WO2022206775A1 - 一种多播广播业务的传输切换方法及装置 - Google Patents

一种多播广播业务的传输切换方法及装置 Download PDF

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Publication number
WO2022206775A1
WO2022206775A1 PCT/CN2022/083765 CN2022083765W WO2022206775A1 WO 2022206775 A1 WO2022206775 A1 WO 2022206775A1 CN 2022083765 W CN2022083765 W CN 2022083765W WO 2022206775 A1 WO2022206775 A1 WO 2022206775A1
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network device
data packet
access network
information
sequence number
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PCT/CN2022/083765
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English (en)
French (fr)
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高云龙
罗海燕
朱元萍
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华为技术有限公司
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0007—Control or signalling for completing the hand-off for multicast or broadcast services, e.g. MBMS
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/02—Buffering or recovering information during reselection ; Modification of the traffic flow during hand-off
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/02—Buffering or recovering information during reselection ; Modification of the traffic flow during hand-off
    • H04W36/023—Buffering or recovering information during reselection

Definitions

  • the present application relates to the field of communications, and more particularly, to a method and apparatus for switching transmission of multicast broadcast services.
  • Multicast broadcast service (multicast and broadcast service, MBS) is a point-to-multipoint service within a specific range, which can simultaneously provide multimedia services for a large number of users with the same needs with less resources, such as live broadcast services, public safety services, Batch software update services, etc., so that network resources can be shared.
  • the data of the MBS service comes from the data server, and is sent to the radio access network (radio access network, RAN) node through the core network device, and then sent by the RAN node to at least one terminal device that receives the MBS data.
  • RAN radio access network
  • a terminal device may move across RAN nodes, and the terminal device may move from a RAN node that supports MBS services to a RAN node that does not support MBS services, and vice versa.
  • the terminal equipment is handed over between the above-mentioned different RAN nodes, how to ensure the reliability of MBS data transmission during the handover process is an urgent problem to be solved.
  • the present application provides a method and device for transmission and switching of multicast broadcast services, which can ensure the reliability of MBS data transmission of terminal equipment during the switching process.
  • a first aspect provides a method for switching the transmission of a multicast broadcast service, the method comprising: a source access network device sending a first data packet to a terminal device, where the first data packet is a data packet of the first multicast broadcast service ; the source access network device sends a handover command to the terminal device, instructing the terminal device to switch to the target access network device; the source access network device sends first information to the core network device, and the first information includes the first Identification information of the data packet, the identification information of the first data packet is used by the core network device to determine the second data packet to be sent to the target access network device, where the second data packet is the data packet of the first multicast broadcast service .
  • the source access network device may send the first information to the core network device, where the first information includes the identification information of the first data packet, so that the core network device determines the second data packet of the MBS service sent to the target access network device . Problems such as packet loss of the data of the MBS service received by the terminal device during the handover process are avoided, and the reliability of the data transmission of the MBS service is ensured.
  • the first data packet is the last data packet sent by the source access network device to the terminal device.
  • the identification information of the first data packet includes at least one of the following sequence numbers:
  • the first information further includes identification information of the terminal device, and identification information of the target access network device.
  • the core network device in the process of switching the terminal device from the access network device (S-gNB) that supports the MBS service to the access network device (T-gNB) that does not support the MBS service, the core network device may The target core network device is determined according to the first information, and the data of the first multicast broadcast service is sent to the target access network device through the target core network device.
  • the first information further includes session identification information of the first multicast broadcast service.
  • the session identification information is used by the core network device to determine the target core network device.
  • the source access network device sends downlink data transmission status information to the core network device, where the downlink data transmission status information carries the first information.
  • the source access network device sends the first information to the core network device through the target access network device.
  • the source access network device sends serial number state transition information to the target access network device, where the serial number state transition information carries the first information.
  • the source access network device and the target access network in the quality of service flow identification sequence number of the first multicast broadcast service to the packet data convergence protocol sequence number The mapping relationship is the same; or, the mapping relationship between the serial number of the general packet radio service tunneling protocol on the user plane of the first multicast broadcast service and the serial number of the packet data convergence protocol is the same.
  • the first information further includes second identification information, and the second identification information is used to indicate a third data packet, and the third data packet includes the source access
  • the network device fails to send the successful data packet of the first multicast broadcast service to the terminal device.
  • a method for switching transmission of a multicast broadcast service includes: a core network device receives first information from a source access network device, the first information includes identification information of a first data packet, the The first data packet is a data packet of the first multicast broadcast service of the terminal device; the core network device determines a second data packet to be sent to the target access network device according to the first information, and the second data packet is the first data packet.
  • a data packet of a multicast broadcast service receives first information from a source access network device, the first information includes identification information of a first data packet, the The first data packet is a data packet of the first multicast broadcast service of the terminal device; the core network device determines a second data packet to be sent to the target access network device according to the first information, and the second data packet is the first data packet.
  • a data packet of a multicast broadcast service receives first information from a source access network device, the first information includes identification information of a first data packet, the The first data packet is a data packet of the first multicast broadcast service
  • the core network device may determine the second data packet of the MBS service sent to the target access network device by receiving the first information from the source access network device, where the first information includes identification information of the first data packet. Problems such as packet loss of the data received by the terminal device during the handover process of the MBS service are avoided, thereby ensuring the reliability of the data transmission of the MBS service.
  • the first data packet is the last data packet sent by the source access network device to the terminal device.
  • the identification information of the first data packet includes at least one of the following sequence numbers:
  • the quality of service flow identifier of the first data packet and the serial number of the quality of service flow identifier of the first data packet, the packet data convergence protocol serial number of the data of the first data packet, the user plane general packet of the first data packet The serial number of the wireless service tunneling protocol.
  • the first information further includes identification information of the terminal device and identification information of the target access network device.
  • the first information further includes session identification information of the first multicast broadcast service.
  • the source access network device and the QoS flow identification sequence number of the first multicast broadcast service in the source access network and the target access network are to the packet data convergence protocol sequence number
  • the mapping relationship is the same; or, the mapping relationship between the serial number of the general packet radio service tunneling protocol on the user plane of the first multicast broadcast service and the serial number of the packet data convergence protocol is the same.
  • the first information further includes second identification information, where the second identification information is used to indicate a third data packet, and the third data packet includes the source access
  • the network device fails to send the data packet of the first multicast broadcast service to the terminal device, and the core network device sends the third data packet to the target access network device.
  • a method for switching transmission of multicast broadcast services includes: a target access network device receives a handover request message from a source access network device, where the handover request message is used to request that a terminal device be switched from the The source access network device is switched to the target access network device; the target access network device receives serial number status information from the source access network device, the serial number status information includes identification information of the first data packet, the first data The packet is a data packet of the first multicast broadcast service; the target access network device sends first information to the core network device according to the serial number status information, where the first information is used to determine the second data packet, the second data packet is the data packet of the first multicast broadcast service; the target access network device receives the second data packet.
  • the target access network device in the process of switching the terminal device from the source access network device to the target access network device, can send the first information to the core network device, so that the core network device determines the
  • the second data packet of the first multicast broadcast service sent by the target access network device avoids problems such as packet loss of the data of the first MBS service received by the terminal device during the switching process, and ensures that the terminal device is in the switching process during the switching process.
  • the serial number status information indicates a value of a first serial number
  • the value of the first serial number is a plurality of the first serial number cached by the source access network device.
  • the value of the largest sequence number among the sequence numbers of a data packet is incremented by 1.
  • the target access network device determines, according to the serial number status information, that the value of the first serial number is smaller than the value of the second serial number, and the second serial number is The smallest sequence number among the sequence numbers of multiple third data packets cached by the target access network device, the third data packet is the data packet of the first multicast broadcast service; the target access network sends the core network device to the Send the first information.
  • the source access network device and the first multicast broadcast service in the source access network device and the target access network The service quality flow identification sequence number of the first multicast broadcast service is to the packet data convergence protocol sequence number
  • the mapping relationship is the same; or, the mapping relationship between the serial number of the general packet radio service tunneling protocol on the user plane of the first multicast broadcast service and the serial number of the packet data convergence protocol is the same.
  • the first information includes a third serial number and a fourth serial number
  • the third serial number has a mapping relationship with the first serial number
  • the fourth serial number has a mapping relationship. There is a mapping relationship between the number and the second serial number.
  • the first sequence number and the second sequence number are packet data convergence protocol sequence numbers
  • the third sequence number and the fourth sequence number are quality of service flows Identifies the serial number or the serial number of the General Packet Radio Service Tunneling Protocol on the user plane.
  • the first information is carried in a first message, and the first message is a message in a path switching process.
  • a method for switching transmission of multicast broadcast services comprising: a target access network device receiving switching request information from a source access network device, where the switching request information is used to request that a terminal device be switched from the The source access network device switches to the target access network device; the target access network device sends first information to the core network device, where the first information is used to determine a second data packet, and the second data packet is the first A data packet of a multicast broadcast service; the target access network device receives the second data packet.
  • the target access network device in the process of switching the terminal device from the source access network device to the target access network device, can send the first information to the core network device, so that the core network device determines the
  • the second data packet of the first multicast broadcast service sent by the target access network device avoids problems such as packet loss of the data of the first MBS service received by the terminal device during the switching process, and ensures that the terminal device is in the switching process during the switching process.
  • the first information includes a fourth serial number
  • the fourth serial number has a mapping relationship with the second serial number
  • the second serial number is the target access The smallest sequence number among the sequence numbers of multiple third data packets buffered by the network device, where the third data packet is a data packet of the first multicast broadcast service.
  • the second sequence number is a packet data convergence protocol sequence number
  • the fourth sequence number is a quality of service flow identification sequence number or a user plane general packet radio service tunneling protocol. serial number.
  • the source access network device and the QoS flow identification sequence number of the first multicast broadcast service in the source access network device and the target access network are to the packet data convergence protocol sequence number
  • the mapping relationship is the same; or, the mapping relationship between the serial number of the general packet radio service tunneling protocol on the user plane of the first multicast broadcast service and the serial number of the packet data convergence protocol is the same.
  • the first information is carried in a first message, and the first message is a message in a path switching process.
  • a method for transmitting and switching a multicast broadcast service includes: a core network device receives first information from a target access network device; the core network device determines a second data packet according to the first information , the second data packet is a data packet of the first multicast broadcast service of the terminal device; the core network device sends the second data packet to the target access network device.
  • the core network device in the process of switching the terminal device from the source access network device to the target access network device, can determine the target access network device by receiving the first information sent by the target access network device.
  • the second data packet of the first multicast broadcast service sent by the access network device avoids problems such as packet loss of the data of the first MBS service received by the terminal device during the handover process, and ensures that the terminal device has MBS during the handover process. Reliability of business data transmission.
  • the first information includes a fourth serial number, the fourth serial number has a mapping relationship with the second serial number, and the second serial number is the target access The smallest sequence number among the sequence numbers of multiple third data packets buffered by the network device, where the third data packet is a data packet of the first multicast broadcast service.
  • the core network device determines, according to the first information, that the value of the fourth serial number is greater than the value of the sixth serial number, and the sixth serial number is the core network The largest sequence number among the sequence numbers of multiple fourth data packets sent by the device to the source access network device; the core network device determines that the second data packet includes the data packet corresponding to the seventh sequence number, and the sixth sequence number The value of is greater than or equal to the value of the fifth serial number and less than the value of the third serial number.
  • the first information further includes a third serial number, the third serial number has a mapping relationship with the first serial number, and the value of the first serial number is the The value of the largest sequence number among the sequence numbers of the plurality of first data packets buffered by the source access network device is incremented by 1, and the value of the third sequence number is smaller than the value of the fourth sequence number.
  • the core network device determines, according to the first information, that the second data packet includes a data packet corresponding to a fifth sequence number, and the value of the fifth sequence number is greater than or equal to The value of the third serial number is smaller than the value of the fourth serial number.
  • the first sequence number and the second sequence number are packet data convergence protocol sequence numbers, the third sequence number, the fourth sequence number and the sixth sequence number
  • the sequence number is the quality of service flow identification sequence number or the user plane general packet radio service tunneling protocol sequence number.
  • the QoS flow identification sequence number of the first multicast broadcast service in the source access network device and the target access network is to the packet data convergence protocol sequence number
  • the mapping relationship is the same; or, the mapping relationship between the serial number of the general packet radio service tunneling protocol on the user plane of the first multicast broadcast service and the serial number of the packet data convergence protocol is the same.
  • the first information is carried in a first message, and the first message is a message in a path switching process.
  • a communication device in a sixth aspect, includes a sending unit configured to send a first data packet to a terminal device, where the first data packet is a data packet of a first multicast broadcast service; the sending unit further uses sending a handover command to the terminal device, instructing the terminal device to switch to the target access network device; the sending unit is further configured to send first information to the core network device, where the first information includes the identification information of the first data packet, The identification information of the first data packet is used by the core network device to determine a second data packet to be sent to the target access network device, where the second data packet is a data packet of the first multicast broadcast service.
  • the sending unit may send the first information to the core network device, where the first information includes identification information of the first data packet, so that the core network device determines the second data packet of the MBS service sent to the target access network device. Problems such as packet loss of the data received by the terminal device during the handover process of the MBS service are avoided, thereby ensuring the reliability of the data transmission of the MBS service.
  • the first data packet is the last data packet successfully sent by the source access network device to the terminal device.
  • the identification information of the first data packet includes at least one of the following sequence numbers:
  • the first information further includes identification information of the terminal device, and identification information of the target access network device.
  • the first information further includes session identification information of the first multicast broadcast service.
  • the session identification information is used by the core network device to determine the target core network device.
  • the sending unit is specifically configured to send downlink data transmission status information to the core network device, where the downlink data transmission status information carries the first information.
  • the sending unit is specifically configured to send the first information to the core network device through the target access network device.
  • the sending unit is specifically configured to send serial number state transition information to the target access network device, where the serial number state transition information carries the first information.
  • the mapping relationship between the QoS flow identification sequence number of the first multicast broadcast service in the communication device and the target access network to the packet data convergence protocol sequence number Alternatively, the mapping relationship between the serial number of the general packet radio service tunneling protocol on the user plane of the first multicast broadcast service and the serial number of the packet data convergence protocol is the same.
  • the first information further includes second identification information, and the second identification information is used to indicate a third data packet, and the third data packet includes the source access
  • the network device fails to send the successful data packet of the first multicast broadcast service to the terminal device.
  • a communication device including a receiving unit configured to receive first information from a source access network device, where the first information includes identification information of a first data packet, and the first data packet is a terminal a data packet of the first multicast broadcast service of the device; the processing unit is configured to determine, according to the first information, a second data packet to be sent to the target access network device, where the second data packet is the first multicast broadcast service the data package.
  • the receiving unit of the communication device may determine the first information of the MBS service sent to the target access network device by receiving the first information from the source access network device, where the first information includes the identification information of the first data packet. Two packets. Problems such as packet loss of the data received by the terminal device during the handover process of the MBS service are avoided, thereby ensuring the reliability of the data transmission of the MBS service.
  • the first data packet is the last data packet successfully sent by the source access network device to the terminal device.
  • the identification information of the first data packet includes at least one of the following sequence numbers:
  • the quality of service flow identifier of the first data packet and the serial number of the quality of service flow identifier of the first data packet, the packet data convergence protocol serial number of the data of the first data packet, the user plane general packet of the first data packet The serial number of the wireless service tunneling protocol.
  • the first information further includes identification information of the terminal device and identification information of the target access network device.
  • the first information further includes session identification information of the first multicast broadcast service.
  • the source access network device and the target access network in the quality of service flow identification sequence number of the first multicast broadcast service to the packet data convergence protocol sequence number The mapping relationship is the same; or, the mapping relationship between the serial number of the general packet radio service tunneling protocol on the user plane of the first multicast broadcast service and the serial number of the packet data convergence protocol is the same.
  • the first information further includes second identification information, where the second identification information is used to indicate a third data packet, and the third data packet includes the source access
  • the network device fails to send the data packet of the first multicast broadcast service to the terminal device, and the core network device sends the third data packet to the target access network device.
  • a communication device including a receiving unit configured to receive a handover request message from a source access network device, where the handover request message is used to request that a terminal device be handed over from the source access network device to target access network equipment; the receiving unit is further configured to receive serial number status information from the source access network equipment, where the serial number status information includes identification information of a first data packet, and the first data packet is a first multicast The data packet of the broadcast service; the processing unit is used to send the first information to the core network device according to the serial number status information, the first information is used to determine the second data packet, and the second data packet is the first multicast broadcast The data packet of the service; the receiving unit is further configured to receive the second data packet.
  • the serial number status information indicates a value of a first serial number
  • the value of the first serial number is a plurality of the first serial number cached by the source access network device.
  • the value of the largest sequence number among the sequence numbers of a data packet is incremented by 1.
  • the processing unit is specifically configured to determine that the value of the first serial number is smaller than the value of the second serial number, and the second serial number is the target access network device the smallest sequence number among the sequence numbers of a plurality of buffered third data packets, where the third data packet is a data packet of the first multicast broadcast service; the communication device further includes a sending unit for sending the data to the core network equipment Send the first information.
  • the source access network device and the mapping of the QoS flow identification sequence number of the first multicast broadcast service in the source access network device to the packet data convergence protocol sequence number The relationship is the same; or, the mapping relationship between the serial number of the general packet radio service tunneling protocol on the user plane of the first multicast broadcast service and the serial number of the packet data convergence protocol is the same.
  • the first information includes a third serial number and a fourth serial number
  • the third serial number has a mapping relationship with the first serial number
  • the fourth serial number has a mapping relationship. There is a mapping relationship between the number and the second serial number.
  • the first sequence number and the second sequence number are packet data convergence protocol sequence numbers
  • the third sequence number and the fourth sequence number are quality of service flows Identifies the serial number or the serial number of the General Packet Radio Service Tunneling Protocol on the user plane.
  • the first information is carried in a first message, and the first message is a message in a path switching process.
  • a communication apparatus including a receiving unit configured to receive handover request information from a source access network device, where the handover request information is used to request handover of a terminal device from the source access network device to the source access network device a target access network device; a sending unit, configured to send first information to a core network device, where the first information is used to determine a second data packet, where the second data packet is a data packet of the first multicast broadcast service; The receiving unit is further configured to receive the second data packet.
  • the first information includes a fourth serial number
  • the fourth serial number has a mapping relationship with the second serial number
  • the second serial number is the target access The smallest sequence number among the sequence numbers of multiple third data packets buffered by the network device, where the third data packet is a data packet of the first multicast broadcast service.
  • the second sequence number is a packet data convergence protocol sequence number
  • the fourth sequence number is a quality of service flow identification sequence number or a user plane general packet radio service tunneling protocol. serial number.
  • the source access network device and the mapping of the quality of service flow identification sequence number of the first multicast broadcast service in the communication device to the packet data convergence protocol sequence number The relationship is the same; or, the mapping relationship between the serial number of the general packet radio service tunneling protocol on the user plane of the first multicast broadcast service and the serial number of the packet data convergence protocol is the same.
  • the first information is carried in a first message, and the first message is a message in a path switching process.
  • a communication device comprising: a receiving unit configured to receive first information from a target access network device; and a processing unit configured to determine a second data packet according to the first information, the second data
  • the packet is a data packet of the first multicast broadcast service of the terminal device; the sending unit is configured to send the second data packet to the target access network device.
  • the first information includes a fourth serial number
  • the fourth serial number has a mapping relationship with the second serial number
  • the second serial number is the target access The smallest sequence number among the sequence numbers of multiple third data packets buffered by the network device, where the third data packet is a data packet of the first multicast broadcast service.
  • the communication device includes a processing unit configured to determine, according to the first information, that the value of the fourth serial number is greater than the value of the sixth serial number, and the sixth The sequence number is the largest sequence number among the sequence numbers of the plurality of fourth data packets sent by the core network device to the source access network device; the processing unit is further configured to determine that the second data packet includes a sequence number corresponding to the seventh sequence number. In the data packet, the value of the sixth sequence number is greater than or equal to the value of the fifth sequence number and less than the value of the third sequence number.
