SMF can send the multicast address and optional source address information To the PCF so that the PCF can obtain the PCC rule corresponding to the multicast service according to the multicast address and optional source address information.
  • the PCF may send a feedback message to the SMF, and the feedback message may include the PCC rules of the multicast service.
  • the PCC rule of the multicast service may include at least one of the following: MCID, description information of one or more multicast service streams, QoS information of each multicast service stream (used to generate multicast QoS Stream), where the description information of the multicast service stream may include at least one of the following: the source address and destination address of the multicast service stream, and the 5QI of the multicast service stream (representing a set of QoS parameters, including bandwidth, delay jitter, Etc.), at least one of the QoS parameters of the multicast service.
  • the SMF can determine the sending mode of the multicast service. That is, the SMF may determine to deliver the multicast service in a multicast manner according to the multicast capability information of the UE and/or the multicast capability information of the gNB, or to deliver the multicast service in a unicast manner.
  • SMF determines whether both the UE and the gNB support multicast. The following respectively describes the two cases that the UE and/or gNB do not support multicast and that both the UE and gNB support multicast.
  • the SMF determines that the multicast service transmission mode is unicast. That is, the SMF determines to deliver the multicast service to the UE through the tunnel of the PDU session. In this case, the SMF maps the multicast service flow of the multicast service to the unicast QoS flow in the PDU session, and then delivers the multicast service to the UE through the unicast QoS flow.
  • the SMF can determine one or more multicast service streams (including the QoS information and QFI of the multicast service stream) of the multicast service according to the PCC rules, and then the SMF is a multicast within the scope of the UE’s PDU session
  • the multicast QoS flow corresponding to the service flow is assigned the QFI corresponding to the unicast QoS flow, that is, the QFI of the unicast QoS flow allocated by the SMF for the multicast QoS flow is the unused QFI of other unicast QoS flows in the current PDU session
  • the embodiment of this application is also referred to as "mapping a multicast QoS flow to a unicast QoS flow in the PDU session".
  • QFI is a service quality index, used to describe a set of service qualities. It should be noted that, as mentioned above, the QFI of the unicast QoS flow allocated by the SMF for the multicast QoS flow is different from the QFI of other unicast QoS flows of the PDU session (that is, the allocated QFI is unique within the UE's PDU session) , So that SMF can distinguish the unicast QoS flow corresponding to the multicast service from the ordinary unicast QoS.
  • the SMF After the SMF allocates the QFI of the corresponding unicast QoS flow to the multicast QoS flow, the SMF needs to modify the PDU session of the UE to complete the delivery of the multicast QoS flow to the UE through the PDU session.
  • the SMF can send the multicast service information and the QFI of the unicast QoS flow to the UPF, so that the UPF can modify the parameters, thereby mapping the multicast QoS flow to the PDU session tunnel of the PDU session for unicast QoS Stream transmission, where the foregoing multicast service information may include data detection rules (packets detection rule, PDR).
  • the PDR is a collection of filters, and each filter is a five-tuple containing the source address, destination address, source port number, destination port number, and protocol number of the service, and is used to filter application data.
  • the SMF can determine the QoS parameters of the corresponding unicast QoS flow according to the QoS parameters of the multicast QoS flow, and then send the QFI of the unicast QoS flow and the QoS parameters of the unicast QoS flow to the gNB, so that the gNB can according to the QoS Parameter preparation radio bearer (data radio bearer, DRB).
  • the SMF determines that the multicast service transmission mode is the multicast mode.
  • a multicast session tunnel can be established between gNB and UPF, and gNB uses PTM to deliver multicast services to the UE.
  • the SMF may also generate the mapping relationship between the QFI of the multicast QoS flow and the QFI of the unicast QoS flow in the PDU session of the UE in the manner in the above case 1, and combine The mapping relationship is sent to the gNB so that the gNB can save the mapping relationship.
  • the SMF may also store the above-mentioned mapping relationship.
  • the gNB accessed by the UE supports multicast, that is, multicast services are delivered through the multicast session tunnel, and unicast services are delivered through the PDU session tunnel where the PDU session is located.
  • the UE has mobility, and the subsequent UE may move to another gNB, and the other gNB may not support multicast.
  • SMF can store in advance the QFI of the multicast QoS flow and the QFI of the unicast QoS flow.
  • the SMF knows that the other gNB that the UE will switch to does not support multicast, it will notify the UPF (send the PDR and the mapping relationship to the UPF) to map the multicast service to the PDU session tunnel where the PDU session is located.
  • the UPF sends the PDR and the mapping relationship to the UPF to map the multicast service to the PDU session tunnel where the PDU session is located.
  • the purpose of sending PDR is to filter, that is, to filter out which of the application service streams arriving at the UPF belong to the multicast service.
  • the mapped QFI for example, , The audio, image, and text in the multicast service will have different QFIs), thereby forming different unicast QoS streams (that is, all unicast QFIs mapped from the multicast QFI).
  • S805 The SMF sends a query message to the UDM to query whether the multicast service currently requested by the UE exists in the gNB. After UDM query, the query result is fed back to SMF.
  • the query message may include the identifier of the gNB and the multicast service identifier, and the UDM determines whether the multicast service exists in the gNB according to the query message provided by the SMF, and feeds back the query result to the SMF.
  • SMF can learn whether the multicast service exists in the gNB according to the query result.
  • the multicast service identifier may also be referred to as the identifier information of the multicast service.
  • the identifier of the multicast/broadcast service may be any one of the following, or a combination of one or more of the following, without limitation: the identifier of the multicast/broadcast service, the group The name of the broadcast/broadcast service, the multicast/broadcast address of the multicast/broadcast service, the multicast/broadcast IP address of the multicast/broadcast service, and the temporary mobile group identity (TMGI) corresponding to the multicast/broadcast service ), the session address of the multicast/broadcast service of the multicast/broadcast service, etc.
  • TMGI temporary mobile group identity
  • the service identifier of the multicast service may also be carried in other messages, for example, in N1N2 information transfer (Namf_Communication_N1N2Message Transfer). Specifically, in S806 and/or S814 in FIG. 8, the N1N2 information as shown in S906 and/or S914 in FIG. equipment.
  • the other message may also be an N2 message.
  • the N2 message may be an N2 PDU session request, a PDU session resource establishment request, or a PDU session resource modification, etc.
  • S806-S808 are executed, that is, the SMF only needs to send a request to the gNB to join the UE to the multicast service, and the following steps are specifically performed:
  • the SMF sends a request message to the gNB to request the UE to join the multicast service.
  • the gNB receives the request message, and adds the UE to the multicast service according to the request message.
  • the request message is forwarded via AMF.
  • the request message sent by the SMF may carry the identifier of the multicast service, and the request message may be sent through signaling related to the PDU session.
  • the gNB receives the request message and saves the identifier of the multicast service in the context of the PDU session, that is, the so-called PDU session is associated with the multicast service, in other words, the PDU session includes the multicast service.
  • the request message may also carry the mapping relationship between the QFI of the multicast QoS flow and the QFI of the unicast QoS flow.
  • the gNB may save the mapping relationship in the context of the PDU session of the UE.
  • the AMF may store the information contained in the request message, that is, the mapping relationship between the QFI of the multicast QoS flow and the QFI of the unicast QoS flow and the PDU session of the switched UE Whether it is associated with the multicast service.
  • the request message may also include a NAS message that requests the gNB to send to the UE.
  • the NAS message carries the mapping relationship between the QFI of the multicast QoS flow and the QFI of the unicast QoS flow and the PDU associated with the multicast service. Session ID.
  • the gNB sends an RRC message to the UE.
  • the RRC message may include radio configuration information required for the UE to access the base station.
  • the UE receives the RRC message, and performs wireless configuration according to the RRC message issued by the gNB, so that it can subsequently receive the multicast service.
  • the gNB sends a response message to the SMF, and correspondingly, the SMF can receive the response message.
  • the response message may be an N2 response message, and the N2 response message is sent to the SMF via the AMF.
  • the gNB indicates to the SMF whether the UE has successfully joined the multicast service. If it is unsuccessful, the gNB can send a reason value to the SMF.
  • the SMF sends a radio bearer creation request to the gNB, requesting the gNB to allocate radio resources for the multicast service (that is, requesting the gNB to create a radio bearer for the multicast service).
  • the gNB receives the radio bearer creation request.
  • the radio bearer creation request may be an N2 request message, and the N2 request message includes the QFI of the multicast service flow of the multicast service and the QoS parameter of the multicast service flow.
  • the N2 request message can be sent to gNB via AMF.
  • the AMF may store the content carried in the N2 request message, such as the identifier of the multicast service.
  • the gNB creates a radio bearer related to the multicast service.
  • the gNB can create the context of the multicast service, save the QoS information and QFI of the multicast service flow related to the multicast service, and prepare a radio bearer for the multicast service.
  • the gNB can also allocate a downlink tunnel address for the multicast service, and the downlink tunnel address is used for the gNB to connect to the UPF to receive the downlink multicast data of the multicast service.
  • the gNB sends a radio bearer creation response to the SMF, and correspondingly, the SMF receives the radio bearer creation response.
  • the radio bearer creation response may be an N2 response message.
  • the response message may include the downlink tunnel address allocated by the gNB for the multicast service.
  • the gNB may carry the cause of the creation failure in the radio bearer creation response, such as the shortage of radio resources of the gNB.
  • a PCC association is created between the SMF and the PCF, and the PCC association is used to update the PCC rules of the multicast service.
  • S813 The SMF sends a registration message to the UDM to register the operating status information of the multicast service. That is, SMF informs UDM that the multicast service is already running in the gNB or is ready to run immediately. Correspondingly, UDM receives the registration message and updates the operating status of the multicast service.
  • the registration message may include the identifier of the gNB, the identifier of the multicast service, and the operating status identifier allocated by the SMF for the multicast service.
  • the registration message may also include the identification of the SMF.
  • the SMF sends a request message to the gNB to request the UE to join the multicast service.
  • the gNB receives the request message, and adds the UE to the multicast service according to the request message.
  • the request message is forwarded via AMF.
  • S814 is the same as S806, and will not be repeated here. It should be understood that S814 can be executed simultaneously with S809, that is, when the SMF requests the gNB to add the UE to the multicast service, it also requests the gNB to create a radio bearer for the multicast service. Alternatively, S809 is performed first, and then S814 is performed, which is not limited in the embodiment of the present application.
  • S815 The gNB sends an RRC message to the UE, where the RRC message may include radio configuration information required for the UE to access the base station.
  • the UE receives the RRC message, and performs wireless configuration according to the RRC message issued by the gNB, so that it can subsequently receive the multicast service.
  • S815 is the same as S807.
  • the gNB sends a response message to the SMF, and correspondingly, the SMF receives the response message.
  • the response message may be an N2 response message, and the N2 response message is sent to the SMF via the AMF.
  • the gNB indicates to the SMF whether the UE has successfully joined the multicast service. If it is unsuccessful, the gNB can send a reason value to the SMF.
  • the SMF sends a tunnel establishment request to the UPF, requesting the UPF to establish a multicast session tunnel.
  • the UPF receives the tunnel establishment request and establishes the multicast session tunnel.
  • the gNB allocates the downlink tunnel address of the gNB for the multicast service, and the SMF sends the downlink tunnel address to the UPF to establish a multicast session tunnel from the UPF to the gNB.
  • the multicast session tunnel Used to send data related to the multicast service.
  • UPF allocates a downlink tunnel address for connecting to MUF for establishing a connection between UPF and MUF Tunnel. It should be understood that the tunnel between UPF and MUF is a data plane tunnel.
  • the SMF sends a notification message to the MCF, and the notification message carries the downlink tunnel address of the UPF, so as to establish a tunnel from the MUF to the UPF.
  • the MCF receives the notification message.
  • the notification message may also carry identification information of the multicast service.
  • the identification information of the multicast service may be the MCID assigned by the MCF, or the identification information of the multicast service may include the multicast address, destination port number, source address, etc. of the multicast service.
  • the MCF can save the identification information, and can use the identification information to identify the multicast service when the multicast service is updated subsequently.
  • the aforementioned notification message may also carry an identifier of the gNB, and the MCF may store the identifier of the gNB.
  • the MCF may request the MUF to establish a tunnel from the MUF to the UPF.
  • the MCF sends the downlink tunnel address of the UPF to the MUF for the MUF to connect to the UPF, so that the MUF sends the downlink data of the multicast service to the UPF through the tunnel.
  • the above-mentioned tunnel between MUF and UPF may be a unicast tunnel (that is, the IP address of the UPF is a unicast address) or a multicast tunnel (that is, the IP address of the UPF is a multicast IP address), the embodiment of the present application There is no restriction on this.
  • the “multicast session tunnel” mentioned above refers to the tunnel between the gNB and the UPF of the nearest hop to the gNB.
  • the tunnel can be a unicast tunnel (that is, the IP address of the UPF is a unicast address) or Multicast tunnel (that is, the IP address of the UPF is a multicast IP address).
  • the gNB can follow the PTM Or PTP is sent to the UE; and for the PDU session tunnel, the data in the PDU session tunnel received by the gNB can only be sent to the UE in the PTP mode.
  • the method for transmitting multicast services can ensure that when a UE first applies to join a multicast service, the core network equipment will determine according to the multicast capability information of the UE and/or the multicast capability information of the gNB accessed by the UE.
  • the sending method of the multicast service can more effectively deliver the multicast service to the UE, reduce the delay of the UE requesting to join the multicast service, and thereby improve the reliability of the multicast service transmission.
  • FIG. 9 is a schematic flowchart of another method 900 for transmitting a multicast service according to an embodiment of the present application.
  • the method 900 can be applied to the system architecture 200 shown in FIG. 2.
  • S901 The UE joins and requests to join the multicast service through the Internet Group Management Protocol (IGMP).
  • IGMP Internet Group Management Protocol
  • the IGMP join message is sent to the SMF via UPF, requesting to join the multicast service.
  • the IGMP join message may carry the multicast address and optional source address of the multicast service that the UE requests to join, so as to identify the multicast service.
  • the IGMP join message can be sent through the user plane of the established PDU session, that is, the UE sends the IGMP join message to gNB, gNB sends the IGMP join message to UPF, UPF sends the IGMP join message to SMF, and SMF receives IGMP. Message, it is learned that the UE requests to join the multicast service.
  • the SMF obtains the multicast capability information of the UE and/or the multicast capability information of the gNB.
  • the embodiment of the present application does not limit the sequence of S902 and S901, and this step can be implemented in the following multiple ways.
  • the UE may send the multicast capability information of the UE to the SMF.
  • the UE carries the multicast capability information of the UE in the NAS message of the PDU session establishment request.
  • the UE may also send the UE's new multicast capability information to the SMF through a PDU session modification request (NAS message).
  • NAS message PDU session modification request
  • the AMF may not make any judgments, and directly combine the multicast capability information of the UE and/or the group of the base station (which may include the gNB accessed by the UE in this embodiment).
  • the broadcast capability information is sent to the SMF; or, the AMF may selectively send the multicast capability information of the UE and/or the multicast capability information of the base station to the SMF.
  • the AMF can be based on DNN (for example, multicast services can be accessed through the DNN), S-NSSAI (for example, EMBB slices may support access to multicast services), multicast service indication information ( For example, at least one item in the multicast service identifier supported by the PDU session) determines whether to send the multicast capability information of the UE and/or the multicast capability information of the gNB to the SMF. If the established PDU session supports multicast, AMF can send UE multicast capability information and/or base station multicast capability information to SMF; otherwise, AMF does not send UE multicast capability information and/or base station group information Broadcast capability information.
  • DNN for example, multicast services can be accessed through the DNN
  • S-NSSAI for example, EMBB slices may support access to multicast services
  • multicast service indication information For example, at least one item in the multicast service identifier supported by the PDU session
  • AMF can send UE multicast capability information and/or base station multicast capability information to
  • the SMF may subscribe to the AMF for the multicast capability information of the UE and/or the multicast capability information of the base station.
  • the SMF can subscribe to the AMF in advance according to the attributes of the PDU session (that is, whether the PDU session supports multicast). Therefore, the SMF can receive the multicast capability information of the UE and/or the multicast capability information of the base station sent by the AMF.
  • the SMF sends a subscription message to the AMF.
  • the SMF can query the AMF for the capabilities of the UE and/or the base station. Specifically, the SMF may query the AMF for the multicast capability information of the UE and/or the multicast capability information of the base station accessed by the UE upon receiving the UE's request to join the multicast service. In the embodiment of the present application, after S901, the SMF may perform the query step, that is, query the AMF whether the UE supports multicast and/or whether the gNB supports multicast.
  • the AMF may obtain the multicast capability information of the UE and/or the multicast capability of the gNB accessed by the UE information.
  • the multicast capability information of the gNB may be reported by the gNB to the AMF when the gNB is powered on; the multicast capability information of the UE may be reported to the AMF when the UE sends a PDU session establishment/modification request to the AMF.
  • the method for transmitting multicast services in the embodiments of the application can ensure that when a UE first applies to join a multicast service, the SMF can determine the multicast capability information according to the multicast capability information of the UE and/or the multicast capability information of the gNB that the UE accesses.
  • the sending method of the multicast service can more effectively deliver the multicast service to the UE, reduce the delay of the UE requesting to join the multicast service, and thereby improve the reliability of the multicast service transmission.
  • the difference between the above method 800 and the method 900 is that in the method 800, the UE requests to join the multicast service through a NAS message, that is, the SMF receives a message from the AMF requesting to join the multicast service; In 900, the UE requests to join the multicast service through the PDU session user plane IGMP join message, that is, the SMF receives a message from the UPF requesting to join the multicast service.
  • FIG. 10 is a schematic flowchart of another method 1000 for transmitting a multicast service according to an embodiment of the present application.
  • the method 1000 can be applied to the system architecture 200 shown in FIG. 2. It should be understood that this embodiment assumes that all UEs support multicast, and the discussion is only based on the capabilities of T-gNB. However, in other possible implementations, the SMF can also make a comprehensive judgment based on the multicast capability information of the UE and/or the multicast capability information of the T-gNB. For the specific method, refer to the above-mentioned embodiments, and will not be repeated here. .
  • the UE switches from the source access network device (referred to as S-gNB in this embodiment) to the target access network device (T-gNB).
  • S-gNB source access network device
  • T-gNB target access network device
  • the S-gNB can learn the multicast capability information of the T-gNB.
  • the T-gNB can send its own multicast capability information to the S-gNB through the Xn interface.
  • T-gNB can send the multicast capability information to S-gNB, and when T-gNB does not support multicast, T-gNB does not send the multicast capability information, so If the S-gNB does not receive the multicast capability information sent by the T-gNB, it can assume that the T-gNB does not support multicast.
  • the UE sends a measurement report to the S-gNB, which is used to indicate the signal measurement result of the UE on the neighboring cell.
  • the S-gNB receives the measurement report, and based on the measurement report, decides to switch the UE to the T-gNB.
  • the S-gNB sends a handover request to the T-gNB for requesting the UE to be handed over to the T-gNB.
  • the T-gNB receives the handover request.
  • the handover request may include PDU session information of the UE to be handed over and information about the multicast service associated with the PDU session.
  • the PDU session information may include the PDU session identifier and the QoS information of the unicast QoS flow of the unicast service associated with the PDU session.
  • the QoS information of the unicast QoS flow may include the QFI and QoS parameters of the unicast QoS flow.
  • the current switching of the UE’s PDU session is associated with the multicast service
  • the S-gNB can map the multicast QoS flow to the QFI of the multicast QoS flow and the QFI of the unicast QoS flow according to the mapping relationship between the QFI of the multicast QoS flow and the QFI of the unicast QoS flow Unicast QoS flow.
  • the unicast QoS flow associated in the PDU session not only includes the unicast QoS flow of the existing unicast service, but also includes the unicast QoS flow to which the above-mentioned multicast QoS flow is mapped.
  • the S-gNB can obtain the mapping relationship between the multicast QoS flow and the unicast QoS flow in the following manner:
  • the S-gNB can obtain the group of the multicast service from the SMF.
  • the mapping relationship may include the QFI of the multicast QoS flow and the QFI of the unicast QoS flow corresponding to the multicast QoS flow.
  • the QFI of the unicast QoS flow corresponding to the multicast QoS flow is different from the QFI of other unicast QoS flows in the PDU session of the UE.
  • the QFIs of the unicast QoS streams corresponding to the multicast QoS streams of different multicast services are different, so as to distinguish the unicast mapped to the current multicast QoS streams of the multicast service.
  • the unicast QoS flow mapped by the QoS flow and the multicast QoS flow of other multicast services are different, so as to distinguish the unicast mapped to the current multicast QoS streams of the multicast service.
  • the aforementioned handover request may also include the service flow identifier that the S-gNB wants to forward through the forwarding tunnel.
  • the S-gNB may include the QFI of the unicast QoS flow corresponding to the multicast QoS flow in the handover request.
  • the reason why the service flow is forwarded through the forwarding tunnel is that after the S-gNB sends a handover command to the UE in the subsequent S1004, the UE will disconnect from the S-gNB until the UE accesses the T-gNB in the next step. Therefore, the data during this period of time cannot be received by the UE through the S-gNB temporarily.
  • the forwarding tunnel is a logical tunnel between the S-gNB and the T-gNB, and the logical tunnel is established based on the physical connection between the S-gNB and the T-gNB.
  • the SMF when the S-gNB sends a handover request to the T-gNB, the SMF first sends the multicast QoS flow of the multicast service associated with the PDU session of the handover UE that is being performed by the S-gNB to the T-gNB.
  • the mapping is a unicast QoS flow.
  • the SMF After the UE accesses the T-gNB, the SMF then makes a judgment based on the multicast capability information of the T-gNB.
  • SMF can restore the multicast QoS flow mapped to the unicast QoS flow to the multicast QoS flow, and send it through the multicast session tunnel of T-gNB; when T-gNB does not support group When broadcasting, the SMF can still deliver the unicast QoS flow corresponding to the multicast QoS flow to the UE through the PDU session tunnel of the T-gNB according to the unicast mode.
  • the SMF first maps the multicast QoS flow of the multicast service associated with the PDU session of the switched UE that is being performed by the S-gNB into a unicast QoS flow, because the UE is accessing S-gNB requests both unicast services and multicast services.
  • unicast services are transmitted in the PDU session tunnel
  • multicast services are transmitted in the multicast session tunnel.
  • the service continuity of the UE can be guaranteed.
  • the so-called service continuity includes the continuity of unicast services and the continuity of multicast services.
  • the UE since the UE switches from S-gNB to T-gNB, if the multicast QoS flow in the S-gNB multicast session tunnel is not mapped to the unicast QoS flow in the PDU session tunnel where the S-gNB PDU session is located If the T-gNB does not support multicast after the handover (that is, the multicast session tunnel cannot be established), then the multicast service of the UE will be interrupted and service continuity cannot be maintained.
  • the multicast QoS flow is mapped to the unicast QoS flow at the S-gNB (that is, before the UE switches to the T-gNB), and the unicast handover is performed, and then the SMF is in the handover process
  • the SMF is in the handover process
  • the T-gNB prepares radio resources for the UE, and sends a handover response to the S-gNB. Correspondingly, the S-gNB receives the handover response.
  • the T-gNB prepares radio resources for the UE according to the service flow description information received from the S-gNB. Since S-gNB receives all unicast service flow description information (including the unicast QoS flow of the unicast service mapped from the multicast QoS flow of the multicast service), the T-gNB can provide the unicast QoS for each unicast service. The stream allocates unicast resources. The T-gNB may send a handover response to the S-gNB after preparing the radio resources. The T-gNB may send the information relayed to the UE through the S-gNB to the S-gNB.
  • the T-gNB may send the radio bearer configuration information of the T-gNB to the UE through the S-gNB. If the above handover request contains the service flow identifier that S-gNB wants to forward through the forwarding tunnel, and T-gNB supports data forwarding, then T-gNB allocates forwarding tunnel identifier (this identifier is used for T-gNB to connect to S-gNB), And in the handover response, the forwarding tunnel identifier is sent to the S-gNB, so as to establish a forwarding tunnel from the S-gNB to the T-gNB for the PDU session of the UE.
  • the T-gNB may also notify the S-gNB which unicast QoS flows in the PDU session support forwarding. Specifically, the T-gNB may send the QFI identifiers of these unicast QoS flows to the S-gNB.
  • the S-gNB sends a handover command to the UE.
  • the UE receives the handover command.
  • the S-gNB can carry the configuration information of the radio bearer in the handover command.
  • the S-gNB stops sending any downlink data to the UE, and for the unicast QoS flow that supports data forwarding, the S-gNB can send the data corresponding to the unicast QoS flow to the T-gNB through the forwarding tunnel.
  • the UE accesses the T-gNB.
  • the UE accesses the T-gNB according to the radio bearer configuration information sent by the T-gNB.
  • the T-gNB sends the forwarded data received from the S-gNB to the UE.
  • the T-gNB sends an N2 path switching request to the AMF, and correspondingly, the AMF receives the N2 path switching request.
  • the N2 path switching request may include the QFI of the unicast QoS flow that is successfully and failed in the PDU session (including the QFI that maps the multicast QoS flow to the unicast QoS flow in the S-gNB).
  • the above-mentioned QFI may be encapsulated in the N2 SM information body.
  • the N2 path switching request may also include indication information of whether the multicast service associated with the PDU session of the UE exists in the T-gNB.
  • the AMF sends a PDU session update request to the SMF, and correspondingly, the SMF receives the PDU session update request.
  • the PDU session update request may include information included in the N2 path switching request.
  • the N2 path switching request includes the indication information of whether the multicast service exists in the T-gNB
  • the PDU session update request may also include the indication information of whether the multicast service exists in the T-gNB, and the SMF can follow this
  • the instruction information determines whether the multicast service associated with the PDU session of the switched UE exists in the T-gNB.
  • the SMF judges whether the T-gNB supports multicast based on the multicast capability information of the T-gNB.
  • the multicast capability information may be carried in the aforementioned PDU session update request.
  • SMF can obtain the multicast capability information of T-gNB through one of the following three methods:
  • the AMF includes the collected multicast capability information of the T-gNB as information elements in the PDU session update request sent by the AMF to the SMF;
  • the AMF can selectively send the multicast capability information of the T-gNB to the SMF based on its own judgment. Specifically, if the UE’s PDU session supports multicast, the AMF sends the T-gNB multicast capability information to the SMF; if the UE’s PDU session does not support multicast, the AMF may not send the T-gNB multicast capability information. Among them, the AMF can learn whether the UE's PDU session supports multicast when the UE applies to join the multicast service (see method 800 or 900 for details).