  • the first information further includes a third serial number, the third serial number has a mapping relationship with the first serial number, and the value of the first serial number is the The value of the largest sequence number among the sequence numbers of the plurality of first data packets buffered by the source access network device is incremented by 1, and the value of the third sequence number is smaller than the value of the fourth sequence number.
  • the processing unit is specifically configured to determine, according to the first information, that the second data packet includes a data packet corresponding to a fifth sequence number, and the value of the fifth sequence number Greater than or equal to the value of the third serial number and less than the value of the fourth serial number.
  • the first sequence number and the second sequence number are the packet data convergence protocol sequence number, the third sequence number, the fourth sequence number and the sixth sequence number
  • the sequence number is the quality of service flow identification sequence number or the user plane general packet radio service tunneling protocol sequence number.
  • the QoS flow identification sequence number of the first multicast broadcast service in the source access network device and the target access network is to the packet data convergence protocol sequence number
  • the mapping relationship is the same; or, the mapping relationship between the serial number of the general packet radio service tunneling protocol on the user plane of the first multicast broadcast service and the serial number of the packet data convergence protocol is the same.
  • the first information is carried in a first message, and the first message is a message in a path switching process.
  • a communication device comprising: a memory for storing a computer program; a processor for executing the computer program stored in the memory, so that the communication device executes any one of the first aspects
  • the method of possible implementations, or the implementation of any of the possible implementations of the second aspect, or the implementation of any of the possible implementations of the third aspect, or the implementation of any of the fourth aspects the method in one possible implementation manner, or perform the method in any one possible implementation manner of the fifth aspect.
  • a twelfth aspect provides a computer-readable storage medium, where a computer program is stored on the computer-readable storage medium, and when the computer program is run on a computer, the computer is made to perform any possible implementation of the first aspect.
  • the method in the implementation mode, or the method in any possible implementation mode of the second aspect, or the method in any possible implementation mode of the third aspect, or the implementation of any possible implementation mode of the fourth aspect The method in the implementation manner of the fifth aspect, or execute the method in any possible implementation manner of the fifth aspect.
  • a thirteenth aspect provides a system-on-chip, the system-on-chip comprising: a processor for calling and running a computer program from a memory, so that a communication device installed with the system-on-chip executes any possibility of executing the second aspect
  • FIG. 1 is a schematic diagram of a network architecture suitable for the method provided by the embodiment of the present application.
  • FIG. 2 is a schematic diagram of a system architecture suitable for the method provided by the embodiment of the present application.
  • FIG. 3 is a schematic flowchart of a terminal device switching process.
  • FIG. 4 is a schematic flowchart of a method for switching transmission of multicast broadcast services of the present application.
  • FIG. 5 is another schematic flow chart of the method for switching the transmission of multicast broadcast service according to the present application.
  • FIG. 6 is another schematic flowchart of the method for switching the transmission of multicast broadcast services of the present application.
  • FIG. 7 is another schematic flowchart of the method for switching the transmission of multicast broadcast services of the present application.
  • FIG. 8 is another schematic flowchart of the method for switching the transmission of multicast broadcast services of the present application.
  • FIG. 9 is another schematic flow chart of the method for switching the transmission of multicast broadcast service according to the present application.
  • FIG. 10 is another schematic flowchart of the method for switching the transmission of multicast broadcast service according to the present application.
  • FIG. 11 is a schematic block diagram of an example of the communication device of the present application.
  • FIG. 12 is a schematic block diagram of another example of the communication device of the present application.
  • FIG. 13 is a schematic block diagram of another example of the communication device of the present application.
  • FIG. 14 is a schematic block diagram of another example of the communication device of the present application.
  • FIG. 15 is a schematic configuration diagram of an example of the communication device of the present application.
  • LTE long term evolution
  • FDD frequency division duplex
  • TDD time division duplex
  • UMTS universal mobile telecommunication system
  • 5th generation, 5G new radio
  • new radio new radio, NR
  • the technical solutions provided in this application can also be applied to machine type communication (MTC), long term evolution-machine (LTE-M), device-to-device (D2D) Network, machine to machine (M2M) network, internet of things (IoT) network or other network.
  • the IoT network may include, for example, the Internet of Vehicles.
  • vehicle to X, V2X, X can represent anything
  • the V2X may include: vehicle to vehicle (vehicle to vehicle, V2V) communication, vehicle and vehicle Infrastructure (V2I) communication, vehicle to pedestrian (V2P) or vehicle to network (V2N) communication, etc.
  • FIG. 1 is a schematic diagram of a network architecture suitable for an embodiment of the present application.
  • the network architecture can be divided into two parts: a service and/or application (service and/or application) layer and a transport (transport) layer.
  • the service and/or application layer can be used to generate MBS data or request basic multicast transmission required for MBS services;
  • the transmission layer mainly includes the following key network elements: access and mobility management functions, AMF), session management function (session management function, SMF), user plane function (user plane function, UPF), policy control function (policy control function, PCF) and unified data management (unified data management, UDM) and so on.
  • User equipment can be called terminal equipment, access terminal, subscriber unit, subscriber station, mobile station, mobile station, remote station, remote terminal, mobile equipment, user terminal, terminal, wireless communication equipment, User Agent or User Device.
  • the terminal device may be a device that provides voice/data connectivity to the user, such as a handheld device with a wireless connection function, a vehicle-mounted device, and the like.
  • some examples of terminals are: mobile phone (mobile phone), tablet computer, notebook computer, palmtop computer, mobile internet device (MID), wearable device, virtual reality (virtual reality, VR) device, augmented reality (augmented reality, AR) equipment, wireless terminals in industrial control, wireless terminals in self-driving, wireless terminals in remote medical surgery, smart grid wireless terminal in transportation safety, wireless terminal in smart city, wireless terminal in smart home, cellular phone, cordless phone, session initiation protocol protocol, SIP) telephone, wireless local loop (wireless local loop, WLL) station, personal digital assistant (personal digital assistant, PDA), wireless communication-capable handheld device, computing device or other processing device connected to a wireless modem, Vehicle-mounted devices, wearable devices, terminal devices in a 5G network, or terminal devices in a future evolved public land mobile network (public land mobile network, PLMN), etc.,
  • the terminal device may also be a wearable device.
  • Wearable devices can also be called wearable smart devices, which are the general term for the intelligent design of daily wear and the development of wearable devices using wearable technology, such as glasses, gloves, watches, clothing and shoes.
  • a wearable device is a portable device that is worn directly on the body or integrated into the user's clothing or accessories. Wearable device is not only a hardware device, but also realizes powerful functions through software support, data interaction, and cloud interaction.
  • wearable smart devices include full-featured, large-scale, complete or partial functions without relying on smart phones, such as smart watches or smart glasses, and only focus on a certain type of application function, which needs to cooperate with other devices such as smart phones.
  • the terminal device may also be a terminal device in an Internet of Things (IoT) system.
  • IoT Internet of Things
  • IoT is an important part of the future development of information technology, and its main technical feature is that items pass through communication technology Connect with the network, so as to realize the intelligent network of human-machine interconnection and interconnection of things.
  • radio access network, RAN node
  • the access network may be an access network using different access technologies.
  • 3GPP access technologies such as those employed in 3G, 4G or 5G systems
  • non-3GPP (non-3GPP) access technologies 3GPP access technologies
  • 3GPP access technology refers to the access technology that conforms to the 3GPP standard specifications.
  • the access network equipment in the 5G system is called the next generation Node Base station (gNB).
  • gNB next generation Node Base station
  • a non-3GPP access technology refers to an access technology that does not conform to 3GPP standard specifications, for example, an air interface technology represented by an access point (AP) in wireless fidelity (WiFi).
  • AP access point
  • WiFi wireless fidelity
  • An access network that implements access network functions based on wireless communication technology can be called a radio access network (RAN).
  • the radio access network can manage radio resources, provide access services for terminal equipment, and then complete the forwarding of control signals and user data between the terminal and the core network.
  • a radio access network may include, but is not limited to: a radio network controller (RNC), a Node B (Node B, NB), a base station controller (BSC), a base transceiver station (base transceiver station, BTS), home base station (for example, home evolved NodeB, or home Node B, HNB), baseband unit (baseband unit, BBU), AP in WiFi system, wireless relay node, wireless backhaul node, transmission point (transmission point) , TP) or transmission and reception point (transmission and reception point, TRP), etc., it can also be a gNB or a transmission point (TRP or TP) in a 5G (eg, NR) system, one or a group of base stations in a 5G system ( Including multiple antenna panels) antenna panels, or, it can also be a network node that constitutes a gNB or a transmission point, such as a baseband unit (BBU), or a distributed unit (DU), or in the next generation communication 6
  • a gNB may include a centralized unit (CU) and a DU.
  • the gNB may also include an active antenna unit (active antenna unit, AAU for short).
  • CU implements some functions of gNB
  • DU implements some functions of gNB.
  • CU is responsible for processing non-real-time protocols and services, implementing radio resource control (RRC), and packet data convergence protocol (PDCP) layer function.
  • RRC radio resource control
  • PDCP packet data convergence protocol
  • the DU is responsible for processing physical layer protocols and real-time services, and implementing the functions of the radio link control (RLC) layer, the media access control (MAC) layer and the physical (PHY) layer.
  • RLC radio link control
  • MAC media access control
  • PHY physical
  • the access network device may be a device including one or more of a CU node, a DU node, and an AAU node.
  • the CU can also be divided into network devices in a core network (core network, CN), which is not limited in this application.
  • the access network device is a network device in the wireless access network, which is used to provide services for the cell, and the terminal device uses the transmission resources (for example, frequency domain resources, or frequency spectrum) allocated by the access network device.
  • resources for example, frequency domain resources, or frequency spectrum
  • the cell may belong to a macro base station (for example, a macro eNB or a macro gNB, etc.), or it may belong to a base station corresponding to a small cell (small cell), where the small cell may include: urban cell (metro cell) , micro cell (micro cell), pico cell (pico cell), femto cell (femto cell), etc.
  • These small cells have the characteristics of small coverage and low transmission power, and are suitable for providing high-speed data transmission services.
  • Access network equipment may include base stations (gNBs), such as macro base stations, micro base stations, indoor hotspots, and relay nodes, etc.
  • the function is to send radio waves to terminal equipment, on the one hand to realize downlink data transmission, and on the other hand to send scheduling information to control Uplink transmission, and receive radio waves sent by terminal equipment, receive uplink data transmission.
  • gNBs base stations
  • the function is to send radio waves to terminal equipment, on the one hand to realize downlink data transmission, and on the other hand to send scheduling information to control Uplink transmission, and receive radio waves sent by terminal equipment, receive uplink data transmission.
  • the access network device may also be used to receive MBS service data (MBS data) through a shared N3 interface, and use point-to-point (point to point, PTP) or point-to-multipoint ( point to multi-point, PTM) transmission mode to transmit MBS data to terminal equipment; or, manage QoS flow of MBS session through N2 interface; receive QoS flow of MBS session at the access stratum (AS); control terminal Device switching between PTM and PTP transmission, etc.
  • MBS service data MBS service data
  • PTP point to point
  • PTM point to multi-point
  • the user equipment or the access 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.
  • This hardware layer includes hardware such as central processing unit (CPU), memory management unit (MMU), and memory (also called main memory).
  • the operating system may be any one or more computer operating systems that implement business processing through processes, such as a Linux operating system, a Unix operating system, an Android operating system, an iOS operating system, or a Windows operating system.
  • the application layer includes applications such as browsers, address books, word processing software, and instant messaging software.
  • the present application does not specifically limit the specific structure of the execution body of the method provided by the embodiment of the present application, as long as the program that records the code of the method provided by the embodiment of the present application can perform communication according to the method provided by the embodiment of the present application That is, for example, the execution subject of the method provided by the embodiments of the present application may be user equipment or access network equipment, or a functional module in the user equipment or access network equipment that can call and execute programs.
  • Access management network element used for routing and forwarding user plane data, or quality of service (quality of service, QoS) processing of user plane data, etc.
  • the access management network element may be an access and mobility management function (AMF) network element.
  • AMF access and mobility management function
  • the access management network element may still be an AMF network element, or may have other names, which are not limited in this application.
  • the access management network element may also perform the following functions: select a session management function network element (multicast broadcast SMF, MB-SMF) with an MBS function; perform an MBS session with the access network device and the MB-SMF Management signaling interaction; select access network equipment to broadcast, etc.
  • a session management function network element multicast broadcast SMF, MB-SMF
  • Session management network element It can be used for session management, Internet Protocol (IP) address allocation and management of terminal equipment, selection of endpoints that can manage user plane functions, policy control and charging function interfaces, and downlink data notification Wait.
  • IP Internet Protocol
  • the session management network element may be a session management function (session management function, SMF) network element.
  • SMF session management function
  • the session management network element may still be an SMF network element, or may have other names, which are not limited in this application.
  • MB-SMF Multicast broadcast session management function network element, that is, a session management function network element with MBS function.
  • MB-SMF can be used for MBS session management (including QoS control), and control of MBS transport, including configuration of data plane gateways MB-UPF and RAN nodes for MBS streaming based on policy rules from PCF or local MBS traffic (via AMF ).
  • the MB-SMF can also be connected with the server of the MBS service or the multicast broadcast service function (MBSF) or the network exposure function (NEF), so as to receive the relevant information of the MBS service (for example, description of the MBS service).
  • the MB-SMF can also be connected to the PCF to create resources for MBS services.
  • MB-SMF can be integrated in PCF or SMF as a functional module, or can be deployed independently, which is not limited in this application.
  • UPF That is, the data plane gateway. It can be used for packet routing and forwarding, or quality of service (QoS) processing of user plane data. User data can be accessed to a data network (DN) through this network element.
  • DN data network
  • the UPF may also perform the following functions: interact with the SMF, receive multicast data from the MB-UPF for individual transmission, and send multicast data to the access network device for unicast transmission.
  • MB-UPF that is, a multicast broadcast data plane gateway (multicast broadcast UPF, MB-UPF).
  • QoS flow for transporting MBS traffic to the RAN.
  • the functions that MB-UPF supports for MBS services include: filtering downlink packets of MBS flows; distributing MBS data packets to RAN nodes (or UPF); QoS enhancement and counting/reporting based on existing methods.
  • the MB-UPF can be integrated into the UPF as a functional module, or deployed independently, which is not limited in this application.
  • Policy control network element a unified policy framework for guiding network behavior, providing policy rule information for network network elements (such as AMF, SMF network elements, etc.) or terminal equipment.
  • the policy control network element may be a policy and charging rules function (policy and charging rules function, PCRF) network element.
  • policy control network element may be a policy control function (PCF) network element.
  • PCF policy control function
  • the policy control network element may still be the PCF network element, or may have other names, which are not limited in this application.
  • the PCF may also provide policies for the MBS service, receive MBS information from the AF, and perform the following functions to support the MBS:
  • QoS processing of MBS sessions including QoS parameters such as 5QI, max bit rate (MBR), guaranteed bit rate (GBR), etc.; provides policy information about MBS sessions to MB-SMF to authorize Relevant QoS profiles; receive MBS information or QoS requirements.
  • QoS parameters such as 5QI, max bit rate (MBR), guaranteed bit rate (GBR), etc.
  • Network opening network element mainly used to support the opening of capabilities and events.
  • the network exposure network element may be a network exposure function (NEF) network element.
  • NEF network exposure function
  • the network opening network element may still be the NEF network element, or may have other names, which are not limited in this application.
  • the NEF can interact with content providers that reserve receiving resources for multicast groups and receive QoS requirements, UE authorization information, service area, and start and end times of MBS sessions.
  • the NEF may also choose the SMF to handle multicast transmissions, store information related to multicast sessions in the UDR, etc.
  • An application function entity (application function, AF), an application point that provides service access, and the data of these service applications are transmitted to the terminal device through the MBS.
  • Multicast broadcast service control plane function network element (MBSF control plane, MBSF-C), which can perform the following functions:
  • MBMS multimedia broadcast multicast service
  • Multicast broadcast service user plane function network element (MBSF user plane, MBSF-U), which can be used for the general data packet transmission function of any IP multicast-enabled application.
  • MB-SMF, MB-UPF, MBSF-C and MBSF-U are all functional units, which can be deployed independently or can be co-located with other network elements, which is not limited in this application.
  • the RAN is connected to the AMF through the N2 interface, the RAN is connected to the UPF through the N3 interface, and the MB-UPF is connected through the MB-N3 interface.
  • SMF controls UPF through N4 interface
  • SMF is connected with AMF and MB-SMF through N11 interface and N16a interface respectively
  • UPF is connected with MB-UPF through MB-N9 interface.
  • PCF is connected with MB-SMF and AMF through N7 interface and N15 interface respectively.
  • MB-SMF accesses the service-oriented architecture through the Nmbsmf interface; similarly, NEF, MBSF-U, MBSF-C, and AF access the service-oriented architecture through their respective interfaces to provide corresponding services.
  • Npcf, Namf, Nmbsmf, Nmbsu, N2, N3, N4, etc. are interface serial numbers.
  • 3rd generation partnership project 3rd generation partnership project, 3GPP
  • the network architecture to which the embodiment of the present application can be applied as shown in FIG. 1 is only an example, and the network architecture applicable to the embodiment of the present application is not limited to this, and any network architecture that can realize the functions of the above-mentioned network elements is applicable. in the examples of this application.
  • unicast refers to sending service data to a terminal through a protocol data unit (PDU) session.
  • the unicast mode of the multicast broadcast service can refer to sending the data of the multicast broadcast service to the terminal device through the PDU session, which can be referred to as the unicast mode in the following, and the unicast mode can also be called the 5GC independent multicast broadcast service traffic transmission mode ( 5G core individual MBS traffic delivery method).
  • Multicast/broadcast At the core network level, multicast/broadcast refers to sending data of multicast broadcast services to terminal devices through a multicast/broadcast session. It can be referred to as multicast broadcast mode later, or multicast broadcast mode can also be used. It is called 5GC shared multicast broadcast service traffic transmission method (5G core shared MBS traffic delivery method).
  • 5G core shared MBS traffic delivery method 5GC shared multicast broadcast service traffic transmission method
  • the multicast broadcast service can be described by the information of the multicast broadcast service.
  • the information of the multicast broadcast service at least includes the description information of the multicast broadcast service, and the description information of the multicast broadcast service may include the description information of one or more multicast broadcast service flows, wherein the description information of the multicast broadcast service flow Including at least one of the following: the quality of service identifier (QoS flow identifier, QFI) of the multicast broadcast service flow, the characteristic information of the multicast broadcast service flow (such as the destination address, destination port number, source address, etc. of the multicast broadcast service) , QoS requirements (eg, jitter, delay, packet loss rate, bandwidth, etc.) of the multicast broadcast service flow.
  • QoS flow identifier QoS flow identifier
  • the data packets of the multicast broadcast service flow can be identified by the QoS flow sequence number (QFI sequence number, QFI SN) or the user plane general packet radio service (general packet radio service, GPRS) tunneling protocol (GPRS Tunnelling Protocol user plane, GTP-U ) sequence number (GTP-U sequence number, GTP-U SN) identification.
  • QFI sequence number QFI SN
  • GPRS general packet radio service
  • GTP-U GPRS Tunnelling Protocol user plane
  • Protocol data unit (PDU) session PDU session: 5G core network (5G core network, 5GC) supports PDU connection services.
  • the PDU connection service may refer to the service of exchanging PDU data packets between a terminal device and a data network (DN).
  • the PDU connection service is realized through the establishment of a PDU session initiated by the terminal device. After a PDU session is established, a PDU session tunnel is established.
  • the PDU session tunnel corresponds to the UE, and the service data in the PDU session tunnel can be transmitted in the form of a unicast QoS stream. In other words, PDU sessions are UE-level.