  • AMF can send the multicast capability information of T-gNB to SMF based on SMF subscription.
  • SMF After SMF receives the multicast capability information of T-gNB sent by AMF, it can first check whether T-gNB supports multicast. If T-gNB does not support multicast, you can execute S1011-S1013; if T-gNB supports multicast , You can perform S1010-S1013.
  • the SMF can also send a request message to the T-gNB to request the transfer
  • the UE joins the multicast service; or, the SMF can request the T-gNB to join the UE to the multicast service after performing this handover procedure; or, the SMF can request the T-gNB at any time after receiving the above PDU session update request
  • the UE is added to the multicast service, which is not limited in the embodiment of the present application.
  • the SMF can delete the PDR formulated for the multicast service associated with the PDU session of the UE, and delete the mapping relationship between the multicast QoS flow and the unicast QoS flow .
  • S1008 The SMF sends a query request to UDM to query whether the multicast service associated with the PDU session of the UE exists in the T-gNB.
  • UDM receives the query request.
  • the SMF can first query whether the multicast service exists in the T-gNB through UDM. If the multicast service does not exist in the T-gNB, while performing S1011-S1013 described below, SMF also interacts with UPF and T-gNB to complete the establishment of the multicast service and join the UE to the multicast service For the specific process, refer to method 800, which will not be repeated here.
  • the SMF can also send a request message to the T-gNB to request the UE to join the multicast service, or the SMF can be executed after this After the handover process, the T-gNB is requested to join the UE to the multicast service.
  • the SMF can request the T-gNB to join the UE to the multicast service at any time after determining that the multicast service already exists in the T-gNB. This embodiment of the application There is no restriction on this.
  • the SMF can delete the PDR formulated for the multicast service associated with the PDU session of the UE, and delete the mapping relationship between the multicast QoS flow and the unicast QoS flow.
  • the SMF sends an N4 session update request to the UPF, notifying the UPF to map the multicast QoS flow of the multicast service to the unicast QoS flow of the unicast service according to the mapping relationship, so that the UPF can multicast QoS through the PDU session tunnel of the PDU session
  • the stream is sent to T-gNB.
  • the SMF has already saved the mapping relationship between the QFI of the multicast QoS flow and the QFI of the unicast QoS flow. For specific operations, refer to the foregoing method 800, which will not be repeated here.
  • the SMF sends a PDU session update response to the AMF.
  • the AMF sends an N2 path switching response to the T-gNB.
  • radio bearer configuration information can be replaced with the configuration information of radio resources, and the radio bearer configuration can be replaced with the configuration of radio resources.
  • the radio resource may include a radio bearer
  • the configuration information of the radio resource may include radio bearer configuration information, which is not limited.
  • the method for transmitting multicast services in the embodiments of the present application can ensure that when the UE switches from S-gNB that supports multicast functions to T-gNB, regardless of whether the T-gNB supports multicast or not, the multicast services of the UE in the S-gNB and Unicast services are not interrupted due to handover, ensuring the service continuity of the UE, and can reduce packet loss during the handover process, thereby reducing the handover delay.
  • the handover process in the embodiment of the present application is based on the improvement of the existing process, and only needs to increase the judgment of the multicast capability of the gNB and the judgment of whether the multicast service associated with the UE's PDU session exists in the T-gNB. It can be backward compatible and easy to implement.
  • FIGS 11 and 12 are schematic diagrams of tunnels for transmitting multicast services provided by embodiments of the present application.
  • the multicast network elements serving the S-gNB’s multicast service are MCF (control plane) and MUF (user plane), then MUF can communicate with the UE’s PDU
  • MCF control plane
  • MUF user plane
  • the T-gNB in Figure 11 supports multicast
  • the T-gNB in Figure 12 does not support multicast.
  • the multicast session tunnel between the UPF and the T-gNB can be established through the above method, and then the multicast service can be delivered to the UE through the multicast session tunnel.
  • T-gNB since T-gNB does not support multicast, there is only a PDU session tunnel between UPF and T-gNB.
  • the multicast QoS flow is mapped to a unicast QoS flow, and the multicast service is delivered through the PDU session tunnel. .
  • FIG. 13 is a schematic flowchart of another method 1300 for transmitting a multicast service according to an embodiment of the present application.
  • the method 1300 can be applied to the system architecture 200 shown in FIG. 2. It should be understood that this embodiment assumes that all UEs support multicast, and the discussion is only based on the capabilities of T-gNB. However, in other possible implementations, the SMF can also make a comprehensive judgment based on the multicast capability information of the UE and/or the multicast capability information of the T-gNB. For the specific method, refer to the above-mentioned embodiments, and will not be repeated here. .
  • the UE switches from the source access network device (referred to as S-gNB in this embodiment) to the target access network device (T-gNB), and both AMF and UPF are switched. That is, the network elements that provide services for S-gNB are S-AMF and S-UPF, and the network elements that provide services for T-gNB are T-AMF and T-UPF.
  • the UE sends a measurement report to the S-gNB, which is used to indicate the signal measurement result of the UE.
  • the S-gNB receives the measurement report, and based on the measurement report, decides to switch the UE to the T-gNB.
  • S1302 The S-gNB sends a handover request to the S-AMF, and the S-AMF is connected to the S-gNB. Correspondingly, S-AMF receives the handover request.
  • the handover request may include the PDU session information of the UE, and the PDU session information includes the PDU session identifier and the QoS information corresponding to the unicast service flow included in the PDU session.
  • the QoS information corresponding to the unicast service flow may include 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 the unicast QoS flow according to the mapping relationship between the multicast QoS flow QFI and the unicast QoS flow QFI.
  • the SMF when the S-gNB sends a handover request to the T-gNB, the SMF first sends the multicast QoS flow of the multicast service associated with the PDU session of the handover UE that is being performed by the S-gNB to the T-gNB.
  • the mapping is a unicast QoS flow.
  • the SMF After the UE accesses the T-gNB, the SMF then makes a judgment based on the multicast capability information of the T-gNB.
  • SMF can restore the multicast QoS flow mapped to the unicast QoS flow into a multicast QoS flow, and deliver it through the multicast session tunnel of T-gNB; when T-gNB supports multicast At this time, the SMF can still deliver the unicast QoS flow corresponding to the multicast QoS flow to the UE through the PDU session tunnel of the T-gNB according to the unicast mode.
  • T-gNB supports multicast
  • the SMF can still deliver the unicast QoS flow corresponding to the multicast QoS flow to the UE through the PDU session tunnel of the T-gNB according to the unicast mode.
  • the S-gNB knows the multicast capability information of the T-gNB.
  • the S-gNB can obtain the multicast capability information of the T-gNB through the Xn connection with the T-gNB and is used to indicate that the multicast service associated with the PDU session with the UE is in the T-gNB.
  • Information about the existence of gNB may also include the multicast capability information of the T-gNB and the multicast capability information used to indicate that the multicast service associated with the PDU session of the UE is in the T- Information about the existence of gNB.
  • the S-AMF can select the T-AMF according to the identity (ID) of the target cell, and the T-AMF is connected to the T-gNB.
  • the S-AMF sends a UE context creation request to the T-AMF, and correspondingly, the T-AMF receives the UE context creation request.
  • the UE context creation request may include the context information of the UE and the PDU session information of the UE stored in the S-AMF, where the PDU session information may include information such as the PDU session identifier, DNN, and S-NSSAI.
  • the UE context creation request may also include the information carried in the handover request in S1302.
  • the S-AMF may also send the association information to the T-AMF.
  • the T-AMF sends a PDU session update request to the SMF, and correspondingly, the SMF receives the PDU session update request.
  • the foregoing PDU session update request may carry T-gNB multicast capability information; T-AMF may send T-gNB multicast capability information to SMF through additional signaling, which is not limited in this embodiment of the application.
  • T-AMF may send the multicast capability information of T-gNB to SMF; or, T-AMF may selectively send the multicast capability information of T-gNB to SMF according to whether the PDU session is associated with a multicast service SMF; or, if SMF subscribes to T-AMF for notification of changes in the multicast capability information of T-gNB, when the multicast capability information of T-gNB changes (for example, T-gNB never supports multicast upgrade to support Multicast), T-AMF can send T-gNB multicast capability information to SMF.
  • S1306 The SMF judges whether to perform UPF reselection.
  • S1307 The SMF judges whether the T-gNB supports multicast.
  • the S-gNB has obtained the multicast capability information of the T-gNB through the Xn connection with the T-gNB and whether the multicast service associated with the PDU session of the UE exists in the T-gNB.
  • the S-gNB can pass the above information to the SMF, and the SMF can know whether the T-gNB supports multicast and whether the multicast service associated with the PDU session of the UE exists in the T-gNB.
  • the SMF can determine whether the T-gNB supports multicast according to the multicast capability information of the T-gNB sent from the T-AMF.
  • the SMF maps the multicast QoS flow to a unicast QoS flow, and switches the unicast QoS flow and other unicast QoS flows to the T-gNB together.
  • the subsequent handover procedure can be referred to the prior art (for example, the N2 handover procedure in 3GPP TS 23.502), which will not be repeated here.
  • the SMF can determine whether the multicast service associated with the PDU session of the UE exists in the T-gNB.
  • the SMF can request the T-gNB to join the UE to the multicast service after the handover procedure ends or at any time during the handover procedure. Since the T-gNB supports multicast and the multicast service exists in the T-gNB, the SMF can request the T-gNB to add the UE to the multicast service at the same time as the unicast service switching or after the unicast switching ends.
  • the SMF can continue to switch the unicast service flow to the T-gNB according to the handover procedure in 3GPP TS 23.502. At the same time, the SMF can also perform one of the following operations:
  • the multicast service since the multicast service does not exist in the T-gNB and the multicast service has been mapped in the S-gNB for the PDU session tunnel where the PDU session is located, it can still pass through the T-gNB
  • the gNB's PDU session tunnel delivers the multicast service.
  • SMF still maps the multicast QoS flow sent by the multicast service source to T-gNB to unicast QoS flow, and switches to T-gNB together with other unicast QoS flows.
  • T-gNB does not support groups The description of the broadcast.
  • SMF can request T-UPF to establish a multicast session tunnel with T-gNB and run the multicast service on T-gNB while switching unicast services, and then request T-gNB to connect The UE joins the multicast service.
  • the SMF may request T-UPF and T-gNB to create a multicast session tunnel and run the multicast service when receiving the T-AMF request message; or, the SMF may also wait until the unicast service switching is completed, and then Request the T-UPF and T-gNB to create a multicast session tunnel and run the associated multicast service, and then request the T-gNB to join the UE to the multicast service.
  • TS is the abbreviation of technical specification
  • 23.502 is the version number of the technical specification.
  • the method for transmitting multicast services in the embodiments of the present application can ensure that when the UE switches from S-gNB that supports multicast functions to T-gNB, regardless of whether the T-gNB supports multicast or not, the multicast services of the UE in the S-gNB and Unicast services are not interrupted due to handover, ensuring the service continuity of the UE, and can reduce packet loss during the handover process, thereby reducing the handover delay.
  • the handover process in the embodiment of the present application is based on the improvement of the existing process, and only needs to increase the judgment of the multicast capability of the gNB and the judgment of whether the multicast service associated with the UE's PDU session exists in the T-gNB. It can be backward compatible and easy to implement.
  • FIGS 14 and 15 are schematic diagrams of tunnels for transmitting multicast services provided by embodiments of the present application.
  • the multicast network elements serving the S-gNB’s multicast service are MCF (control plane) and MUF (user plane), then MUF can communicate with the UE’s PDU
  • MCF control plane
  • MUF user plane
  • the anchor point UPF (PSA-UPF) where the session is located is connected.
  • the anchor point UPF is connected to S-UPF and T-UPF respectively.
  • S-UPF is connected to S-gNB, and T-UPF is connected to T-gNB.
  • An indirect forwarding tunnel can be formed between S-gNB to S-UPF to T-UPF to T-gNB.
  • the T-gNB in Figure 14 supports multicast, and the T-gNB in Figure 15 does not support multicast.
  • the multicast session tunnel between the UPF and the T-gNB can be established by the above method, and then the multicast service can be delivered to the UE through the multicast session tunnel.
  • T-gNB since T-gNB does not support multicast, there is only a PDU session tunnel between UPF and T-gNB.
  • the multicast QoS flow is mapped to a unicast QoS flow, and the multicast service is delivered through the PDU session tunnel. .
  • FIG. 16 is a schematic flowchart of another method 1600 for transmitting a multicast service according to an embodiment of the present application. As shown in Figure 16:
  • S1610 The UE sends a measurement report (measurement report) to the source base station.
  • the measurement report includes the signal measurement strength of multiple (eg, 8) surrounding cells.
  • the source base station can determine the target base station of the UE according to the measurement report. For example, the source base station may determine the target cell with the strongest signal strength as the target cell to which the UE needs to handover, and then determine the base station of the target cell as the target base station.
  • S1620 The source base station sends a handover request (handover request) to the target base station.
  • the handover request may include PDU session information of the UE to be handed over.
  • the PDU session information may include the identifier of the PDU session and the QoS information corresponding to the services included in the PDU session.
  • Services may include unicast services and/or multicast.
  • the PDU session of the UE to be switched is associated with the multicast/broadcast service (that is, the UE has joined the multicast/broadcast service at the source base station), then the PDU session
  • the information may also include QoS information of the multicast/broadcast service corresponding to the associated multicast/broadcast service.
  • the QoS information of the service included in the PDU session may include: the QFI of the unicast QoS flow corresponding to the unicast service, the QoS parameter information corresponding to the QFI of the unicast QoS flow, and/or the multicast/broadcast service corresponding to multicast/ The QFI of the broadcast QoS flow, and the QoS parameter information corresponding to the QFI of the multicast/broadcast QoS flow.
  • the QoS information of the services included in the PDU session includes the QFI of the unicast QoS flow corresponding to the unicast service, and the QoS parameter information corresponding to the QFI of the unicast QoS flow.
  • the QoS information of the services included in the PDU session includes the QFI of the multicast/broadcast QoS flow, and the QFI of the unicast QoS flow corresponding to the QFI of the multicast/broadcast QoS flow (e.g. , The QFI of the mapped unicast QoS flow), the QoS parameter information corresponding to the QFI of the multicast/broadcast QoS flow.
  • the QoS information of the services included in the PDU session includes the QFI of the unicast QoS flow (including the QFI of the multicast/broadcast QoS flow and the corresponding QFI of the unicast QoS flow ( For example, the QFI of the mapped unicast QoS flow, the QoS parameter information corresponding to the QFI of the unicast QoS flow, the QFI of the multicast/broadcast QoS flow, and the QoS parameter information corresponding to the QFI of the multicast/broadcast QoS flow.
  • the QoS parameter corresponding to the QFI of the unicast QoS flow can be used by the base station to configure air interface resources, and the QoS parameter corresponding to the unicast QFI can be indexed by the 5QI.
  • the QoS parameter information corresponding to the QFI of the unicast QoS flow corresponding to the multicast/broadcast service may include: the QFI of the unicast QoS flow corresponding to the QFI of the multicast/broadcast QoS flow, and the QFI of the multicast/broadcast QoS flow The QoS parameter corresponding to the QFI of the unicast QoS flow corresponding to the QFI.
  • the unicast QFI corresponding to the multicast QFI can be understood as the unicast QFI mapped by the multicast QFI.
  • the handover request further includes: the QFI suggested by the source base station for forwarding through the forwarding tunnel and the forwarding tunnel identification information generated by the source base station. For example, if the unicast QoS flow included in the service of the PDU session can be forwarded through the forwarding tunnel corresponding to the PDU session, the handover request includes the unicast QFI corresponding to the unicast QoS flow.
  • the switching request includes the unicast QFI corresponding to the first QoS flow.
  • the unicast QFI can also be understood as the QFI of the unicast QoS flow mapped or corresponding to the QFI of the multicast/broadcast QoS flow.
  • the target base station configures radio resources for the UE according to the handover request.
  • S1630 may include that the target base station prepares or configures radio resources for the UE according to the PDU session information in the handover request. For example, according to the QoS information of the service included in the PDU session in the PDU session information, radio resources are prepared or configured for the UE.
  • wireless resources may include wireless resources used to transmit data of a PDU session, and specifically, wireless resources used to transmit data of a PDU session may include wireless resources used to transmit multicast/broadcast service data.
  • the target base station may correspond to the QFI of each unicast QoS flow (for example, including the QFI of the unicast QoS flow mapped by the multicast QoS flow).
  • QoS parameters determine the number of data radio bearers (DRB) and the mapping relationship between QFI and DRB.
  • the target base station can also determine the configuration of the DRB according to the QoS parameters corresponding to the QFI mapped by each DRB Parameters (for example, whether the PDCP layer corresponding to the DRB is encrypted, whether the radio link control (RLC) layer adopts the confirmed mode or the non-confirmed mode, and the configuration of logical channels, transmission channels, physical channels, modulation and coding methods, etc. ), and finally, the target base station creates a corresponding DRB.
  • the QoS parameters corresponding to the QFI mapped by each DRB Parameters for example, whether the PDCP layer corresponding to the DRB is encrypted, whether the radio link control (RLC) layer adopts the confirmed mode or the non-confirmed mode, and the configuration of logical channels, transmission channels, physical channels, modulation and coding methods, etc.
  • the above method further includes: the target base station sends a handover request ACK (handover request ACK) to the source base station.
  • a handover request ACK handover request ACK
  • the handover request response may include the configuration information of the wireless resource used to transmit the data of the PDU session,
  • the configuration information of the wireless resource may be the configuration information of the wireless data bearer.
  • the configuration parameters corresponding to the above DRB may be the configuration parameters corresponding to the above DRB.
  • the source base station sends the configuration information of the radio resources from the target base station to the UE, which can be specifically implemented by using step S1640.
  • the configuration information of the radio resource can be used for the UE to access the target base station in S1650 described later, and after the UE accesses the target base station, the UE receives the service data contained in the PDU session (for example, the data related to the multicast/broadcast service). ).
  • the source base station sends a handover command (Handover Command) to the UE.
  • the handover command may carry the configuration information of the above-mentioned wireless resource.
  • S1650 The UE sends a handover confirmation (Handover Confirm) to the target base station.
  • the UE may send a handover confirmation to the target base station according to the configuration information of the radio resources.
  • the UE may receive service data included in the PDU session.
  • the target base station receives the handover confirmation, and sends an N2 path switch request (N2 path switch request) or path switch request (path switch request) to the AMF.
  • N2 path switch request N2 path switch request
  • path switch request path switch request
  • the N2 path in the request can include N2 SM Information (N2 SM information), and can also include UE location information, etc.; N2 SM information includes the QFI (including the QFI of the unicast QoS flow for which the handover succeeds and the handover fails in the PDU session).
  • the unicast QFI mapped by the multicast/broadcast QoS flow, the above-mentioned QFI is encapsulated in the N2 SM information), and also contains the identification information of the PDU session tunnel allocated by the target base station.
  • the target base station if the target base station supports multicast/broadcast, the target base station also includes the multicast/broadcast capability information of the target base station in the N2 path switch request or path switch request.
  • the multicast/broadcast capability information of the target base station may be used to indicate whether the target base station supports multicast/broadcast.
  • the capability information may be an indication, a tag, or An information element (IE).
  • whether the target base station supports multicast/broadcast can also be characterized by whether specific information or information elements or tags are carried in the above S1660.
  • carrying the multicast/broadcast capability information of the target base station indicates that the target base station supports multicast/broadcast, but does not carry the multicast/broadcast capability information of the target base station, and indicates that the target base station does not support multicast/broadcast.
  • the capability information may be included in the N2 SM information (N2 SM information) cell, or may be included in the N2 path switch request or the newly added cell in the path switch request.
  • the N2 SM information may be path switch request transfer (path switch request transfer).
  • it carries the multicast/broadcast capability information of the target base station and characterizes whether the target base station supports multicast/broadcast, for example, in a Boolean manner (that is, 1 means support, 0 means not support).
  • S1670 The AMF sends a PDU session context update request to the SMF.
  • the PDU session context update request may be used to request the context of the PDU session, for example, a PDU session context update request (Nsmf_PDUSession_UpdateSMContext Request).
  • the PDU session context update request can carry the multicast/broadcast capability information of the target base station, which indicates that the target base station supports multicast/broadcast, but does not carry the multicast/broadcast capability information of the target base station, and indicates that the target base station does not support multicast/broadcast. .
  • the PDU session context update request includes the multicast/broadcast capability information of the target base station.
  • the PDU session context update request may include the N2 SM information involved in S1660, where the N2 SM information includes the multicast/broadcast capability information of the target base station.
  • the PDU session context update request includes N2
  • the SM information also contains the multicast/broadcast capability information of the target base station.
  • the PDU session context update request may be an example of the "second message" in this application.
  • the SMF determines whether the target base station supports multicast/broadcast according to the PDU session context update request message.
  • the PDU session context update request can carry the multicast/broadcast capability information of the target base station, which indicates that the target base station supports multicast/broadcast, but does not carry the multicast/broadcast capability information of the target base station, and indicates that the target base station does not support multicast/broadcast. .
  • the SMF determines that the sending mode of the multicast service is the multicast mode.
  • the multicast mode may include, but is not limited to, one or more of the following transmission modes:
  • 5GC shared multicast/broadcast service traffic transmission method (5GC Shared MBS traffic delivery method), shared multicast/broadcast service traffic transmission method (Shared MBS traffic delivery method), or shared transmission method (Shared delivery method).
  • the SMF determines that the sending mode of the multicast service is the multicast mode.
  • the SMF determines that the sending mode of the multicast service is unicast.
  • SMF can determine whether the target base station supports multicast/broadcast in the following ways:
  • Manner 1 Determine whether the target base station supports multicast/broadcast according to the multicast/broadcast capability information of the target base station carried in the PDU session context update request in S1670.
  • the multicast/broadcast capability information of the target base station can indicate whether the target base station supports multicast/broadcast, for example, in a Boolean (Boolen) manner, when the multicast/broadcast capability information of the target base station is 1, it means that the target base station supports multicast /Broadcast, when the multicast/broadcast capability information of the target base station is 0, it means that the target base station does not support multicast/broadcast.
  • Boolean Boolean
  • the SMF may determine that the target base station supports multicast/broadcast according to the multicast/broadcast capability information of the target base station.
  • the N2 SM information carried in the PDU session context update request may include the multicast/broadcast capability information of the target base station, and the PDU session context update request may also include the multicast/broadcast capability information of the target base station, which is not limited. .
  • Manner 2 Determine whether the target base station supports multicast/broadcast according to whether the PDU session context update request in S1670 carries the multicast/broadcast capability information of the target base station.
  • the PDU session context update request contains specific information or information elements or tags mentioned in S1660 (for example, multicast/broadcast capability information of the target base station), it is determined that the target base station supports multicast/broadcast.
  • the N2 SM information carried in the PDU session context update request may include the multicast/broadcast capability information of the target base station, and the PDU session context update request may also include the multicast/broadcast capability information of the target base station.
  • the unicast mode may include, but is not limited to, one or more of the following transmission modes:
  • 5GC personal multicast/broadcast service traffic transmission method (5GC Individual MBS (Multicast Broadcast Service) traffic delivery method), personal multicast/broadcast service traffic transmission method (Individual MBS traffic delivery method) or individual delivery method (Individual delivery method).
  • the SMF and anchor UPF serving the PDU session of the handover UE (that is, UPF for Figure 11, Figure 12 and Figure 16 are UPF, for Figure 14 and Figure 15 are PSA-UPF) unchanged.
  • MUF-1 can be connected to the UPF anchor point where the PDU session of the UE is located (that is, the special scenarios shown in Figures 11, 12, 14, 15, and 16).
  • MUF-1 can also be directly connected to the source base station.
  • MUF-1 can also be connected to the source base station through other UPFs (that is, the anchor point UPF of the non-UE PDU session), which is not limited in the embodiment of the present application.
  • the network elements serving the multicast service may be MCF-1 and MUF- 1. It may also be other MCF and MUF.
  • the MUF can be directly connected to the target base station, or it can be connected to the anchor point UPF of the PDU session of the handover UE, or it can be connected to the target base station through other UPF (ie, the anchor point UPF of the non-UE PDU session). The embodiment does not limit this.
  • the embodiment of the present application provides a device for transmitting a multicast service.
  • the device is used to implement the steps or procedures corresponding to the session management network element in the foregoing method embodiment.
  • the device is used to implement the steps or processes corresponding to the access and mobility management network elements in the foregoing method embodiment.
  • the apparatus is used to implement the steps or procedures corresponding to the access network equipment in the foregoing method embodiments.
  • FIG. 17 shows an apparatus 1700 for transmitting a multicast service provided by an embodiment of the present application.
  • the device 1700 includes: a transceiver unit 1710 and a processing unit 1720.
  • the device 1700 may be the session management network element in the foregoing embodiment, or may be a chip in the session management network element.
  • the device 1700 can implement the steps or processes performed by the session management network element corresponding to the above method embodiment, wherein the transceiving unit 1710 is configured to perform operations related to the receiving and sending of the session management network element in the above method embodiment, and the processing unit 1720 is used to perform operations related to the processing of the session management network element in the above method embodiment.
  • the transceiving unit 1710 is used to receive a first message or a second message, the first message is used to request the terminal device to join the multicast service, and the second message is used to update the protocol of the terminal device Data unit PDU session, the PDU session is associated with a multicast service;
  • the processing unit 1720 is configured to: determine the multicast service according to the multicast capability information of the terminal device and/or the multicast capability information of the access network device
  • the multicast capability information of the terminal device is used to indicate whether the terminal device supports multicast, and the multicast capability information of the access network device is used to indicate whether the access network device supports multicast,
  • the access network device is the access network device currently accessed by the terminal device or the target access network device of the terminal device.
  • the processing unit 1720 is specifically configured to: when the transmission mode is a unicast mode, the processing unit is specifically configured to: determine the group according to the multicast service quality QoS information of the multicast service The unicast QoS flow corresponding to the broadcast service; the unicast QoS flow is added to the protocol data unit PDU session of the terminal device, and the unicast QoS flow is used to transmit the data of the multicast service.
  • the processing unit 1720 is further specifically configured to: when the transmission mode is a unicast mode, the processing unit is specifically configured to: according to the QoS information of the multicast service, set the PDU of the terminal device At least one unicast QoS flow is selected from the unicast QoS flow of the session, and the at least one unicast QoS flow is used to transmit the data of the multicast service; the transceiver unit 1710 is also used to send the user plane function network element Correspondence between the packet detection rule of the multicast service and the identifier of the at least one unicast QoS flow.
  • the corresponding relationship is carried in an eighth message, and the eighth message is an N4 session modification request message or PFCP session modification request information.
  • the transceiving unit 1710 is further configured to: send the multicast service information and the quality of service flow index QFI of the unicast QoS flow to the user plane network element; the processing unit 1720 is further configured to: The QoS parameters of the multicast QoS flow determine the QoS parameters of the unicast QoS flow; the transceiver unit 1710 is further configured to: send the QFI of the unicast QoS flow and the unicast QoS flow to the access network device. Broadcast the QoS parameters of the QoS flow.
  • the processing unit 1720 is specifically configured to: when the sending mode is a multicast mode, the transceiving unit is further configured to send the service identifier of the multicast service to the access network device.
  • the transceiving unit 1710 is further configured to send information about the multicast QoS flow of the multicast service to the access network device.
  • processing unit 1720 is further configured to: before sending the third message to the access network device, determine that the access network device has the multicast service.
  • the transceiving unit 1710 is further configured to: receive a fourth message from a unified data management network element, where the fourth message is used to indicate that the access network device has the multicast service; the processing unit 1720 is specifically configured to: determine, according to the fourth message, that the access network device has the multicast service.
  • the processing unit 1720 is further configured to: before sending the third message to the access network device, determine that the access network device does not have the multicast service; the transceiving unit 1710 is further configured to : Sending information about the multicast QoS flow of the multicast service to the access network device; receiving indication information from the access network device for indicating that the radio bearer corresponding to the multicast QoS flow is successfully created.
  • the transceiver unit 1710 is further configured to: according to the instruction information, send a fifth message to the unified data management network element, where the fifth message is used to indicate that the multicast service is in the access network device Already exists in.
  • the processing unit 1720 is further configured to: determine the unicast QoS flow corresponding to the multicast QoS flow; the transceiving unit 1710 is further configured to: send the first mapping relationship to the access network device The first mapping relationship is used to indicate the corresponding relationship between the QFI of the multicast QoS flow and the QFI of the unicast QoS flow.
  • the transceiving unit 1710 is further configured to receive multicast capability information of the terminal device and/or multicast capability information of the access network device from the access and mobility management network element.
  • the transceiving unit 1710 is further configured to: before receiving the multicast capability information of the terminal device and/or the multicast capability information of the access network device from the access and mobility management network element, Send a request message to the access and mobility management network element, where the request message is used to request the multicast capability information of the terminal device and/or the multicast capability information of the access network device.
  • processing unit 1720 is further configured to: before sending a request message to the access and mobility management network element, determine that the PDU session of the terminal device supports multicast.
  • the transceiving unit 1710 is further configured to: send a subscription message to the access and mobility management network element, where the subscription message is used by the mobility management network element in the terminal device and/or where When the multicast capability of the access network device changes, the multicast capability information of the terminal device and/or the multicast capability information of the access network device is sent to the session management network element.
  • the transceiving unit 1710 is further configured to: receive the first message from an access and mobility management network element; or, receive the first message from a user plane network element.
  • the device 1700 may be the access and mobility management network element in the foregoing embodiment, or may be a chip in the access and mobility management network element.
  • the device 1700 can implement the steps or processes performed by the access and mobility management network element in the above method embodiment, wherein the transceiver unit 1710 is configured to execute the access and mobility management network element in the above method embodiment
  • the processing unit 1720 is configured to perform operations related to the processing of accessing the mobility management network element in the foregoing method embodiment.
  • the processing unit 1720 is configured to obtain multicast capability information of a terminal device and/or multicast capability information of an access network device, and the multicast capability information of the terminal device is used to indicate that the terminal device Whether to support multicast, the multicast capability information of the access network device is used to indicate whether the access network device supports multicast, the access network device is the access network device currently accessed by the terminal device, or The target access network device of the terminal device; the transceiving unit 1710 is configured to send the multicast capability information of the terminal device and/or the multicast capability information of the access network device to the session management network element.
  • the processing unit is further configured to: before sending the multicast capability information of the terminal device and/or the multicast capability information of the access network device to the session management network element, determine the The protocol data unit PDU session supports multicast, and the terminal device accesses the access network device.
  • the transceiving unit 1710 is further configured to: receive reference information of the PDU session from the terminal device, where the reference information includes indication information for indicating whether the PDU session supports multicast, the One or more of the data network name of the PDU session DNN and the single network slice selection auxiliary information S-NSSAI of the PDU session; the processing unit 1720 is further configured to: determine the PDU session according to the reference information Support multicast.
  • the transceiving unit 1710 is further configured to: receive a request message from the session management network element, where the request message is used to request multicast capability information of the terminal device and/or the access network device Multicast capability information.
  • the transceiving unit 1710 is further configured to receive a subscription message from the session management network element, and the subscription request message is used by the mobility management network element in the terminal device and/or the interface.
  • the multicast capability of the network access device changes, the multicast capability information of the terminal device and/or the multicast capability information of the access network device is sent to the session management network element.
  • the multicast capability information of the access network device is carried in the next generation NG establishment request message.
  • the multicast capability information of the terminal device is carried in a PDU session establishment/modification request message.
  • the apparatus 1700 may be the access network device in the foregoing embodiment, or may be a chip in the access network device.
  • the apparatus 1700 can implement the steps or processes performed by the access network equipment in the above method embodiment, wherein the transceiver unit 1710 is configured to perform operations related to the transmission and reception of the access network equipment in the above method embodiment, and the processing unit 1720 is used to perform operations related to the processing of the access network device in the above method embodiment.
  • the processing unit 1720 is used to obtain the multicast capability information of the access network device; the transceiving unit 1710 is used to send the multicast capability information of the access network device, and the The multicast capability information is used to indicate whether the device supports multicast.
  • the transceiving unit 1710 is specifically configured to send the multicast capability information to an access and mobility management network element or an adjacent access network device of the access network device.
  • the transceiver unit 1710 is further configured to: receive a handover request message from another access network device, the handover request message including the identifier of the protocol data unit PDU session of the terminal device, and the PDU session is associated with multicast Service; Send indication information to a core network device, where the indication information is used to indicate whether the access network device has the multicast service.
  • the device 1700 here is embodied in the form of a functional unit.
  • the term "unit” here can refer to application specific integrated circuits (ASICs), electronic circuits, processors used to execute one or more software or firmware programs (such as shared processors, proprietary processors, or groups). Processor, etc.) and memory, merged logic circuits, and/or other suitable components that support the described functions.
  • ASICs application specific integrated circuits
  • the apparatus 1700 may be specifically the session management network element in the foregoing embodiment, and may be used to execute each process and/or session management network element corresponding to the session management network element in the foregoing method embodiment.
  • the apparatus 1700 may be specifically the access and mobility management network element in the foregoing embodiment, and may be used to execute each process and/or step corresponding to the access and mobility management network element in the foregoing method embodiment, Alternatively, the apparatus 1700 may be specifically the access network device in the foregoing embodiment, and may be used to execute each process and/or step corresponding to the access network device in the foregoing method embodiment. To avoid repetition, details are not described herein again.
  • the apparatus 1700 of each of the foregoing solutions has the function of implementing the corresponding steps performed by the session management network element in the foregoing method, or the apparatus 1700 of each of the foregoing solutions has the function of implementing the corresponding steps performed by the access and mobility management network element in the foregoing method.
  • Function, or, the apparatus 1700 of each of the foregoing solutions has the function of implementing the corresponding steps performed by the access network device in the foregoing method.
  • the function can be realized by hardware, or by hardware executing corresponding software.
  • the hardware or software includes one or more modules corresponding to the above functions; for example, the transceiver unit can be replaced by a transceiver (for example, the sending unit in the transceiver unit can be replaced by a transmitter, and the receiving unit in the transceiver unit can be replaced by a receiver.
  • Machine replacement other units, such as processing units, etc., can be replaced by processors to perform the transceiver operations and related processing operations in each method embodiment respectively.
  • the above-mentioned transceiving unit may also be a transceiving circuit (for example, it may include a receiving circuit and a transmitting circuit), and the processing unit may be a processing circuit.
  • the device in FIG. 17 may be the network element or device in the foregoing embodiment, or may be a chip or a chip system, for example, a system on chip (SoC).
  • the transceiver unit may be an input/output circuit or a communication interface; the processing unit is a processor, microprocessor, or integrated circuit integrated on the chip. There is no limitation here.
  • FIG. 18 shows another apparatus 1800 for transmitting a multicast service provided by an embodiment of the present application.
  • the device 1800 includes a processor 1810 and a transceiver 1820.
  • the processor 1810 and the transceiver 1820 communicate with each other through an internal connection path, and the processor 1810 is used to execute instructions to control the transceiver 1820 to send signals and/or receive signals.
  • the device 1800 may further include a memory 1830, and the memory 1830, the processor 1810, and the transceiver 1820 communicate with each other through an internal connection path.
  • the memory 1830 is used to store instructions, and the processor 1810 can execute the instructions stored in the memory 1830.
  • the apparatus 1800 is configured to implement each process and step corresponding to the session management network element in the foregoing method embodiment.
  • the apparatus 1800 is configured to implement each process and step corresponding to the access and mobility management network element in the foregoing method embodiment.
  • the apparatus 1800 is configured to implement each process and step corresponding to the access network device in the foregoing method embodiment.
  • the apparatus 1800 may be specifically a session management network element, an access and mobility management network element, or an access network device in the foregoing embodiment, or may be a chip or a chip system.
  • the transceiver 1820 may be the transceiver circuit of the chip, which is not limited here.
  • the apparatus 1800 may be used to execute the steps and/or processes corresponding to the session management network element, the access and mobility management network element, or the access network equipment in the foregoing method embodiment.
  • the memory 1830 may include a read-only memory and a random access memory, and provide instructions and data to the processor. A part of the memory may also include a non-volatile random access memory.
  • the memory can also store device type information.
  • the processor 1810 may be used to execute instructions stored in the memory, and when the processor 1810 executes the instructions stored in the memory, the processor 1810 is used to execute the above-mentioned session management network element, access and mobility management network element Or each step and/or process of the method embodiment corresponding to the access network device.