  • Each end device can establish one or more PDU sessions.
  • a PDU session for transmitting multicast broadcast service data may be referred to as a multicast session, a multicast session, a broadcast session, or a multicast and broadcast service (MBS) session (MBS session).
  • MBS multicast and broadcast service
  • Multicast broadcast session can provide services for a multicast broadcast service.
  • a multicast broadcast session includes unicast or group broadcast from the data network to the core network equipment and then to the access network equipment.
  • the data of the multicast broadcast service can be sent from the 5G CN to UE1, UE2, UE3 and UE4.
  • the transmission path from 5G CN to 5G RAN can be a multicast broadcast session tunnel, that is, an N3 tunnel between MB-UPF and NG-RAN.
  • 5G CN sends data of multicast broadcast service to UE1 and UE2, and the multicast broadcast session tunnel of UE1 and UE2 is shared.
  • the RAN can send the above multicast broadcast data to UE1 and UE2 in a point-to-multipoint (PTM) manner, that is, only one piece of data needs to be sent, and both UEs can receive it.
  • the RAN may also send service data to UE1 and UE2 in a unicast manner, that is, a point-to-point (point-to-point, PTP) manner.
  • the multicast broadcast data sent by the 5G CN can also be sent to the UE through the corresponding PDU sessions of the UE. For example, 5G CN sends data of multicast broadcast service to UE3 and UE4, and different PDU sessions have different PDU session tunnels.
  • the RAN can send service data to UE3 and UE4 in a PTP manner, respectively.
  • a terminal device When a terminal device receives service data, it may move across RAN nodes, thereby triggering a handover procedure of the terminal device.
  • the handover process of the terminal device is briefly described below with reference to FIG. 3 .
  • the core network device sends the packet data of the terminal device service to the source access network device, and correspondingly, the source access network device receives the packet data and sends the packet data to the terminal device.
  • the terminal device in the radio resource control (radio resource control, RRC) connected state sends a measurement report (measurement report) according to the measurement reporting triggering criterion configured by the source access network device.
  • RRC radio resource control
  • the source access network device determines, according to the measurement report of the terminal device, when the terminal device satisfies the handover condition, determines the target access network device for the terminal device.
  • the source access network device sends a handover request to the target access network device, and sends context (UE Context) information of the terminal device to the target access network device along with the handover request.
  • context UE Context
  • the target access network device reserves resources for the terminal device to be handed over, and at the same time allocates a cell radio network temporary identifier (C-RNTI) and other parameters to the terminal device, and sends it to the terminal device with the handover request confirmation message.
  • C-RNTI cell radio network temporary identifier
  • the source access network device After receiving the handover request confirmation message, the source access network device prepares to forward the packet data to the target access network device.
  • the source access network device sends a handover command (handover command) to the terminal device.
  • the handover command may include the following information, C-RNTI, system information block (system information block, SIB) of the target access network device, configuration information of the terminal device, etc.
  • SIB system information block
  • the terminal device stops uplink or downlink data transmission with the source gNB.
  • the source access network device sends sequence number (sequence number, SN) status information to the target access network device.
  • the terminal device synchronizes with the target access network device.
  • the terminal device sends a handover confirmation message to the target access network device, indicating that the handover is completed.
  • the target access network device indicates to the source access network device that the handover is complete, so that the source access network device releases the context information of the terminal device.
  • the target access network device notifies the core network device to update the information of the data forwarding destination access network device, so that the core network can send the data of the terminal device to the target access network device.
  • the source access network device and the target access network device may be respectively an access network device that supports multicast broadcasting services or an access network device that does not support multicast broadcasting services. That is to say, it is possible for the terminal device to move from an access network device that supports the multicast broadcast service to an access network device that does not support the multicast broadcast service, and vice versa.
  • the fact that the access network equipment supports the multicast broadcast service can be understood as the fact that the access network equipment supports the transmission of the data of the multicast broadcast service in the multicast broadcast manner.
  • the fact that the access network device does not support the multicast broadcast service can be understood that the access network device does not support the transmission of multicast broadcast service data in the multicast broadcast mode, or the access network device only supports the transmission of the multicast broadcast service data in the unicast mode.
  • network services of terminal devices can be implemented through PDU sessions.
  • the multicast broadcast service data can be received from the core network through the multicast broadcast session tunnel and sent to multiple terminal devices that join the multicast broadcast service.
  • the multicast broadcast service data After the multicast broadcast service data arrives at the RAN, it passes through the Service Data Adaptation Protocol (SDAP) layer of the RAN, the Packet Data Convergence Protocol (PDCP) layer, the Radio Link Control (radio Link control, RLC) layer, media access control (media access control, MAC) layer, physical (physical, PHY) layer processing, sent to each terminal equipment receiving multicast broadcast service data.
  • SDAP Service Data Adaptation Protocol
  • PDCP Packet Data Convergence Protocol
  • RLC Radio Link Control
  • media access control media access control
  • MAC physical (physical, PHY) layer processing
  • the terminal device switching from the source access network device (Source-gNB, S-gNB) to the target access network device (Target-gNB, T-gNB) as an example, where the S-gNB is an access network that supports MBS services equipment, and the terminal equipment receives data of the MBS service through the S-gNB, and the T-gNB is an access network equipment that does not support the MBS service.
  • the core network device In the handover process of the terminal device, after the terminal device disconnects from the S-gNB, the core network device will continue to send the data of the MBS service to the S-gNB, and when the terminal device accesses the T-gNB When the core network device transmits the MBS service data to the target access network device according to the current progress of transmitting the MBS service data to the source access network device, it may cause packet loss of the MBS data of the terminal device during the handover process. And other issues.
  • the T-gNB is an access network device that does not support the MBS service, it receives the data of the MBS service through the UPF (target UPF), and the MB-UPF needs to obtain the relevant information of the target UPF, so as to follow the data of the MBS service It is sent to the target UPF, and sent to the T-gNB via the target UPF, so as to ensure the reliable transmission of MBS service data of the terminal device during the handover process.
  • the S-gNB is an access network device that does not support MBS services
  • the T-gNB is an access network device that supports MBS services
  • the S-gNB and T-gNB may appear.
  • the progress of the data transmission of the MBS service by the gNB is different, which may cause problems such as packet loss of the MBS data of the terminal equipment in the handover process. Therefore, how to ensure the reliability of the MBS service data transmission in the handover process is: An urgent problem to be solved.
  • the present application proposes a method for transmission and switching of multicast broadcast services, which can ensure the reliability of MBS service data transmission when a terminal device switches between the above two access network devices.
  • FIG. 4 is a method for switching transmission of a multicast broadcast service provided by an embodiment of the present application. The method includes at least the following steps.
  • the terminal device receives the first data packet of the first multicast broadcast service (the first MBS service) sent by the source access network device (S-gNB).
  • the S-gNB is an access network device supporting the MBS service, that is, the S-gNB supports sending data of the MBS service to the terminal device in a multicast broadcast manner.
  • the method may further include S401, preset the S-gNB and the target access network device (T-gNB), the identification information of the first MBS service data to the PDCP sequence number (sequence number, SN) ) have the same mapping relationship. That is to say, in S-gNB and T-gNB, the same PDCP SN can be obtained according to the identification information of the same data packet and the mapping relationship.
  • the identification information of the first MBS service data may include QFI SN or GTP-US SN.
  • the mapping relationship may be preset, for example, the mapping relationship is preset through a protocol agreement, core network configuration, or network management configuration. Taking the identification information of the data of the first MBS service as the QFI SN as an example, the mapping relationship can be expressed as:
  • PDCP SN (QFI SN)mod[max(PDCP SN)+1] (1)
  • the size (size) of the PDCP SN is not greater than the size (size) of the QFI SN.
  • the PDCP SN size is 12 bits (bit) or 18 bits
  • the QFI SN size is 24 bits, so S-gNB and T-gNB can launch the same PDCP SN for a QFI SN according to this formula, That is, the PDCP SN number is unique.
  • the combined mapping relationship between the identification information of the data of the first MBS service and the PDCP SN may not be limited to the formula (1), as long as the S-gNB and the T-gNB can be the same as the data of the first MBS service according to the formula.
  • the identification information can deduce the same PDCP SN.
  • the S-gNB determines, according to the measurement report of the terminal equipment, to switch the terminal equipment to the T-gNB, and the T-gNB is not Access network equipment that supports MBS services.
  • the steps of deciding to switch the terminal device to the T-gNB based on the measurement report are similar to those in S320 to S340, and are not repeated here.
  • the S-gNB sends a handover command (handover command) to the terminal device, and accordingly, the terminal device receives the handover command.
  • the handover command is used to instruct the terminal device to switch from the S-gNB to the T-gNB.
  • the terminal device disconnects the connection with the S-gNB, that is, stops the uplink or downlink data transmission with the S-gNB. .
  • the terminal equipment synchronizes to the T-gNB.
  • the S-gNB sends the first information to the core network device, and correspondingly, the core network device receives the first information.
  • the first information includes identification information of the data packet #1 (an example of the first data packet), and the data packet #1 may be the last data packet of the first multicast broadcast service that has been sent by the S-gNB.
  • the identification information of the data packet #1 may include at least one of the following sequence numbers.
  • the QFI of packet #1 and the QFI SN of packet #1 The QFI of packet #1 and the QFI SN of packet #1, the packet data convergence protocol sequence number (PDCP sequence number, PDCP SN) of the data of packet #1, and the GTP-US SN of packet #1.
  • PDCP sequence number the packet data convergence protocol sequence number (PDCP sequence number, PDCP SN) of the data of packet #1
  • GTP-US SN the GTP-US SN
  • the S-gNB sends the first information to the core network device through a control plane method.
  • the S-gNB sends the QFI and Last QFI SN information of packet #1 to the AMF, for example , the S-gNB sends a PDU session resource modification indication (PDU session resource modify indication) message to the AMF, and the message may include the QFI and Last QFI SN information of the data packet #1.
  • the AMF sends the first information to the MB-SMF and to the MB-UPF via the MB-SMF.
  • the AMF may also send the first information to the MB-UPF through other core network elements, and the AMF sends the first information to the MB-SMF through the SMF, and sends the first information to the MB-UPF through the MB-SMF.
  • the first information may also include identification information of the terminal device, identification information of the T-gNB, and session identification information of the first MBS service.
  • the SMF or MB-SMF The SMF can determine the target UPF according to the identification information of the terminal device, the identification information of the T-gNB, and the session identification information of the first MBS service, so that the MB-UPF can subsequently send the first UPF to the target access network device through the target UPF.
  • One MBS service data is used to determine the target UPF according to the identification information of the terminal device, the identification information of the T-gNB, and the session identification information of the first MBS service.
  • the S-gNB sends the first information to the core network device through a user plane method.
  • the S-gNB sends downlink data delivery status information (downlink data delivery status) to the core network device, and the downlink data delivery status information includes the first information, that is, the S-gNB can indicate through the downlink data delivery status information QFI and Last QFI SN information of packet #1.
  • the first information may further include the identification information of the terminal device and the identification information of the T-gNB.
  • the MB-UPF may send the identification information of the terminal device, the identification information of the T-gNB, and the session identification information of the first MBS service to the MB-SMF, so that the MB-SMF determines the target UPF.
  • the MB-UPF receives the identification information of the target UPF determined by the MB-SMF.
  • the S-gNB sends the first information to the core network device through the T-gNB.
  • the S-gNB sends sequence number status information to the T-gNB, where the sequence number status information includes the first information.
  • the T-gNB sends the first information to the core network device through a control plane or user plane method.
  • the T-gNB feeds back the downlink data delivery status (DDDS) to the target UPF, which carries the first information, and the UPF sends the first information to the core network device.
  • DDDS downlink data delivery status
  • the T-gNB sends the first information to the core network device.
  • the method may further include S430b, the S-gNB sends the first information to the core network device, and correspondingly, the core network device receives the first information.
  • the first information further includes identification information of a third data packet, and before the third data packet includes the sequence number of the data packet #1, the S-gNB fails to send the data packet of the first MBS service to the terminal device successfully.
  • the core network device determines, according to the first information, a second data packet to be sent to the T-gNB, where the second data packet is a data packet of the first MBS service.
  • the first information including the identification information of the data packet #1 is the QFI of the data packet #1 and the QFI SN (Last QFI SN) of the data packet #1 as an example, wherein, the data packet #1 can be The last data packet of the first MBS service that has been sent by the S-gNB.
  • the core network device determines, according to the QFI and the Last QFI SN, that the Last QFI SN is incremented by 1, and sends the data packet of the first MBS service to the T-gNB through the target UPF, that is, the second data packet of the first MBS service includes the Last QFI The data packet corresponding to the SN plus 1 and the data packet after the sequence number.
  • the core network device sends the second data packet to the T-gNB.
  • the method may further include S460, a data forwarding process. That is, the S-gNB forwards the third data packet to the T-gNB, so that the T-gNB sends the third data packet to the terminal device in a unicast manner.
  • the method may further include S470, the core network device determines the third data packet according to the identification information of the third data packet carried in the first information, and sends the third data packet to the terminal device.
  • the core network device may By receiving the first information from the S-gNB, where the first information includes identification information of the first data packet, the second data packet of the MBS service sent to the T-gNB is determined. Problems such as packet loss of the data received by the terminal device during the handover process of the MBS service are avoided, thereby ensuring the reliability of the data transmission of the MBS service.
  • FIG. 5 shows another exemplary flowchart of a method for switching transmission of multicast broadcast services provided by an embodiment of the present application.
  • the method can be applied to switching a terminal device from an access network device that supports MBS services to a device that does not support MBS services.
  • the method is a detailed process of the method 400 in FIG. 4 .
  • the following describes in detail with reference to FIG. 5 , wherein, for simplicity, MB-gNB is used to represent the access network equipment supporting the MBS service.
  • the method includes steps S501 to S505.
  • the MB-UPF sends the data of the first MBS service to the S-gNB (MB-gNB), and accordingly, the MB-gNB receives the data of the first MBS service of the terminal device sent by the MB-UPF.
  • the mapping relationship between the identification information of the data of the first MBS service in the preset MB-gNB and the gNB to the PDCP SN is the same, and the specific process is similar to that in S401, and will not be repeated here.
  • the method may include S501b, the MB-UPF sends the data of the first MBS service to the S-gNB (MB-gNB), and accordingly, the MB-gNB receives the data of the first MBS service of the terminal device sent by the MB-UPF. data.
  • the MB-gNB sends the data of the first MBS service to the terminal device.
  • the MB-gNB can send the data of the first MBS service to the terminal device in the form of PTM or PTP, and the MB-gNB can also use the combination of PTP and PTM to deliver the data of the MBS service to the terminal device . This step is similar to that in S410.
  • the MB-gNB may determine to switch the terminal device to the T-gNB (gNB) according to the measurement report of the terminal device.
  • S503 to S505 are part of the steps in the terminal device switching process, and the specific process is similar to that in S330 to S360. For the sake of simplicity, details are not described herein again.
  • the S-gNB sends the first information to the MB-UPF, and accordingly, the MB-UPF receives the first information.
  • the first information includes identification information of a first data packet (data packet #1), and data packet #1 is the last data in the data packet of the first MBS service that has been sent by the MB-gNB to the terminal device packet, the identification information of the data packet #1 is similar to that in S430a.
  • the S-gNB can send the first information to the MB-UPF in two ways.
  • the MB-gNB sends the first information to the MB-UPF by using a control plane method.
  • the identification information of the data packet #1 as the QFI of the data packet #1 and the QFI SN (Last QFI SN) of the data packet #1 as an example, the following steps can be used specifically.
  • the MB-gNB sends the first information to the AMF, and accordingly, the AMF receives the first information.
  • the MB-gNB sends a PDU session resource modification indication (PDU session resource modify indication) message to the AMF, and the message may include the first information.
  • PDU session resource modify indication PDU session resource modify indication
  • AMF sends QFI and Last QFI SN, UE ID, gNB ID, MBS session ID information to MB-SMF, and accordingly, MB-SMF receives these information.
  • the MB-SMF determines the target UPF according to the UE ID, the gNB ID and the MBS Session ID.
  • the MB-SMF sends the target UPF identifier and the QFI and the Last QFI SN to the MB-UPF.
  • the MB-UPF receives the target UPF identity, QFI and Last QFI SN.
  • the MB-gNB sends the first information to the MB-UPF by using a user plane method.
  • the MB-gNB sends the downlink data delivery status (DDDS) to the MB-UPF, which carries the first information, that is, the QFI and Last QFI SN, UE ID, and gNB ID that carry the data packet #1 . Accordingly, the MB-UPF receives the information, so that the data transmission progress of the MB-gNB can be determined according to the information.
  • DDDS downlink data delivery status
  • MB-UPF sends UE ID, gNB ID and MBS Session ID to MB-SMF, correspondingly, MB-UPF receives UE ID, gNB ID and MBS Session ID information.
  • the MB-SMF determines the target UPF according to the UE ID, the gNB ID and the MBS Session ID.
  • the MB-SMF sends the target UPF identifier to the MB-UPF, so that the MB-UPF can know the UPF of the T-gNB connection, and starts from the first multicast broadcast data packet after the data packet #1 to the gNB transmission.
  • the method may further include:
  • the terminal device sends a handover confirmation message to the T-gNB (gNB), indicating that the handover is completed.
  • gNB T-gNB
  • the terminal device After the terminal device disconnects the data transmission with the MB-gNB, it starts the downlink synchronization process with the gNB, and then initiates the random access process to obtain the uplink timing and uplink resource allocation.
  • the terminal device sends an RRC connection reconfiguration complete message to the gNB to indicate that the handover is complete.
  • the MB-UPF triggers a path switch (path switch), and performs a new process of the N3GTP-u tunnel on the T-gNB side.
  • path switch path switch
  • the specific establishment process adopts the technology of establishing a tunnel at present.
  • the MB-gNB sends a context release message of the terminal device to the gNB.
  • the MB-UPF sends the data of the first MBS service to the T-gNB (gNB) through the target UPF.
  • the data corresponds to the data packet (second data packet) of the first MBS service after the data packet #1, and this step is similar to that in S450.
  • the method may also include steps S5100 similar to those in S460. , data forwarding.
  • the S-gNB fails to send the first MBS service to the terminal device. data pack.
  • the MB-UPF may also determine to send the third data packet to the terminal device according to the first information. Then the data forwarding process is not required at this time. The process is similar to that in S470.
  • the T-gNB sends the subsequent data (second data packet) of the first MBS service to the terminal device.
  • the MB-UPF in the process of switching the terminal equipment from the access network equipment (S-gNB) that supports the MBS service to the access network equipment (T-gNB) that does not support the MBS service, the MB-UPF can By receiving the first information from the S-gNB, the second data packet of the MBS service sent to the T-gNB is determined. Problems such as packet loss of the data received by the terminal device during the handover process of the MBS service are avoided, thereby ensuring the reliability of the data transmission of the MBS service.
  • FIG. 6 shows another exemplary flowchart of the method for transmitting a multicast service provided by an embodiment of the present application, and the method can also be applied to switching a terminal device from an access network device that supports the MBS service to an access network device that does not support the MBS service.
  • This method is a detailed process of the method 400 in FIG. 4 , and the difference between the method and the method 500 in FIG. 5 is that the S-gNB sends the first information to the core network device through the T-gNB. The method will be described in detail below with reference to FIG. 6 .
  • steps S601 to S604 are included.
  • the MB-UPF sends the data of the first MBS service to the MB-gNB.
  • the MB-gNB can determine to switch the terminal device to the T-gNB (gNB) according to the measurement report of the terminal device.
  • the gNB does not support it.
  • Access network equipment for multicast broadcast services The specific process is similar to that in S501 to S504, and for the sake of brevity, details are not described here in this application.
  • the MB-gNB sends sequence number status information to the gNB, where the sequence number status information includes the first information.