  • each step of the above method can be completed by an integrated logic circuit of hardware in the processor or instructions in the form of software.
  • the steps of the method disclosed in combination with the embodiments of the present application may be directly embodied as being executed and completed by a hardware processor, or executed and completed by a combination of hardware and software modules in the processor.
  • the software module can be located in a mature storage medium in the field, such as random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, registers.
  • the storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware. To avoid repetition, it will not be described in detail here.
  • the processor in the embodiment of the present application may be an integrated circuit chip with signal processing capability.
  • the steps of the foregoing method embodiments may be completed by hardware integrated logic circuits in the processor or instructions in the form of software.
  • the above-mentioned processor may be a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components .
  • DSP digital signal processor
  • ASIC application specific integrated circuit
  • FPGA field programmable gate array
  • the methods, steps, and logical block diagrams disclosed in the embodiments of the present application can be implemented or executed.
  • the general-purpose processor may be a microprocessor or the processor may also be any conventional processor or the like.
  • the steps of the method disclosed in the embodiments of the present application may be directly embodied as being executed and completed by a hardware decoding processor, or executed and completed by a combination of hardware and software modules in the decoding processor.
  • the software module can be located in a mature storage medium in the field, such as random access memory, flash memory, read-only memory, programmable read-only memory, or electrically erasable programmable memory, registers.
  • the storage medium is located in the memory, and the processor reads the information in the memory and completes the steps of the above method in combination with its hardware.
  • the memory in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memory.
  • the non-volatile memory can be read-only memory (ROM), programmable read-only memory (programmable ROM, PROM), erasable programmable read-only memory (erasable PROM, EPROM), and electrically available Erase programmable read-only memory (electrically EPROM, EEPROM) or flash memory.
  • the volatile memory may be random access memory (RAM), which is used as an external cache.
  • RAM random access memory
  • static random access memory static random access memory
  • dynamic RAM dynamic RAM
  • DRAM dynamic random access memory
  • synchronous dynamic random access memory synchronous DRAM, SDRAM
  • double data rate synchronous dynamic random access memory double data rate SDRAM, DDR SDRAM
  • enhanced synchronous dynamic random access memory enhanced SDRAM, ESDRAM
  • synchronous connection dynamic random access memory serial DRAM, SLDRAM
  • direct rambus RAM direct rambus RAM
  • the present application also provides a computer program product.
  • the computer program product includes: computer program code.
  • the computer program code runs on a computer, the computer executes the steps shown in FIGS. 5 to 16. In the illustrated embodiment, each step or process performed by the session management network element, the access and mobility management network element, or the access network device.
  • the present application also provides a computer-readable storage medium that stores program code, and when the program code runs on a computer, the computer executes FIGS. 5 to 16 In the illustrated embodiment, each step or process performed by the session management network element, the access and mobility management network element, or the access network device.
  • the present application also provides a communication system, which includes the aforementioned session management network element, access and mobility management network element, and access network equipment.
  • the computer program product includes one or more computer instructions.
  • the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.
  • the computer instructions may be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website, computer, server, or data center.
  • the computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server or a data center integrated with one or more available media.
  • the usable medium may be a magnetic medium (for example, a floppy disk, a hard disk, and a magnetic tape), an optical medium (for example, a high-density digital video disc (digital video disc, DVD)), or a semiconductor medium (for example, a solid state disk (solid state disc), SSD)) etc.
  • the network equipment in each of the above-mentioned device embodiments corresponds completely to the network equipment or terminal equipment in the terminal equipment and method embodiments, and the corresponding modules or units execute the corresponding steps.
  • the transceiver unit performs the receiving or In the sending step, other steps except sending and receiving can be executed by the processing unit (processor).
  • the processing unit processor
  • the functions of specific units refer to the corresponding method embodiments. Among them, there may be one or more processors.
  • component used in this specification are used to denote computer-related entities, hardware, firmware, a combination of hardware and software, software, or software in execution.
  • the component may be, but is not limited to, a process, a processor, an object, an executable file, an execution thread, a program, and/or a computer running on a processor.
  • the application running on the computing device and the computing device can be components.
  • One or more components may reside in processes and/or threads of execution, and components may be located on one computer and/or distributed between two or more computers.
  • these components can be executed from various computer-readable storage media having various data structures stored thereon.
  • the component can be based on, for example, a signal having one or more data packets (e.g. data from two components interacting with another component in a local system, a distributed system, and/or a network, such as the Internet that interacts with other systems through a signal) Communicate through local and/or remote processes.
  • a signal having one or more data packets (e.g. data from two components interacting with another component in a local system, a distributed system, and/or a network, such as the Internet that interacts with other systems through a signal) Communicate through local and/or remote processes.
  • At least one in this document refers to one or more, and “plurality” refers to two or more than two.
  • “And/or” describes the association relationship of the associated objects, indicating that there can be three relationships, for example, A and/or B, which can mean: A alone exists, A and B exist at the same time, and B exists alone, where A, B can be singular or plural.
  • the character “/” generally indicates that the associated objects before and after are in an “or” relationship.
  • the following at least one item (a) or similar expressions refers to any combination of these items, including any combination of a single item (a) or a plurality of items (a).
  • At least one of a, b, and c can mean: a, or b, or c, or a and b, or a and c, or b and c, or a, b and c, where a, b, c can be single or multiple.
  • the disclosed system, device, and method can be implemented in other ways.
  • the device embodiments described above are only illustrative.
  • the division of the units is only a logical function division, and there may be other divisions in actual implementation, for example, multiple units or components may be combined or It can be integrated into another system, or some features can be ignored or not implemented.
  • the displayed or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, 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 the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solutions of the embodiments.
  • the functional units in the various embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units may be integrated into one unit.
  • each functional unit may be implemented in whole or in part by software, hardware, firmware, or any combination thereof.
  • software When implemented by software, it can be implemented in the form of a computer program product in whole or in part.
  • the computer program product includes one or more computer instructions (programs).
  • programs When the computer program instructions (programs) are loaded and executed on the computer, the processes or functions described in the embodiments of the present application are generated in whole or in part.
  • the computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices.
  • the computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium.
  • the computer instructions may be transmitted from a website, computer, server, or data center. Transmission to another website, computer, server or data center via wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.).
  • the computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server or a data center integrated with one or more available media.
  • the usable medium may be a magnetic medium (for example, a floppy disk, a hard disk, and a magnetic tape), an optical medium (for example, a DVD), or a semiconductor medium (for example, a solid state disk (SSD)).
  • the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium.
  • the technical solution of the present application essentially or the part that contributes to the existing technology or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including Several instructions are used to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in the various embodiments of the present application.
  • the aforementioned storage media include: U disk, mobile hard disk, read-only memory (read-only memory, ROM), random access memory (random access memory, RAM), magnetic disks or optical disks and other media that can store program codes. .

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Abstract

本申请提供了一种传输组播业务的方法和装置，能够在无论系统中是否存在支持组播的设备的情况下，实现组播业务的传输，从而提高组播业务传输的灵活性和可靠性。该方法包括：会话管理网元接收第一消息或第二消息，该第一消息用于请求将终端设备加入组播业务，该第二消息用于更新该终端设备的协议数据单元PDU会话，该PDU会话关联组播业务；会话管理网元根据终端设备的组播能力信息和/或接入网设备的组播能力信息，确定该组播业务的发送方式，该接入网设备为该终端设备当前接入的接入网设备或者该终端设备的目标接入网设备。

Description

传输组播业务的方法和装置
本申请要求于2020年02月21日提交中国专利局、申请号为202010107929.X、申请名称为“传输组播业务的方法和装置”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，并且更具体地，涉及通信领域中的传输组播业务的方法和装置。
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终端与移动互联网收看热点节目，因此，视频业务对移动网络的冲击愈发强烈，若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，组播方案的推广遇到了较大的困难。具体地，现有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，不但增加了运营商角的开销，还提高了终端的复杂度。
在第5代(the 5th generation，5G)移动通信技术以及未来的其他移动通信技术中，亟需提供一种方法以克服上述困难。
发明内容
本申请提供一种传输组播业务的方法和装置，能够在无论系统中是否存在支持组播的设备的情况下，实现组播业务的传输，从而提高组播业务传输的灵活性和可靠性。
第一方面，提供了一种传输组播业务的方法，包括：会话管理网元接收第一消息或第二消息，所述第一消息用于请求将终端设备加入组播业务，所述第二消息用于更新所述终端设备的协议数据单元PDU会话，所述PDU会话关联组播业务；所述会话管理网元根据所述终端设备的组播能力信息和/或接入网设备的组播能力信息，确定所述组播业务的发送方式，所述终端设备的组播能力信息用于表示所述终端设备是否支持组播，所述接入网设备的组播能力信息用于表示所述接入网设备是否支持组播，所述接入网设备为所述终端设备当前接入的接入网设备或者所述终端设备的目标接入网设备。
所述接入网设备支持组播是指接入网设备的空口支持点到多点的传输。所述终端设备支持组播是指该终端设备支持通过空口组播模式接收组播业务。
在本申请实施例中，会话管理网元可以在终端设备请求加入组播业务或者请求更新PDU会话时，根据该终端设备的组播能力信息和/或接入网设备的组播能力信息，确定组播业务的发送方式，从而更有效地为终端设备下发组播业务，提高组播业务传输的灵活性 和可靠性。
示例性地，在终端设备初始加入组播业务时，接入与移动性管理网元可以向会话管理网元发送上述第一消息，用于请求将终端设备加入组播业务。示例性地，在终端设备从源接入网设备切换至目标接入网设备的场景下，接入与移动性管理网元可以向会话管理网元发送上述第二消息，用于对PDU会话进行更新。应理解，终端设备从源接入网设备切换至目标接入网设备本质上是指将终端设备的PDU会话从源接入网设备切换至目标接入网设备。换句话说，“切换终端设备的PDU会话”是指因为终端设备由源接入网设备向目标接入网设备移动时，为了保持业务的连续性，该终端设备的PDU会话可以从源接入网设备切换到目标接入网设备。
结合第一方面，在第一方面的某些实现方式中，当所述发送方式为单播方式时，所述方法还包括：所述会话管理网元根据所述组播业务的组播服务质量QoS信息，确定所述组播业务的服务数据流(Service data flow,SDF)对应的单播QoS流；所述会话管理网元在所述终端设备的协议数据单元PDU会话中增加所述单播QoS流，所述单播QoS流用于传输所述组播业务的数据。
其中，所述组播业务的服务质量QOS信息可以包括组播业务的组播QoS流的QoS流标识(QoS flow identification,QFI)，组播QoS流对应的服务数据流(Service data flow,SDF)，组播QoS流的QFI对应的QoS参数，例如，5G QoS指示符(5G QoS identifier,5QI)(代表一组QoS参数，包括带宽、时延抖动、等)、分配保留优先级(Allocation retention priority,ARP)、保证的比特速率(Guaranteed bit rate,GBR)、最大比特速率(Maximum bit rate,MBR)、QoS通知控制(QoS notification control,QNC)，等。
具体而言，若上述终端设备不支持组播和/或接入网设备不支持组播，则组播业务的发送方式为单播方式。在这种情况下，会话管理网元可以将组播业务的组播QoS流映射到单播QoS流，从而在PDU会话中增加该单播QoS流，以便后续通过单播方式为该终端设备下发该组播业务。关于将组播业务的组播QoS流映射到单播QoS流，即为建立组播QoS流与单播QoS流之间的对应关系，以便采用该单播QoS流传递该组播业务。应理解，为了便于区分，会话管理网元所确定的单播QoS流的QFI不能与已有的单播QoS流的QFI相同。根据组播QoS流的QFI确定单播QoS流的QFI的过程即可以称为映射，本申请实施例将组播QoS流的QFI与单播QoS流的QFI之间的对应关系称为第一映射关系。
结合第一方面，在第一方面的某些实现方式中，当所述发送方式为单播方式时，所述方法还包括：所述会话管理网元根据所述组播业务的QoS信息，在所述终端设备的PDU会话的单播QoS流中选择至少一个单播QoS流，所述至少一个单播QoS流用于传输所述组播业务的数据；所述会话管理网元向用户面功能网元发送所述组播业务的数据包检测规则与所述至少一个单播QoS流的标识之间的对应关系。
结合第一方面，在第一方面的某些实现方式中，所述对应关系携带于第八消息中，所述第八消息为N4会话修改请求或报文转发控制协议PFCP会话修改请求。
其中，对应关系可以为所述的第八消息同时包含所述组播业务的数据包检测规则(PDR,Packet Detection Rule)，与所述组播业务的数据包检测规则对应的所述至少一个单播QoS流的标识，可以用于表征所述组播业务的数据包检测规则与所述至少一个单播QoS流的标识之间对应关系。
结合第一方面，在第一方面的某些实现方式中，所述会话管理网元在所述终端设备的PDU会话中增加所述单播QoS流，包括：所述会话管理网元向用户面网元发送所述组播业务的信息和所述单播QoS流的QFI；所述会话管理网元根据所述组播QoS流的QoS参数，确定所述单播QoS流的QoS参数；所述会话管理网元向所述接入网设备发送所述单播QoS流的QFI和所述单播QoS流的QoS参数。
在一种可能的实现方式中，该组播业务的信息可以包括组播业务的目的地址，可选地，还可以包括源地址或端口号中的至少一项。
在另一种可能的实现方式中，该组播业务通过另一个用户面网元发送给当前的用户面网元，那么会话管理网元还将该另一个用户面网元的隧道标识(便于当前的用户面网元与其进行连接)发送给当前的用户面网元。在这种情况下，该组播业务的信息可以包括另一个用户面网元的隧道标识。
结合第一方面，在第一方面的某些实现方式中，当所述发送方式为组播方式时，所述方法还包括：所述会话管理网元向所述接入网设备发送所述组播业务的业务标识。
具体而言，若终端设备支持组播，并且接入网设备支持组播，则组播业务的发送方式为组播方式。在这种情况下，会话管理网元可以请求接入网设备将终端设备加入组播业务，以便后续通过组播方式为该终端设备下发该组播业务。
结合第一方面，在第一方面的某些实现方式中，所述方法还包括：所述会话管理网元向所述接入网设备发送所述组播业务的组播QoS流的信息。
结合第一方面，在第一方面的某些实现方式中，在所述会话管理网元向所述接入网设备发送所述组播业务的业务标识之前，所述方法还包括：所述会话管理网元确定所述接入网设备存在所述组播业务。
应理解，组播业务在接入网设备可能存在，也可能不存在(需要创建)，因此，在一种可能的实现方式中，会话管理网元可以先判断接入网设备是否存在该组播业务，若接入网设备存在该组播业务，该会话管理网元再请求该接入网设备将该终端设备加入该组播业务；若该接入网设备不存在该组播业务，该会话管理网元可以先请求该接入网设备创建该组播业务，在该组播业务创建完成之后，该会话管理网元再请求该接入网设备将该终端设备加入该组播业务。
在另一种可能的实现方式中，会话管理网元可以不作任何判断，在请求该接入网设备将该终端设备加入该组播业务的同时，向该接入网设备发送该组播业务的组播QoS流的信息。这样，即使该接入网设备上不存在该组播业务，该接入网设备也可以根据该组播QoS流的信息，为该终端设备创建该组播业务，再将该终端设备加入该组播业务。
在本申请实施例中，会话管理网元可以通过多种方式确定接入网设备是否存在该组播业务，本申请实施例对此不作限定。
结合第一方面，在第一方面的某些实现方式中，所述会话管理网元确定所述接入网设备存在所述组播业务，包括：所述会话管理网元接收来自统一数据管理网元的第四消息，所述第四消息用于指示所述接入网设备存在所述组播业务；所述会话管理网元根据所述第四消息，确定所述接入网设备存在所述组播业务。
会话管理网元可以通过统一数据管理网元确定该接入网设备是否存在该组播业务。示例性地，统一数据管理网元可以自主(例如周期性地)向会话管理网元发送上述第四消息， 将接入网设备上存在的组播业务的信息告知会话管理网元。示例性地，会话管理网元可以向统一数据管理网元查询，即向统一数据管理网元发送查询消息，查询当前终端设备请求加入的组播业务是否在该终端设备所接入的接入网设备上存在，会话管理网元接收统一数据管理网元反馈的查询结果(即上述第四消息)，根据该查询结果即可确定该接入网设备是否存在该组播业务。可选地，在会话管理网元向统一数据管理网元发送查询消息的情况下，统一数据管理网元可以不反馈查询结果，会话管理网元在一段时间内未收到查询结果则默认该接入网设备不存在该组播业务(或者，默认该接入网设备存在该组播业务)，但本申请实施例对此不作限定。
结合第一方面，在第一方面的某些实现方式中，在所述会话管理网元向所述接入网设备发送所述组播业务的业务标识之前，所述方法还包括：所述会话管理网元确定所述接入网设备不存在所述组播业务；所述会话管理网元向所述接入网设备发送所述组播业务的组播QoS流的信息；所述会话管理网元接收来自所述接入网设备的用于指示所述组播QoS流对应的组播业务创建成功的指示信息。
具体而言，若接入网设备不存在该终端设备请求加入的组播业务，该会话管理网元可以向接入网设备发送该组播业务的组播QoS流的信息，该组播QoS流的信息可以包括该组播QoS流的QFI和组播QoS流的QoS参数。接入网设备在接收到该组播QoS流的信息之后，便可以根据该组播QoS流的信息创建相应的组播业务，为后续将终端设备加入该组播业务做准备。
结合第一方面，在第一方面的某些实现方式中，所述方法还包括：所述会话管理网元根据所述指示信息，向统一数据管理网元发送第五消息，所述第五消息用于指示所述组播业务在所述接入网设备中已经存在。
在上述接入网设备不存在该终端设备请求加入的组播业务，且会话管理网元已经创建了该组播业务的情况下，该会话管理网元可以通知统一数据管理网元该组播业务已经存在。上述第五消息中可以携带组播业务的标识和接入网设备的标识。
结合第一方面，在第一方面的某些实现方式中，所述方法还包括：所述会话管理网元确定所述组播QoS流对应的单播QoS流；所述会话管理网元向所述接入网设备发送所述第一映射关系，所述第一映射关系用于表示所述组播QoS流的QFI和所述单播QoS流的QFI之间的对应关系。
具体而言，在接入网设备支持组播的情况下，会话管理网元也可以生成组播QoS流的QFI与单播QoS流的QFI的映射关系，但无需修改PDU会话(即无需在PDU会话中新增该单播QoS流)。
这是因为存在一种场景是终端设备所接入的接入网设备支持组播，即组播业务通过组播会话隧道中下发，单播业务通过PDU会话所在的PDU会话隧道中下发。然而，终端设备具有移动性，后续终端设备存在移动到另一接入网设备的可能，该另一接入网设备可能不支持组播。为了避免由于另一接入网设备不支持组播而导致终端设备从接入网设备切换至另一接入网设备时组播业务的传输不连续的问题，因此，会话管理网元可以提前存储上述组播QoS流的QFI和单播QoS流的QFI之间映射关系，以便该会话管理网元在得知终端设备将要切换到的另一接入网设备不支持组播时，通知用户面网元将组播业务映射到PDU会话所在的PDU会话隧道中下发给终端设备，从而保证组播业务的连续性。
结合第一方面，在第一方面的某些实现方式中，所述方法还包括：所述会话管理网元接收来自接入与移动性管理网元的所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
结合第一方面，在第一方面的某些实现方式中，在所述会话管理网元接收来自接入与移动性管理网元的所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息之前，所述方法还包括：所述会话管理网元向所述接入与移动性管理网元发送请求消息，所述请求消息用于请求所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
结合第一方面，在第一方面的某些实现方式中，在所述会话管理网元向所述接入与移动性管理网元发送请求消息之前，所述方法还包括：所述会话管理网元确定所述终端设备的PDU会话支持组播。
具体而言，上述接入网设备的组播能力信息可以是会话管理网元请求接入与移动性管理网元发送的。进一步地，可选地，会话管理网元可以在PDU会话支持组播的情况下，请求接入与移动性管理网元发送终端设备的组播能力信息和/或接入网设备的组播能力信息。PDU会话是否支持组播，可以根据DNN(例如，通过该DNN可访问组播业务)、S-NSSAI(例如，EMBB切片就可能支持访问组播业务)、组播业务指示信息(例如，PDU会话支持的组播业务标识)中的至少一项进行判断。
结合第一方面，在第一方面的某些实现方式中，所述方法还包括：所述会话管理网元向所述接入与移动性管理网元发送订阅消息，所述订阅消息用于所述移动性管理网元在所述终端设备和/或所述接入网设备的组播能力改变时向所述会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
具体地，上述终端设备的组播能力信息和/或上述接入网设备的组播能力信息可以是会话管理网元通过订阅获取的。即会话管理网元向接入与移动性管理网元发送订阅消息，该订阅消息用于移动性管理网元在终端设备的能力改变和/或接入网设备的能力改变时向会话管理网元发送终端设备的组播能力信息和/或接入网设备的组播能力信息。则对应地，接入与移动性管理网元接收来自会话管理网元的订阅消息，并在终端设备和/或接入网设备的能力改变时向该会话管理网元发送终端设备的组播能力信息和/或接入网设备的组播能力信息。示例性地，在终端设备的能力改变时，接入与移动性管理网元可以向会话管理网元发送该终端设备的组播能力信息；在接入网设备的能力改变时，接入与移动性管理网元可以向会话管理网元发送该接入网设备的组播能力信息；在终端设备的能力与接入网设备的能力都改变时，接入与移动性管理网元可以向会话管理网元发送该终端设备的组播能力信息和该接入网设备的组播能力信息。
结合第一方面，在第一方面的某些实现方式中，所述会话管理网元接收第一消息，包括：所述会话管理网元接收来自接入与移动性管理网元的所述第一消息；或者，所述会话管理网元接收来自用户面网元的所述第一消息。
第二方面，提供了另一种传输组播业务的方法，包括：接入与移动性管理网元获取终端设备的组播能力信息和/或接入网设备的组播能力信息，所述终端设备的组播能力信息用于表示所述终端设备是否支持组播，所述接入网设备的组播能力信息用于表示所述接入网设备是否支持组播，所述接入网设备为所述终端设备当前接入的接入网设备或者所述终 端设备的目标接入网设备；所述接入与移动性管理网元向会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
结合第二方面，在第二方面的某些实现方式中，在所述接入与移动性管理网元向会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息之前，所述方法还包括：所述接入与移动性管理网元确定所述终端设备的PDU会话支持组播。
结合第二方面，在第二方面的某些实现方式中，所述接入与移动性管理网元确定终端设备的PDU会话支持组播，包括：所述接入与移动性管理网元接收来自所述终端设备的所述PDU会话的参考信息，所述参考信息包括用于指示所述PDU会话是否支持组播的指示信息、所述PDU会话的数据网络名称DNN、所述PDU会话的单网络切片选择辅助信息S-NSSAI中的一项或多项；所述接入与移动性管理网元根据所述参考信息，确定所述PDU会话支持组播。
结合第二方面，在第二方面的某些实现方式中，所述方法还包括：所述接入与移动性管理网元接收来自所述会话管理网元的请求消息，所述请求消息用于请求所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
结合第二方面，在第二方面的某些实现方式中，所述方法还包括：所述接入与移动性管理网元接收来自所述会话管理网元的订阅消息，所述订阅请求消息用于所述移动性管理网元在所述终端设备和/或所述接入网设备的组播能力改变时向所述会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
结合第二方面，在第二方面的某些实现方式中，所述接入网设备的组播能力信息携带在下一代NG建立请求消息中。
结合第二方面，在第二方面的某些实现方式中，所述终端设备的组播能力信息携带在PDU会话建立/修改请求消息中。
第三方面，提供了另一种传输组播业务的方法，包括：接入网设备获取所述接入网设备的组播能力信息；所述接入网设备发送所述接入网设备的组播能力信息，所述组播能力信息用于表示所述接入网设备是否支持组播。
结合第三方面，在第三方面的某些实现方式中，所述接入网设备发送所述接入网设备的组播能力信息，包括：所述接入网设备向接入与移动性管理网元或所述接入网设备的相邻接入网设备发送所述组播能力信息。
结合第三方面，在第三方面的某些实现方式中，所述方法还包括：所述接入网设备接收来自另一接入网设备的切换请求消息，所述切换请求消息包括终端设备的PDU会话的标识，所述PDU会话支持组播；所述接入网设备向核心网设备发送指示信息，所述指示信息用于指示所述接入网设备是否存在所述组播业务。
第四方面，提供了一种传输组播业务的装置，用于执行上述各个方面或各个方面任意可能的实现方式中的方法。具体地，该装置包括用于执行上述各个方面或各个方面任意可能的实现方式中的方法的单元。
在一种设计中，该装置可以包括执行上述各个方面中所描述的方法/操作/步骤/动作所一一对应的模块，该模块可以是硬件电路，也可是软件，也可以是硬件电路结合软件实现。
在一种设计中，该装置为通信芯片，通信芯片可以包括用于发送信息或数据的输入电路或者接口，以及用于接收信息或数据的输出电路或者接口。
在另一种设计中，该装置为通信设备，通信设备可以包括用于发送信息或数据的发射机，以及用于接收信息或数据的接收机。
在另一种设计中，该装置用于执行上述各个方面或各个方面中任意可能的实现方式中的方法，该装置可以配置在上述会话管理网元中，或者该装置本身即为会话管理网元。
第五方面，提供了另一种传输组播业务的装置，该装置包括：处理器，该处理器与存储器耦合，该存储器用于存储计算机程序，该处理器用于从存储器中调用并运行该计算机程序，使得该装置执行上述各个方面或各个方面任意可能实现方式中的传输组播业务的方法。
可选地，所述处理器为一个或多个，所述存储器为一个或多个。
可选地，所述存储器可以与所述处理器集成在一起，或者所述存储器与处理器分离设置。
可选地，该装置还包括，发射机(发射器)和接收机(接收器)，发射机和接收机可以分离设置，也可以集成在一起，称为收发机。
第六方面，提供了一种系统，该系统包括用于实现上述第一方面或第一方面的任一种可能实现的方法的装置、用于实现上述第二方面或第二方面的任一种可能实现的方法的装置以及用于实现上述第三方面或第三方面的任一种可能实现的方法的装置。
第七方面，提供了一种计算机程序产品，所述计算机程序产品包括：计算机程序代码，当所述计算机程序代码被计算机运行时，使得所述计算机执行上述各个方面或各个方面的任一种可能实现方式中的方法。
第八方面，提供了一种计算机可读介质，用于存储指令，当所述指令在计算机上运行时，使所述计算机执行上述各个方面或各个方面的任一种可能的实现方式中的方法的指令。
第九方面，本申请实施例提供了一种芯片系统，该芯片系统包括一个或多个处理器，用于从存储器中调用并运行存储器中存储的指令，使得上述各个方面或各个方面的任一种可能实现方式中的方法被执行。该芯片系统可以由芯片构成，也可以包含芯片和其他分立器件。
其中，该芯片系统可以包括用于发送信息或数据的输入电路或者接口，以及用于接收信息或数据的输出电路或者接口。
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是本申请实施例提供的另一系统架构的示意图。
图3是本申请实施例提供的一种业务数据的传输示意图。
图4是本申请实施例提供的另一业务数据的传输示意图。
图5是本申请实施例提供的传输组播业务的方法的示意性流程图。
图6是本申请实施例提供的另一传输组播业务的方法的示意性流程图。
图7是本申请实施例提供的另一传输组播业务的方法的示意性流程图。
图8是本申请实施例提供的另一传输组播业务的方法的示意性流程图。
图9是本申请实施例提供的另一传输组播业务的方法的示意性流程图。
图10是本申请实施例提供的另一传输组播业务的方法的示意性流程图。
图11是本申请实施例提供的传输组播业务的隧道示意图。
图12是本申请实施例提供的另一传输组播业务的隧道示意图。
图13是本申请实施例提供的另一传输组播业务的方法的示意性流程图。
图14是本申请实施例提供的另一传输组播业务的隧道示意图。
图15是本申请实施例提供的另一传输组播业务的隧道示意图。
图16是本申请实施例提供的另一传输组播业务的方法的示意性流程图。
图17是本申请实施例提供的传输组播业务的装置的示意性框图。
图18是本申请实施例提供的另一传输组播业务的装置的示意性框图。
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：长期演进(long term evolution，LTE)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)、第五代(5th generation，5G)系统或新无线(new radio，NR)或者其他演进的通信系统等。
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未来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，该终端设备还可以是可穿戴设备。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。
另外，本申请实施例中的接入网设备可以是传输接收点(transmission reception point，TRP)，还可以是LTE系统中的演进型基站(evolved NodeB，eNB或eNodeB)，还可以是家庭基站(例如，home evolved NodeB，或home Node B，HNB)、基带单元(base band unit，BBU)，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，或者该接入网设备可以为中继站、接入点、车载设备、可穿戴设备以及5G网络中的接入网设备或者未来演进的陆上公用移动通信网(public land mobile network，PLMN)网络中的接入网设备等，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。在一种网络结构中，接入网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。
在本申请实施例中，终端设备或各个网络设备包括硬件层、运行在硬件层之上的操作系统层，以及运行在操作系统层上的应用层。该硬件层包括中央处理器(central processing unit，CPU)、内存管理单元(memory management unit，MMU)和内存(也称为主存)等硬件。该操作系统可以是任意一种或多种通过进程(process)实现业务处理的计算机操作系统，例如，Linux操作系统、Unix操作系统、Android操作系统、iOS操作系统或windows操作系统等。该应用层包含浏览器、通讯录、文字处理软件、即时通信软件等应用。并且，本申请实施例并未对本申请实施例提供的方法的执行主体的具体结构特别限定，只要能够通过运行记录有本申请实施例的提供的方法的代码的程序，以根据本申请实施例提供的方法进行通信即可，例如，本申请实施例提供的方法的执行主体可以是网络设备，或者，是网络设备中能够调用程序并执行程序的功能模块。
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。
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、接入与移动性管理网元130以及会话管理网元140。
其中，接入与移动性管理网元130和会话管理网元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第5代(the 5th generation，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)：又可称为会话管理功能网元，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。具体地，图1中的源会话管理网元110、锚点会话管理网元120、目标会话管理网元190均可为SMF。
应理解，在上述系统架构100中，接入网设备120可以为图2中的RAN；接入与移动性管理网元130可以为图2中的AMF；会话管理网元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)：又可称为用户面功能或用户面网元或用户面功能网元，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(anchor-UPF，A-UPF)。其中，I-UPF与接入网RAN连接，A-UPF为会话锚点的UPF，A-UPF又可以称为PDU会话锚点(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)：用于对组播业务进行控制，MCF与服务提供商(content provider，CP)对接，以便接收组播业务相关信息(例如组播业务的描述)，MCF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网元还可以是其它名称，其实现的是组播业务的控制面功能。
13、组播用户面功能(multicast user plane function，MUF)：用于传递组播业务相关数据，即，将从CP接收到的组播数据发送给UPF。此处应注意，在5G网络中，上述MUF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。
该系统架构200中，MCF可以集成到PCF(或SMF)中，MUF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3是本申请实施例提供的一种业务数据的传输示意图。图3所示的示意图用于传输组播业务数据。在图3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UE 3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。在图3的示例中，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。
图4是本申请实施例提供的另一业务数据的传输示意图。图4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4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。
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。
考虑到网络中可能同时存在支持组播的接入网设备与不支持组播的接入网设备，可能同时存在支持组播的终端设备与不支持组播的终端设备，本申请实施例提出了一种传输组播业务的方法，能够在无论系统中是否存在支持组播的设备的情况下，实现组播业务的传输，从而提高组播业务传输的可靠性。
在本申请的实施例中，用户平面功能又可称为用户面功能或用户面网元或用户面功能网元，四种名称可以互相替换。
图5示出了本申请实施例的传输组播业务的方法500的示意性流程图。该方法500可以应用于图1所示的系统架构100，也可以应用于图2所示的系统架构200，本申请实施例不限于此。
S510，会话管理网元接收第一消息。
其中，所述第一消息用于请求将终端设备加入组播业务。
具体地，该第一消息可以来自接入与移动性管理网元或者用户面功能网元(例如，UPF)。
S520，所述会话管理网元根据所述终端设备的组播能力信息和/或所述终端设备所接入的接入网设备的组播能力信息，确定所述组播业务的发送方式。
其中，所述发送方式为单播方式或者组播方式。所述终端设备的组播能力信息是指终端设备是否支持组播，所述接入网设备的组播能力信息用于表示所述接入网设备是否支持组播。
具体地，所述接入网设备支持组播是指接入网设备的空口支持点到多点的传输。所述终端设备支持组播是指该终端设备支持通过空口组播模式接收组播业务。
在本申请实施例中，会话管理网元可以在终端设备请求加入组播业务时，根据该终端设备的组播能力信息和/或该终端设备所接入的接入网设备的组播能力信息，将终端设备加入组播业务，从而更有效地为终端设备下发组播业务，减少终端设备请求加入组播业务的时延，从而提高组播业务传输的灵活性和可靠性。
应理解，在通信网络中所有的终端设备都支持组播的情况下，S520中会话管理网元可以不参考上述终端设备的组播能力信息，仅参考接入网设备的组播能力信息，即判断该终端设备所接入的接入网设备是否支持组播。
在通信网络中所有的接入网设备都支持组播的情况下，S520中会话管理网元可以不参考上述接入网设备的组播能力信息，仅参考终端设备的组播能力信息，即判断终端设备是否支持组播。
在通信网络中同时存在支持组播的接入网设备与不支持组播的接入网设备，并且同时存在支持组播的终端设备与不支持组播的终端设备的情况下，在S520中，会话管理网元可以参考上述终端设备的组播能力信息和接入网设备的组播能力信息。
基于终端设备的组播能力信息和/或接入网设备的组播能力信息，步骤S520可以分为如下两种情况：
情况1、终端设备的组播能力信息表示该终端设备不支持组播，和/或，接入网设备的组播能力信息表示该接入网设备不支持组播。
可选地，作为情况1的一个实施方式，步骤S520包括：当所述发送方式为单播方式时，所述方法还包括：所述会话管理网元根据所述组播业务的组播服务质量QoS信息，确定所述组播业务对应的单播QoS流；所述会话管理网元在所述终端设备的协议数据单元PDU会话中增加所述单播QoS流，所述单播QoS流用于传输所述组播业务的数据。在可能实现的一种方式中，所述会话管理网元在所述终端设备的PDU会话中增加所述单播QoS流，可以包括：该会话管理网元从组播/广播会话管理功能网元获取所述组播业务的QoS信息，包括组播业务的组播QoS流的QFI，组播QoS流对应的服务数据流(Service data flow,SDF)，组播QoS流的QFI对应的QoS参数，例如，QoS参数可以包括：5QI,ARP,GBR,MBR,QNC(QoS notification control),等。具体地，可以根据所述组播业务的组播QoS流对应的QoS信息找到与之值相同的单播QoS流对应的QoS参数，进而确定该单播QOS流就是确定的单播QoS flow。
作为一个可选的实施例，该会话管理网元在该终端设备的PDU会话中增加该单播QoS流，包括：该会话管理网元向用户面网元发送用于识别该组播业务的过滤器信息(例如，数据包检测规则(packet detection rule,PDR))和该单播QoS流的QFI；该会话管理网元根据该组播QoS流的QoS参数，确定该单播QoS流的QoS参数；该会话管理网元向目标接入网设备发送该单播QoS流的QFI和该单播QoS流的QoS参数。
作为一个可选的实施例，该会话管理网元在该终端设备的PDU会话中增加该单播QoS流，包括：该会话管理网元向用户面网元发送N4会话修改请求(N4 session modification request)或报文转发控制协议(Packet forwarding control protocol,PFCP)会话修改请求(PFCP session modification request),在该映射的单播QoS流上添加用于过滤该组播/广播业务数据的过滤器。即，基于本技术方案，该映射的单播QoS流之前已经用于传输PDU会话中的业务数据。其中，所述数据包检测规则(PDR,packet detection rule)，例如，可以是所述组播业务的过滤器，过滤器是一个五元组，包括源地址，目标地址，源端口号，目标端口号，协议号，可以用于识别该组播业务的数据。
换言之，若上述终端设备不支持组播和/或接入网设备不支持组播，则组播业务的发送方式为单播方式。在这种情况下，会话管理网元将组播业务的组播QoS流映射到单播QoS流，从而在PDU会话中增加该单播QoS流，以便后续通过单播方式为该终端设备下发该组播业务。
关于将组播业务的组播QoS流映射到单播QoS流，可以指的是建立组播QoS流与单播QoS流之间的对应关系，以便采用该单播QoS流传递该组播业务。
应理解，为了便于区分，会话管理网元所确定的单播QoS流的QFI与已有的单播QoS流的QFI不同。示例性地，假设单播QoS流的QFI可以使用的值为(10-64)，若终端设 备已经有2个单播业务，例如，优酷视频与微信，其中，优酷视频包括3个单播QoS流(分别是QFI＝12、QFI＝13、QFI＝16)，微信包括2个单播QoS流(分别是QFI＝11、QFI＝12)，那么这两个单播业务共对应4个单播QoS流(分别是QFI＝11、QFI＝12、QFI＝13、QFI＝16)。因此，单播QoS流的QFI还剩50个QFI值可以使用，SMF可以确定组播QoS流对应的单播QoS流的QFI为其中未使用的QFI。根据组播QoS流的QFI确定单播QoS流的QFI的过程即可以称为映射，本申请实施例将组播QoS流的QFI与单播QoS流的QFI之间的对应关系称为第一映射关系。在具体实现时，一个组播QoS流可映射为一个单播QoS流，或者，多个组播QoS流可映射为一个单播QoS流，本申请实施例对于如何映射不作限制。
在可能实现的一种方式中，所述会话管理网元在所述终端设备的PDU会话中增加所述单播QoS流，可以包括：该会话管理网元从组播/广播会话管理功能网元获取所述组播业务的服务数据流(service data flow,SDF)的QoS信息，例如，QoS信息可以包括：5QI,ARP,GBR,MBR,QNC(QoS notification control),等。具体地，可以根据所述组播业务的业务数据流SDF对应的QoS信息找到与之值相同的单播QoS流对应的QoS参数，进而确定该单播QOS流就是确定的单播QoS flow。所述会话管理网元向用户面网元发送用于识别该组播业务的过滤器信息(例如，数据包检测规则(packet detection rule，PDR))，以及所述组播业务的信息和所述单播QoS流的QFI；所述会话管理网元根据所述组播QoS流的QoS参数，确定所述单播QoS流的QoS参数；所述会话管理网元向所述接入网设备发送所述单播QoS流的QFI和所述单播QoS流的QoS参数。其中，所述数据包检测规则(PDR,packet detection rule)，例如，可以是所述组播业务的过滤器，过滤器是一个五元组，包括源地址，目标地址，源端口号，目标端口号，协议号，可以用于识别该组播业务的数据。
在可能实现的另一种方式中，该会话管理网元在该终端设备的PDU会话中增加该单播QoS流，包括：
所述会话管理网元根据所述组播业务的QoS信息，在所述终端设备的PDU会话的单播QoS流中选择至少一个单播QoS流，所述至少一个单播QoS流用于传输所述组播业务的数据，其中，上述单播QoS流为已经存在的QoS流；所述会话管理网元向用户面功能网元发送所述组播业务的数据包检测规则与所述至少一个单播QoS流的标识之间的对应关系。
其中，对应关系可以携在第八消息中，其中，第八消息为N4会话修改请求(N4 session modification request)消息或PFCP会话修改请求(PFCP session modification request)。
示例性地，对应关系可以为所述的第八消息同时包含所述组播业务的数据包检测规则，与所述组播业务的数据包检测规则对应的所述至少一个单播QoS流的标识，可以用于表征所述组播业务的数据包检测规则与所述至少一个单播QoS流的标识之间对应关系。该会话管理网元向用户面网元发送N4会话修改请求(N4Session Modification Request)或PFCP会话修改请求(PFCP session modification request)。所述N4会话修改请求(N4 session modification request)或PFCP会话修改请求消息同时包含所述组播业务的数据包检测规则，与所述组播业务的数据包检测规则对应的所述至少一个单播QoS流的标识，可以用于表征所述组播业务的数据包检测规则与所述至少一个单播QoS流的标识之间对应关系。
其中，所述数据包检测规则，例如，可以是所述组播业务的过滤器，过滤器是一个五元组，包括源地址，目标地址，源端口号，目标端口号，协议号，可以用于识别该组播业 务的数据。
其中，组播业务的信息是指映射到该单播QoS流的组播QoS流所对应的组播业务的信息。示例性地，在确定单播QoS流对应的QoS参数时，会话管理网元可以根据映射到该单播QoS流的所有组播QoS流的QoS参数进行确定，但本申请实施例对此不作限定。
进一步地，会话管理网元还可以指示用户面网元通过PDU会话隧道发送该组播业务的数据包。具体地，用户面网元可以根据组播业务的信息识别该组播业务的数据包，并通过PDU会话隧道向下行节点(例如无线接入网)发送该组播业务的数据包。此外，用户面网元可以根据组播业务的信息和所述单播QoS流的QFI，确定该数据包对应的QFI，并在向下行节点发送该数据包时携带该数据包所对应的单播QoS流的QFI。上述数据包对应的QFI可以是会话管理网元根据组播业务的QoS需求确定的，示例性地，SMF可以从PCF获取组播业务相关的QoS需求(例如，带宽、时延、抖动等)，SMF可以根据QoS需求确定QFI，例如，SMF可以将组播业务所包含的图片的QFI确定为1，将组播业务所包含的语音的QFI确定为3。可选地，该单播QoS流的QFI可以包含于通用分组无线服务隧道协议-用户面(general packet radio service tunneling protocol-user，GTP-U)的包头中，作为GTP-U的包头的一个域。
在一种可能的实现方式中，该组播业务的信息可以包括组播业务的目的地址，进一步地，还可以包括源地址或端口号中的至少一项。
在另一种可能的实现方式中，该组播业务通过另一个用户面网元发送给当前的用户面网元，那么会话管理网元还将该另一个用户面网元的隧道标识(便于当前的用户面网元与其进行连接)发送给当前的用户面网元。在这种情况下，该组播业务的信息可以包括该另一个用户面网元的隧道标识。
情况2、只参考终端设备的组播能力信息(默认接入网设备支持组播)，终端设备的组播能力信息表示该终端设备支持组播；或者，
只参考接入网设备的组播能力信息(默认终端设备支持组播)，接入网设备的组播能力信息表示该接入网设备支持组播；或者，
参考终端设备的组播能力信息和接入网设备的组播能力信息，终端设备的组播能力信息表示该终端设备支持组播，并且，接入网设备的组播能力信息表示该接入网设备支持组播。
可选地，作为情况2的一个实施方式，步骤S520包括：当所述发送方式为组播方式时，所述方法还包括：所述会话管理网元向所述接入网设备发送第三消息，所述第三消息用于请求将所述终端设备加入所述组播业务。
其中，第三消息可以包含上述组播业务的业务标识，也可以称为组播业务的标识信息，例如，可以是以下任意一种，也可以是以下一种或多种的组合，不限定：组播/广播业务的标识，组播/广播业务的名称，组播/广播业务的组播/广播地址，组播/广播业务的组播/广播IP地址，组播/广播业务对应的临时移动组标识(temporary mobile group identity，TMGI)，组播/广播业务的组播/广播业务的会话地址等。
可以理解的是，组播业务的业务标识还可以携带在其它消息中，例如，N1N2信息传递(Namf_Communication_N1N2Message Transfer)中，具体地，通过图8中的S806和/或S814，图9中的S906和/或S914所示的N1N2信息传递发送给AMF，AMF再通过其它消 息将组播业务的业务标识发给接入网设备。该其它消息还可以是N2消息，例如，N2消息可以是N2 PDU session request(N2 PDU会话请求)，PDU session resource setup request(PDU会话资源建立请求)，或PDU session resource modify request(PDU会话资源修改)，等。
对应地，接入网设备接收来自会话管理网元的第三消息，如果当前空口资源充足，该接入网设备可以为终端设备下发相应的无线承载配置信息，该终端设备可以根据无线承载配置信息进行接入层的接收配置，之后便可以接收组播业务的数据，即终端设备成功加入组播业务；如果空口资源紧张，无法配置无线承载，接入网设备便无法为终端设备下发无线承载配置信息，即终端设备无法加入组播业务。应理解，所谓的无线承载配置可以由数据无线承载(data radio bear,DRB)ID标识，其对应了一整套的无线接入层配置。
需要指出的是，上述无线承载配置信息可以替换成无线资源的配置信息，以及无线承载配置可以替换为无线资源的配置。其中，无线资源可以包括无线承载，无线资源的配置信息可以包括无线承载配置信息，不予限制。
具体而言，若上述终端设备支持组播，并且上述接入网设备支持组播，则组播业务的发送方式为组播方式。在这种情况下，会话管理网元可以请求接入网设备将终端设备加入组播业务，以便后续通过组播方式为该终端设备下发该组播业务。
可选地，在第一种实现方式中，在所述会话管理网元向所述接入网设备发送第三消息之前，所述方法还包括：所述会话管理网元确定所述接入网设备存在所述组播业务。换言之，接入网设备已经建立该组播业务的组播会话，或者，接入网设备已参与该组播业务的传输，或者，接入网设备已加入该组播业务。
其中，组播业务的组播会话可以指的是用于传输该组播业务的组播会话。
应理解，接入网设备可能存在组播业务，也可能不存在组播业务，因此，会话管理网元可以先判断接入网设备是否存在该组播业务。若接入网设备存在该组播业务，则该会话管理网元发送第三消息，即请求该接入网设备将该终端设备加入该组播业务；若该接入网设备不存在该组播业务，该会话管理网元可以先请求该接入网设备创建该组播业务的组播会话，在该组播会话创建完成之后，该会话管理网元再发送第三消息，即请求该接入网设备将该终端设备加入该组播业务。
可选地，在第二种实现方式中，会话管理网元可以不执行对所述接入网设备存在所述组播业务作任何判断，而是在请求该接入网设备将该终端设备加入该组播业务的同时，向该接入网设备发送该组播业务的组播QoS流的信息。这样，即使该接入网设备上不存在该组播业务，该接入网设备也可以根据该组播QoS流的信息，为该终端设备创建该组播业务的组播会话，然后，将该终端设备加入该组播业务。
在本申请实施例中，会话管理网元可以通过多种方式确定接入网设备是否存在该组播业务，对此不作限定。
作为一种可选的实施方式，所述会话管理网元确定所述接入网设备存在所述组播业务，包括：所述会话管理网元接收来自统一数据管理网元的第四消息，所述第四消息用于指示所述接入网设备存在所述组播业务；所述会话管理网元根据所述第四消息，确定所述接入网设备存在所述组播业务。
示例性地，统一数据管理网元可以自主(例如周期性地)向会话管理网元发送上述第 三消息，将接入网设备上存在的组播业务的信息告知会话管理网元。
示例性地，会话管理网元可以向统一数据管理网元查询，即向统一数据管理网元发送查询消息，查询当前终端设备请求加入的组播业务是否在该终端设备所接入的接入网设备上存在，会话管理网元接收统一数据管理网元反馈的查询结果(即上述第四消息)，根据该查询结果即可确定该接入网设备是否存在该组播业务。可选地，在会话管理网元向统一数据管理网元发送查询消息的情况下，统一数据管理网元可以不反馈查询结果，会话管理网元在一段时间内未收到查询结果则默认该接入网设备不存在该组播业务(或者，默认该接入网设备存在该组播业务)，但本申请实施例对此不作限定。