  • the first information includes identification information of a first data packet (data packet #1), and data packet #1 is the last data in the data packet of the first MBS service that has been sent by the MB-gNB to the terminal device packet, the identification information of the data packet #1 is similar to that in S430a.
  • the terminal device sends handover confirmation information to the T-gNB, indicating that the handover is completed. This step is similar to S550.
  • the terminal device After the terminal device disconnects the data transmission with the MB-gNB, it starts the downlink synchronization process with the T-gNB, and then initiates the random access process to obtain the uplink timing and uplink resource allocation.
  • the terminal device sends the handover confirmation information to the T-gNB, Indicates that the handover is complete.
  • the T-gNB sends the first information to the MB-UPF, so that the MB-UPF can subsequently send data to the terminal device from the Last QFI SN+1.
  • the T-gNB can send the first information to the MB-UPF in two ways.
  • the gNB sends the first information to the MB-UPF through the user plane method.
  • the gNB feeds back the downlink data delivery status (DDDS) to the UPF, which carries the first information, that is, carries the QFI and Last QFI SN information.
  • DDDS downlink data delivery status
  • the UPF sends the first information to the MB-UPF.
  • the method may further include S650a, triggering a path switch to perform a new process of the N3GTP-u tunnel on the T-gNB (gNB) side.
  • S650a triggering a path switch to perform a new process of the N3GTP-u tunnel on the T-gNB (gNB) side.
  • the gNB sends the first information to the MB-UPF by using a control plane method.
  • the T-gNB sends the first information to the MB-UPF.
  • the T-gNB sends the first information to the AMF, and then the AMF sends the information to the UPF through the SMF, and then the UPF sends the information to the MB-UPF.
  • the T-gNB sends a path switch request message to the AMF, and the path switch request message carries the QFI and Last QFI SN information; then the AMF sends the first message to the UPF through the SMF.
  • the QFI and Last QFI SN information is sent by the UPF to the MB-UPF. So that the MB-UPF can send data to the terminal device from the Last QFI SN+1 later.
  • the MB-UPF can know the target UPF identifier at the same time, and the subsequent MB-UPF sends the data to the target UPF, and the target UPF then sends the data to the target UPF. Data is sent to the gNB and unicast to the terminal device.
  • the method may further include S860, the MB-gNB sends a UE context release message to the gNB.
  • the MB-UPF sends the data of the first MBS service to the T-gNB (gNB) through the target UPF. Similar to in S580, the data includes the data packets following the data packet #1.
  • the method may also include S690, data forwarding (data forwarding). )process.
  • the MB-UPF sends the third data packet to the terminal device, and no data forwarding process is required at this time.
  • the T-gNB sends the subsequent data of the first MBS service to the terminal device.
  • FIG. 7 shows another exemplary flowchart of a method for switching transmission of multicast broadcast services provided by an embodiment of the present application.
  • the method can be applied to switching a terminal device from an access network device that does not support MBS services to a device that supports MBS services.
  • the method includes at least the following steps.
  • the S-gNB sends a handover request message to the T-gNB, and accordingly, the T-gNB receives the handover request message.
  • the S-gNB is an access network device that does not support the MBS service, that is, the S-gNB only supports sending data of the MBS service to the terminal device in a unicast manner.
  • the S-gNB receives data of the first MBS service sent by the core network device (MB-UPF) through the UPF, and sends the first data packet of the first MBS service to the terminal device in a unicast manner.
  • M-UPF core network device
  • the S-gNB may determine, according to the measurement report of the terminal device, to switch the terminal device to the T-gNB, and the T-gNB supports For the access network equipment of the MBS service, the S-gNB sends the handover request message to the T-gNB.
  • the S-gNB sends a sequence number (sequence number, SN) status information (SN status transfer) to the T-gNB.
  • the sequence number state information includes identification information of the first data packet, the first data packet is the data packet of the first MBS service, and the identification information of the first data packet may be the PDCP SN.
  • the serial number status information indicates the value of the first serial number.
  • the sequence number status information includes the PDCP SN of the data packet #2, PDCP SN_2, wherein, the PDCP SN_2 (an example of the first sequence number) is equal to the PDCP SN_1 plus 1, the PDCP SN_1 is the PDCP SN of the data packet #1, and the data packet #1 is a data packet with the largest PDCP SN value among the data packets of the first MBS service buffered by the S-gNB.
  • the data of the first MBS service buffered by the S-gNB includes a data packet in which the S-gNB has allocated a PDCP SN, and a data packet in which the S-gNB has not allocated a PDCP SN, and the one with the largest value of the PDCP SN.
  • the data packet is the one with the largest PDCP SN value among the data packets to which the S-gNB has allocated the PDCP SN. That is, the T-gNB can determine the next PDCP SN that the S-gNB should send or buffer through the sequence number status information.
  • the T-gNB determines, according to the sequence number state information, that the value of the first sequence number is smaller than the value of the second sequence number.
  • the S-gNB After receiving the sequence number state information, the S-gNB determines the value of the first sequence number according to the sequence number state information, and the T-gNB determines that the value of the first sequence number is smaller than the value of the second sequence number.
  • the second sequence number may be the smallest sequence number among the sequence numbers of multiple third data packets buffered by the T-gNB, or the second sequence number may also be a data packet (the third data packet that is to be sent by the T-gNB) an example of a package) serial number.
  • the first sequence number and the second sequence number may be PDCP SN, and the third data packet is a data packet of the first MBS service.
  • the T-gNB sends the first information to the core network device, and correspondingly, the core network device receives the first information.
  • the T-gNB determines that the value of the first sequence number is smaller than the value of the second sequence number, and sends first information to the core network device, where the first information includes the third sequence number and the fourth sequence number.
  • the first serial number and the third serial number have a mapping relationship
  • the second serial number and the fourth serial number have a mapping relationship.
  • the third serial number and the fourth serial number can be QFI SN or GTP-US SN.
  • the T-gNB determines that the data progress of the first MBS service transmitted by the S-gNB is slower than that of the T-gNB, and the T-gNB sends the third sequence number and the fourth sequence to the core network equipment, which are used to indicate the S-gNB and The T-gNB transmits the progress information of the first MBS service, so that the core network device can determine the "gap data" generated due to the difference in the transmission progress between the S-gNB and the T-gNB.
  • the T-gNB transmits the first information through signaling exchange between the T-gNB and the core network device when the path is switched in the handover process. For example, the T-gNB sends a path switch request (path switch request) message to the AMF, the request message carries the first information, and the AMF sends the first information to the core network device (MB-UPF).
  • path switch request path switch request
  • MMF core network device
  • the core network device determines, according to the first information, a second data packet to be sent to the T-gNB, where the second data packet is a data packet of the first MBS service.
  • the core network device determines, through the first information, that the data packet corresponding to the fifth sequence number in the data of the first MBS service is the second data packet.
  • the value of the fifth serial number is greater than or equal to the third serial number and less than the fourth serial number.
  • the data packet (the second data packet) corresponding to the fifth sequence number is the above-mentioned "gap data”.
  • the core network device sends the second data packet to the T-gNB. So that the T-gNB sends the second data packet to the terminal device in a unicast manner.
  • the method may further include S770, the core network device sends the second data packet to the S-gNB, and accordingly, the S-gNB receives the second data packet.
  • the method may further include S780, a data forwarding process. That is, the S-gNB forwards to the T-gNB the data of the first MBS service that is not successfully sent to the terminal device before the first sequence number. Meanwhile, in the process of data forwarding, the S-gNB sends the second data packet to the T-gNB.
  • S780 a data forwarding process. That is, the S-gNB forwards to the T-gNB the data of the first MBS service that is not successfully sent to the terminal device before the first sequence number. Meanwhile, in the process of data forwarding, the S-gNB sends the second data packet to the T-gNB.
  • the core network device in the process that the terminal device receives the data of the first MBS service from the S-gNB and switches the terminal device from the S-gNB to the T-gNB, can receive the data from the T-gNB
  • the first information of the gNB determines the second data packet sent to the T-gNB, that is, the "gap data" generated due to the difference in the progress of the transmission of the first MBS service data between the S-gNB and the T-gNB, which prevents the terminal equipment from switching
  • the problem of packet loss and other problems is solved, thereby ensuring the reliability of MBS data transmission of the terminal device in the handover process.
  • the S-gNB is an access network device that does not support the MBS service
  • the T-gNB is an access network device that supports the MBS service.
  • FIG. 8 shows another exemplary flowchart of a method for switching transmission of multicast broadcast services provided by an embodiment of the present application.
  • the method can be applied to switching a terminal device from an access network device that does not support MBS services to a device that supports MBS services.
  • the method is a detailed process of the method 700 in FIG. 7 .
  • the following describes in detail with reference to FIG. 8 , wherein, for simplicity, MB-gNB is used to represent the access network equipment supporting the MBS service.
  • the method further includes steps S801 to S804.
  • the S-gNB receives, via the UPF, the data of the first MBS service sent by the MB-UPF. And the mapping relationship between the identification information of the data of the first MBS service in the preset MB-gNB and the gNB to the PDCP SN is consistent.
  • the gNB sends the data of the first MBS service to the terminal device.
  • the gNB may determine to switch the terminal device to T-gNB (MB-gNB) according to the measurement report of the terminal device.
  • S803 is the handover preparation stage, and S804 is similar to that in S710, the S-gNB sends a handover request message to the T-gNB.
  • the gNB sends SN status information to the MB-gNB, and accordingly, the MB-gNB receives the SN status information, where the SN status information indicates the value of the first sequence number.
  • the SN status information includes identification information of the first data packet, and the identification information of the first data packet is similar to that in S720. That is, the first data packet includes data packet #2, and the identification information of data packet 2# can be PDCP SN_2 (an example of the first sequence number), PDCP SN_2 is equal to PDCP SN_1 plus 1, and PDCP SN_1 is the PDCP SN of data packet #1 , the data packet #1 is a data packet with the largest PDCP SN value among the data packets of the first multicast broadcast service buffered by the source access network device.
  • the target access network device can determine the identification information of the next data packet that the gNB should send or buffer through the SN status information.
  • the method may further include S820, the terminal device sends handover confirmation information to the T-gNB (MB-gNB), indicating that the handover is completed.
  • MB-gNB T-gNB
  • the T-gNB determines, according to the SN status information, that the data transmission progress of the first MBS service data transmitted by the gNB is slower than the data transmission progress of the MB-gNB transmission of the first MBS service data.
  • the MB-gNB determines the first sequence number according to the SN state information, and the MB-gNB determines that the value of the first sequence number is smaller than the second sequence number, and this step is similar to that in S730. That is, the data packet corresponding to the second sequence number is the data packet with the smallest sequence number among the multiple first MBS service data packets buffered in the MB-gNB, and the MB-gNB determines that the value of the first sequence number is less than the value of the second sequence number. value, that is, it is determined that the data transmission progress of the first MBS service data transmitted by the gNB is slower than that of the MB-gNB.
  • the MB-gNB sends the first information to the MB-UPF through the path switching process, and accordingly, the MB-UPF receives the first information.
  • the MB-gNB sends the first information to the MB-UPF through signaling interaction between the MB-gNB and the MB-UPF.
  • the first information includes a third serial number and a fourth serial number, and the third serial number and the fourth serial number have a mapping relationship with the first serial number and the second serial number, respectively, and this step is similar to S740.
  • the MB-UPF sends the second data packet to the MB-gNB, and accordingly, the MB-gNB receives the second data packet.
  • the MB-UPF determines through the first information that the data packet corresponding to the fifth sequence number in the data of the first multicast broadcast service is the second data packet.
  • the value of the fifth serial number is greater than or equal to the third serial number and less than the fourth serial number.
  • the MB-UPF sends the second data packet to the MB-gNB, so that the MB-gNB sends the second data packet to the terminal device in a unicast manner, and this step is similar to S760.
  • the method may further include S850b, the MB-UPF sends the second data packet to the gNB, and this step is similar to S770.
  • the method may further include S860, the MB-gNB sends a UE context release message to the gNB.
  • the method may further include S851, a data forwarding process.
  • the gNB can send the second data packet received in S850b to the MB-gNB.
  • the MB-gNB receives the data of the subsequent first MBS service sent by the MB-UPF, and sends the data of the subsequent first MBS service to the terminal device.
  • the terminal device receives the data of the first multicast broadcast service from the S-gNB (access network device that does not support the multicast broadcast service), and switches from the S-gNB to the T-gNB (supports the multicast broadcast service).
  • the core network equipment can determine the second data packet sent to the T-gNB by receiving the first information from the T-gNB, that is, because the S-gNB and the T-gNB.
  • the "gap data" generated by the difference in the transmission progress avoids the problem of packet loss of the data received by the terminal equipment during the switching process of the first multicast broadcast service, and ensures the reliability of the multicast broadcast data transmission of the terminal equipment during the switching process. sex.
  • FIG. 9 shows another exemplary flowchart of a method for switching transmission of multicast broadcast services provided by an embodiment of the present application.
  • the method can be applied to switching a terminal device from an access network device that does not support MBS services to a device that supports MBS services.
  • the method includes at least the following steps.
  • the S-gNB sends a handover request message to the T-gNB, and accordingly, the T-gNB receives the handover request message.
  • the S-gNB is an access network device that does not support the MBS service, and the S-gNB receives the data of the first MBS service sent by the core network device (MB-UPF) through the UPF, and sends the data to the terminal device in a unicast manner. Send the first data packet of the first MBS service. This step is similar to S710.
  • the T-gNB sends the first information to the core network device, and correspondingly, the core network device receives the first information.
  • this process can occur at the moment after the terminal device disconnects the uplink or downlink data transmission with the S-gNB.
  • the process can be that the S-gNB sends the sequence number status information (SN status transfer) to the T-gNB. )after.
  • the mapping relationship between the identification information of the first MBS service data and the PDCP SN is the same, and this step is similar to S401.
  • the T-gNB sends first information to the core network device, where the first information includes the fourth sequence number.
  • the first information includes the fourth sequence number.
  • the second sequence number may be the smallest sequence number among the sequence numbers of multiple third data packets buffered by the T-gNB, or the second sequence number
  • the number may also be the sequence number of the data packet (an example of the third data packet) to be sent by the T-gNB.
  • the fourth serial number may be a QFI SN or a GTP-US SN, and the second serial number may be a PDCP SN. That is, the fourth sequence indicates the progress information of the T-gNB transmitting the first MBS service.
  • the specific process of the T-gNB sending the first information to the core network device is similar to that in S740, and details are not repeated here.
  • the core network device determines that the value of the fourth serial number is greater than the sixth serial number.
  • the core network device determines the value of the fourth sequence number according to the first information, and determines that the value of the fourth sequence number is greater than the sixth sequence number, where the sixth sequence number is a plurality of first sequence numbers that the core network device has sent to the S-gNB.
  • the largest sequence number among the sequence numbers of the four data packets, or the sixth sequence number may be the sequence number of the data packet of the first MBS service to be sent by the core network device to the S-gNB.
  • the core network device determines that the S-gNB transmits the first MBS service data slower than the T-gNB by determining that the value of the fourth sequence number is greater than the sixth sequence number.
  • the core network device sends a second data packet to the T-gNB, so that the T-gNB sends the second data packet to the terminal device in a unicast manner, where the second data packet is a data packet of the first MBS service.
  • the second data includes a data packet corresponding to a seventh sequence number, and the value of the seventh sequence number is greater than or equal to the sixth sequence number and less than the value of the fourth sequence number. That is, the data packet (the second data packet) corresponding to the seventh sequence number is "gap data" generated due to the different progress of the S-gNB and the T-gNB in transmitting the first MBS service data.
  • the method may further include S950, the core network device sends the second data packet to the S-gNB, and accordingly, the S-gNB receives the second data packet.
  • the method may further include S960, a data forwarding process. That is, the S-gNB forwards the data of the first MBS service that has not been successfully sent to the T-gNB. Meanwhile, in the process of data forwarding, the S-gNB sends the second data packet to the T-gNB, so that the T-gNB sends the second data packet to the terminal device in a unicast manner.
  • S960 a data forwarding process. That is, the S-gNB forwards the data of the first MBS service that has not been successfully sent to the T-gNB. Meanwhile, in the process of data forwarding, the S-gNB sends the second data packet to the T-gNB, so that the T-gNB sends the second data packet to the terminal device in a unicast manner.
  • the core network device in the process that the terminal device receives the data of the first MBS service from the S-gNB and switches the terminal device from the S-gNB to the T-gNB, can receive the data from the T-gNB
  • the first information of the gNB determines the second data packet sent to the T-gNB, that is, the "gap data" generated due to the different progress of the transmission of the first MBS service data between the S-gNB and the T-gNB.
  • the packet loss of the data of the first MBS service is received, thereby ensuring the reliability of the MBS data transmission of the terminal device during the handover process.
  • FIG. 10 shows another exemplary flowchart of a method for switching transmission of multicast broadcast services provided by an embodiment of the present application.
  • the method can be applied to switching a terminal device from an access network device that does not support MBS services to a device that supports MBS services.
  • the method is a detailed process of the method 900 in FIG. 9 . The method is described in detail below with reference to FIG. 10 .
  • the method further includes steps S1001 to S1006.
  • the S-gNB receives the data of the first MBS service sent by the MB-UPF via the UPF, and the gNB sends the data of the first MBS service to the terminal device.
  • the mapping relationship between the identification information of the data of the first MBS service in the preset MB-gNB and the gNB to the PDCP SN is consistent.
  • the gNB may determine to switch the terminal device to T-gNB (MB-gNB) according to the measurement report of the terminal device.
  • the method may further include S1003 to S1005.
  • S1003 is the handover preparation; S1004, the S-gNB sends the handover command to the terminal device, and the process may be that after the S-gNB sends the handover request to the T-gNB (similar to S910), the terminal device receives the handover command Then, after disconnecting the data transmission with the gNB, start the downlink synchronization process with the MB-gNB; optionally, the method may further include S1005, the S-gNB sends the sequence number status information to the T-gNB.
  • the terminal device sends handover confirmation information to the T-gNB (MB-gNB), indicating that the handover is completed.
  • T-gNB T-gNB
  • the MB-gNB sends the first information to the MB-UPF through the path switching process, and accordingly, the MB-UPF receives the first information.
  • the first information includes a fourth serial number.
  • the fourth sequence number has a mapping relationship with the second sequence number, and the second sequence number is the smallest sequence number among the sequence numbers of the plurality of third data packets buffered by the MB-gNB. That is to say, the fourth sequence number is used to indicate progress information of the MB-gNB transmitting the first multicast broadcast service.
  • the MB-gNB sends the first information to the MB-UPF in the path switching process, which may be to transmit the first information through signaling interaction between the MB-gNB and the MB-UPF. This step is similar to S920.
  • the MB-UPF determines that the value of the fourth serial number is greater than the sixth serial number.
  • the sixth sequence number is the largest sequence number among the sequence numbers of the plurality of fourth data packets that have been sent by the MB-UPF to the gNB.
  • the MB-UPF determines that the gNB transmits the data of the first multicast broadcast service slower than the MB-gNB. That is, the MB-UPF determines that the data packet (the second data packet) corresponding to the seventh sequence number is "gap data" generated due to the difference in the transmission progress between the gNB and the MB-gNB.
  • the MB-UPF sends the second data packet to the MB-gNB, and accordingly, the MB-gNB receives the second data packet.
  • the second data packet is the above-mentioned "gap data”.
  • the MB-UPF sends the second data packet to the MB-gNB, so that the MB-gNB sends the second data packet to the terminal device in a unicast manner.
  • the method may further include S1030b, the MB-UPF sends the second data packet to the gNB, and accordingly, the gNB receives the second data packet.
  • the MB-gNB sends a UE context release message to the gNB.
  • the method may further include S1031, a data forwarding process. That is, the gNB forwards the data of the first multicast broadcast service that is not successfully sent to the terminal device before the first sequence number to the MB-gNB. Meanwhile, in the process of data forwarding, the gNB sends the second data packet to the MB-gNB.