可选地，在第三种实现方式中，在所述会话管理网元向所述接入网设备发送第三消息之前，所述方法还包括：所述会话管理网元确定所述接入网设备不存在所述组播业务；所述会话管理网元向所述接入网设备发送所述组播业务的组播QoS流的信息；所述会话管理网元接收来自所述接入网设备的用于指示所述组播QoS流对应的无线承载创建成功的指示信息。
具体地，若接入网设备不存在该终端设备请求加入的组播业务，该会话管理网元可以向接入网设备发送该组播业务的组播QoS流的信息，该组播QoS流的信息可以包括该组播QoS流的QFI和组播QoS流的QoS参数。接入网设备在接收到该组播QoS流的信息之后，便可以根据该组播QoS流的信息创建相应的组播业务，为后续将终端设备加入该组播业务做准备。
作为一个可选的实施例，所述方法还包括：所述会话管理网元根据所述指示信息，向统一数据管理网元发送第五消息，所述第五消息用于指示所述接入网设备中已经存在所述组播业务。
示例性地，在上述接入网设备不存在该终端设备请求加入的组播业务，且会话管理网元已经创建了该组播业务的情况下，该会话管理网元可以通知统一数据管理网元上述接入网设备已经存在该组播业务。上述第五消息中可以携带组播业务的标识和接入网设备的标识。
结合上述情况2的实施方式，所述方法还可以包括：所述会话管理网元确定所述组播QoS流对应的单播QoS流；所述会话管理网元向所述接入网设备发送第一映射关系，所述第一映射关系用于表示所述组播QoS流的QFI和所述单播QoS流的QFI之间的对应关系。
需要说明的是，在终端设备和接入网设备支持组播的情况下，会话管理网元也可以生成组播QoS流的QFI与单播QoS流的QFI的映射关系，但无需修改PDU会话(即无需在PDU会话中新增该单播QoS流)。这是因为存在一种场景是终端设备所接入的接入网设备支持组播，即组播业务通过组播会话隧道中下发，单播业务通过PDU会话所在的PDU会话隧道中下发。然而，终端设备具有移动性，后续终端设备存在移动到另一接入网设备的可能，该另一接入网设备可能不支持组播。为了避免由于另一接入网设备不支持组播而导致终端设备从接入网设备切换至另一接入网设备时组播业务的传输不连续的问题，因此，会话管理网元可以提前存储上述组播QoS流的QFI和单播QoS流的QFI之间映射关系，以便该会话管理网元在得知终端设备将要切换到的另一接入网设备不支持组播时，通知用户面网元将组播业务映射到PDU会话所在的PDU会话隧道中下发给终端设备，从而 保证组播业务的连续性。
鉴于会话管理网元是根据终端设备的组播能力信息和/或终端设备所接入的接入网设备的组播能力信息，确定组播业务的发送方式，因此，会话管理网元需要获取该终端设备的组播能力信息和/或该接入网设备的组播能力信息。在本申请实施例中，会话管理网元可以采用多种方式获取该终端设备的组播能力信息和/或该接入网设备的组播能力信息，具体可以包括如下多种实现方式。
作为第一个可选的实施例，所述方法还可以包括：接入与移动性管理网元向所述会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。相应地，所述会话管理网元接收来自接入与移动性管理网元的所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
作为第二个可选的实施例，上述方法还可以包括：所述接入与移动性管理网元确定所述终端设备的协议数据单元PDU会话是否支持组播，在所述PDU会话支持组播的情况下，所述接入与移动性管理网元向所述会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。相应地，所述会话管理网元接收来自接入与移动性管理网元的所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
可选地，所述接入与移动性管理网元确定终端设备的PDU会话支持组播，包括：所述接入与移动性管理网元接收来自所述终端设备的所述PDU会话的参考信息，所述参考信息包括用于指示所述PDU会话是否支持组播的指示信息、所述PDU会话的数据网络名称DNN、所述PDU会话的单网络切片选择辅助信息S-NSSAI中的一项或多项；所述接入与移动性管理网元根据所述参考信息，确定所述PDU会话支持组播。
作为第三个可选的实施例，所述方法还可以包括：所述会话管理网元向所述接入与移动性管理网元发送请求消息，所述请求消息用于请求所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。相应地，所述接入与移动性管理网元接收来自所述会话管理网元的请求消息，并根据请求消息向会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
作为第四个可选的实施例，所述方法还包括：所述会话管理网元向所述接入与移动性管理网元发送订阅消息，所述订阅消息用于所述移动性管理网元在所述终端设备和/或所述接入网设备的组播能力改变时向所述会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。则对应地，接入与移动性管理网元接收来自会话管理网元的订阅消息，并在终端设备和/或接入网设备的能力改变时向该会话管理网元发送终端设备的组播能力信息或接入网设备的组播能力信息。
具体地，上述终端设备的组播能力信息和/或上述接入网设备的组播能力信息可以是会话管理网元通过订阅获取的。即会话管理网元向接入与移动性管理网元发送订阅消息，该订阅消息用于移动性管理网元在终端设备的组播能力改变和/或接入网设备的组播能力改变时向会话管理网元发送终端设备的组播能力信息或接入网设备的组播能力信息。示例性地，在终端设备的能力改变时，接入与移动性管理网元可以向会话管理网元发送该终端设备的组播能力信息；在接入网设备的能力改变时，接入与移动性管理网元可以向会话管理网元发送该接入网设备的组播能力信息；在接入网设备的能力与终端设备的能力都改变时，接入与移动性管理网元可以向会话管理网元发送接入网设备的组播能力信息和终端设 备的组播能力信息。
应理解，在仅参考终端设备的组播能力信息的情况下，会话管理网元可以仅获取终端设备的组播能力信息，在仅参考接入网设备的组播能力信息的情况下，会话管理网元可以仅获取接入网设备的组播能力信息，在参考终端设备的组播能力信息和接入网设备的组播能力信息的情况下，会话管理网元可以同时获取上述终端设备的组播能力信息和接入网设备的组播能力信息，也可以分别获取上述终端设备的组播能力信息和接入网设备的组播能力信息，本申请实施例对此不作限定。示例性地，上述终端设备的组播能力信息可以是接入与移动性管理网元主动发送给会话管理网元的，而上述接入网设备的组播能力信息可以是会话管理网元请求接入与移动性管理网元发送的。或者，示例性地，上述接入网设备的组播能力信息可以是接入与移动性管理网元主动发送给会话管理网元的，上述终端设备的组播能力信息可以是会话管理网元请求接入与移动性管理网元发送的。
图6示出了本申请实施例的传输组播业务的方法600的示意性流程图。该方法600可以应用于图1所示的系统架构100，也可以应用于图2所示的系统架构200，本申请实施例不限于此。
S610，接入与移动性管理网元向会话管理网元发送第二消息；对应地，该会话管理网元接收来自该接入与移动性管理网元的第二消息。
其中，所述第二消息用于更新终端设备的PDU会话，所述PDU会话关联组播业务。示例性地，该第二消息具体可以为Nsmf_PDUSession_UpdateSMContext Request消息。
S620，所述会话管理网元根据所述终端设备的组播能力信息和/或所述终端设备的目标接入网设备的组播能力信息，确定所述组播业务的发送方式。
其中，所述发送方式为单播方式或者组播方式。所述终端设备的组播能力信息用于表示所述终端设备是否支持组播，所述目标接入网设备的组播能力信息用于表示所述目标接入网设备是否支持组播。
示例性地，在终端设备从源接入网设备切换至目标接入网设备的场景下，接入与移动性管理网元可以向会话管理网元发送上述第二消息，用于对PDU会话进行更新。应理解，终端设备从源接入网设备切换至目标接入网设备可以是指将终端设备的PDU会话从源接入网设备切换至目标接入网设备。换句话说，“切换终端设备的PDU会话”是指因为终端设备由源接入网设备向目标接入网设备移动时，为了保持业务的连续性，该终端设备的PDU会话从源接入网设备切换到目标接入网设备。
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。
在本申请实施例中，会话管理网元可以在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时，根据该目标接入网设备的组播能力信息，确定该组播业务切换后的发送方式，无论该目标接入网设备是否支持组播，终端设备在源接入网设备的组播业务与单播业务皆可以不因切换发生中断，保证了终端设备的服务连续性，并且能够在切换过 程中减少丢包，降低切换时延。
应理解，在PDU会话切换前，若终端设备与源接入网设备都支持组播，该PDU会话关联的组播业务可以通过组播隧道传输至终端设备，即组播业务的发送方式为组播方式；若终端设备不支持组播、或者源接入网设备不支持组播，该PDU会话关联的组播业务的组播QoS流可以被映射进PDU会话的单播QoS流，并通过PDU会话隧道发送给终端设备，即组播业务的发送方式为单播方式。在PDU会话切换后，会话管理网元可以根据终端设备的组播能力信息和/或目标接入网设备的组播能力信息，重新确定该组播业务的发送方式。因此，本申请实施例的确定组播业务的发送方式的方法与上述方法500类似，将上述方法500中的接入网设备替换成目标接入网设备即可，具体可参考上述方法500，此处不再赘述。
作为一个可选的实施例，上述方法还包括：当PDU会话从源接入网设备切换到目标接入网设备时，会话管理网元可以根据该组播业务的组播QoS流确定单播QoS流，并在上述PDU会话中增加该单播QoS流，通过PDU会话隧道发送该单播QoS流，即，在PDU会话切换到目标接入网设备之后，采用单播方式发送该PDU会话关联的组播业务。具体地，会话管理网元在PDU会话中增加单播QoS流的描述，可以参考S520中关于会话管理网元在终端设备的PDU会话中增加单播QoS流的描述，为了简洁，本申请在此不再赘述。
所述会话管理网元向用户面功能网元发送所述组播业务的数据包检测规则与所述至少一个单播QoS流的标识之间的对应关系。对应关系携在第八消息中，其中，第八消息为N4会话修改请求消息或PFCP会话修改请求。对应关系可以为所述的第八消息同时包含所述组播业务的数据包检测规则，与所述组播业务的数据包检测规则对应的所述至少一个单播QoS流的标识，可以用于表征所述组播业务的数据包检测规则与所述至少一个单播QoS流的标识之间对应关系。该会话管理网元向用户面网元发送N4会话修改请求或PFCP会话修改请求。所述N4会话修改请求或PFCP会话修改请求消息同时包含所述组播业务的数据包检测规则，与所述组播业务的数据包检测规则对应的所述至少一个单播QoS流的标识，可以用于表征所述组播业务的数据包检测规则与所述至少一个单播QoS流的标识之间对应关系。其中，所述数据包检测规则，例如，可以是所述组播业务的过滤器，过滤器是一个五元组，包括源地址，目标地址，源端口号，目标端口号，协议号，可以用于识别该组播业务的数据。示例性地，会话管理网元接收到上述第二消息之后，可以根据第二消息确定该切换的PDU会话关联组播业务，再根据该组播业务的标识确定该组播业务的QoS需求，从而确定该组播业务的组播QoS流，再获得该组播QoS流对应的单播QoS流。
作为一个可选的实施例，所述会话管理网元在所述终端设备的PDU会话中增加所述单播QoS流，包括：所述会话管理网元向用户面网元发送所述组播业务的过滤器的信息(例如，数据包检测规则(Packet detection rule,PDR))和所述单播QoS流的QFI；所述会话管理网元根据所述组播QoS流的QoS参数，确定所述单播QoS流的QoS参数；所述会话管理网元向目标接入网设备发送所述单播QoS流的QFI和所述单播QoS流的QoS参数。
作为一个可选的实施例，该会话管理网元在该终端设备的PDU会话中增加该单播QoS 流，包括：该会话管理网元向用户面网元发送N4会话修改请求或PFCP会话修改请求，在该映射的单播QoS流上添加用于过滤该组播/广播业务的过滤器。即，基于本技术方案，该映射的单播QoS流之前已经用于传输PDU会话中的业务数据。
其中，组播业务的信息是指映射到该单播QoS流的组播QoS流所对应的组播业务的信息，确定单播QoS流时根据映射到该单播QoS流的所有组播QoS流的QoS参数。
作为一个可选的实施例，在所述会话管理网元确定所述组播QoS流对应的单播QoS流之前，所述方法还包括：所述会话管理网元确定所述终端设备不支持组播和/或所述目标接入网设备不支持组播。
应理解，会话管理网元可以在终端设备不支持组播和/或目标接入网设备不支持组播的情况下，将组播QoS流映射到单播QoS流，也可以不进行判断，直接将组播QoS流映射到单播QoS流，在终端设备接入目标接入网设备之后，会话管理网元再根据终端设备的组播能力信息和/或目标接入网设备的组播能力信息进行判断。当目标接入网设备支持组播时，会话管理网元可以将映射到单播QoS流的组播QoS流还原为组播QoS流，并通过目标接入网设备的组播会话隧道下发；当目标接入网设备不支持组播时，会话管理网元可以仍按照单播方式将组播QoS流对应的单播QoS流通过目标接入网设备的PDU会话隧道下发给终端设备。
应理解，会话管理网元先将组播QoS流映射为单播QoS流，这是因为终端设备在接入源接入网设备时既请求了单播业务又请求了组播业务，其中，单播业务在PDU会话隧道中传输，组播业务组播会话隧道中传输，终端设备的服务连续性可以得到保证。所谓的服务连续性包括单播业务的连续性以及组播业务的连续性。但是，由于终端设备从源接入网设备切换至目标接入网设备，如果不先将源接入网设备组播会话隧道中的组播QoS流映射进源接入网设备的PDU会话所在的PDU会话隧道中的单播QoS流，如果切换之后目标接入网设备不支持组播(即无法建立组播会话隧道)，那么终端设备的组播业务会发生中断，无法保持服务连续性。因此，为了保证终端设备的服务连续性，可以先在源接入网设备处(即在终端设备切换至目标接入网设备之前)将组播QoS流映射到单播QoS流，以单播切换进行，然后会话管理网元在切换流程中知道目标接入网设备的组播能力信息之后，可以再根据目标接入网设备是否支持组播进行操作，以便以合适的方式在目标接入网设备将终端设备加入该组播业务。
作为一个可选的实施例，若会话管理网元在切换前不进行判断，直接将组播QoS流映射到单播QoS流，那么在终端设备接入目标接入网设备之后，会话管理网元可以再根据终端设备的组播能力信息和/或目标接入网设备的组播能力信息进行判断。此时，若会话管理网元确定该组播业务的发送方式可以为组播方式，所述方法还包括：所述会话管理网元向用户面网元发送第六消息，所述第六消息用于指示删除所述PDU会话中的所述单播QoS流；所述会话管理网元向所述目标接入网设备发送第七消息，所述第七消息用于指示释放所述单播QoS流对应的无线承载。
则对应地，用户面网元接收该第六消息，并删除上述PDU会话中的单播QoS流。目标接入网设备接收该第七消息，并释放上述单播QoS流对应的无线承载。
这里，单播QoS流指的是组播QoS流所映射的单播QoS流。
考虑到目标接入网设备支持组播，可以通过组播会话隧道为终端设备下发组播业务， 会话管理网元可以将映射到单播QoS流的组播QoS流还原为组播QoS流，即删除该单播QoS流以及相应的无线承载。
应理解，本申请的方法600仅与上述方法500场景不同，关于会话管理网元确定组播业务的发送方式、请求将所述终端设备加入所述组播业务、以及获取终端设备的组播能力信息和/或接入网设备的组播能力信息等流程都是类似的，将上述方法500中的接入网设备替换成目标接入网设备即可，具体可参考上述方法500，此处不再赘述。
在本申请实施例中，所述第二消息可以携带所述终端设备的组播能力信息和/或目标接入网设备的组播能力信息，但本申请实施例对此不作限定。
可选地，上述方法还包括：目标接入网设备向AMF发送目标接入网设备的组播/广播能力信息。
其中，目标接入网设备可以通过N2路径切换请求(N2 path switch request)/路径切换请求(path switch request)向AMF发送目标接入网设备的组播/广播能力信息。
在可能实现的一种方式中，目标接入设备在接收来自UE的切换确认(handover confirm)之后，发送N2路径切换请求/路径切换请求。其中，N2路径切换请求/路径切换请求携带目标接入网设备的组播/广播能力信息。
在可能实现的另一种方式中，目标接入设备可以从本地获取目标接入网设备的能力信息，并向AMF发送目标接入网设备的组播/广播能力信息。
在可能实现的另一种方式中，目标接入网设备可以从操作、管理和维护(operation administration and maintenance,OAM)获取目标接入网设备的能力信息，并向AMF发送目标接入网设备的组播/广播能力信息。
图7示出了本申请实施例的传输组播业务的方法700的示意性流程图。该方法700可以应用于图1所示的系统架构100，也可以应用于图2所示的系统架构200，本申请实施例不限于此。
S710，接入网设备获取所述接入网设备的组播能力信息；
S720，所述接入网设备发送所述接入网设备的组播能力信息，所述接入网设备的组播能力信息用于表示所述接入网设备是否支持组播。
在本申请实施例中，接入网设备支持组播是指该接入网设备支持自身到UPF之间的组播会话隧道的建立，以及该接入网设备在空口支持采用PTM传输。
作为一个可选的实施例，接入网设备可以向接入与移动性管理网元发送自身的组播能力信息，则对应地，接入与移动性管理网元可以接收该接入网设备的组播能力信息。示例性地，接入网设备可以将自身的组播能力信息作为信元包含在下一代(next generation，NG)建立请求消息中，上报给接入与移动性管理网元。这里的NG建立请求消息是一条信令，该信令用于当接入网设备上电后，该接入网设备请求与接入与移动性管理网元之间建立连接，该信令可以包括一个或多个信元。在一种可能的设计中，接入网设备将自身的组播能力信息作为信元包含在NG建立请求消息中，是指接入网设备在当前的NG建立请求消息中所包含的已有信元的基础之上，再将自身的组播能力信息作为新的信元添加至该NG建立请求消息中。但应理解，接入网设备还可以通过其他消息向接入与移动性管理网元发送组播能力信息，本申请实施例对此不作限定。通过上述方式，接入与移动性管理网元便可以收集到接入网设备(可以包括图1和图2所示的接入网设备以及其他多个接入网 设备)的组播能力信息。应理解，上述NG建立流程是已有协议中的流程，其可用于当接入网设备上电后，接入与移动性管理网元收集与接入网设备相关的信息。因此，本申请实施例涉及的NG建立流程可以基于现有流程进行改进，向后兼容，易于实施。
在上述方法中，可选地，该接入与移动性管理网元可以向会话管理网元发送该接入网设备的组播能力信息，以便该会话管理网元根据该接入网设备的组播能力信息，确定该接入网设备是否支持组播。
作为一个可选的实施例，接入网设备可以向该接入网设备的相邻接入网设备发送自身的组播能力信息。示例性地，在切换场景中，终端设备可以从源接入网设备切换至目标接入网设备，该源接入网设备和目标接入网设备之间存在Xn连接，因此，目标接入网设备可以将自身的组播能力信息通过Xn连接发送给源接入网设备，以便源接入网设备获知目标接入网设备是否支持组播。在一种可能的实现方式中，当目标接入网设备支持组播时，该目标接入网设备可以向源接入网设备发送该组播能力信息，当目标接入网设备不支持组播时，该目标接入网设备可以不发送任何信息，源接入网设备若未收到信息，则默认目标接入网设备不支持组播。
作为一个可选的实施例，所述方法还包括：所述接入网设备接收来自另一接入网设备的切换请求消息，所述切换请求消息包括终端设备的协议数据单元PDU会话的标识，所述PDU会话关联组播业务；所述接入网设备向核心网设备发送指示信息，所述指示信息用于指示所述接入网设备是否存在所述组播业务。
上述接入网设备可以作为切换场景中的目标接入网设备，若终端设备从源接入网设备切换至目标接入网设备，该目标接入网设备可以向核心网设备发送指示信息，指示该目标接入网设备是否存在终端设备所请求接入的组播业务。在本实施例中，核心网设备可以通过目标接入网设备确定组播业务是否存在，无需再向统一数据管理网元查询。
作为一个可选的实例，上述方法还包括：终端设备获取所述终端设备的组播能力信息；所述终端设备发送所述终端设备的组播能力信息，所述终端设备的组播能力信息用于表示所述终端设备是否支持组播。
在本申请实施例中，终端设备支持组播是指该终端设备支持通过组播会话接收组播业务，或者，所述终端设备支持空口组播模式接收组播业务。
作为一个可选的实例，终端设备可以发送自身的组播能力信息，则对应地，接入与移动性管理网元可以接收该终端设备发送的非接入层(non-access stratum，NAS)消息。
可选地，该终端设备的组播能力信息可以携带在PDU会话建立/修改请求消息中，该PDU会话建立/修改请求消息是终端设备发送给接入与移动性管理网元的。
示例性地，终端设备可以将自身的组播能力信息作为信元包含在PDU会话建立/修改请求(例如，PDU Session Establishment Request)消息的信元5GSM核心网能力(5GSM Core Network Capability)中，上报给接入与移动性管理网元。应理解，这里的PDU会话建立/修改请求消息是一条NAS信令，该信令用于当终端设备请求建立/修改PDU会话时，由终端设备经过接入与移动性管理网元发送给会话管理网元，该信令可以包括一个或多个信元，5GSM Core Network Capability是其中一个信元，该信元又包含一些子信元。在一种可能的设计中，终端设备将自身的组播能力信息作为信元包含在PDU会话建立请求消息的信元5GSM Core Network Capability中，是指终端设备在当前的5GSM Core Network  Capability中所包含的已有信元的基础之上，终端设备再将自身的组播能力信息作为新的子信元添加至该信元中。但应理解，终端设备还可以通过其他消息向接入与移动性管理网元发送终端设备的组播能力信息，本申请实施例对此不作限定。
可选地，当接入与移动性管理网元收到上述来自终端设备的PDU会话建立/修改请求消息之后，该接入与移动性管理网元可以将终端设备的组播能力信息上报给会话管理网元。在一种可能的实现方式中，接入与移动性管理网元可以通过创建上下文请求消息(例如，Nsmf_PDUSession_CreateSMContext Request)发送终端设备的能力信息，该创建上下文请求消息是接入与移动性管理网元在接收到PDU会话建立/修改请求消息后，向会话管理网元发送的。应理解，该创建上下文请求消息是一条信令，该信令可以包含一个或多个信元，5GSM Core Network Capability是其中一个信元，该信元又包含一些子信元。终端设备的组播能力信息还是可以包含在5GSM Core Network Capability中。但应理解，接入与移动性管理网元还可以通过其他消息向会话管理网元发送终端设备的组播能力信息，本申请实施例对此不作限定。
为便于理解，下面以图2中的网元为例，结合图8至图15对本申请实施例进行详细说明。
图8是本申请实施例提供的另一传输组播业务的方法800的示意性流程图。该方法800可以应用于图2所示的系统架构200。
在本实施例中，假设MCF已经从CP处获得了组播业务信息。
S801，UE向AMF发送请求加入组播业务的消息，则对应地，AMF接收该消息。
示例性地，UE可以通过非接入层(non access stratum，NAS)消息向AMF发送加入组播业务的请求。在一种可能的实现方式中，UE已经获得了组播业务的MCID(例如CP可以通过应用层下发组播业务信息，其中包括该组播业务的MCID)，则UE可以发送该组播业务的MCID用以标识该组播业务。在另一种可能的实现方式中，UE可以发送该组播业务的组播地址和可选的源地址信息用以标识该组播业务(例如CP可以通过应用层下发组播业务信息，其中包括该组播业务的组播地址和可选的源地址)。
可选地，UE发送的请求加入组播业务的消息中包括UE支持组播能力的指示。
S802，AMF接收到UE发送的请求加入组播业务的消息之后，将该UE的组播能力信息以及该UE所接入的gNB的组播能力信息发送给SMF。
AMF还将UE请求加入组播业务的消息发送给SMF。
可选地，在AMF向SMF发送gNB的组播能力信息之前，AMF获取该该UE所接入gNB的组播能力信息。可选地，gNB的组播能力信息是gNB上电时由gNB上报给AMF的，具体可参见方法700。
S803，SMF获取与组播业务相关的PCC规则。
具体地，若SMF本地已经有该组播业务的信息，则SMF可以不用向PCF发送请求消息，若SMF本地没有该组播业务的信息，则SMF可以向PCF发送请求消息，通过PCF获取组播业务的PCC规则。
此外，在一种可能的实现方式中，UE发送的请求加入组播业务的消息中携带了组播业务的MCID，则SMF可以将该MCID发送给PCF，以便PCF根据MCID获取该组播业务所对应的PCC规则。在另一种可能的实现方式中，UE发送的请求加入组播业务的消息 中携带了组播地址和可选的源地址信息，则SMF可以将该组播地址和可选的源地址信息发送给PCF，以便PCF根据该组播地址和可选的源地址信息获取该组播业务所对应的PCC规则。
PCF可以向SMF发送反馈消息，反馈消息可以包含该组播业务的PCC规则。在本申请实施例中，组播业务的PCC规则可以包括如下至少一项：MCID、一个或多个组播业务流的描述信息、每个组播业务流的QoS信息(用于生成组播QoS流)，其中，组播业务流的描述信息可以包括如下至少一项：组播业务流的源地址、目的地址、组播业务流的5QI(代表一组QoS参数，包括带宽、时延抖动、等)、组播业务的QoS参数中的至少一项。
S804，SMF可以确定组播业务的发送方式。即SMF可以根据UE的组播能力信息和/或gNB的组播能力信息确定采用组播方式下发该组播业务，或者，采用单播方式下发该组播业务。
具体而言，SMF判断UE与gNB是否都支持组播。下面按照UE和/或gNB不支持组播和UE与gNB都支持组播两种情况分别进行描述。
情况1、UE不支持组播，和/或，gNB不支持组播，不执行S805-S819。
若UE的组播能力信息指示该UE不支持组播，和/或，gNB的组播能力信息指示该gNB不支持组播，则SMF确定该组播业务的发送方式为单播方式。即SMF确定通过PDU会话的隧道向UE下发组播业务。在这种情况下，SMF将组播业务的组播业务流映射到PDU会话中的单播QoS流，进而通过单播QoS流将该组播业务下发给UE。
具体而言，SMF可以根据PCC规则确定该组播业务的一个或多个组播业务流(包括组播业务流的QoS信息和QFI)，然后，SMF在该UE的PDU会话范围内为组播业务流对应的组播QoS流分配对应单播QoS流的QFI，即SMF为该组播QoS流所分配的单播QoS流的QFI是在当前PDU会话内的其他单播QoS流未使用的QFI，本申请实施例也称为“将组播QoS流映射为该PDU会话中的单播QoS流”。QFI是服务质量索引，用于描述一组服务质量。需要注意的是，如上所述，SMF为组播QoS流分配的单播QoS流的QFI与该PDU会话的其他单播QoS流的QFI不同(即所分配的QFI在UE的PDU会话内唯一)，以便SMF可以将对应组播业务的单播QoS流和普通的单播QoS进行区分。
在SMF为组播QoS流分配了其对应的单播QoS流的QFI之后，SMF需对UE的PDU会话进行修改，才能完成将组播QoS流通过PDU会话下发给UE。示例性地，SMF可以向UPF发送该组播业务的信息和该单播QoS流的QFI，以便UPF进行参数的修改，从而将组播QoS流映射到PDU会话的PDU会话隧道中以单播QoS流的方式传输，其中上述组播业务信息可以包含数据检测规则(packets detection rule，PDR)。应理解，PDR是过滤器的集合，每一个过滤器是一个五元组，包含业务的源地址、目的地址、源端口号、目标端口号、协议号，用于对应用数据进行过滤。该SMF可以根据该组播QoS流的QoS参数，确定其对应的单播QoS流的QoS参数，进而向gNB发送该单播QoS流的QFI和该单播QoS流的QoS参数，以便gNB根据QoS参数准备无线承载(data radio bearer，DRB)。
情况2、UE与gNB都支持组播，执行S805-S819。
若UE的组播能力信息指示该UE支持组播，且gNB的组播能力信息指示该gNB支持组播，则SMF确定该组播业务的发送方式为组播方式。在这种情况下，gNB与UPF之 间可以建立组播会话隧道，并且gNB使用PTM方式向UE下发组播业务。
可选地，在gNB支持组播的情况下，SMF也可以按照上述情况1中的方式生成组播QoS流的QFI与该UE的PDU会话中的单播QoS流的QFI的映射关系，并将该映射关系发送给gNB，以便gNB保存该映射关系。可选地，SMF还可存储上述映射关系。
这是因为当前场景是UE所接入的gNB支持组播，即组播业务通过组播会话隧道中下发，单播业务通过PDU会话所在的PDU会话隧道中下发。然而，UE具有移动性，后续UE存在移动到另一gNB的可能，该另一gNB可能不支持组播。为了避免由于另一gNB不支持组播而导致UE从gNB切换至另一gNB时组播业务的传输不连续的问题，SMF可以提前存储上述组播QoS流的QFI和单播QoS流的QFI之间映射关系，以便SMF在得知UE将要切换到的另一gNB不支持组播时，通知UPF(发送PDR以及映射关系给UPF)将组播业务映射到PDU会话所在的PDU会话隧道中下发给UE，保证组播业务的连续性。应理解，发送PDR是为了过滤，也即筛选出到达UPF的应用业务流中哪些是该组播业务的，进一步地，对于组播业务流，进行有区分地添加上经映射后的QFI(例如，组播业务中的音频、图像、文字会有不同的QFI)，从而形成不同的单播QoS流(即，都是由组播QFI映射过来的单播QFI)。
S805，SMF向UDM发送查询消息，查询当前UE所请求加入的组播业务在gNB是否存在。UDM查询后向SMF反馈查询结果。
具体地，该查询消息可以包含gNB的标识和组播业务标识，UDM根据SMF提供的查询消息，确定gNB是否存在该组播业务，并向SMF反馈查询结果。SMF根据查询结果便可获知gNB是否存在该组播业务。其中，组播业务标识也可以称为组播业务的标识信息，例如，可以是以下任意一种，也可以是以下一种或多种的组合，不限定：组播/广播业务的标识，组播/广播业务的名称，组播/广播业务的组播/广播地址，组播/广播业务的组播/广播IP地址，组播/广播业务对应的临时移动组标识(temporary mobile group identity，TMGI)，组播/广播业务的组播/广播业务的会话地址等。
可以理解的是，组播业务的业务标识还可以携带其它消息中，例如，在N1N2信息传递(Namf_Communication_N1N2Message Transfer)中。具体地，如图8中的S806和/或S814，图9中的S906和/或S914所示的N1N2信息传递发送给AMF，AMF再通过其它消息将组播业务的业务标识发给接入网设备。该其它消息还可以是N2消息，例如，N2消息可以是N2 PDU会话请求，PDU会话资源建立请求，或PDU会话资源修改，等。
在一种可能的实现方式中，该组播业务已经存在，则执行S806-S808，即SMF仅需向gNB发送将UE加入组播业务的请求，具体执行如下步骤：
S806，SMF向gNB发送请求消息请求将UE加入组播业务。gNB接收该请求消息，并根据该请求消息将该UE加入组播业务。该请求消息经由AMF转发。
具体地，SMF发送的请求消息可以携带组播业务的标识，该请求消息可以通过该PDU会话相关的信令发送。gNB接收该请求消息，将组播业务的标识保存到该PDU会话的上下文中，也就是所说的PDU会话与组播业务关联，或者说，PDU会话包含组播业务。
可选地，该请求消息还可以携带上述组播QoS流的QFI与单播QoS流的QFI的映射关系。在一种可能的实现方式中，gNB可以将该映射关系保存到UE的PDU会话的上下文中。
可选地，由于上述请求消息是经过AMF转发的，AMF可以存储该请求消息中包含的信息，即上述组播QoS流的QFI与单播QoS流的QFI的映射关系以及切换的UE的PDU会话是否与组播业务关联。
可选地，该请求消息中还可以包括请求gNB发送给UE的NAS消息，该NAS消息中携带上述组播QoS流的QFI与单播QoS流的QFI的映射关系以及组播业务所关联的PDU会话标识。
S807，gNB向UE发送RRC消息，该RRC消息中可以包括UE接入基站所需的无线配置信息。则对应地，UE接收该RRC消息，根据gNB下发的RRC消息进行无线配置，以便后续能够接收组播业务。
S808，gNB向SMF发送响应消息，则对应地，SMF可以接收该响应消息。
示例性地，该响应消息可以为N2响应消息，该N2响应消息经过AMF发送给SMF。在N2响应消息中，gNB向SMF指示是否成功将UE加入该组播业务，若不成功，gNB可以向SMF发送原因值。
应理解，若gNB成功将UE加入了该组播业务，继续执行S817-S819；否则，本流程结束。
在另一种可能的实现方式中，该组播业务不存在，则执行S809-S816，即先创建并运行该组播业务，然后再将UE加入该组播业务，具体执行如下步骤：
S809，SMF向gNB发送无线承载创建请求，请求gNB为该组播业务分配无线资源(即请求gNB为该组播业务创建无线承载)。则对应地，gNB接收该无线承载创建请求。
示例性地，该无线承载创建请求可以是N2请求消息，该N2请求消息包括该组播业务的组播业务流的QFI和组播业务流的QoS参数。该N2请求消息可以经过AMF发送给gNB。可选地，由于该N2请求消息经由AMF转发，AMF可以存储该N2请求消息所携带的内容，例如组播业务的标识。
S810，gNB创建组播业务相关的无线承载。
具体地，gNB在接收到上述无线承载创建请求消息之后，可以创建该组播业务的上下文，保存该组播业务相关的组播业务流的QoS信息和QFI，为该组播业务准备无线承载。此外，gNB还可以为该组播业务分配下行隧道地址，该下行隧道地址用于gNB对接UPF接收该组播业务的下行组播数据。
S811，gNB向SMF发送无线承载创建响应，则对应地，SMF接收该无线承载创建响应。
示例性地，该无线承载创建响应可以是N2响应消息。可选地，该响应消息中可以包含gNB为该组播业务分配的下行隧道地址。
应理解，若上述组播业务的无线承载创建失败，则gNB在该无线承载创建响应中可以携带创建失败的原因，例如gNB的无线资源紧张等。
S812，SMF与PCF之间创建PCC关联，该PCC关联用于对组播业务进行PCC规则更新。
S813，SMF向UDM发送注册消息，对该组播业务的运行状态信息进行注册。即SMF告知UDM该组播业务在gNB中已经运行或马上准备运行。则对应地，UDM接收该注册消息，并更新该组播业务的运行状态。