  • the MB-gNB receives the data of the subsequent first MBS service sent by the MB-UPF, and sends the data of the subsequent first MBS service to the terminal device.
  • the terminal device receives the data of the first multicast broadcast service from the S-gNB (access network device that does not support the multicast broadcast service), and switches from the S-gNB to the T-gNB (supports the multicast broadcast service).
  • the core network equipment can determine the second data packet sent to the T-gNB by receiving the first information from the T-gNB, that is, because the S-gNB and the T-gNB.
  • the "gap data" generated by the difference in the transmission progress avoids the problem of packet loss of the data received by the terminal equipment during the switching process of the first multicast broadcast service, and finally ensures that the terminal equipment transmits multicast broadcast data during the switching process. reliability.
  • the size of the sequence numbers of each process does not mean the order of execution, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application. .
  • FIG. 11 shows a schematic block diagram of a communication apparatus provided by an embodiment of the present application.
  • the apparatus 1100 includes a sending unit 1110 and a receiving unit 1120 .
  • the communication apparatus 1100 may correspond to the source access network device in the methods 400, 500 and 600 according to the embodiments of the present application.
  • the communication apparatus 1100 may include means for performing the method performed by the source access network device in the method 400 in FIG. 4 , the method 500 in FIG. 5 , and the method 600 in FIG. 6 .
  • the units in the communication device 1100 and the above-mentioned other operations and/or functions are respectively to implement the corresponding processes of the method 400 in FIG. 4 , the method 500 in FIG. 5 , and the method 600 in FIG. 6 .
  • the sending unit 1110 can be used to execute S410 , S420 , S430 a or S430 b , and S460 in the method 400 .
  • the sending unit 1110 can be used to perform S502 to S505, S510a or S510b, and S5110 in the method 500; the receiving unit 1120 can be used to perform S501a or S501b in the method 500, and the S570.
  • the communication device 1100 is used to perform the method 600 in FIG.
  • the sending unit 1110 can be used to perform S602 to S610 and S690 in the method 600 ; the receiving unit 1120 can be used to perform S601 a or S601 b and S660 in the method 600 . It should be understood that the specific process of each unit performing the above-mentioned corresponding steps has been described in detail in the above-mentioned method embodiments, and for the sake of brevity, it will not be repeated here.
  • FIG. 12 shows a schematic block diagram of a communication apparatus provided by an embodiment of the present application.
  • the apparatus 1200 includes a sending unit 1210 and a receiving unit 1220 .
  • the communication apparatus 1200 may correspond to the core network equipment in the methods 400, 500 and 600 according to the embodiments of the present application.
  • the communication apparatus 1200 may include a unit for performing the method performed by the core network device in the method 400 in FIG. 4 , the method 500 in FIG. 5 , and the method 600 in FIG. 6 .
  • the units in the communication device 1200 and the above-mentioned other operations and/or functions are respectively to implement the corresponding processes of the method 400 in FIG. 4 , the method 500 in FIG. 5 , and the method 600 in FIG. 6 .
  • the sending unit 1210 can be used to execute S450 and S470 in the method 400 .
  • the sending unit 1210 can be used to perform S520b and S580 in the method 500 ;
  • the receiving unit 1220 can be used to perform S540a , S510b , and S540b in the method 500 .
  • the sending unit 1210 can be used to perform S601 a or S601 b and S670 of the method 600 ;
  • the receiving unit 1220 can be used to perform S640 of the method 600 .
  • FIG. 13 is a schematic block diagram of a communication apparatus provided by an embodiment of the present application.
  • the communication apparatus 1300 may include a sending unit 1310 , a receiving unit 1320 and a processing unit 1330 .
  • the communication apparatus 1300 may correspond to the target access network device in the methods 700, 800, 900 and 1000 according to the embodiments of the present application.
  • the communication apparatus 1300 may include means for performing the method 700 in FIG. 7 , the method 900 in FIG. 9 , the method 800 in FIG. 8 , and the method performed by the target access network device in the method 1000 in FIG. 10 .
  • each unit in the communication device 1300 and the above-mentioned other operations and/or functions are respectively to implement the corresponding methods of the method 700 in FIG. 7 , the method 800 in FIG. 8 , the method 900 in FIG. 9 and the method 1000 in FIG. 10 . process.
  • the sending unit 1310 can be used to execute S740 in the method 700; the receiving unit 1320 can be used to execute S710, S720, S760 and S780 in the method 700; the processing unit 1330 may be used to perform S730 in method 700 .
  • the sending unit 1310 can be used to perform S920 in the method 900 ; the receiving unit 1320 can be used to perform S910 and S960 in the method 900 .
  • FIG. 14 is a schematic block diagram of a communication apparatus provided by an embodiment of the present application.
  • the communication apparatus 1400 may include a sending unit 1410 , a receiving unit 1420 and a processing unit 1430 .
  • the communication apparatus 1400 may correspond to the core network equipment in the methods 700, 800, 900 and 1000 according to the embodiments of the present application.
  • the communication apparatus 1400 may include means for performing the method 700 in FIG. 7 , the method 800 in FIG. 8 , the method 900 in FIG. 9 , and the method performed by the core network device in the method 1000 in FIG. 10 .
  • each unit in the communication device 1400 and the above-mentioned other operations and/or functions are respectively to implement the corresponding methods of the method 700 in FIG. 7 , the method 800 in FIG. 8 , the method 900 in FIG. 9 and the method 1000 in FIG. 10 . process.
  • the sending unit 1410 can be used to execute S760 and S770 of the method 700; the receiving unit 1420 can be used to execute S740 of the method 700; the processing unit 1430 can be used to execute S750 in method 700.
  • the sending unit 1410 can be used to execute S940 and S950 of the method 900 ; the receiving unit 1420 can be used to execute S920 of the method 900 ; the processing unit 1430 can be used to execute the method 900 S930.
  • FIG. 15 is a structural block diagram of a communication apparatus 1500 provided according to an embodiment of the present application.
  • the communication apparatus 1500 shown in FIG. 15 includes: a processor 1510 , a memory 1520 and a transceiver 1530 .
  • the processor 1510 is coupled to the memory 1520 for executing instructions stored in the memory 1520 to control the transceiver 1530 to transmit and/or receive signals.
  • processor 1510 and the memory 1520 may be combined into a processing device, and the processor 1510 is configured to execute the program codes stored in the memory 1520 to realize the above-mentioned functions.
  • the memory 1520 may also be integrated in the processor 1510 or independent of the processor 1510 .
  • the processor 1510 may also correspond to each processing unit in the foregoing communication apparatus, and the transceiver 1530 may correspond to each receiving unit and transmitting unit in the foregoing communication apparatus.
  • transceiver 1530 may include a receiver (or, receiver) and a transmitter (or, transmitter).
  • the transceiver may further include antennas, and the number of the antennas may be one or more.
  • the transceiver may also be a communication interface or interface circuit.
  • the communication apparatus 1500 may correspond to the core network equipment in the methods 400 , 500 and 600 according to the embodiments of the present application, the target access network equipment in the methods 700 and 800 , or the core network equipment in the methods 900 and 1000 equipment.
  • the communication apparatus 1500 may include the unit of the method performed by the core network device in the methods 400, 500 and 600, the unit of the method performed by the target access network device of the methods 700 and 800, or the core of the methods 900 and 1000.
  • a unit of a method performed by a network device It should be understood that the specific process of each unit performing the above-mentioned corresponding steps has been described in detail in the above-mentioned method embodiments, and for the sake of brevity, it will not be repeated here.
  • the chip When the communication device 1500 is a chip, the chip includes a transceiver unit and a processing unit.
  • the transceiver unit may be an input/output circuit or a communication interface;
  • the processing unit may be a processor, a microprocessor or an integrated circuit integrated on the chip.
  • each step of the above-mentioned method can be completed by a hardware integrated logic circuit in a processor or an instruction in the form of software.
  • the steps of the methods disclosed in conjunction with the embodiments of the present application may be directly embodied as executed by a hardware processor, or executed by a combination of hardware and software modules in the processor.
  • the software modules may be located in random access memory, flash memory, read-only memory, programmable read-only memory or electrically erasable programmable memory, registers and other storage media mature in the art.
  • the storage medium is located in the memory, and the processor reads the information in the memory, and completes the steps of the above method in combination with its hardware. To avoid repetition, detailed description is omitted here.
  • the processor in this embodiment of the present application may be an integrated circuit chip, which has a signal processing capability.
  • each step of the above method embodiments may be completed by a hardware integrated logic circuit in a processor or an instruction in the form of software.
  • the aforementioned processors may be general purpose processors, digital signal processors (DSPs), application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components .
  • DSPs digital signal processors
  • ASICs application specific integrated circuits
  • FPGAs field programmable gate arrays
  • the methods, steps, and logic block diagrams disclosed in the embodiments of this application can be implemented or executed.
  • a general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.
  • the steps of the methods disclosed in conjunction with the embodiments of the present application may be directly embodied as executed by a hardware decoding processor, or executed by a combination of hardware and software modules in the decoding processor.
  • the software module may be located in random access memory, flash memory, read-only memory, programmable read-only memory or electrically erasable programmable memory, registers and other storage media mature in the art.
  • the storage medium is located in the memory, and the processor reads the information in the memory, and completes the steps of the above method in combination with its hardware.
  • the present application also provides a computer program product, the computer program product includes: computer program code, when the computer program code is run on a computer, the computer is made to execute the steps shown in FIG. 4 to FIG. 10 .
  • the present application further provides a computer-readable medium, where the computer-readable medium stores program codes, and when the program codes are executed on a computer, the computer is made to execute the programs shown in FIG. 3 to FIG. 9 .
  • the present application further provides a system, which includes the foregoing apparatus or equipment.
  • a component may be, but is not limited to, a process running on a processor, a processor, an object, an executable, a thread of execution, a program, and/or a computer.
  • an application running on a computing device and the computing device may be components.
  • One or more components may reside within a process and/or thread of execution, and a component may be localized on one computer and/or distributed between 2 or more computers.
  • these components can execute from various computer readable media having various data structures stored thereon.
  • a component may, for example, be based on a signal having one or more data packets (eg, data from two components interacting with another component between a local system, a distributed system, and/or a network, such as the Internet interacting with other systems via signals) Communicate through local and/or remote processes.
  • data packets eg, data from two components interacting with another component between a local system, a distributed system, and/or a network, such as the Internet interacting with other systems via signals
  • the disclosed system, apparatus and method may be implemented in other manners.
  • the apparatus embodiments described above are only illustrative.
  • the division of the units is only a logical function division. In actual implementation, there may be other division methods.
  • multiple units or components may be combined or Can be integrated into another system, or some features can be ignored, or not implemented.
  • the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, and may be in electrical, mechanical or other forms.
  • the units described as separate components may or may not be physically separated, and components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.
  • each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit.
  • the functions, if implemented in the form of software functional units and sold or used as independent products, may be stored in a computer-readable storage medium.
  • the technical solution of the present application can be embodied in the form of a software product in essence, or the part that contributes to the prior art or the part of the technical solution.
  • the computer software product is stored in a storage medium, including Several instructions are used to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application.
  • the aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (Read-Only Memory, ROM), random access memory (Random Access Memory, RAM), magnetic disk or optical disk and other media that can store program codes .

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Abstract

本申请提供了一种多播广播业务的传输切换方法，包括，源接入网设备向终端设备发送第一数据包，该第一数据包为第一多播广播业务的数据包；该源接入网设备向该终端设备发送切换命令，指示该终端设备向目标接入网设备切换；该源接入网设备向核心网设备发送第一信息，该第一信息包括该第一数据包的标识信息，该第一数据包的标识信息用于该核心网设备确定向目标接入网设备发送的第二数据包，该第二数据包为该第一多播广播业务的数据包。通过源接入网设备向核心网设备发送第一信息，该第一信息包括第一数据包的标识信息，确定向目标接入网设备发送的第二数据包，能够保证终端设备在切换过程中多播广播业务数据传输的可靠性。

Description

一种多播广播业务的传输切换方法及装置
本申请要求于2021年4月1日提交中国专利局、申请号为202110357628.7、申请名称为“一种多播广播业务的传输切换方法及装置”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，涉及多播广播业务的传输切换方法和装置。
背景技术
多播广播业务(multicast and broadcast service，MBS)是在特定范围内一点到多点的业务，可以以较少的资源为大量具有相同需求的用户同时提供多媒体业务，例如直播业务、公共安全业务、批量软件更新业务等，使得网络资源可以得到共享。
MBS业务的数据来自数据服务器，经由核心网设备发送到无线接入网(radio access network，RAN)节点，再由RAN节点发送给接收MBS数据的至少一个终端设备。终端设备在接收MBS数据时，其可能跨RAN节点移动，并且该终端设备有可能从支持MBS业务的RAN节点移动到不支持MBS业务的RAN节点，反之亦然。终端设备在上述不同RAN节点间切换时，如何保证切换过程中MBS数据传输的可靠性是一个亟待解决的问题。
发明内容
本申请提供一种多播广播业务的传输切换方法及装置，可以保证终端设备在切换过程中MBS数据传输的可靠性。
第一方面，提供了一种多播广播业务的传输切换方法，该方法包括：源接入网设备向终端设备发送第一数据包，该第一数据包为第一多播广播业务的数据包；该源接入网设备向该终端设备发送切换命令，指示该终端设备向目标接入网设备切换；该源接入网设备向核心网设备发送第一信息，该第一信息包括该第一数据包的标识信息，该第一数据包的标识信息用于该核心网设备确定向目标接入网设备发送的第二数据包，该第二数据包为该第一多播广播业务的数据包。
根据本申请实施例的方案，在将终端设备由支持MBS业务的接入网设备(源接入网设备)切换至不支持MBS业务的接入网设备(目标接入网设备)的过程中，源接入网设备可以通过向核心网设备发送第一信息，该第一信息包括第一数据包的标识信息，使得核心网设备确定向目标接入网设备发送的该MBS业务的第二数据包。避免了该终端设备在切换过程中接收该MBS业务的数据的丢包等问题，保证了该MBS业务数据传输的可靠性。
结合第一方面，在第一方面的某些实施方式中，该第一数据包为该源接入网设备向该终端设备发送的最后一个数据包。
结合第一方面，在第一方面的某些实施方式中，该第一数据包的标识信息包括以下序 列号中的至少一种：
该第一数据包的服务质量流标识和该第一数据包的服务质量流标识序列号，该第一数据包的数据的分组数据汇聚协议序列号，该第一数据包的用户面通用分组无线业务隧道协议序列号。
结合第一方面，在第一方面的某些实施方式中，该第一信息还包括该终端设备的标识信息，该目标接入网设备的标识信息。
根据本申请实施例的方案，在将终端设备由支持MBS业务的接入网设备(S-gNB)切换至不支持MBS业务的接入网设备(T-gNB)的过程中，核心网设备可以根据该第一信息确定目标核心网设备，通过该目标核心网设备向该目标接入网设备发送该第一多播广播业务的数据。
结合第一方面，在第一方面的某些实施方式中，该第一信息还包括该第一多播广播业务的会话标识信息。该会话标识信息用于核心网设备确定目标核心网设备。
结合第一方面，在第一方面的某些实施方式中，该源接入网设备向该核心网设备发送下行数据传输状态信息，该下行数据传输状态信息携带该第一信息。
结合第一方面，在第一方面的某些实施方式中，该源接入网设备通过所述目标接入网设备向该核心网设备发送该第一信息。
结合第一方面，在第一方面的某些实施方式中，该源接入网设备向该目标接入网设备发送序列号状态转移信息，该序列号状态转移信息携带该第一信息。
结合第一方面，在第一方面的某些实施方式中，该源接入网设备和该目标接入网中该第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，该第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
结合第一方面，在第一方面的某些实施方式中，该第一信息还包括第二标识信息，该第二标识信息用于指示第三数据包，该第三数据包包括该源接入网设备向该终端设备未发送成功的该第一多播广播业务的数据包。
第二方面，提供了一种多播广播业务的传输切换方法，该方法包括，核心网设备接收来自源接入网设备的第一信息，该第一信息包括第一数据包的标识信息，该第一数据包为终端设备的第一多播广播业务的数据包；该核心网设备根据该第一信息确定向目标接入网设备发送的第二数据包，该第二数据包为所述第一多播广播业务的数据包。
根据本申请实施例的方案，在将终端设备由支持MBS业务的接入网设备(源接入网设备)切换至不支持MBS业务的接入网设备(目标接入网设备)的过程中，核心网设备可以通过接收来自源接入网设备的第一信息，该第一信息包括第一数据包的标识信息，确定向目标接入网设备发送的该MBS业务的第二数据包。避免了该终端设备在切换过程中接收该MBS业务的数据的丢包等问题，从而保证了该MBS业务数据传输的可靠性。
结合第二方面，在第二方面的某些实施方式中，该第一数据包为该源接入网设备向该终端设备发送的最后一个数据包。
结合第二方面，在第二方面的某些实施方式中，该第一数据包的标识信息包括以下序列号中的至少一种：
该第一数据包的服务质量流标识和所述第一数据包的服务质量流标识序列号，该第一 数据包的数据的分组数据汇聚协议序列号，该第一数据包的用户面通用分组无线业务隧道协议序列号。
结合第二方面，在第二方面的某些实施方式中，该第一信息还包括，该终端设备的标识信息，该目标接入网设备的标识信息。
结合第二方面，在第二方面的某些实施方式中，该第一信息还包括该第一多播广播业务的会话标识信息。
结合第二方面，在第二方面的某些实施方式中，该源接入网设备和该目标接入网中该第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，该第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
结合第二方面，在第二方面的某些实施方式中，该第一信息还包括第二标识信息，该第二标识信息用于指示第三数据包，该第三数据包包括该源接入网设备向该终端设备未发送成功的该第一多播广播业务的数据包，该核心网设备向该目标接入网设备发送该第三数据包。
第三方面，提供了一种多播广播业务的传输切换方法，该方法包括，目标接入网设备接收来自源接入网设备的切换请求消息，该切换请求消息用于请求将终端设备从该源接入网设备切换至目标接入网设备；该目标接入网设备接收来自源接入网设备的序列号状态信息，该序列号状态信息包括第一数据包的标识信息，该第一数据包为第一多播广播业务的数据包；该目标接入网设备根据该序列号状态信息向核心网设备发送第一信息，该第一信息用于确定第二数据包，该第二数据包为该第一多播广播业务的数据包；该目标接入网设备接收该第二数据包。
根据本申请实施例的方案，在终端设备从源接入网设备切换至目标接入网设备的过程中，目标接入网设备可以通过向核心网设备发送第一信息，使得核心网设备确定向该目标接入网设备发送的第一多播广播业务的第二数据包，避免了终端设备在切换过程中接收该第一MBS业务的数据的丢包等问题，保证了该终端设备在切换过程中MBS业务数据传输的可靠性。
结合第三方面，在第三方面的某些实施方式中，该序列号状态信息指示第一序列号的值，所述第一序列号的值为该源接入网设备缓存的多个该第一数据包的序列号中最大的序列号的值加1。
结合第三方面，在第三方面的某些实施方式中，该目标接入网设备根据该序列号状态信息确定该第一序列号的值小于第二序列号的值，该第二序列号为该目标接入网设备缓存的多个第三数据包的序列号中最小的序列号，该第三数据包为该第一多播广播业务的数据包；该目标接入网向该核心网设备发送该第一信息。
结合第三方面，在第三方面的某些实施方式中，该源接入网设备和该目标接入网中该第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，该第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
结合第三方面，在第三方面的某些实施方式中，该第一信息包括第三序列号和第四序列号，该第三序列号与该第一序列号存在映射关系，该第四序列号与该第二序列号存在映 射关系。
结合第三方面，在第三方面的某些实施方式中，该第一序列号和该第二序列号为分组数据汇聚协议序列号，该第三序列号和该第四序列号为服务质量流标识序列号或者用户面通用分组无线业务隧道协议序列号。
结合第三方面，在第三方面的某些实施方式中，该第一信息承载于第一消息，该第一消息为路径切换流程中的消息。
第四方面，提供了一种多播广播业务的传输切换方法，该方法包括，目标接入网设备接收来自源接入网设备的切换请求信息，该切换请求信息用于请求将终端设备从该源接入网设备切换到该目标接入网设备；该目标接入网设备向核心网设备发送第一信息，该第一信息用于确定第二数据包，该第二数据包为所述第一多播广播业务的数据包；该目标接入网设备接收该第二数据包。
根据本申请实施例的方案，在终端设备从源接入网设备切换至目标接入网设备的过程中，目标接入网设备可以通过向核心网设备发送第一信息，使得核心网设备确定向该目标接入网设备发送的第一多播广播业务的第二数据包，避免了终端设备在切换过程中接收该第一MBS业务的数据的丢包等问题，保证了该终端设备在切换过程中MBS业务数据传输的可靠性。
结合第四方面，在第四方面的某些实施方式中，该第一信息包括第四序列号，该第四序列号与第二序列号存在映射关系，该第二序列号为该目标接入网设备缓存的多个第三数据包的序列号中最小的序列号，该第三数据包为该第一多播广播业务的数据包。
结合第三方面，在第三方面的某些实施方式中，该第二序列号为分组数据汇聚协议序列号，该第四序列号为服务质量流标识序列号或者用户面通用分组无线业务隧道协议序列号。
结合第四方面，在第四方面的某些实施方式中，该源接入网设备和该目标接入网中该第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，该第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
结合第四方面，在第四方面的某些实施方式中，该第一信息承载于第一消息，该第一消息为路径切换流程中的消息。
第五方面，提供了一种多播广播业务的传输切换方法，该方法包括，核心网设备接收来自目标接入网设备的第一信息；该核心网设备根据该第一信息确定第二数据包，该第二数据包为终端设备的第一多播广播业务的数据包；该核心网设备向该目标接入网设备发送该第二数据包。
根据本申请实施例的方案，在终端设备从源接入网设备切换至目标接入网设备的过程中，核心网设备可以通过接收目标接入网设备设备发送的第一信息，确定向该目标接入网设备发送的第一多播广播业务的第二数据包，避免了终端设备在切换过程中接收该第一MBS业务的数据的丢包等问题，保证了该终端设备在切换过程中MBS业务数据传输的可靠性。
结合第五方面，在第五方面的某些实施方式中，该第一信息包括第四序列号，该第四序列号与第二序列号存在映射关系，该第二序列号为该目标接入网设备缓存的多个第三数 据包的序列号中最小的序列号，该第三数据包为该第一多播广播业务的数据包。
结合第五方面，在第五方面的某些实施方式中，该核心网设备根据该第一信息确定该第四序列号的值大于第六序列号的值，该第六序列号为该核心网设备向该源接入网设备发送的多个第四数据包的序列号中最大的序列号；该核心网设备确定该第二数据包包括第七序列号对应的数据包，该第六序列号的值大于等于该第五序列号的值，且小于该第三序列号的值。
结合第五方面，在第五方面的某些实施方式中，该第一信息还包括第三序列号，该第三序列号与第一序列号存在映射关系，该第一序列号的值为该源接入网设备缓存的多个该第一数据包的序列号中最大的序列号的值加1，该第三序列号的值小于该第四序列号的值。
结合第五方面，在第五方面的某些实施方式中，该核心网设备根据该第一信息确定该第二数据包包括第五序列号对应的数据包，该第五序列号的值大于等于该第三序列号的值，且小于该第四序列号的值。
结合第五方面，在第五方面的某些实施方式中，该第一序列号和该第二序列号为分组数据汇聚协议序列号，该第三序列号，该第四序列号和该第六序列号为服务质量流标识序列号或用户面通用分组无线业务隧道协议序列号。
结合第五方面，在第五方面的某些实施方式中，该源接入网设备和该目标接入网中该第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，该第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
结合第五方面，在第五方面的某些实施方式中，该第一信息承载于第一消息，该第一消息为路径切换流程中的消息。
第六方面，提供了一种通信装置，该装置包括，发送单元，用于向终端设备发送第一数据包，该第一数据包为第一多播广播业务的数据包；该发送单元还用于向该终端设备发送切换命令，指示该终端设备向目标接入网设备切换；该发送单元还用于向核心网设备发送第一信息，该第一信息包括该第一数据包的标识信息，该第一数据包的标识信息用于该核心网设备确定向目标接入网设备发送的第二数据包，该第二数据包为该第一多播广播业务的数据包。
根据本申请提供的通信装置，在将终端设备由支持MBS业务的接入网设备(源接入网设备)切换至不支持MBS业务的接入网设备(目标接入网设备)的过程中，发送单元可以通过向核心网设备发送第一信息，该第一信息包括第一数据包的标识信息，使得核心网设备确定向目标接入网设备发送的该MBS业务的第二数据包。避免了该终端设备在切换过程中接收该MBS业务的数据的丢包等问题，从而保证了该MBS业务数据传输的可靠性。
结合第六方面，在第六方面的某些实施方式中，该第一数据包为该源接入网设备向该终端设备发送成功的最后一个数据包。
结合第六方面，在第六方面的某些实施方式中，该第一数据包的标识信息包括以下序列号中的至少一种：
该第一数据包的服务质量流标识和该第一数据包的服务质量流标识序列号，该第一数据包的数据的分组数据汇聚协议序列号，该第一数据包的用户面通用分组无线业务隧道协 议序列号。
结合第六方面，在第六方面的某些实施方式中，该第一信息还包括该终端设备的标识信息，该目标接入网设备的标识信息。
结合第六方面，在第六方面的某些实施方式中，该第一信息还包括该第一多播广播业务的会话标识信息。该会话标识信息用于核心网设备确定目标核心网设备。
结合第六方面，在第六方面的某些实施方式中，该发送单元具体用于，向该核心网设备发送下行数据传输状态信息，该下行数据传输状态信息携带该第一信息。
结合第六方面，在第六方面的某些实施方式中，该发送单元具体用于，通过所述目标接入网设备向该核心网设备发送该第一信息。
结合第六方面，在第六方面的某些实施方式中，该发送单元具体用于，向该目标接入网设备发送序列号状态转移信息，该序列号状态转移信息携带该第一信息。
结合第六方面，在第六方面的某些实施方式中，该通信装置和该目标接入网中该第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，该第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
结合第六方面，在第六方面的某些实施方式中，该第一信息还包括第二标识信息，该第二标识信息用于指示第三数据包，该第三数据包包括该源接入网设备向该终端设备未发送成功的该第一多播广播业务的数据包。
第七方面，提供了一种通信装置，包括，接收单元，用于接收来自源接入网设备的第一信息，该第一信息包括第一数据包的标识信息，该第一数据包为终端设备的第一多播广播业务的数据包；处理单元，用于根据该第一信息确定向目标接入网设备发送的第二数据包，该第二数据包为所述第一多播广播业务的数据包。
根据本申请实施例提供的通信装置，在将终端设备由支持MBS业务的接入网设备(源接入网设备)切换至不支持MBS业务的接入网设备(目标接入网设备)的过程中，通信装置的接收单元可以通过接收来自源接入网设备的第一信息，该第一信息包括第一数据包的标识信息，处理单元确定向目标接入网设备发送的该MBS业务的第二数据包。避免了该终端设备在切换过程中接收该MBS业务的数据的丢包等问题，从而保证了该MBS业务数据传输的可靠性。
结合第七方面，在第七方面的某些实施方式中，该第一数据包为该源接入网设备向该终端设备发送成功的最后一个数据包。
结合第七方面，在第七方面的某些实施方式中，该第一数据包的标识信息包括以下序列号中的至少一种：
该第一数据包的服务质量流标识和所述第一数据包的服务质量流标识序列号，该第一数据包的数据的分组数据汇聚协议序列号，该第一数据包的用户面通用分组无线业务隧道协议序列号。
结合第七方面，在第七方面的某些实施方式中，该第一信息还包括，该终端设备的标识信息，该目标接入网设备的标识信息。
结合第七方面，在第七方面的某些实施方式中，该第一信息还包括该第一多播广播业务的会话标识信息。
结合第七方面，在第七方面的某些实施方式中，该源接入网设备和该目标接入网中该第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，该第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
结合第七方面，在第七方面的某些实施方式中，该第一信息还包括第二标识信息，该第二标识信息用于指示第三数据包，该第三数据包包括该源接入网设备向该终端设备未发送成功的该第一多播广播业务的数据包，该核心网设备向该目标接入网设备发送该第三数据包。
第八方面，提供了一种通信装置，包括，接收单元，用于备接收来自源接入网设备的切换请求消息，该切换请求消息用于请求将终端设备从该源接入网设备切换至目标接入网设备；该接收单元还用于，接收来自源接入网设备的序列号状态信息，该序列号状态信息包括第一数据包的标识信息，该第一数据包为第一多播广播业务的数据包；处理单元，用于根据该序列号状态信息向核心网设备发送第一信息，该第一信息用于确定第二数据包，该第二数据包为该第一多播广播业务的数据包；该接收单元还用于接收该第二数据包。
结合第八方面，在第八方面的某些实施方式中，该序列号状态信息指示第一序列号的值，所述第一序列号的值为该源接入网设备缓存的多个该第一数据包的序列号中最大的序列号的值加1。
结合第八方面，在第八方面的某些实施方式中，该处理单元具体用于确定该第一序列号的值小于第二序列号的值，该第二序列号为该目标接入网设备缓存的多个第三数据包的序列号中最小的序列号，该第三数据包为该第一多播广播业务的数据包；该通信装置还包括发送单元，用于该向该核心网设备发送该第一信息。