示例性地，该注册消息可以包括gNB的标识、组播业务的标识、SMF为组播业务分配的运行状态标识。可选地，该注册消息中还可以包括该SMF的标识。
S814，SMF向gNB发送请求消息请求将UE加入组播业务。gNB接收该请求消息，并根据该请求消息将该UE加入组播业务。该请求消息经由AMF转发。
S814同S806，此处不再赘述。应理解，S814可以与S809同时执行，即SMF在请求gNB将UE加入组播业务的同时，请求gNB为该组播业务创建无线承载。或者，先执行S809，再执行S814，本申请实施例对此不作限定。
S815，gNB向UE发送RRC消息，该RRC消息中可以包括UE接入基站所需的无线配置信息。则对应地，UE接收该RRC消息，根据gNB下发的RRC消息进行无线配置，以便后续能够接收组播业务。S815同S807。
S816，gNB向SMF发送响应消息，则对应地，SMF接收该响应消息。
示例性地，该响应消息可以为N2响应消息，该N2响应消息经过AMF发送给SMF。在N2响应消息中，gNB向SMF指示是否成功将UE加入该组播业务，若不成功，gNB可以向SMF发送原因值。
S817，SMF向UPF发送隧道建立请求，请求UPF建立组播会话隧道。则对应地，UPF接收该隧道建立请求，并建立组播会话隧道。
示例性地，在上述S810中，gNB为组播业务分配了该gNB的下行隧道地址，SMF将该下行隧道地址发送给UPF，用于建立UPF到gNB的组播会话隧道，该组播会话隧道用于发送与该组播业务相关的数据。
可选地，若UPF从MUF接收到组播业务的数据，并且，此时UPF与MUF之间的隧道还未建立，UPF分配用于对接MUF的下行隧道地址，用于建立UPF和MUF之间的隧道。应理解，UPF和MUF之间的隧道为数据面隧道。
S818，SMF向MCF发送通知消息，该通知消息中携带UPF的下行隧道地址，以便建立MUF到UPF的隧道。则对应地，MCF接收该通知消息。
具体地，为了标识组播业务，该通知消息中还可以携带该组播业务的标识信息。示例性地，该组播业务的标识信息可以是由MCF分配的MCID，或者，该组播业务的标识信息可以包括该组播业务的组播地址、目的端口号、源地址等。MCF可以保存该标识信息，在后续对该组播业务进行更新时可使用该标识信息标识该组播业务。可选地，上述通知消息中还可以携带gNB的标识，MCF可以存储该gNB的标识。
S819，MCF在接收到上述通知消息之后，可以请求MUF建立MUF到UPF的隧道。MCF将UPF的下行隧道地址发送给MUF，用于MUF对接UPF，以便MUF将该组播业务的下行数据通过该隧道发送给UPF。
应理解，上述MUF和UPF之间的隧道可以是单播隧道(即，UPF的IP地址为单播地址)或者组播隧道(即，UPF的IP地址为多播IP地址)，本申请实施例对此不作限定。而前文所说的“组播会话隧道”是指gNB以及与gNB最近一跳的UPF之间的隧道，该隧道可以为单播隧道(即，UPF的IP地址为单播地址)，也可以为多播隧道(即，UPF的IP地址为多播IP地址)，但是，不管该组播会话隧道是单播隧道还是多播隧道，gNB收到该组播会话隧道中的数据后，可以按照PTM或者PTP的方式下发给UE；而对于PDU会话隧道，gNB收到PDU会话隧道中的数据只能按照PTP方式下发给UE。
本申请实施例的传输组播业务的方法，可以保障UE在初次申请加入组播业务时，核心网设备根据该UE的组播能力信息和/或UE所接入的gNB的组播能力信息确定该组播业务的发送方式，从而更有效地为UE下发组播业务，减少UE请求加入组播业务的时延，从而提高组播业务传输的可靠性。
图9是本申请实施例提供的另一传输组播业务的方法900的示意性流程图。该方法900可以应用于图2所示的系统架构200。
S901，UE通过网际组管理协议(internet group management protocol，IGMP)加入请求加入组播业务。在这种情况下，IGMP加入消息是经过UPF发送给SMF的，请求加入组播业务。
示例性地，IGMP加入消息中可以携带UE所请求加入的组播业务的组播地址和可选的源地址，用以标识该组播业务。IGMP加入消息可以通过已建立的PDU会话的用户面进行发送，即UE将IGMP加入消息发送至gNB，gNB将该IGMP加入消息发送至UPF，UPF将该IGMP加入消息发送至SMF，SMF接收到IGMP消息，获知UE请求加入组播业务。
S902，SMF获取UE的组播能力信息和/或gNB的组播能力信息。
本申请实施例对S902与S901的先后顺序不作限定，且该步骤可以通过下列多种方式实现。
在PDU会话建立时，UE可以将UE的组播能力信息发送给SMF，例如，UE在PDU会话建立请求NAS消息中携带UE的组播能力信息。UE也可以通过PDU会话修改请求(NAS消息)将UE的新组播能力信息发送给SMF。
在一种可能的实现方式中，在PDU会话建立时，AMF可以不做任何判断，直接将UE的组播能力信息和/或基站(可以包括本实施例中UE所接入的gNB)的组播能力信息发送给SMF；或者，AMF可以选择性地将UE的组播能力信息和/或基站的组播能力信息发给SMF。示例性地，当PDU会话建立时，AMF可以根据DNN(例如，通过该DNN可访问组播业务)、S-NSSAI(例如，EMBB切片就可能支持访问组播业务)、组播业务指示信息(例如，PDU会话支持的组播业务标识)中的至少一项，确定是否将UE的组播能力信息和/或gNB的组播能力信息发送给SMF。若所建立的PDU会话支持组播，则AMF可以将UE的组播能力信息和/或基站的组播能力信息发送给SMF；否则，AMF不发送UE的组播能力信息和/或基站的组播能力信息。
在另一种可能的实现方式中，SMF可以向AMF订阅UE的组播能力信息和/或基站的组播能力信息。具体而言，SMF可根据PDU会话的属性(即PDU会话是否支持组播)提前向AMF订阅，因此，SMF可以接收到AMF发送的UE的组播能力信息和/或基站的组播能力信息。示例性地，在PDU会话支持组播的情况下，SMF向AMF发送订阅消息。
在又一种可能的实现方式中，SMF可以向AMF查询UE的能力和/或基站的能力。具体而言，SMF可以在收到UE加入组播业务请求时，再向AMF查询该UE的组播能力信息和/或该UE所接入的基站的组播能力信息。在本申请实施例中，在S901之后，SMF可以执行该查询步骤，即向AMF查询UE是否支持组播和/或gNB是否支持组播。
可选地，在AMF向SMF发送UE的组播能力信息和/或gNB的组播能力信息之前，AMF可以获取该UE的组播能力信息和/或该UE所接入的gNB的组播能力信息。可选地， gNB的组播能力信息可以是gNB上电时由gNB上报给AMF的；UE的组播能力信息可以是UE向AMF发送PDU会话建立/修改请求时上报给AMF的。
后续步骤S903-S919与S803-S819类似，此处不再赘述。
本申请实施例的传输组播业务的方法，可以保障UE在初次申请加入组播业务时，SMF可以根据该UE的组播能力信息和/或UE所接入的gNB的组播能力信息确定该组播业务的发送方式，从而更有效地为UE下发组播业务，减少UE请求加入组播业务的时延，从而提高组播业务传输的可靠性。
应理解，上述方法800和方法900的区别在于：在方法800中，UE是通过NAS消息请求加入组播业务的，即SMF接收到的是来自AMF的请求加入组播业务的消息；而在方法900中，UE是通过PDU会话用户面IGMP加入消息请求加入组播业务的，即SMF接收到的是来自UPF的请求加入组播业务的消息。
图10是本申请实施例提供的另一传输组播业务的方法1000的示意性流程图。该方法1000可以应用于图2所示的系统架构200。应理解，本实施例默认UE都支持组播的情况，仅以T-gNB的能力进行讨论。但是，在其他可能的实现方式中，SMF也可以根据UE的组播能力信息和/或T-gNB的组播能力信息进行综合判断，具体方法可以参考前文所述实施例，此处不再赘述。
在方法1000中，UE从源接入网设备(本实施例称为S-gNB)切换至目标接入网设备(T-gNB)。
可选地，S-gNB可以获知T-gNB的组播能力信息。在S-gNB与T-gNB之间存在Xn连接的情况下，T-gNB可以通过Xn接口将自身的组播能力信息发送给S-gNB。示例性地，当T-gNB支持组播时，T-gNB可以向S-gNB发送该组播能力信息，当T-gNB不支持组播时，T-gNB不发送该组播能力信息，因此，若S-gNB未收到T-gNB发送的组播能力信息，可以默认该T-gNB不支持组播。
S1001，UE向S-gNB发送测量报告，用于表示UE对邻小区的信号测量结果。则对应地，S-gNB接收该测量报告，并基于该测量报告，决定将UE切换至T-gNB。
S1002，S-gNB向T-gNB发送切换请求，用于请求将UE切换至T-gNB。则对应地，T-gNB接收该切换请求。
具体而言，该切换请求中可以包括待切换UE的PDU会话信息以及该PDU会话所关联的组播业务的信息。其中，PDU会话信息可以包括PDU会话标识和PDU会话所关联的单播业务的单播QoS流的QoS信息。其中，单播QoS流的QoS信息可以包括该单播QoS流的QFI和QoS参数。在本申请实施例中，当前切换UE的PDU会话关联组播业务，则S-gNB可以根据组播QoS流的QFI与单播QoS流的QFI之间的映射关系，将组播QoS流映射为单播QoS流。此时，该PDU会话中所关联的单播QoS流中除了包括已经存在的单播业务的单播QoS流之外，还包括上述组播QoS流所映射的单播QoS流。
应理解，S-gNB可以通过下述方式获得组播QoS流与单播QoS流之间的映射关系：在将UE加入组播业务时，S-gNB可以从SMF处获得该组播业务的组播QoS流与单播QoS流的映射关系。该映射关系可以包括组播QoS流的QFI以及该组播QoS流对应的单播QoS流的QFI。该组播QoS流所对应的单播QoS流的QFI与UE的PDU会话中的其它单播QoS流的QFI不同。此外，若UE加入了多个组播业务，不同组播业务的组播QoS流所 对应的单播QoS流的QFI也不相同，以便区分当前组播业务的组播QoS流所映射的单播QoS流和其他组播业务的组播QoS流所映射的单播QoS流。
可选地，上述切换请求还可以包括S-gNB希望通过转发隧道转发的业务流标识。示例性地，若组播QoS流通过转发隧道转发，则S-gNB在切换请求中可以包括该组播QoS流对应的单播QoS流的QFI。之所以通过转发隧道进行业务流转发，原因是在后续S1004中S-gNB发送切换命令给UE后，UE会与S-gNB断开连接，直到下一步UE接入T-gNB。因此，在这段时间内的数据UE暂时无法通过S-gNB接收，由于UE还未接入T-gNB，在这段时间内的数据通过转发隧道转发至T-gNB进行缓存，等到UE接入T-gNB之后下发给UE。该转发隧道是S-gNB与T-gNB之间的逻辑隧道，该逻辑隧道基于S-gNB与T-gNB之间的物理连接建立。
需要说明的是，在本申请实施例中，S-gNB在发送切换请求至T-gNB时，SMF先将S-gNB正在进行的与切换UE的PDU会话关联的组播业务的组播QoS流映射为单播QoS流，在UE接入T-gNB后，SMF再根据T-gNB的组播能力信息进行判断。当T-gNB支持组播时，SMF可以将映射到单播QoS流的组播QoS流还原为组播QoS流，并通过T-gNB的组播会话隧道下发；当T-gNB不支持组播时，SMF可以仍按照单播方式将组播QoS流对应的单播QoS流通过T-gNB的PDU会话隧道下发给UE。
应理解，在本申请实施例中，SMF先将S-gNB正在进行的与切换的UE的PDU会话关联的组播业务的组播QoS流映射为单播QoS流，这是因为UE在接入S-gNB时既请求了单播业务又请求了组播业务，其中，单播业务在PDU会话隧道中传输，组播业务在组播会话隧道中传输，UE的服务连续性可以得到保证。所谓的服务连续性包括单播服务的连续性以及组播服务的连续性。但是，由于UE从S-gNB切换至T-gNB，如果不先将S-gNB组播会话隧道中的组播QoS流映射进S-gNB的PDU会话所在的PDU会话隧道中的单播QoS流，如果切换之后T-gNB不支持组播(即无法建立组播会话隧道)，那么UE的组播业务会发生中断，无法保持服务连续性。因此，为了保证UE的服务连续性，先在S-gNB处(即在UE切换至T-gNB之前)将组播QoS流映射到单播QoS流，以单播切换进行，然后SMF在切换流程中知道T-gNB的组播能力信息之后，可以再根据T-gNB是否支持组播进行操作，以便以合适的方式在T-gNB将UE加入该组播业务(即将UE的组播业务从S-gNB切换至T-gNB)。
S1003，T-gNB为UE准备无线资源，并向S-gNB发送切换响应。则对应地，S-gNB接收该切换响应。
具体而言，T-gNB根据从S-gNB收到的业务流描述信息为UE准备无线资源。由于S-gNB收到的都是单播业务流描述信息(其中包括从组播业务的组播QoS流映射的单播业务的单播QoS流)，因此T-gNB可以为每个单播QoS流分配单播资源。T-gNB在准备好无线资源之后可以向S-gNB发送切换响应。T-gNB可以将通过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。若上述切换请求中包含了S-gNB希望通过转发隧道转发的业务流标识，并且T-gNB支持数据转发，则T-gNB分配转发隧道标识(该标识用于T-gNB对接S-gNB)，并在切换响应中将转发隧道标识发送给S-gNB，以便为UE的PDU会话建立从S-gNB到T-gNB的转发隧道。可选地，T-gNB还可以通知S-gNB该PDU会话中的哪些单播QoS流支持转发， 具体地，T-gNB可以向S-gNB发送这些单播QoS流的QFI标识。
S1004，S-gNB向UE发送切换命令。则对应地，UE接收该切换命令。
具体地，若T-gNB给UE发送无线承载的配置信息，则S-gNB在切换命令中可以携带无线承载的配置信息。此时，S-gNB停止向UE发送任何下行数据，并且，针对支持数据转发的单播QoS流，S-gNB可以将该单播QoS流所对应的数据通过转发隧道发送给T-gNB。
S1005，UE接入T-gNB。UE根据T-gNB发送的无线承载配置信息接入T-gNB。T-gNB将从S-gNB收到的转发数据发送给UE。
S1006，T-gNB向AMF发送N2路径切换请求，则对应地，AMF接收该N2路径切换请求。
示例性地，该N2路径切换请求中可以包含该PDU会话中切换成功以及切换失败的单播QoS流的QFI(包含S-gNB中将组播QoS流映射为单播QoS流的QFI)。可选地，上述QFI可以被封装在N2 SM信息体中。可选地，该N2路径切换请求中还可以包含与UE的PDU会话所关联的组播业务在T-gNB是否存在的指示信息。
S1007，AMF向SMF发送PDU会话更新请求，则对应地，SMF接收该PDU会话更新请求。
可选地，该PDU会话更新请求可以包含N2路径切换请求所包含的信息。可选地，若N2路径切换请求中包含了组播业务在T-gNB是否存在的指示信息，该PDU会话更新请求还可以包含组播业务在T-gNB是否存在的指示信息，SMF可以根据该指示信息判断与切换的UE的PDU会话所关联的组播业务在T-gNB是否存在。
在该步骤中，SMF通过T-gNB的组播能力信息判断T-gNB是否支持组播。该组播能力信息可以携带在上述PDU会话更新请求中。可选地，SMF主要可以通过以下三种方式之一获取T-gNB的组播能力信息：
1、AMF将收集到的T-gNB的组播能力信息作为信元包含于AMF发送给SMF的PDU会话更新请求中；
2、AMF可以基于自身的判断选择性地向SMF发送T-gNB的组播能力信息。具体而言，若UE的PDU会话支持组播，则AMF将T-gNB的组播能力信息发送给SMF；若UE的PDU会话不支持组播，则AMF可以不发送T-gNB的组播能力信息。其中，AMF可以在UE申请加入组播业务时获知UE的PDU会话是否支持组播(详见上述方法800或900)。
3、AMF可以基于SMF的订阅，按需将T-gNB的组播能力信息发送给SMF。
SMF收到AMF发送的T-gNB的组播能力信息后，可以先查看T-gNB是否支持组播，若T-gNB不支持组播，则可以执行S1011-S1013；若T-gNB支持组播，则可以执行S1010-S1013。
若T-gNB支持组播并且与UE的PDU会话关联的组播业务在T-gNB中存在，则在执行下文所述的S1011-S1013的同时，SMF还可以向T-gNB发送请求消息请求将UE加入组播业务；或者，SMF可以在执行完本切换流程之后，再请求T-gNB将UE加入组播业务；或者，SMF可以在收到上述PDU会话更新请求之后的任何时间请求T-gNB将UE加入组播业务，本申请实施例对此不做限定。T-gNB将UE加入组播业务的具体方法可参见上述方法800，此处不再赘述。
可选地，在将该UE加入了组播业务之后，SMF可以删除为该UE的PDU会话所关联的组播业务制定的PDR，并删除组播QoS流与单播QoS流之间的映射关系。
S1008，SMF发送查询请求至UDM，查询UE的PDU会话所关联的组播业务在T-gNB是否存在。则对应地，UDM接收该查询请求。
在T-gNB支持组播，并且SMF请求T-gNB将UE加入组播业务的情况下，SMF可以先通过UDM查询该组播业务是否存在于T-gNB。若该组播业务在T-gNB不存在，则在执行下文所述S1011-S1013的同时，SMF还与UPF和T-gNB进行交互，完成组播业务的建立，并将UE加入该组播业务，具体流程可参见方法800，此处不再赘述。若该组播业务在T-gNB已经存在，则在执行下文所述S1011-S1013的同时，SMF还可以向T-gNB发送请求消息请求将UE加入组播业务，或者，SMF可在执行完本切换流程后再请求T-gNB将UE加入组播业务，或者，SMF可以在确定该组播业务在T-gNB已经存在之后的任何时间请求T-gNB将UE加入组播业务，本申请实施例对此不做限定。在将该UE加入了组播业务之后，SMF可以删除为该UE的PDU会话所关联组播业务制定的PDR，并删除组播QoS流与单播QoS流之间的映射关系。
S1009，SMF向UPF发送N4会话更新请求，通知UPF根据映射关系将组播业务的组播QoS流映射为单播业务的单播QoS流，使得UPF可以通过PDU会话的PDU会话隧道将组播QoS流发送至T-gNB。
应理解，UE在加入组播业务时，SMF已经保存了组播QoS流的QFI与单播QoS流的QFI之间的映射关系，具体操作可参见上述方法800，此处不再赘述。
S1010，SMF向AMF发送PDU会话更新响应。
S1011，AMF向T-gNB发送N2路径切换响应。
需要指出的是，上述无线承载配置信息可以替换成无线资源的配置信息，以及无线承载配置可以替换为无线资源的配置。其中，无线资源可以包括无线承载，无线资源的配置信息可以包括无线承载配置信息，不予限制。
本申请实施例的传输组播业务的方法，可以保障UE由支持组播功能的S-gNB切换至T-gNB时，无论T-gNB是否支持组播，UE在S-gNB的组播业务与单播业务皆可以不因切换发生中断，保证了UE的服务连续性，并且能够在切换过程中减少丢包，从而降低切换时延。此外，本申请实施例的切换流程是基于现有流程的改进，只需增加对gNB的组播能力的判断，以及对UE的PDU会话所关联的组播业务在T-gNB是否存在的判断，能够实现向后兼容，易于实施。
图11和图12是本申请实施例提供的传输组播业务的隧道示意图。对于UE的PDU会话在S-gNB所关联的组播业务，为S-gNB的组播业务服务的组播网元为MCF(控制面)与MUF(用户面)，则MUF可以与UE的PDU会话所在的UPF相连。其中，图11中的T-gNB支持组播，图12中的T-gNB不支持组播。在图11中，由于T-gNB支持组播，能够通过上述方法建立UPF与T-gNB之间的组播会话隧道，进而通过该组播会话隧道向UE下发组播业务。在图12中，由于T-gNB不支持组播，UPF与T-gNB之间仅存在PDU会话隧道，将组播QoS流映射到单播QoS流，通过该PDU会话隧道下发该组播业务。
图13是本申请实施例提供的另一传输组播业务的方法1300的示意性流程图。该方法1300可以应用于图2所示的系统架构200。应理解，本实施例默认UE都支持组播的情况， 仅以T-gNB的能力进行讨论。但是，在其他可能的实现方式中，SMF也可以根据UE的组播能力信息和/或T-gNB的组播能力信息进行综合判断，具体方法可以参考前文所述实施例，此处不再赘述。
在方法1300中，UE从源接入网设备(本实施例称为S-gNB)切换至目标接入网设备(T-gNB)，且AMF、UPF均发生了切换。即为S-gNB提供服务的网元为S-AMF和S-UPF，为T-gNB提供服务的网元为T-AMF和T-UPF。
S1301，UE向S-gNB发送测量报告，用于表示UE的信号测量结果。则对应地，S-gNB接收该测量报告，并基于该测量报告，决定将UE切换至T-gNB。
S1302，S-gNB向S-AMF发送切换请求，S-AMF与S-gNB相连。则对应地，S-AMF接收该切换请求。
示例性地，该切换请求可以包含UE的PDU会话信息，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，单播业务流对应的QoS信息可以包括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。
需要说明的是，在本申请实施例中，S-gNB在发送切换请求至T-gNB时，SMF先将S-gNB正在进行的与切换UE的PDU会话关联的组播业务的组播QoS流映射为单播QoS流，在UE接入T-gNB后，SMF再根据T-gNB的组播能力信息进行判断。当T-gNB支持组播时，SMF可以将映射到单播QoS流的组播QoS流还原为组播QoS流，并通过T-gNB的组播会话隧道下发；当T-gNB支持组播时，SMF可以仍按照单播方式将组播QoS流对应的单播QoS流通过T-gNB的PDU会话隧道下发给UE。关于这一点的具体说明可参见上述方法1000，此处不再赘述。
若当前切换的UE的PDU会话关联组播业务，那么S-gNB知道T-gNB的组播能力信息。在一种可能的实现方法中，S-gNB可以通过与T-gNB之间的Xn连接获取T-gNB的组播能力信息以及用于指示与UE的PDU会话所关联的组播业务在T-gNB是否存在的信息。因此，在这种情况下，上述S-gNB发送给S-AMF的切换请求中还可以包括T-gNB的组播能力信息以及用于指示与UE的PDU会话所关联的组播业务在T-gNB是否存在的信息。
S1303，S-AMF可以根据目标小区的标识(ID)选择T-AMF，T-AMF与T-gNB相连。
S1304，S-AMF向T-AMF发送创建UE上下文请求，则对应地，T-AMF接收该创建UE上下文请求。
示例性地，该创建UE上下文请求中可以包含S-AMF存储的UE的上下文信息、UE的PDU会话信息，其中，该PDU会话信息可以包含PDU会话标识、DNN和S-NSSAI等信息。
可选地，该创建UE上下文请求中还可以包括S1302中切换请求所携带的信息。
可选地，若在UE初次加入组播业务时，S-AMF保存了PDU会话与组播业务的关联信息，则S-AMF还可将该关联信息发送给T-AMF。
S1305，T-AMF向SMF发送PDU会话更新请求，则对应地，SMF接收该PDU会话更新请求。
上述PDU会话更新请求中可以携带T-gNB的组播能力信息；T-AMF可以通过额外的 信令向SMF发送T-gNB的组播能力信息，本申请实施例对此不作限定。示例性地，T-AMF可以将T-gNB的组播能力信息发送给SMF；或者，T-AMF可以根据PDU会话是否关联组播业务，选择性地将T-gNB的组播能力信息发送给SMF；或者，SMF向T-AMF订阅了T-gNB的组播能力信息的改变通知，则当T-gNB的组播能力信息发生变化时(例如，T-gNB从不支持组播升级为支持组播)，T-AMF可以向SMF发送T-gNB的组播能力信息。
S1306，SMF判断是否进行UPF重选。
S1307，SMF判断T-gNB是否支持组播。
在一种可能的实现方式中，S-gNB已经通过与T-gNB的Xn连接获取了T-gNB的组播能力信息以及与UE的PDU会话关联的组播业务在T-gNB是否存在的信息，则S-gNB可将上述信息传递到SMF，SMF便可知道T-gNB是否支持组播以及与UE的PDU会话关联的组播业务在T-gNB是否存在。
在另一种可能的实现方式中，SMF可以根据从T-AMF发送来的T-gNB的组播能力信息来判断T-gNB是否支持组播。
若T-gNB不支持组播，则SMF将组播QoS流映射为单播QoS流，将该单播QoS流和其他单播QoS流一起切换至T-gNB。后续切换流程可参见现有技术(例如，3GPP TS 23.502中的N2切换流程)，这里不再赘述。
若T-gNB支持组播，则SMF可以判断与UE的PDU会话所关联的组播业务在T-gNB是否存在。
若该组播业务在T-gNB存在，则继续执行现有3GPP TS 23.502中的切换流程，以便将UE的PDU会话包含的单播业务流切换到T-gNB。而SMF可在切换流程结束后，或者在切换流程进行过程中的任何时刻，请求T-gNB将UE加入该组播业务。由于T-gNB支持组播并且组播业务在T-gNB存在，因此，SMF可在单播业务切换的同时或单播切换结束后，请求T-gNB将UE加入组播业务。
若该组播业务在T-gNB中不存在，则SMF可以继续将单播业务流按照3GPP TS 23.502中的切换流程切换到T-gNB，同时，SMF还可以执行如下操作之一：
在一种可能的实现方式中，由于组播业务在T-gNB不存在并且该组播业务已经在S-gNB中被映射进行了PDU会话所在的PDU会话隧道，那么，可以仍然通过在T-gNB的PDU会话隧道下发该组播业务。换句话说，SMF将组播业务源发送给T-gNB的组播QoS流仍映射为单播QoS流，和其他单播QoS流一起切换至T-gNB，具体可参见T-gNB不支持组播时的描述。
在另一种可能的实现方式中，SMF可以在单播业务切换的同时，请求T-UPF与T-gNB建立组播会话隧道并在T-gNB运行该组播业务，之后请求T-gNB将UE加入该组播业务。示例性地，SMF可以在接收到T-AMF的请求消息时就请求T-UPF与T-gNB创建组播会话隧道并运行组播业务；或者，SMF也可以等到单播业务切换完成后，再请求T-UPF与T-gNB创建组播会话隧道并运行所关联的组播业务，然后请求T-gNB将UE加入该组播业务。
在S1307之后可以继续进行后续的切换流程，可参见3GPP TS23.502，此处不再赘述。其中，TS是技术规范(techinical specification)的缩写，23.502为该技术规范的版本号。
本申请实施例的传输组播业务的方法，可以保障UE由支持组播功能的S-gNB切换至T-gNB时，无论T-gNB是否支持组播，UE在S-gNB的组播业务与单播业务皆可以不因切换发生中断，保证了UE的服务连续性，并且能够在切换过程中减少丢包，从而降低切换时延。此外，本申请实施例的切换流程是基于现有流程的改进，只需增加对gNB的组播能力的判断，以及对UE的PDU会话所关联的组播业务在T-gNB是否存在的判断，能够实现向后兼容，易于实施。
图14和图15是本申请实施例提供的传输组播业务的隧道示意图。对于UE的PDU会话在S-gNB所关联的组播业务，为S-gNB的组播业务服务的组播网元为MCF(控制面)与MUF(用户面)，则MUF可以与UE的PDU会话所在的锚点UPF(PSA-UPF)相连。锚点UPF分别于S-UPF和T-UPF相连接。S-UPF与S-gNB连接，T-UPF与T-gNB连接。S-gNB至S-UPF至T-UPF至T-gNB之间可以形成间接转发隧道。其中，图14中的T-gNB支持组播，图15中的T-gNB不支持组播。在图14中，由于T-gNB支持组播，能够通过上述方法建立UPF与T-gNB之间的组播会话隧道，进而通过该组播会话隧道向UE下发组播业务。在图15中，由于T-gNB不支持组播，UPF与T-gNB之间仅存在PDU会话隧道，将组播QoS流映射到单播QoS流，通过该PDU会话隧道下发该组播业务。
图16是本申请实施例提供的另一传输组播业务的方法1600的示意性流程图。如图16所示：
S1610，UE向源基站发送测量报告(measurement report)。
例如，该测量报告包括周围多个(例如，8个)小区的信号测量强度。
从而，源基站可以根据测量报告，确定该UE的目标基站。例如，源基站可以将信号强度最强的目标小区确定为UE需要切换至的目标小区，进而将该目标小区的基站确定为目标基站。
S1620，源基站向目标基站发送切换请求(handover request)。
其中，该切换请求中可以包含待切换的UE的PDU会话信息。
其中，PDU会话信息可以包含PDU会话的标识和PDU会话中所包含的业务对应的QoS信息。业务可以包括单播业务和/或组播。
在一种实现方式中，若源基站支持组播/广播，并且待切换的UE的PDU会话关联组播/广播业务(也即，UE在源基站加入了组播/广播业务)，则PDU会话信息还可以包括所关联的组播/广播业务对应的组播/广播业务的QoS信息。
其中，PDU会话包含的业务的QoS信息可以包括：单播业务对应的单播QoS流的QFI，该单播QoS流的QFI对应的QoS参数信息，和/或组播/广播业务对应组播/广播的QoS流的QFI，该组播/广播QoS流的QFI对应的QoS参数信息。
例如，针对上述业务仅包括单播业务的场景，PDU会话包含的业务的QoS信息包括单播业务对应的单播QoS流的QFI，该单播QoS流的QFI对应的QoS参数信息。
针对上述业务仅包括组播/广播业务的场景，PDU会话包含的业务的QoS信息包括组播/广播的QoS流的QFI，组播/广播QoS流的QFI对应的单播QoS流的QFI(例如，映射的单播QoS流的QFI)，该组播/广播QoS流的QFI对应的QoS参数信息。
针对上述业务包括单播和组播/广播业务的场景，PDU会话包含的业务的QoS信息包括单播QoS流的QFI(包含组播/广播的QoS流的QFI对应的单播QoS流的QFI(例如，映 射的单播QoS流的QFI)，单播QoS流的QFI对应的QoS参数信息，组播/广播的QoS流的QFI，该组播/广播QoS流的QFI对应的QoS参数信息。
作为一种示例，单播QoS流的QFI对应的QoS参数可以用于基站进行空口资源的配置，可以由5QI来索引该单播QFI对应的QoS参数。
在本申请中，组播/广播业务对应的单播QoS流的QFI对应的QoS参数信息可以包括：组播/广播QoS流的QFI对应的单播QoS流的QFI，组播/广播QoS流的QFI对应的单播QoS流的QFI所对应的QoS参数。
其中，组播QFI对应的单播QFI可以理解为组播QFI所映射的单播QFI。
作为一种示例，在切换请求中还包括：源基站建议通过转发隧道转发的QFI和源基站生成的转发隧道标识信息。例如，若PDU会话的业务包含的单播QoS流可以通过该PDU会话对应的转发隧道转发，则在切换请求中包含该单播QoS流所对应的单播QFI。
再例如，若PDU会话中的第一QoS流用于传输组播/广播业务的数据，且第一QoS流可以转发，则在切换请求中包含该第一QoS流所对应的单播QFI。其中，该单播QFI也可以理解为由组播/广播QoS流的QFI所映射或所对应的单播QoS流的QFI。
S1630，目标基站根据切换请求为UE配置无线资源。
具体地，S1630可以包括目标基站根据切换请求中PDU会话信息，为UE准备或配置无线资源。例如，根据PDU会话信息中PDU会话包含的业务的QoS信息，为UE准备或配置无线资源。
例如，无线资源可以包括用于传输PDU会话的数据的无线资源，具体地，用于传输PDU会话的数据的无线资源可以包括用于传输组播/广播业务数据的无线资源。
具体而言，对于用于传输PDU会话的数据的无线资源，目标基站可以根据每个单播QoS流的QFI(例如，包括由组播QoS流所映射的单播QoS流的QFI)所对应的QoS参数确定无线数据承载(Data radio bearer,DRB)的数量，QFI到DRB之间的映射关系，此外，目标基站还可根据每个DRB所映射的QFI所对应的QoS参数确定该DRB对应的配置参数(例如，该DRB所对应的PDCP层是否加密，无线链路控制(Radio link control,RLC)层采用确认模式还是非确认模式，以及逻辑信道、传输信道、物理信道的配置、调制编码方式等)，最后，目标基站创建相应的DRB。
可选地，在S1630之后，上述方法还包括：目标基站向源基站发送切换请求应答(handover request ACK)。
其中，切换请求响应可以包含用于传输PDU会话的数据的无线资源的配置信息，
其中，无线资源的配置信息可以为无线数据承载的配置信息。例如，上述DRB对应的配置参数。
进一步地，源基站将来自目标基站的无线资源的配置信息发送给UE，具体地可以采用步骤S1640来实现。
其中，该无线资源的配置信息可以用于UE在后述S1650中接入目标基站，并且UE在接入目标基站后接收上述PDU会话包含的业务的数据(例如，与组播/广播业务的数据)。
S1640，源基站向UE发送切换命令(Handover Command)。
其中，切换命令可以携带上述无线资源的配置信息。
S1650，UE向目标基站发送切换确认(Handover Confirm)。
具体地，UE可以根据无线资源的配置信息向目标基站发送切换确认。
进一步地，UE可以接收PDU会话包含的业务的数据。
S1660，目标基站接收切换确认，并向AMF发送N2路径切换请求(N2 path switch request)或路径切换请求(path switch request)。
其中，该请求中N2路径可以包含N2 SM Information(N2 SM信息)，还可以包含UE的位置信息等；N2 SM信息中包含该PDU会话中切换成功以及切换失败的单播QoS流的QFI(包含由组播/广播QoS流映射的单播QFI，上述QFI封装在N2 SM信息中)，还包含目标基站分配的PDU会话隧道的标识信息。
可选地，在一种实现方式中，若目标基站支持组播/广播，目标基站还在N2路径切换请求或路径切换请求中包含目标基站的组播/广播能力信息。
其中，该目标基站的组播/广播能力信息可以用于指示目标基站是否支持组播/广播，例如，该能力信息可以是一个指示(indication)，也可以是一个tag(标签)，也可以是一个信元(information element,IE)。
需要指出的是，本申请中也可以通过上述S1660中是否携带特定的信息或信元或标签来表征目标基站是否支持组播/广播。例如，携带目标基站的组播/广播能力信息，表征目标基站支持组播/广播，不携带目标基站的组播/广播能力信息，表征目标基站不支持组播/广播。
例如，该能力信息可以包含在N2 SM信息(N2 SM information)信元中，也可以包含在上述N2路径切换请求或路径切换请求中新增的信元中。
其中，N2 SM信息可以是路径切换请求传输(path switch request transfer)。
再例如，携带目标基站的组播/广播能力信息，并表征目标基站是否支持组播/广播，例如，以布尔的方式(也即，1代表支持，0代表不支持)。
S1670，AMF向SMF发送PDU会话上下文更新请求。
其中，PDU会话上下文更新请求可以用于请求PDU会话的上下文，例如，PDU会话上下文更新请求(Nsmf_PDUSession_UpdateSMContext Request)。
例如，可以通过PDU会话上下文更新请求携带目标基站的组播/广播能力信息，表征目标基站支持组播/广播，不携带目标基站的组播/广播能力信息，表征目标基站不支持组播/广播。