结合第八方面，在第八方面的某些实施方式中，该源接入网设备和该通信装置中该第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，该第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
结合第八方面，在第八方面的某些实施方式中，该第一信息包括第三序列号和第四序列号，该第三序列号与该第一序列号存在映射关系，该第四序列号与该第二序列号存在映射关系。
结合第八方面，在第八方面的某些实施方式中，该第一序列号和该第二序列号为分组数据汇聚协议序列号，该第三序列号和该第四序列号为服务质量流标识序列号或者用户面通用分组无线业务隧道协议序列号。
结合第八方面，在第八方面的某些实施方式中，该第一信息承载于第一消息，该第一消息为路径切换流程中的消息。
第九方面，提供了一种通信装置，包括，接收单元，用于接收来自源接入网设备的切换请求信息，该切换请求信息用于请求将终端设备从该源接入网设备切换到该目标接入网设备；发送单元，用于向核心网设备发送第一信息，该第一信息用于确定第二数据包，该第二数据包为所述第一多播广播业务的数据包；该接收单元还用于，接收该第二数据包。
结合第九方面，在第九方面的某些实施方式中，该第一信息包括第四序列号，该第四序列号与第二序列号存在映射关系，该第二序列号为该目标接入网设备缓存的多个第三数 据包的序列号中最小的序列号，该第三数据包为该第一多播广播业务的数据包。
结合第九方面，在第九方面的某些实施方式中，该第二序列号为分组数据汇聚协议序列号，该第四序列号为服务质量流标识序列号或者用户面通用分组无线业务隧道协议序列号。
结合第九方面，在第九方面的某些实施方式中，该源接入网设备和该通信装置中该第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，该第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
结合第九方面，在第九方面的某些实施方式中，该第一信息承载于第一消息，该第一消息为路径切换流程中的消息。
第十方面，提供了一种通信装置，包括，接收单元，用于接收来自目标接入网设备的第一信息；处理单元，用于根据该第一信息确定第二数据包，该第二数据包为终端设备的第一多播广播业务的数据包；发送单元，用于向该目标接入网设备发送该第二数据包。
结合第十方面，在第十方面的某些实施方式中，该第一信息包括第四序列号，该第四序列号与第二序列号存在映射关系，该第二序列号为该目标接入网设备缓存的多个第三数据包的序列号中最小的序列号，该第三数据包为该第一多播广播业务的数据包。
结合第十方面，在第十方面的某些实施方式中，该通信装置该包括处理单元，用于根据该第一信息确定该第四序列号的值大于第六序列号的值，该第六序列号为该核心网设备向该源接入网设备发送的多个第四数据包的序列号中最大的序列号；该处理单元还用于确定该第二数据包包括第七序列号对应的数据包，该第六序列号的值大于等于该第五序列号的值，且小于该第三序列号的值。
结合第十方面，在第十方面的某些实施方式中，该第一信息还包括第三序列号，该第三序列号与第一序列号存在映射关系，该第一序列号的值为该源接入网设备缓存的多个该第一数据包的序列号中最大的序列号的值加1，该第三序列号的值小于该第四序列号的值。
结合第十方面，在第十方面的某些实施方式中，该处理单元具体用于根据该第一信息确定该第二数据包包括第五序列号对应的数据包，该第五序列号的值大于等于该第三序列号的值，且小于该第四序列号的值。
结合第十方面，在第十方面的某些实施方式中，该第一序列号和该第二序列号为分组数据汇聚协议序列号，该第三序列号，该第四序列号和该第六序列号为服务质量流标识序列号或用户面通用分组无线业务隧道协议序列号。
结合第十方面，在第十方面的某些实施方式中，该源接入网设备和该目标接入网中该第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，该第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
结合第十方面，在第十方面的某些实施方式中，该第一信息承载于第一消息，该第一消息为路径切换流程中的消息。
第十一方面，提供了一种通信装置，该装置包括：存储器，用于存储计算机程序；处理器，用于执行存储器中存储的计算机程序，以使得该通信装置执行第一方面的任一种可能的实现方式中的方法，或执行第二方面的任一种可能的实现方式中的方法，或执行第三 方面的任一种可能的实现方式中的方法，或执行第四方面的任一种可能的实现方式中的方法，或执行第五方面的任一种可能的实现方式中的方法。
第十二方面，提供了一种计算机可读存储介质，该计算机可读存储介质上存储有计算机程序，当该计算机程序在计算机上运行时，使得该计算机执行第一方面的任一种可能的实现方式中的方法，或执行第二方面的任一种可能的实现方式中的方法，或执行第三方面的任一种可能的实现方式中的方法，或执行第四方面的任一种可能的实现方式中的方法，或执行第五方面的任一种可能的实现方式中的方法。
第十三方面，提供了一种芯片系统，该芯片系统包括：处理器，用于从存储器中调用并运行计算机程序，使得安装有该芯片系统地通信设备执行执行第二方面的任一种可能的实现方式中的方法，或执行第三方面的任一种可能的实现方式中的方法，或执行第五方面的任一种可能的实现方式中的方法。
附图说明
图1是适用于本申请实施例提供的方法的网络架构的示意图。
图2是适用于本申请实施例提供的方法的系统架构的示意图。
图3是终端设备切换过程的示意性流程图。
图4是本申请的多播广播业务的传输切换方法的一示意性流程图。
图5是本申请的多播广播业务的传输切换方法的另一示意性流程图。
图6是本申请的多播广播业务的传输切换方法的另一示意性流程图。
图7是本申请的多播广播业务的传输切换方法的另一示意性流程图。
图8是本申请的多播广播业务的传输切换方法的另一示意性流程图。
图9是本申请的多播广播业务的传输切换方法的另一示意性流程图。
图10是本申请的多播广播业务的传输切换方法的另一示意性流程图。
图11是本申请的通信装置的一例的示意性框图。
图12是本申请的通信装置的另一例的示意性框图。
图13是本申请的通信装置的另一例的示意性框图。
图14是本申请的通信装置的另一例的示意性框图。
图15是本申请的通信装置的一例的示意性结构图。
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。
应理解，本申请中所有节点、消息的名称仅仅是本申请为描述方便而设定的名称，在实际网络中的名称可能不同，不应理解本申请限定各种节点、消息的名称，相反，任何具有和本申请中用到的节点或消息具有相同或类似功能的名称都视作本申请的方法或等效替换，都在本申请的保护范围之内，以下不再赘述。
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。
本申请提供的技术方案还可以应用于未来的通信系统，如第六代移动通信系统等。本申请对此不作限定。
本申请提供的技术方案还可以应用于机器类通信(machine type communication，MTC)、机器间通信长期演进技术(long term evolution-machine，LTE-M)、设备到设备(device-to device，D2D)网络、机器到机器(machine to machine，M2M)网络、物联网(internet of things，IoT)网络或者其他网络。其中，IoT网络例如可以包括车联网。其中，车联网系统中的通信方式统称为车到其他设备(vehicle to X，V2X，X可以代表任何事物)，例如，该V2X可以包括：车辆到车辆(vehicle to vehicle，V2V)通信，车辆与基础设施(vehicle to infrastructure，V2I)通信、车辆与行人之间的通信(vehicle to pedestrian，V2P)或车辆与网络(vehicle to network，V2N)通信等。
图1是适用于本申请实施例的网络架构的示意图。如图1所示，该网络架构可以分为业务和/或应用(service and/or application)层和传输(transport)层两部分。其中，业务和/或应用层可用于产生MBS数据或请求MBS业务所需的基础组播传输；传输层主要包括以下几个关键网元：接入和移动性管理功能(access and mobility management function，AMF)、会话管理功能(session management function，SMF)、用户面功能(user plane function，UPF)、策略控制功能(policy control function，PCF)和统一数据管理(unified data management，UDM)等。
下面对图1中示出的各网元做简单介绍：
1、用户设备(user equipment，UE)：可以称终端设备、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。
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。
2、(无线)接入网(radio access network，RAN)节点(node)：为用户设备提供入网功能，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。接入网络可以为采用不同接入技术的接入网络。目前的无线接入技术有两种类型：3GPP接入技术(例如3G、4G或5G系统中采用的无线接入技术)和非3GPP(non-3GPP)接入技术。3GPP接入技术是指符合3GPP标准规范的接入技术，例如，5G系统中的接入网设备称为下一代基站节点(next generation Node Base station，gNB)。非3GPP接入技术是指不符合3GPP标准规范的接入技术，例如，以无线保真(wireless fidelity，WiFi)中的接入点(access point，AP)为代表的空口技术。
基于无线通信技术实现接入网络功能的接入网可以称为无线接入网(radio access network，RAN)。无线接入网能够管理无线资源，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和核心网之间的转发。
无线接入网可以包括但不限于：无线网络控制器(radio network controller，RNC)、节点B(Node B，NB)、基站控制器(base station controller，BSC)、基站收发台(base transceiver station，BTS)、家庭基站(例如，home evolved NodeB，或home Node B，HNB)、基带单元(baseband unit，BBU)，WiFi系统中的AP、无线中继节点、无线回传节点、传输点(transmission point，TP)或者发送接收点(transmission and reception point，TRP)等，还可以为5G(如，NR)系统中的gNB或传输点(TRP或TP)，5G系统中的基站的一个或一组(包括多个天线面板)天线面板，或者，还可以为构成gNB或传输点的网络节点，如基带单元(BBU)，或，分布式单元(distributed unit，DU)，或者下一代通信6G系统中的基站等。本申请实施例对无线接入网设备所采用的具体技术和具体设备形态不做限定。
在一些部署中，gNB可以包括集中式单元(centralized unit，CU)和DU。gNB还可以包括有源天线单元(active antenna unit，简称AAU)。CU实现gNB的部分功能，DU实现gNB的部分功能，比如，CU负责处理非实时协议和服务，实现无线资源控制(radio resource control，RRC)，分组数据汇聚层协议(packet data convergence protocol，PDCP)层的功能。DU负责处理物理层协议和实时服务，实现无线链路控制(radio link control，RLC)层、媒体接入控制(media access control，MAC)层和物理(physical，PHY)层的功能。AAU实现部分物理层处理功能、射频处理及有源天线的相关功能。由于RRC层的信息最终会变成PHY层的信息，或者，由PHY层的信息转变而来，因而，在这种架构下，高层信令，如RRC层信令，也可以认为是由DU发送的，或者，由DU+AAU发送的。可以理解的是，接入网设备可以为包括CU节点、DU节点、AAU节点中一项或多项的设备。此外，也可以将CU划分为核心网(core network，CN)中的网络设备，本申请对此不做 限定。
在本申请实施例中，接入网设备为无线接入网中的网络设备，用于为小区提供服务，终端设备通过接入网设备分配的传输资源(例如，频域资源，或者说，频谱资源)与小区进行通信，该小区可以属于宏基站(例如，宏eNB或宏gNB等)，也可以属于小小区(small cell)对应的基站，这里的小小区可以包括：城市小区(metro cell)、微小区(micro cell)、微微小区(pico cell)、毫微微小区(femto cell)等，这些小小区具有覆盖范围小、发射功率低的特点，适用于提供高速率的数据传输服务。接入网设备可以包括基站(gNB)，例如宏站、微基站、室内热点、以及中继节点等，功能是向终端设备发送无线电波，一方面实现下行数据传输，另一方面发送调度信息控制上行传输，并接收终端设备发送的无线电波，接收上行数据传输。
此外，在本申请实施例中，接入网设备还可以用于通过共享的N3接口接收MBS业务的数据(MBS数据)，并使用点到点(point to point，PTP)或点到多点(point to multi-point，PTM)传输方式将MBS数据传输给终端设备；或者，通过N2接口管理MBS会话的QoS流；在接入层(access stratum，AS)进行MBS会话的QoS流接收；控制终端设备在PTM和PTP传输之间的切换等。
在本申请实施例中，用户设备或接入网设备包括硬件层、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。
本申请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用户设备或接入网设备，或者，是用户设备或接入网设备中能够调用程序并执行程序的功能模块。
3、接入管理网元：用于路由和转发用户面数据，或用户面数据的服务质量(quality of service，QoS)处理等。
在5G通信系统中，该接入管理网元可以是接入管理功能(access and mobility management function，AMF)网元。在未来通信系统中，接入管理网元仍可以是AMF网元，或者，还可以有其它的名称，本申请不做限定。
在本申请实施例中，接入管理网元还可以执行以下功能：选择具有MBS功能的会话管理功能网元(multicast broadcast SMF，MB-SMF)；与接入网设备、MB-SMF进行MBS会话管理的信令交互；选择接入网设备进行广播等。
4、会话管理网元：可用于会话管理、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、策略控制和收费功能接口的终结点以及下行数据通知等。
在5G通信系统中，该会话管理网元可以是会话管理功能(session management function，SMF)网元。在未来通信系统中，会话管理网元仍可以是SMF网元，或者，还可以有其它的名称，本申请不做限定。
5、MB-SMF：多播广播会话管理功能网元，即具有MBS功能的会话管理功能网元。MB-SMF可以用于MBS会话管理(包括QoS控制)，以及MBS传输的控制，包括基于来自PCF或本地的MBS业务的策略规则为MBS流传输配置数据面网关MB-UPF和RAN节点(通过AMF)。MB-SMF还可以与MBS业务的服务器或多播广播业务功能网元(multicast broadcast service function，MBSF)或能力开放网元(network exposure function，NEF)相连，以便接收MBS业务的相关信息(例如，MBS业务的描述)。此外，MB-SMF还可以与PCF相连，以便为MBS业务创建资源。MB-SMF可以集成在PCF或SMF中作为一个功能模块，也可以单独部署，本申请对此不做限定。
6、UPF：即，数据面网关。可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。用户数据可通过该网元接入到数据网络(data network，DN)。
在本申请实施例中，UPF还可以执行以下功能：与SMF交互，从MB-UPF接收组播数据以进行单独传送；向接入网设备发送组播以进行单播传输。
7、MB-UPF：即，多播广播数据面网关(multicast broadcast UPF，MB-UPF)。用于向RAN传输MBS业务的QoS流。MB-UPF支持MBS业务的功能有：对MBS流的下行包进行过滤；将MBS数据包分发到RAN节点(或UPF)；基于现有方法的QoS增强和计数/报告。MB-UPF可以集成到UPF中作为一个功能模块，或者单独部署，本申请对此不做限定。
8、策略控制网元：用于指导网络行为的统一策略框架，为网络网元(例如AMF，SMF网元等)或终端设备提供策略规则信息等。
在4G通信系统中，该策略控制网元可以是策略和计费规则功能(policy and charging rules function，PCRF)网元。在5G通信系统中，该策略控制网元可以是策略控制功能(policy control function，PCF)网元。在未来通信系统中，策略控制网元仍可以是PCF网元，或者，还可以有其它的名称，本申请不做限定。
在本申请实施例中，PCF还可以为MBS业务提供策略，从AF接收MBS信息，PCF执行以下功能以支持MBS：
支持MBS会话的QoS处理，包括5QI、最大比特速率(max bit rate，MBR)、保证的比特速率(guaranteed bit rate，GBR)等QoS参数；向MB-SMF提供有关MBS会话的策略信息，以授权相关QoS配置文件；接收MBS信息或QoS要求。
9、网络开放网元：主要用于支持能力和事件的开放。
在5G通信系统中，该网络开放网元可以是网络开放功能(network exposure function，NEF)网元。在未来通信系统中，网络开放网元仍可以是NEF网元，或者，还可以有其它的名称，本申请不做限定。
NEF可以与为多播组保留接收资源的内容提供者进行交互，并接收QoS要求、UE授权信息、服务区域以及MBS会话的开始和结束时间。NEF还可以选择SMF处理多播传输，在UDR中存储与多播会话有关的信息等。
10、应用功能实体(application function，AF)，提供业务接入的应用点，这些业务应用的数据通过MBS传输到终端设备。
11、多播广播业务控制面功能网元(MBSF control plane，MBSF-C)，可以执行以下功能：
支持MBS业务以及与LTE中多媒体广播多播业务(multimedia broadcast multicast service，MBMS)互通的业务级别功能；与AF，MB-SMF交互以进行MBS会话操作和传输；选择用于MBS会话的MB-SMF，以及与MB-SMF交互以确定MBS会话传输的参数。
12、多播广播业务用户面功能网元(MBSF user plane，MBSF-U)，可用于任何启用IP多播的应用程序的通用数据包传输功能。
应理解，MB-SMF，MB-UPF，MBSF-C和MBSF-U均为功能性单元,其可以单独部署，也可以与其他网元合设，本申请对此不做限定。
在图1所示的网络架构中，RAN通过N2接口与AMF连接，RAN通过N3接口与UPF连接，通过MB-N3接口与MB-UPF连接。
SMF通过N4接口控制UPF，SMF分别通过N11接口、N16a接口与AMF和MB-SMF连接，UPF通过MB-N9接口与MB-UPF连接。
PCF分别通过N7接口、N15接口与MB-SMF和AMF连接。
MB-SMF经过Nmbsmf接口接入服务化架构；同理，NEF、MBSF-U、MBSF-C以及AF经过各自对应的接口接入服务化架构，提供相应的服务。
图1中Npcf、Namf、Nmbsmf、Nmbsu、N2、N3、N4等为接口序列号。这些接口序列号的含义可参见第三代合作伙伴计划(3 rd generation partnership project，3GPP)标准协议中定义的含义，在此不做限制。
需要说明的是，图1中所涉及的各个网元以及网元之间的通信接口的名称是以目前协议中规定的为例进行简单说明的，但并不限定本申请实施例只能够应用于目前已知的通信系统。因此，以目前协议为例描述时出现的标准名称，都是功能性描述，本申请对于网元、接口或信令等的具体名称并不限定，仅表示网元、接口或者信令的功能，可以对应的扩展到其它系统，比如2G、3G、4G或未来通信系统中。
上述图1所示的本申请实施例能够应用的网络架构仅是一种举例说明，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。
为了便于理解，首先对本申请中涉及的一些术语进行说明。
1、单播：在核心网层面，单播是指通过协议数据单元(protocol data unit，PDU)会话向终端发送业务数据。多播广播业务的单播方式可以是指通过PDU会话向终端设备发送多播广播业务的数据，后续可以简称为单播方式，单播方式也可以称作5GC单独多播广播业务流量传送方式(5G core individual MBS traffic delivery method)。
2、多播/广播：在核心网层面，多播/广播是指通过多播/广播会话向终端设备发送多播广播业务的数据，后续可以简称为多播广播方式，多播广播方式也可以称作5GC共享多播广播业务流量传送方式(5G core shared MBS traffic delivery method)。
3、多播广播业务：多播广播业务可以通过多播广播业务的信息来描述。多播广播业务的信息至少包括多播广播业务的描述信息，该多播广播业务的描述信息中可以包括一个或多个多播广播业务流的描述信息，其中，多播广播业务流的描述信息包括下列至少一项：该多播广播业务流的服务质量标识(QoS flow identifier，QFI)、多播广播业务流的特征信息(如多播广播业务的目的地址、目的端口号、源地址等)、多播广播业务流的QoS需求(如，抖动、时延、丢包率、带宽等)。多播广播业务流的数据包可以用QoS流标 识序列号(QFI sequence number,QFI SN)或用户面通用分组无线业务(general packet radio service，GPRS)隧道协议(GPRS Tunnelling Protocol user plane，GTP-U)序列号(GTP-U sequence number，GTP-U SN)标识。
4、协议数据单元(protocol data unit，PDU)会话(PDU session)：5G核心网(5G core network，5GC)支持PDU连接业务。PDU连接业务可以是指终端设备与数据网络(data network，DN)之间交换PDU数据包的业务。PDU连接业务通过终端设备发起PDU会话的建立来实现。一个PDU会话建立后，也就是建立了一条PDU会话隧道，PDU会话隧道与UE相对应，PDU会话隧道内的业务数据可以以单播QoS流的形式传输。换句话说，PDU会话是UE级别的。每个终端设备可以建立一个或多个PDU会话。用于传输多播广播业务数据的PDU会话可以称为多播会话，组播会话，广播会话，或多播广播业务(multicast and broadcast service，MBS)会话(MBS session)。
5、多播广播会话(MBS session)：一个多播广播会话可以为一个多播广播业务提供服务，一个多播广播会话包括从数据网络到核心网设备再到接入网设备的单播或组播隧道、以及接入网设备分配的用于发送该多播广播业务的单播或多播广播空口资源。
以图2所示的系统架构中多播广播数据的传输为例，多播广播业务的数据可以从5G CN发送至UE1、UE2、UE3和UE4。其中，5G CN到5G RAN的传输路径可以是多播广播会话隧道，也即，MB-UPF与NG-RAN之间的N3隧道。例如，5G CN向UE1和UE2发送多播广播业务的数据，UE1和UE2的多播广播会话隧道是共享的。在空口上，RAN可以通过点到多点(point-to-multipoint，PTM)方式向UE1、和UE2发送上述多播广播数据，即只需要发送一份数据，两个UE均可接收。RAN也可以以单播的方式，即点到点(point-to-point，PTP)方式，分别向UE1和UE2发送业务数据。5G CN发送的多播广播数据也可以通过UE各自对应的PDU会话发送给UE。例如，5G CN向UE3和UE4发送多播广播业务的数据，不同的PDU会话具有不同的PDU会话隧道。在空口上，RAN可以以PTP方式分别向UE3和UE4发送业务数据。
终端设备在接收业务的数据时，其可能跨RAN节点移动，从而触发终端设备的切换流程。下面结合图3对终端设备的切换流程进行简单描述。
在S310之前，包括S301和S302，核心网设备向源接入网设备发送终端设备业务的分组数据，相应地，源接入网设备接收该分组数据，并将该分组数据发送至终端设备。
S310，处于无线资源控制(radio resource control，RRC)连接态的终端设备根据源接入网设备配置的测量上报触发准则，发送测量报告(measurement report)。
S320，源接入网设备根据终端设备的测量报告，确定当终端设备满足切换条件时，为终端设备确定目标接入网设备。
S330，源接入网设备向目标接入网设备发送切换请求，并将终端设备的上下文(UE Context)信息随切换请求发送至目标接入网设备。
S340，目标接入网设备为即将切换过来的终端设备预留资源，同时为终端设备分配小区无线网络临时标识(cell radio network temporary identifier，C-RNTI)和其他参数，随切换请求确认消息发送至源接入网设备。在收到切换请求确认消息后，源接入网设备准备将分组数据转发至目标接入网设备。
S350，源接入网设备向终端设备发送切换命令(handover command)。该切换命令中 可以包括以下信息，C-RNTI、目标接入网设备的系统信息块(system information block，SIB)、终端设备的配置信息等。终端设备在接收到切换命令后，停止与源gNB的上行或下行数据传输。
S360，源接入网设备向目标接入网设备发送序列号(sequence number，SN)状态信息。
S370，终端设备向目标接入网设备进行同步。
S380，终端设备向目标接入网设备发送切换确认消息，指示切换完成。
S390，目标接入网设备向源接入网设备指示切换完成，以便于源源接入网设备释放终端设备的上下文信息。
S3100，目标接入网设备通知核心网设备更新数据转发目的接入网设备的信息，以便使核心网可以将该终端设备的数据发送到目标接入网设备。