在一个示例中，如果上述S1660中的N2路径切换请求或路径切换请求包含目标基站的组播/广播能力信息，那么PDU会话上下文更新请求包含目标基站的组播/广播能力信息。
例如，该PDU会话上下文更新请求中可以包括上述S1660中涉及的N2 SM信息，其中，N2 SM信息中包含目标基站的组播/广播能力信息。
再例如，如果目标基站的组播/广播能力信息包含在上述S1660中涉及的N2路径切换请求或路径切换请求中除N2 SM信息之外的任一信元中，那么PDU会话上下文更新请求包括N2 SM信息，还包含目标基站的组播/广播能力信息。
其中，该PDU会话上下文更新请求可以为本申请的“第二消息”的一例。SMF根据PDU会话上下文更新请求消息，确定目标基站是否支持组播/广播。
例如，可以通过PDU会话上下文更新请求携带目标基站的组播/广播能力信息，表征 目标基站支持组播/广播，不携带目标基站的组播/广播能力信息，表征目标基站不支持组播/广播。
再例如，若目标基站支持组播/广播，则SMF确定所述组播业务的发送方式为组播方式。
其中，该组播方式可以包括但不限于以下一种或多种传输方式：
5GC共享组播/广播业务流量传输方式(5GC Shared MBS traffic delivery method)、共享组播/广播业务流量传输方式(Shared MBS traffic delivery method)、或共享传输方式(Shared delivery method)。
再例如，若目标基站支持组播/广播，并且UE也支持组播/广播，则SMF确定所述组播业务的发送方式为组播方式。
再例如，若目标基站不支持组播/广播，则SMF确定所述组播业务的发送方式为单播方式。
其中，SMF可以通过以下方式确定目标基站是否支持组播/广播：
方式一、根据S1670中PDU会话上下文更新请求携带目标基站的组播/广播能力信息来确定目标基站是否支持组播/广播。
其中，目标基站的组播/广播能力信息可以表征目标基站是否支持组播/广播，例如，布尔(Boolen)的方式，当目标基站的组播/广播能力信息为1时代表目标基站支持组播/广播，当目标基站的组播/广播能力信息为0是代表目标基站不支持组播/广播。
进一步地，SMF可以根据目标基站的组播/广播能力信息确定目标基站支持组播/广播。
具体地，可以在PDU会话上下文更新请求携带的N2 SM信息中包含目标基站的组播/广播能力信息，也可以在PDU会话上下文更新请求中携带目标基站的组播/广播能力信息，不予限制。
方式二、根据S1670中PDU会话上下文更新请求是否携带目标基站的组播/广播能力信息来确定目标基站是否支持组播/广播。
例如，若PDU会话上下文更新请求中包含上述S1660中提及的特定的信息或信元或标签(例如，目标基站的组播/广播能力信息)，则确定目标基站支持组播/广播。
具体地，可以在PDU会话上下文更新请求携带的N2 SM information中包含目标基站的组播/广播能力信息，也可以在PDU会话上下文更新请求中携带目标基站的组播/广播能力信息。
其中，该单播方式可以包括但不限于以下一种或多种传输方式：
5GC个人组播/广播业务流量传输方式(5GC Individual MBS(Multicast Broadcast Service)traffic delivery method)、个人组播/广播业务流量传输方式(Individual MBS traffic delivery method)或个人传输方式(Individual delivery method)。
应理解，上述图11、12、14、15、16所示的场景是为方便描述本申请实施例的示例。实际情况中，本申请所应用场景是不受图11、12、14、15、16限定的，也即本申请同样适用于其它未列举的场景。关于图11、12、14、15、16所示的场景以及其它未列举的场景，可以包含以下三个特点：
(1)对于切换的UE的PDU会话，在切换过程中，为该切换的UE的PDU会话服务的SMF与锚点UPF(即，对于图11、图12与图16而言为UPF，对于图14与图15而言 为PSA-UPF)是不变的。
(2)基于(1)，对于切换的UE的PDU会话在源基站所关联的组播业务，假设为其源基站组播业务服务的组播网元为MCF-1(控制面)与MUF-1(用户面)，则MUF-1可以与UE的PDU会话所在的锚点UPF相连(即，图11、12、14、15、16所示特殊场景)。可选地，MUF-1也可以直接与源基站相连。此外，MUF-1还可以通过其它的UPF与源基站相连(即，非UE的PDU会话的锚点UPF)，本申请实施例对此不作限定。
(3)基于(1)和(2)，对于目标基站中，与该切换的UE的PDU会话所相关的该组播业务，为该组播业务服务的网元可能是MCF-1与MUF-1，也可能是其它的MCF与MUF。MUF可以直接与目标基站直接相连，也可以与切换的UE的PDU会话的锚点UPF相连，也可以通过其它的UPF与目标基站相连(即，非UE的PDU会话的锚点UPF)，本申请实施例对此不作限定。
应理解，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。
上文中结合图1至图16，详细描述了根据本申请实施例的传输组播业务的方法，下面将结合图17至图18，详细描述根据本申请实施例的传输组播业务的装置。
本申请实施例提供了一种传输组播业务的装置。在一种可能的实现方式中，该装置用于实现上述方法实施例中的会话管理网元对应的步骤或流程。在另一种可能的实现方式中，该装置用于实现上述方法实施例中的接入与移动性管理网元对应的步骤或流程。在另一种可能的实现方式中，该装置用于实现上述方法实施例中的接入网设备对应的步骤或流程。
图17示出了本申请实施例提供的传输组播业务的装置1700。该装置1700包括：收发单元1710和处理单元1720。
在一种可能的实现方式中，该装置1700可以是前述实施例中的会话管理网元，也可以是会话管理网元中的芯片。该装置1700可实现对应于上文方法实施例中的会话管理网元执行的步骤或者流程，其中，收发单元1710用于执行上文方法实施例中会话管理网元的收发相关的操作，处理单元1720用于执行上文方法实施例中会话管理网元的处理相关的操作。
示例性地，该收发单元1710用于：接收第一消息或第二消息，所述第一消息用于请求将终端设备加入组播业务，所述第二消息用于更新所述终端设备的协议数据单元PDU会话，所述PDU会话关联组播业务；该处理单元1720用于：根据所述终端设备的组播能力信息和/或接入网设备的组播能力信息，确定所述组播业务的发送方式，所述终端设备的组播能力信息用于表示所述终端设备是否支持组播，所述接入网设备的组播能力信息用于表示所述接入网设备是否支持组播，所述接入网设备为所述终端设备当前接入的接入网设备或者所述终端设备的目标接入网设备。
可选地，所述处理单元1720具体用于：当所述发送方式为单播方式时，所述处理单元具体用于：根据所述组播业务的组播服务质量QoS信息，确定所述组播业务对应的单播QoS流；在所述终端设备的协议数据单元PDU会话中增加所述单播QoS流，所述单播QoS流用于传输所述组播业务的数据。
可选地，所述处理单元1720还具体用于：当所述发送方式为单播方式时，所述处理 单元具体用于：根据所述组播业务的QoS信息，在所述终端设备的PDU会话的单播QoS流中选择至少一个单播QoS流，所述至少一个单播QoS流用于传输所述组播业务的数据；所述收发单元1710还用于向用户面功能网元发送所述组播业务的数据包检测规则与所述至少一个单播QoS流的标识之间的对应关系。
可选地，所述对应关系携带于第八消息中，所述第八消息为N4会话修改请求消息或PFCP会话修改请求信息。
可选地，所述收发单元1710还用于：向用户面网元发送所述组播业务的信息和所述单播QoS流的服务质量流索引QFI；所述处理单元1720还用于：根据所述组播QoS流的QoS参数，确定所述单播QoS流的QoS参数；所述收发单元1710还用于：向所述接入网设备发送所述单播QoS流的QFI和所述单播QoS流的QoS参数。
可选地，所述处理单元1720具体用于：当所述发送方式为组播方式时，所述收发单元还用于：向所述接入网设备发送所述组播业务的业务标识。
可选地，所述收发单元1710还用于：向所述接入网设备发送所述组播业务的组播QoS流的信息。
可选地，所述处理单元1720还用于：在向所述接入网设备发送第三消息之前，确定所述接入网设备存在所述组播业务。
可选地，所述收发单元1710还用于：接收来自统一数据管理网元的第四消息，所述第四消息用于指示所述接入网设备存在所述组播业务；所述处理单元1720具体用于：根据所述第四消息，确定所述接入网设备存在所述组播业务。
可选地，所述处理单元1720还用于：在向所述接入网设备发送第三消息之前，确定所述接入网设备不存在所述组播业务；所述收发单元1710还用于：向所述接入网设备发送所述组播业务的组播QoS流的信息；接收来自所述接入网设备的用于指示所述组播QoS流对应的无线承载创建成功的指示信息。
可选地，所述收发单元1710还用于：根据所述指示信息，向统一数据管理网元发送第五消息，所述第五消息用于指示所述组播业务在所述接入网设备中已经存在。
可选地，所述处理单元1720还用于：确定所述组播QoS流对应的单播QoS流；所述收发单元1710还用于：向所述接入网设备发送所述第一映射关系，所述第一映射关系用于表示所述组播QoS流的QFI和所述单播QoS流的QFI之间的对应关系。
可选地，所述收发单元1710还用于：接收来自接入与移动性管理网元的所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
可选地，所述收发单元1710还用于：在接收来自接入与移动性管理网元的所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息之前，向所述接入与移动性管理网元发送请求消息，所述请求消息用于请求所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
可选地，所述处理单元1720还用于：在向所述接入与移动性管理网元发送请求消息之前，确定所述终端设备的PDU会话支持组播。
可选地，所述收发单元1710还用于：向所述接入与移动性管理网元发送订阅消息，所述订阅消息用于所述移动性管理网元在所述终端设备和/或所述接入网设备的组播能力改变时向所述会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组 播能力信息。
可选地，所述收发单元1710还用于：接收来自接入与移动性管理网元的所述第一消息；或者，接收来自用户面网元的所述第一消息。
在另一种可能的实现方式中，该装置1700可以是前述实施例中的接入与移动性管理网元，也可以是接入与移动性管理网元中的芯片。该装置1700可实现对应于上文方法实施例中的接入与移动性管理网元执行的步骤或者流程，其中，收发单元1710用于执行上文方法实施例中接入与移动性管理网元的收发相关的操作，处理单元1720用于执行上文方法实施例中接入与移动性管理网元的处理相关的操作。
示例性地，该处理单元1720用于：用于获取终端设备的组播能力信息和/或接入网设备的组播能力信息，所述终端设备的组播能力信息用于表示所述终端设备是否支持组播，所述接入网设备的组播能力信息用于表示所述接入网设备是否支持组播，所述接入网设备为所述终端设备当前接入的接入网设备或者所述终端设备的目标接入网设备；该收发单元1710用于：用于向会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
可选地，所述处理单元还用于：在向会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息之前，确定所述终端设备的协议数据单元PDU会话支持组播，所述终端设备接入所述接入网设备。
可选地，所述收发单元1710还用于：接收来自所述终端设备的所述PDU会话的参考信息，所述参考信息包括用于指示所述PDU会话是否支持组播的指示信息、所述PDU会话的数据网络名称DNN、所述PDU会话的单网络切片选择辅助信息S-NSSAI中的一项或多项；所述处理单元1720还用于：根据所述参考信息，确定所述PDU会话支持组播。
可选地，所述收发单元1710还用于：接收来自所述会话管理网元的请求消息，所述请求消息用于请求所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
可选地，所述收发单元1710还用于：接收来自所述会话管理网元的订阅消息，所述订阅请求消息用于所述移动性管理网元在所述终端设备和/或所述接入网设备的组播能力改变时向所述会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
可选地，所述接入网设备的组播能力信息携带在下一代NG建立请求消息中。
可选地，所述终端设备的组播能力信息携带在PDU会话建立/修改请求消息中。
在另一种可能的实现方式中，该装置1700可以是前述实施例中的接入网设备，也可以是接入网设备中的芯片。该装置1700可实现对应于上文方法实施例中的接入网设备执行的步骤或者流程，其中，收发单元1710用于执行上文方法实施例中接入网设备的收发相关的操作，处理单元1720用于执行上文方法实施例中接入网设备的处理相关的操作。
示例性地，该处理单元1720用于：用于获取所述接入网设备的组播能力信息；该收发单元1710用于：用于发送所述接入网设备的组播能力信息，所述组播能力信息用于表示所述装置是否支持组播。
可选地，所述收发单元1710具体用于：向接入与移动性管理网元或所述接入网设备的相邻接入网设备发送所述组播能力信息。
可选地，所述收发单元1710还用于：接收来自另一接入网设备的切换请求消息，所 述切换请求消息包括终端设备的协议数据单元PDU会话的标识，所述PDU会话关联组播业务；向核心网设备发送指示信息，所述指示信息用于指示所述接入网设备是否存在所述组播业务。
应理解，这里的装置1700以功能单元的形式体现。这里的术语“单元”可以指应用特有集成电路(application specific integrated circuit，ASIC)、电子电路、用于执行一个或多个软件或固件程序的处理器(例如共享处理器、专有处理器或组处理器等)和存储器、合并逻辑电路和/或其它支持所描述的功能的合适组件。在一个可选例子中，本领域技术人员可以理解，装置1700可以具体为上述实施例中的会话管理网元，可以用于执行上述方法实施例中与会话管理网元对应的各个流程和/或步骤，或者，装置1700可以具体为上述实施例中的接入与移动性管理网元，可以用于执行上述方法实施例中与接入与移动性管理网元对应的各个流程和/或步骤，或者，装置1700可以具体为上述实施例中的接入网设备，可以用于执行上述方法实施例中与接入网设备对应的各个流程和/或步骤，为避免重复，在此不再赘述。
上述各个方案的装置1700具有实现上述方法中会话管理网元所执行的相应步骤的功能，或者，上述各个方案的装置1700具有实现上述方法中接入与移动性管理网元所执行的相应步骤的功能，或者，上述各个方案的装置1700具有实现上述方法中接入网设备所执行的相应步骤的功能。所述功能可以通过硬件实现，也可以通过硬件执行相应的软件实现。所述硬件或软件包括一个或多个与上述功能相对应的模块；例如收发单元可以由收发机替代(例如，收发单元中的发送单元可以由发送机替代，收发单元中的接收单元可以由接收机替代)，其它单元，如处理单元等可以由处理器替代，分别执行各个方法实施例中的收发操作以及相关的处理操作。
此外，上述收发单元还可以是收发电路(例如可以包括接收电路和发送电路)，处理单元可以是处理电路。在本申请的实施例，图17中的装置可以是前述实施例中的网元或设备，也可以是芯片或者芯片系统，例如：片上系统(system on chip，SoC)。其中，收发单元可以是输入输出电路、通信接口；处理单元为该芯片上集成的处理器或者微处理器或者集成电路。在此不做限定。
图18示出了本申请实施例提供的另一传输组播业务的装置1800。该装置1800包括处理器1810和收发器1820。其中，处理器1810和收发器1820通过内部连接通路互相通信，该处理器1810用于执行指令，以控制该收发器1820发送信号和/或接收信号。
可选地，该装置1800还可以包括存储器1830，该存储器1830与处理器1810、收发器1820通过内部连接通路互相通信。该存储器1830用于存储指令，该处理器1810可以执行该存储器1830中存储的指令。在一种可能的实现方式中，装置1800用于实现上述方法实施例中的会话管理网元对应的各个流程和步骤。在另一种可能的实现方式中，装置1800用于实现上述方法实施例中的接入与移动性管理网元对应的各个流程和步骤。在另一种可能的实现方式中，装置1800用于实现上述方法实施例中的接入网设备对应的各个流程和步骤。
应理解，装置1800可以具体为上述实施例中的会话管理网元、接入与移动性管理网元或接入网设备，也可以是芯片或者芯片系统。对应的，该收发器1820可以是该芯片的收发电路，在此不做限定。具体地，该装置1800可以用于执行上述方法实施例中与会话 管理网元、接入与移动性管理网元或接入网设备对应的各个步骤和/或流程。可选地，该存储器1830可以包括只读存储器和随机存取存储器，并向处理器提供指令和数据。存储器的一部分还可以包括非易失性随机存取存储器。例如，存储器还可以存储设备类型的信息。该处理器1810可以用于执行存储器中存储的指令，并且当该处理器1810执行存储器中存储的指令时，该处理器1810用于执行上述与会话管理网元、接入与移动性管理网元或接入网设备对应的方法实施例的各个步骤和/或流程。
在实现过程中，上述方法的各步骤可以通过处理器中的硬件的集成逻辑电路或者软件形式的指令完成。结合本申请实施例所公开的方法的步骤可以直接体现为硬件处理器执行完成，或者用处理器中的硬件及软件模块组合执行完成。软件模块可以位于随机存储器，闪存、只读存储器，可编程只读存储器或者电可擦写可编程存储器、寄存器等本领域成熟的存储介质中。该存储介质位于存储器，处理器读取存储器中的信息，结合其硬件完成上述方法的步骤。为避免重复，这里不再详细描述。
应注意，本申请实施例中的处理器可以是一种集成电路芯片，具有信号的处理能力。在实现过程中，上述方法实施例的各步骤可以通过处理器中的硬件的集成逻辑电路或者软件形式的指令完成。上述的处理器可以是通用处理器、数字信号处理器(DSP)、专用集成电路(ASIC)、现场可编程门阵列(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。可以实现或者执行本申请实施例中的公开的各方法、步骤及逻辑框图。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。结合本申请实施例所公开的方法的步骤可以直接体现为硬件译码处理器执行完成，或者用译码处理器中的硬件及软件模块组合执行完成。软件模块可以位于随机存储器，闪存、只读存储器，可编程只读存储器或者电可擦写可编程存储器、寄存器等本领域成熟的存储介质中。该存储介质位于存储器，处理器读取存储器中的信息，结合其硬件完成上述方法的步骤。
可以理解，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(dynamic RAM，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)。应注意，本文描述的系统和方法的存储器旨在包括但不限于这些和任意其它适合类型的存储器。
根据本申请实施例提供的方法，本申请还提供一种计算机程序产品，该计算机程序产品包括：计算机程序代码，当该计算机程序代码在计算机上运行时，使得该计算机执行图5至图16所示的实施例中会话管理网元、接入与移动性管理网元或接入网设备执行的各个步骤或流程。
根据本申请实施例提供的方法，本申请还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有程序代码，当该程序代码在计算机上运行时，使得该计算机执行图5至16所示的实施例中会话管理网元、接入与移动性管理网元或接入网设备执行的各个步骤或流程。
根据本申请实施例提供的方法，本申请还提供一种通信系统，其包括前述的会话管理网元、接入与移动性管理网元以及接入网设备。
在上述实施例中，可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件实现时，可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括一个或多个计算机指令。在计算机上加载和执行所述计算机指令时，全部或部分地产生按照本申请实施例所述的流程或功能。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、光纤、数字用户线(digital subscriber line，DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含一个或多个可用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质(例如，软盘、硬盘、磁带)、光介质(例如，高密度数字视频光盘(digital video disc，DVD))、或者半导体介质(例如，固态硬盘(solid state disc，SSD))等。
上述各个装置实施例中网络设备与终端设备和方法实施例中的网络设备或终端设备完全对应，由相应的模块或单元执行相应的步骤，例如收发单元(收发器)执行方法实施例中接收或发送的步骤，除发送、接收外的其它步骤可以由处理单元(处理器)执行。具体单元的功能可以参考相应的方法实施例。其中，处理器可以为一个或多个。
在本说明书中使用的术语“部件”、“模块”、“系统”等用于表示计算机相关的实体、硬件、固件、硬件和软件的组合、软件、或执行中的软件。例如，部件可以是但不限于，在处理器上运行的进程、处理器、对象、可执行文件、执行线程、程序和/或计算机。通过图示，在计算设备上运行的应用和计算设备都可以是部件。一个或多个部件可驻留在进程和/或执行线程中，部件可位于一个计算机上和/或分布在两个或更多个计算机之间。此外，这些部件可从在上面存储有各种数据结构的各种计算机可读存储介质执行。部件可例如根据具有一个或多个数据分组(例如来自与本地系统、分布式系统和/或网络间的另一部件交互的二个部件的数据，例如通过信号与其它系统交互的互联网)的信号通过本地和/或远程进程来通信。
应理解，本文中的“至少一个”是指一个或者多个，“多个”是指两个或两个以上。“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的情况，其中A，B可以是单数或者复数。字符“/”一般表示前后关联对象是一种“或”的关系。“以下至少一项(个)”或其类似表达，是指的这些项中的任意组合，包括单项(个)或复数项(个)的任意组合。例如，a、b和c中的至少一项(个)，可以表示：a，或b，或c，或a和b，或a和c，或b和c，或a、b和c，其中a，b，c可以是单个，也可以是多个。
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种说明性逻辑块(illustrative logical block)和步骤(step)，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。
在上述实施例中，各功能单元的功能可以全部或部分地通过软件、硬件、固件或者其任意组合来实现。当使用软件实现时，可以全部或部分地以计算机程序产品的形式实现。所述计算机程序产品包括一个或多个计算机指令(程序)。在计算机上加载和执行所述计算机程序指令(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。所述计算机可以是通用计算机、专用计算机、计算机网络、或者其他可编程装置。所述计算机指令可以存储在计算机可读存储介质中，或者从一个计算机可读存储介质向另一个计算机可读存储介质传输，例如，所述计算机指令可以从一个网站站点、计算机、服务器或数据中心通过有线(例如同轴电缆、光纤、数字用户线(DSL))或无线(例如红外、无线、微波等)方式向另一个网站站点、计算机、服务器或数据中心进行传输。所述计算机可读存储介质可以是计算机能够存取的任何可用介质或者是包含一个或多个可用介质集成的服务器、数据中心等数据存储设备。所述可用介质可以是磁性介质，(例如，软盘、硬盘、磁带)、光介质(例如，DVD)、或者半导体介质(例如固态硬盘(solid state disk，SSD))等。
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 (31)

  1. 一种传输组播业务的方法，其特征在于，包括：
    会话管理网元接收第一消息或第二消息，所述第一消息用于请求将终端设备加入组播业务，所述第二消息用于更新所述终端设备的协议数据单元PDU会话，所述PDU会话关联组播业务；
    所述会话管理网元根据所述终端设备的组播能力信息和/或接入网设备的组播能力信息，确定所述组播业务的发送方式，所述终端设备的组播能力信息用于表示所述终端设备是否支持组播，所述接入网设备的组播能力信息用于表示所述接入网设备是否支持组播，所述接入网设备为所述终端设备当前接入的接入网设备或者所述终端设备的目标接入网设备。
  2. 根据权利要求1所述的方法，其特征在于，当所述发送方式为单播方式时，所述方法还包括：
    所述会话管理网元根据所述组播业务的组播服务质量QoS信息，确定所述组播业务对应的单播QoS流；
    所述会话管理网元在所述终端设备的协议数据单元PDU会话中增加所述单播QoS流，所述单播QoS流用于传输所述组播业务的数据。
  3. 根据权利要求1所述的方法，其特征在于，当所述发送方式为单播方式时，所述方法还包括：
    所述会话管理网元根据所述组播业务的QoS信息，在所述终端设备的PDU会话的单播QoS流中选择至少一个单播QoS流，所述至少一个单播QoS流用于传输所述组播业务的数据；
    所述会话管理网元向用户面功能网元发送所述组播业务的数据包检测规则与所述至少一个单播QoS流的标识之间的对应关系。
  4. 根据权利要求3所述的方法，其特征在于，所述对应关系携带于第八消息中，所述第八消息为N4会话修改请求或报文转发控制协议PFCP会话修改请求。
  5. 根据权利要求1所述的方法，其特征在于，当所述发送方式为组播方式时，所述方法还包括：
    所述会话管理网元向所述接入网设备发送所述组播业务的业务标识。
  6. 根据权利要求1至5中任一项所述的方法，其特征在于，所述方法还包括：
    所述会话管理网元接收来自接入与移动性管理网元的所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
  7. 根据权利要求6所述的方法，其特征在于，所述方法还包括：
    所述会话管理网元向所述接入与移动性管理网元发送订阅消息，所述订阅消息用于所述移动性管理网元在所述终端设备和/或所述接入网设备的目标改变时向所述会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
  8. 一种传输组播业务的方法，其特征在于，包括：
    接入与移动性管理网元获取终端设备的组播能力信息和/或接入网设备的组播能力信 息，所述终端设备的组播能力信息用于表示所述终端设备是否支持组播，所述接入网设备的组播能力信息用于表示所述接入网设备是否支持组播，所述接入网设备为所述终端设备当前接入的接入网设备或者所述终端设备的目标接入网设备；
    所述接入与移动性管理网元向会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
  9. 根据权利要求8所述的方法，其特征在于，在所述接入与移动性管理网元向会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息之前，所述方法还包括：
    所述接入与移动性管理网元确定所述终端设备的协议数据单元PDU会话支持组播。
  10. 根据权利要求9所述的方法，其特征在于，所述接入与移动性管理网元确定所述终端设备的PDU会话支持组播，包括：
    所述接入与移动性管理网元接收来自所述终端设备的所述PDU会话的参考信息，所述参考信息包括用于指示所述PDU会话是否支持组播的指示信息、所述PDU会话的数据网络名称DNN、所述PDU会话的单网络切片选择辅助信息S-NSSAI中的一项或多项；
    所述接入与移动性管理网元根据所述参考信息，确定所述PDU会话支持组播。
  11. 根据权利要求8至10中任一项所述的方法，其特征在于，所述方法还包括：
    所述接入与移动性管理网元接收来自所述会话管理网元的请求消息，所述请求消息用于请求所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
  12. 根据权利要求8至10中任一项所述的方法，其特征在于，所述方法还包括：
    所述接入与移动性管理网元接收来自所述会话管理网元的订阅消息，所述订阅请求消息用于所述移动性管理网元在所述终端设备和/或所述接入网设备的组播能力改变时向所述会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
  13. 根据权利要求8至12中任一项所述的方法，其特征在于，所述接入网设备的组播能力信息携带在下一代NG建立请求消息中。
  14. 根据权利要求8至13中任一项所述的方法，其特征在于，所述终端设备的组播能力信息携带在PDU会话建立/修改请求消息中。
  15. 一种传输组播业务的装置，其特征在于，包括：
    收发单元，用于接收第一消息或第二消息，所述第一消息用于请求将终端设备加入组播业务，所述第二消息用于更新所述终端设备的协议数据单元PDU会话，所述PDU会话关联组播业务；
    处理单元，用于根据所述终端设备的组播能力信息和/或接入网设备的组播能力信息，确定所述组播业务的发送方式，所述终端设备的组播能力信息用于表示所述终端设备是否支持组播，所述接入网设备的组播能力信息用于表示所述接入网设备是否支持组播，所述接入网设备为所述终端设备当前接入的接入网设备或者所述终端设备的目标接入网设备。
  16. 根据权利要求15所述的装置，其特征在于，当所述发送方式为单播方式时，所述处理单元具体用于：
    根据所述组播业务的组播服务质量QoS信息，确定所述组播QoS业务对应的单播QoS流；
    在所述终端设备的协议数据单元PDU会话中增加所述单播QoS流，所述单播QoS流用于传输所述组播业务的数据。
  17. 根据权利要求15所述的装置，其特征在于，当所述发送方式为单播方式时，所述处理单元具体还用于：
    根据所述组播业务的QoS信息，在所述终端设备的PDU会话的单播QoS流中选择至少一个单播QoS流，所述至少一个单播QoS流用于传输所述组播业务的数据；
    所述会话管理网元向用户面网元发送所述组播业务的数据包检测规则与所述至少一个单播QoS流的标识之间的对应关系。
  18. 根据权利要求17所述的装置，其特征在于，所述对应关系携带于第八消息中，所述第八消息为N4会话修改请求消息或PFCP会话修改请求信息。
  19. 根据权利要求15所述的装置，其特征在于，当所述发送方式为组播方式时，所述收发单元还用于：
    向所述接入网设备发送所述组播业务的业务标识。
  20. 根据权利要求15至19中任一项所述的装置，其特征在于，所述收发单元还用于：
    接收来自接入与移动性管理网元的所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
  21. 根据权利要求20所述的装置，其特征在于，所述收发单元还用于：
    向所述接入与移动性管理网元发送订阅消息，所述订阅消息用于所述移动性管理网元在所述终端设备和/或所述接入网设备的组播能力改变时向所述会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
  22. 一种传输组播业务的装置，其特征在于，包括：
    处理单元，用于获取终端设备的组播能力信息和/或接入网设备的组播能力信息，所述终端设备的组播能力信息用于表示所述终端设备是否支持组播，所述接入网设备的组播能力信息用于表示所述接入网设备是否支持组播，所述接入网设备为所述终端设备当前接入的接入网设备或者所述终端设备的目标接入网设备；
    收发单元，用于向会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
  23. 根据权利要求22所述的装置，其特征在于，所述处理单元还用于：
    在向会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息之前，确定所述终端设备的协议数据单元PDU会话支持组播。
  24. 根据权利要求23所述的装置，其特征在于，所述收发单元还用于：
    接收来自所述终端设备的所述PDU会话的参考信息，所述参考信息包括用于指示所述PDU会话是否支持组播的指示信息、所述PDU会话的数据网络名称DNN、所述PDU会话的单网络切片选择辅助信息S-NSSAI中的一项或多项；
    所述处理单元还用于：
    根据所述参考信息，确定所述PDU会话支持组播。
  25. 根据权利要求22至24中任一项所述的装置，其特征在于，所述收发单元还用于：
    接收来自所述会话管理网元的请求消息，所述请求消息用于请求所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
  26. 根据权利要求22至24中任一项所述的装置，其特征在于，所述收发单元还用于：
    接收来自所述会话管理网元的订阅消息，所述订阅请求消息用于所述移动性管理网元在所述终端设备和/或所述接入网设备的组播能力改变时向所述会话管理网元发送所述终端设备的组播能力信息和/或所述接入网设备的组播能力信息。
  27. 根据权利要求22至26中任一项所述的装置，其特征在于，所述接入网设备的组播能力信息携带在下一代NG建立请求消息中。
  28. 根据权利要求22至27中任一项所述的装置，其特征在于，所述终端设备的组播能力信息携带在PDU会话建立/修改请求消息中。
  29. 一种通信装置，其特征在于，包括：处理器、存储器以及存储在所述存储器上并可在所述处理器上运行的指令，当所述指令被运行时，使得所述装置执行权利要求1至12中任一项所述的方法。
  30. 一种计算机可读存储介质，其特征在于，包括指令，当其在计算机上运行时，使得计算机执行权利要求1至14中任一项所述的方法。
  31. 一种芯片系统，其特征在于，包括：处理器，用于从存储器中调用并运行计算机程序，使得安装有所述芯片系统的通信设备执行权利要求1至14中任一项所述的方法。
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