S3110，触发终端设备的路径切换(path switch)流程；S3120，核心网设备将后续分组数据发送至目标接入网设备。
在终端设备的上述切换流程中，源接入网设备和目标接入网设备可以分别为，支持多播广播业务的接入网设备，或者不支持多播广播业务的接入网设备。也就是说，该终端设备有可能从支持多播广播业务的接入网设备移动到不支持多播广播业务的接入网设备，反之亦然。
其中，接入网设备支持多播广播业务可以理解为，接入网设备支持以多播广播方式传输多播广播业务的数据。
接入网设备不支持多播广播业务可以理解为，接入网设备不支持以多播广播方式传输多播广播业务数据，或者接入网设备仅支持以单播方式传输多播广播业务数据。对于不支持多播广播业务的接入网设备，可以通过PDU会话实现终端设备的网络业务。对于支持多播广播业务的接入网设备，可以通过多播广播会话隧道从核心网接收多播广播业务数据并发送给加入该多播广播业务的多个终端设备。应理解，多播广播业务数据到达RAN之后，经过RAN的服务数据适配协议(service data adaptation protocol，SDAP)层、分组数据汇聚协议(packet data convergence protocol，PDCP)层、无线链路控制(radio link control，RLC)层、媒体接入控制(media access control，MAC)层、物理(physical，PHY)层的处理，发送给每个接收多播广播业务数据的终端设备。
以终端设备从源接入网设备(Source-gNB，S-gNB)切换至目标接入网设备(Target-gNB，T-gNB)为例，其中，S-gNB为支持MBS业务的接入网设备，且该终端设备通过该S-gNB接收MBS业务的数据，T-gNB为不支持MBS业务的接入网设备。在该终端设备的切换流程中，当终端设备断开与该S-gNB的连接后，核心网设备会继续向该S-gNB发送该MBS业务的数据，且当该终端设备接入T-gNB时，该核心网设备根据当前向源接入网设备传输该MBS业务数据的进度向目标接入网设备传输该MBS业务的数据，从而可能造成终端设备在该切换过程中的MBS数据的丢包等问题。另外，由于T-gNB是不支持MBS业务的接入网设备，其通过UPF(目标UPF)接收该MBS业务的数据，MB-UPF需获取目标UPF的相关信息，以便后续将该MBS业务的数据发送到目标UPF，经由目标UPF发送至T-gNB，从而保证终端设备在切换过程中MBS业务数据的可靠传输。
或者，如果S-gNB为不支持MBS业务的接入网设备，T-gNB为支持MBS业务的接 入网设备，终端设备在切换至T-gNB的过程中，可能会出现S-gNB和T-gNB传输该MBS业务的数据的进度存在差异的情况，从而可能造成终端设备在该切换过程中的MBS数据的丢包等问题，因此，如何保证该切换过程中MBS业务数据传输的可靠性是一个亟待解决的问题。
本申请提出了一种多播广播业务的传输切换方法，能够保证终端设备在上述两种接入网设备间切换时，MBS业务数据传输的可靠性。
下文将结合多个附图，详细说明本申请实施例提供的多播广播业务的传输切换方法。图4是本申请实施例提供的一种多播广播业务的传输切换方法。该方法至少包括以下步骤。
S410，终端设备接收源接入网设备(S-gNB)发送的第一多播广播业务(第一MBS业务)的第一数据包。
需要说明的是，该S-gNB为支持MBS业务的接入网设备，也就是说，该S-gNB支持以多播广播的方式向该终端设备发送MBS业务的数据。
在S410之前，可选地，该方法还可以包括S401，预设S-gNB和目标接入网设备(T-gNB)中，第一MBS业务数据的标识信息到PDCP序列号(sequence number，SN)的映射关系一致。也就是说，在S-gNB和T-gNB中，根据同一数据包的标识信息以及该映射关系可以得到相同的PDCP SN。该第一MBS业务数据的标识信息可以包括QFI SN或GTP-U SN。通过预设S-gNB和T-gNB中第一MBS业务的数据的标识信息到PDCP SN的映射关系一致，从而保证切换过程中T-gNB和S-gNB对该第一MBS业务数据的理解一致。
具体地，该映射关系可以是预先设置的，例如，通过协议约定、核心网配置或网管配置等方式预设该映射关系。以第一MBS业务的数据的标识信息为QFI SN为例，该映射关系可以表示为：
PDCP SN＝(QFI SN)mod[max(PDCP SN)+1]    (1)
在映射关系为公式(1)的情况下，PDCP SN的尺寸(size)不大于QFI SN的尺寸(size)。根据3GPP TS38.323 v16.1.0，PDCP SN size为12比特(bit)或18bit，而QFI SN size为24bit，从而S-gNB和T-gNB可以根据该公式为一个QFI SN推出相同的PDCP SN，即PDCP SN编号唯一。需要说明的是，第一MBS业务的数据的标识信息到PDCP SN的组合映射关系可以不限于公式(1)，只要S-gNB和T-gNB可以根据公式为同一个第一MBS业务的数据的标识信息推出相同的PDCP SN即可。
在该终端设备接收S-gNB发送的该第一MBS业务的数据的过程中，S-gNB根据该终端设备的测量报告，确定将该终端设备切换至T-gNB，且该T-gNB为不支持MBS业务的接入网设备。其中，基于测量报告决定将终端设备切换至T-gNB的步骤和S320至S340中类似，在此不再赘述。
S420，S-gNB向该终端设备发送切换命令(handover command)，相应地，该终端设备接收该切换命令。该切换命令用于指示该终端设备由S-gNB切换至T-gNB，该终端设备在接收到切换命令后，断开与S-gNB的连接，即停止与S-gNB的上行或下行数据传输。该终端设备向T-gNB进行同步。
S430a，S-gNB向核心网设备发送第一信息，相应地，核心网设备接收该第一信息。
由于该终端设备断开与S-gNB的连接后，核心网设备，也就是MB-UPF会继续向该S-gNB发送该第一MBS业务的数据，因此，S-gNB向MB-UPF发送该第一信息。该第一信息包括数据包#1(第一数据包的一例)的标识信息，数据包#1可以是S-gNB已经发送的该第一多播广播业务的最后一个数据包。示例性地，数据包#1的标识信息可以包括以下序列号中的至少一种。
数据包#1的QFI和数据包#1的QFI SN，数据包#1的数据的分组数据汇聚协议序列号(PDCP sequence number，PDCP SN)，数据包#1的GTP-U SN。
在一种可能的实现方式中，S-gNB通过控制面方法向该核心网设备发送该第一信息。以数据包#1的标识信息为数据包#1的QFI和数据包#1的QFI SN(Last QFI SN)为例，S-gNB向AMF发送数据包#1的QFI、Last QFI SN信息，例如，S-gNB向AMF发送PDU会话资源修改指示(PDU session resource modify indication)消息，该消息中可以包括数据包#1的QFI、Last QFI SN信息。AMF向MB-SMF发送该第一信息，经由MB-SMF发送至MB-UPF。可以理解的是，AMF还可以通过其它核心网网元向MB-UPF发送该第一信息，AMF通过SMF向MB-SMF发送该第一信息，经由MB-SMF发送至MB-UPF。
其中，该第一信息中还可以包括终端设备的标识信息，T-gNB的标识信息，第一MBS业务的会话标识信息，当该第一信息发送至SMF或者MB-SMF时，SMF或者MB-SMF可以根据该终端设备的标识信息，T-gNB的标识信息，以及第一MBS业务的会话标识信息确定目标UPF，以使得MB-UPF后续可以通过该目标UPF向目标接入网设备发送该第一MBS业务的数据。
在另一种可能的实现方式中，S-gNB通过用户面方法向该核心网设备发送该第一信息。例如，S-gNB向核心网设备发送下行数据传输状态信息(downlink data delivery status)，该下行数据传输状态信息中包括该第一信息，也就是说，S-gNB可以通过下行数据传输状态信息指示数据包#1的QFI、Last QFI SN信息。其中，该第一信息中还可以包括终端设备的标识信息，T-gNB的标识信息。MB-UPF可以向MB-SMF发送该终端设备的标识信息，T-gNB的标识信息，以及第一MBS业务的会话标识信息，以使得MB-SMF确定目标UPF。MB-UPF接收MB-SMF确定的该目标UPF的标识信息。
在另一种可能的实现方式中，S-gNB通过T-gNB向该核心网设备发送该第一信息。例如，S-gNB向T-gNB发送序列号状态信息，该序列号状态信息包括第一信息。T-gNB通过控制面或用户面方法向该核心网设备发送该第一信息。例如，T-gNB向目标UPF反馈下行数据传输状态(downlink data delivery status，DDDS)，其中携带该第一信息，UPF向该核心网设备发送该第一信息。或者，在路径切换流程中，T-gNB向该核心网设备发送该第一信息。
可选地，该方法还可以包括S430b，S-gNB向核心网设备发送第一信息，相应地，核心网设备接收该第一信息。其中，该第一信息还包括第三数据包的标识信息，该第三数据包包括数据包#1的序列号之前，S-gNB向终端设备未发送成功的该第一MBS业务的数据包。
S440，核心网设备根据该第一信息确定向T-gNB发送的第二数据包，该第二数据包为第一MBS业务的数据包。
以核心网接收第一信息，第一信息包括数据包#1的标识信息为数据包#1的QFI和数 据包#1的QFI SN(Last QFI SN)为例，其中，数据包#1可以是S-gNB已经发送的该第一MBS业务的最后一个数据包。核心网设备根据QFI和Last QFI SN确定从Last QFI SN加1开始，通过目标UPF向T-gNB发送该第一MBS业务的数据包，即，该第一MBS业务的第二数据包包括Last QFI SN加1对应的数据包及该序列号之后的数据包。
S450，核心网设备向T-gNB发送该第二数据包。
可选地，该方法还可以包括S460，数据前传(data forwarding)过程。即S-gNB将上述第三数据包转发至T-gNB，以使得T-gNB将该第三数据包以单播方式发送至该终端设备。
可选地，该方法还可以包括S470，该核心网设备根据该第一信息携带的第三数据包的标识信息确定第三数据包，并向该终端设备发送该第三数据包。
根据本申请实施例的方案，在将终端设备由支持MBS业务的接入网设备(S-gNB)切换至不支持MBS业务的接入网设备(T-gNB)的过程中，核心网设备可以通过接收来自S-gNB的第一信息，该第一信息包括第一数据包的标识信息，确定向T-gNB发送的该MBS业务的第二数据包。避免了该终端设备在切换过程中接收该MBS业务的数据的丢包等问题，从而保证了该MBS业务数据传输的可靠性。
图5示出了本申请实施例提供的多播广播业务的传输切换方法的另一示例性流程图，该方法可应用于终端设备从支持MBS业务的接入网设备切换至不支持MBS业务的接入网设备的场景中，该方法为图4中方法400的详细过程。下面结合图5详细说明，其中，为了简便，用MB-gNB表示支持MBS业务的接入网设备。
在S510之前，该方法包括步骤S501至S505。
S501a，MB-UPF向S-gNB(MB-gNB)发送第一MBS业务的数据，相应地，MB-gNB接收MB-UPF发送的终端设备的第一MBS业务的数据。且预设MB-gNB和gNB中第一MBS业务的数据的标识信息到PDCP SN的映射关系一致，具体过程和S401中类似，在此不再赘述。
可选地，该方法可以包括S501b，MB-UPF向S-gNB(MB-gNB)发送第一MBS业务的数据，相应地，MB-gNB接收MB-UPF发送的终端设备的第一MBS业务的数据。
S502，MB-gNB向终端设备发送第一MBS业务的数据。
应理解，MB-gNB向终端设备发送第一MBS业务的数据可以是以PTM的方式，或者PTP的方式，MB-gNB也可以使用PTP，PTM的组合向该终端设备下发该MBS业务的数据。该步骤和S410中类似。
MB-gNB向终端设备发送该第一MBS业务的数据的过程中，MB-gNB可以根据该终端设备的测量报告，确定将该终端设备切换至T-gNB(gNB)。
S503至S505为终端设备切换流程中的部分步骤，具体过程与S330至S360中类似，为了简便，本申请在此不再赘述。
S510，S-gNB向MB-UPF发送第一信息，相应地，MB-UPF接收该第一信息。
具体地，该第一信息包括第一数据包(数据包#1)的标识信息，数据包#1为MB-gNB已经向该终端设备发送的该第一MBS业务的数据包中的最后一个数据包，数据包#1的标识信息与S430a中类似。S-gNB向MB-UPF发送该第一信息可以通过两种方式。
方式一，MB-gNB通过控制面方法向MB-UPF发送第一信息。以数据包#1的标识信 息为数据包#1的QFI和数据包#1的QFI SN(Last QFI SN)为例，具体可以通过以下步骤。
S510a，MB-gNB向AMF发送该第一信息，相应地，AMF接收该第一信息。例如，MB-gNB向AMF发送PDU会话资源修改指示(PDU session resource modify indication)消息，该消息中可以包括该第一信息。
S520a，AMF向MB-SMF发送QFI和Last QFI SN、UE ID、gNB ID、MBS session ID信息，相应地，MB-SMF接收这些信息。
S530a，MB-SMF根据UE ID，gNB ID以及MBS Session ID确定目标UPF。
S540a，MB-SMF向MB-UPF发送目标UPF标识，以及QFI和Last QFI SN。相应地，MB-UPF接收目标UPF标识，QFI和Last QFI SN。
方式二，MB-gNB通过用户面方法向MB-UPF发送第一信息。
S510b，MB-gNB向MB-UPF发送下行数据传输状态(downlink data delivery status，DDDS)，其中携带第一信息，也即携带数据包#1的QFI和Last QFI SN、UE ID，以及gNB ID信息。相应地，MB-UPF接收这些信息，从而可以根据该信息确定MB-gNB的数据传输进度。
S520b，MB-UPF向MB-SMF发送UE ID、gNB ID和MBS Session ID，相应地，MB-UPF接收UE ID，gNB ID和MBS Session ID信息。
S530b，MB-SMF根据UE ID，gNB ID和MBS Session ID确定目标UPF。
S540b，MB-SMF向MB-UPF发送该目标UPF标识，以使得MB-UPF能够得知T-gNB连接的UPF，并从数据包#1之后的该第一多播广播的数据包开始向gNB传输。
在S580，MB-UPF通过目标UPF向T-gNB(gNB)发送该第一MBS业务的数据之前，可选地，该方法还可以包括：
S550，终端设备向T-gNB(gNB)发送切换确认消息，指示切换完成。
终端设备断开与MB-gNB的数据传输后，启动与gNB的下行同步过程，然后发起随机接入过程来获取上行的定时和上行资源分配。终端设备向gNB发送RRC连接重配置完成消息，以指示切换完成。
S560，MB-UPF触发路径切换(path switch)，进行T-gNB侧N3GTP-u隧道的新建过程。具体建立过程采用目前建立隧道的技术。
S570，MB-gNB向gNB发送终端设备的上下文释放消息。
S580和S590，MB-UPF通过目标UPF向T-gNB(gNB)发送该第一MBS业务的数据。可以理解的是，该数据对应为数据包#1之后的该第一MBS业务的数据包(第二数据包)，该步骤和S450中类似。
可选地，若预设了MB-gNB和gNB中第一MBS业务的数据的标识信息到PDCP SN的映射关系一致(如S501a中所述)，该方法还可以包括与S460中类似的步骤S5100，数据前传。
可选地，若第一信息中还包括第三数据包的标识信息，该第三数据包包括数据包#1的序列号之前，S-gNB向终端设备未发送成功的该第一MBS业务的数据包。MB-UPF还可以根据该第一信息确定向该终端设备发送该第三数据包。则此时无需data forwarding过程。该过程与S470中类似。
S5110，T-gNB向该终端设备发送后续的第一MBS业务的数据(第二数据包)。
根据本申请实施例的方案，在将终端设备由支持MBS业务的接入网设备(S-gNB)切换至不支持MBS业务的接入网设备(T-gNB)的过程中，MB-UPF可以通过接收来自S-gNB的第一信息，确定向T-gNB发送的该MBS业务的第二数据包。避免了该终端设备在切换过程中接收该MBS业务的数据的丢包等问题，从而保证了该MBS业务数据传输的可靠性。
图6示出了本申请实施例提供的传输多播业务的方法的另一示例性流程图，该方法同样可应用于终端设备从支持MBS业务的接入网设备切换至不支持MBS业务的接入网设备的场景中。该方法为图4中方法400的详细过程，其与图5中方法500的区别在于S-gNB通过T-gNB向核心网设备发送第一信息。下面结合图6详细说明该方法。
在S610之前，包括步骤S601至S604。
MB-UPF向MB-gNB发送第一MBS业务的数据，在该过程中，MB-gNB可以根据该终端设备的测量报告，确定将该终端设备切换至T-gNB(gNB)，gNB为不支持多播广播业务的接入网设备。具体过程与S501至S504中类似，为了简便，本申请在此不再赘述。
S610，MB-gNB向gNB发送序列号状态信息，该序列号状态信息包括第一信息。
具体地，该第一信息包括第一数据包(数据包#1)的标识信息，数据包#1为MB-gNB已经向该终端设备发送的该第一MBS业务的数据包中的最后一个数据包，数据包#1的标识信息与S430a中类似。
S620，终端设备向T-gNB发送切换确认信息，指示切换完成。该步骤与S550类似。
终端设备断开与MB-gNB的数据传输后，启动与T-gNB的下行同步过程，然后发起随机接入过程来获取上行的定时和上行资源分配，端设备向T-gNB发送切换确认信息，指示切换完成。
T-gNB向MB-UPF发送该第一信息，以便MB-UPF后续可以从Last QFI SN+1开始向终端设备发送数据。T-gNB可以通过两种方式向MB-UPF发送第一信息。
方式一，gNB通过用户面方法向MB-UPF该第一信息。
S630，gNB向UPF反馈下行数据传输状态(downlink data delivery status，DDDS)，其中携带第一信息，即携带QFI和Last QFI SN信息。
S640，UPF向MB-UPF发送第一信息。
可选地，该方法还可以包括S650a，触发路径切换进行T-gNB(gNB)侧N3GTP-u隧道的新建过程。
方式二，gNB通过控制面方法向MB-UPF发送第一信息。
S650b，在路径切换流程中，T-gNB向MB-UPF发送第一信息。
在一种可能的实现方式中，T-gNB向AMF发送第一信息，之后由AMF通过SMF将该信息发送到UPF，再由UPF将该信息发送至MB-UPF。例如，T-gNB向AMF发送路径切换请求(path switch request)消息，该路径切换请求消息中携带QFI和Last QFI SN信息；再由AMF通过SMF向UPF发送该第一消息。最后，由UPF将QFI和Last QFI SN信息发送至MB-UPF。以便MB-UPF后续可以从Last QFI SN+1开始向终端设备发送数据。
由于gNB是通过其连接的UPF(目标UPF)向MB-UPF发送该第一信息，因此，MB-UPF可以同时得知目标UPF标识，后续MB-UPF将数据发送到目标UPF，目标UPF再将数据发送至gNB并以单播方式发送给该终端设备。
可选地，该方法还可以包括S860，MB-gNB向gNB发送UE上下文释放消息。
S670和S680，MB-UPF通过目标UPF向T-gNB(gNB)发送第一MBS业务的数据。与S580中类似，该数据包括数据包#1之后的数据包。
可选地，若预设了MB-gNB和gNB中第一MBS业务的数据的标识信息到PDCP SN的映射关系一致(如S601a中所述)，该方法还可以包括S690，数据前传(data forwarding)过程。
可选地，若该第一信息中还包括第三数据包的标识信息。后续，MB-UPF向该终端设备发送该第三数据包，此时无需data forwarding过程。
S6100，T-gNB向该终端设备发送后续的该第一MBS业务的数据。
图7示出了本申请实施例提供的多播广播业务的传输切换方法的另一示例性流程图，该方法可应用于终端设备从不支持MBS业务的接入网设备切换至支持MBS业务的接入网设备的场景中，该方法至少包括以下步骤。
S710，S-gNB向T-gNB发送切换请求消息，相应地，T-gNB接收该切换请求消息。
其中，该S-gNB为不支持MBS业务的接入网设备，也就是说，S-gNB仅支持以单播方式向终端设备发送MBS业务的数据。该S-gNB通过UPF接收核心网设备(MB-UPF)发送的第一MBS业务的数据，并以单播方式向该终端设备发送该第一MBS业务的第一数据包。
在该终端设备接收S-gNB发送的第一MBS业务的数据的过程中，S-gNB可以根据该终端设备的测量报告，确定将该终端设备切换至T-gNB，且该T-gNB为支持MBS业务的接入网设备，S-gNB向T-gNB发送该切换请求消息。
S720，S-gNB向T-gNB发送序列号(sequence number，SN)状态信息(SN status transfer)。
该序列号状态信息包括第一数据包的标识信息，该第一数据包为第一MBS业务的数据包，第一数据包的标识信息可以是PDCP SN。该序列号状态信息指示第一序列号的值。例如，该序列号状态信息包括数据包#2的PDCP SN，PDCP SN_2，其中，PDCP SN_2(第一序列号的一例)等于PDCP SN_1加1，PDCP SN_1为数据包#1的PDCP SN，数据包#1为S-gNB缓存的该第一MBS业务的数据包中PDCP SN的值最大的一个数据包。可以理解的是，该S-gNB缓存的该第一MBS业务的数据包括S-gNB已经分配PDCP SN的数据包，以及S-gNB未分配PDCP SN的数据包，该PDCP SN的值最大的一个数据包为S-gNB已经分配PDCP SN的数据包中PDCP SN的值最大的一个数据包。也就是说，T-gNB通过序列号状态信息可以确定S-gNB应该发送或缓存的下一个PDCP SN。
S730，T-gNB根据序列号状态信息确定第一序列号的值小于第二序列号的值。
应理解，为了保证S-gNB和T-gNB对同一MBS业务的数据标识理解一致，预设S-gNB和目标接入网设备(T-gNB)中，第一MBS业务数据的标识信息到PDCP序列号(sequence number，SN)的映射关系一致。该步骤和S401中类似。
S-gNB接收该序列号状态信息后，根据序列号状态信息确定第一序列号的值，且T-gNB确定第一序列号的值小于第二序列号的值。其中，第二序列号可以是T-gNB缓存的多个第三数据包的序列号中最小的序列号，或者，该第二序列号也可以为T-gNB即将发送的数据包(第三数据包的一例)的序列号。该第一序列号和第二序列号可以为PDCP  SN，该第三数据包为该第一MBS业务的数据包。T-gNB通过确定第一序列号和第二序列号的大小，进而可以确定S-gNB传输该第一MBS业务数据的进度慢于T-gNB。
S740，T-gNB向核心网设备发送第一信息，相应地，核心网设备接收该第一信息。
具体地，T-gNB判断第一序列号的值小于第二序列号的值，并向核心网设备发送第一信息，该第一信息包括第三序列号和第四序列号。其中，第一序列号和第三序列号具有映射关系，第二序列号与第四序列号具有映射关系。该三序列号和第四序列号可以为QFI SN或GTP-U SN。也就是说，T-gNB确定S-gNB传输第一MBS业务的数据进度慢于T-gNB，T-gNB向核心网设备发送第三序列号和第四序列，分别用于表示S-gNB和T-gNB传输第一MBS业务的进度信息，以使得核心网设备确定因S-gNB和T-gNB传输进度差异而产生的“gap数据”。
在一种可能的实现方式中，T-gNB在切换过程中路径切换时，通过T-gNB和核心网设备之间的信令交互传输该第一信息。例如，T-gNB向AMF发送路径切换请求(path switch request)消息，该请求消息中携带该第一信息，AMF向核心网设备(MB-UPF)发送该第一信息。
S750，核心网设备根据该第一信息确定向T-gNB发送的第二数据包，该第二数据包为该第一MBS业务的数据包。
核心网设备通过第一信息确定第一MBS业务的数据中第五序列号对应数据包为第二数据包。该第五序列号的值大于等于第三序列号，且小于第四序列号。或者说，第五序列号对应的数据包(第二数据包)为上述“gap数据”。
S760，核心网设备向T-gNB发送该第二数据包。以使得T-gNB以单播方式向终端设备发送该第二数据包。
可选地，该方法还可以包括S770，核心网设备向S-gNB发送该第二数据包，相应地，S-gNB接收该第二数据包。
可选地，该方法还可以包括S780，数据前传(data forwarding)过程。即S-gNB将第一序列号之前、没有成功发送给终端设备的第一MBS业务的数据转发到T-gNB。同时，在数据前传的过程中，S-gNB向T-gNB发送该第二数据包。
根据本申请实施例的方案，在终端设备从S-gNB接收第一MBS业务的数据，且将该终端设备由S-gNB切换至T-gNB的过程中，核心网设备可以通过接收来自T-gNB的第一信息，确定向T-gNB发送的第二数据包，即因S-gNB和T-gNB传输第一MBS业务数据的进度差异而产生的“gap数据”，避免了终端设备在切换过程中接收第一MBS业务的数据的丢包等问题，进而保证了该终端设备在切换过程中MBS数据传输的可靠性。
其中，S-gNB为不支持MBS业务的接入网设备，T-gNB为支持MBS业务的接入网设备。
图8示出了本申请实施例提供的多播广播业务的传输切换方法的另一示例性流程图，该方法可应用于终端设备从不支持MBS业务的接入网设备切换至支持MBS业务的接入网设备的场景中，该方法为图7中方法700的详细过程。下面结合图8详细说明，其中，为了简便，用MB-gNB表示支持MBS业务的接入网设备。
在S810之前，该方法还包括步骤S801至S804。
S801，S-gNB(gNB)经由UPF接收MB-UPF发送的第一MBS业务的数据。且预设 MB-gNB和gNB中第一MBS业务的数据的标识信息到PDCP SN的映射关系一致。
S802，gNB向终端设备发送该第一MBS业务的数据。
在该过程中，gNB可以根据该终端设备的测量报告，确定将该终端设备切换至T-gNB(MB-gNB)。
S803为切换准备阶段，S804与S710中类似，S-gNB向T-gNB发送切换请求消息。
S810，gNB向MB-gNB发送SN状态信息，相应地，MB-gNB接收该SN状态信息，该SN状态信息指示第一序列号的值。
具体地，该SN状态信息中包括第一数据包的标识信息，该第一数据包的标识信息与S720中类似。即该第一数据包包括数据包#2，数据包2#的标识信息可以是PDCP SN_2(第一序列号的一例)，PDCP SN_2等于PDCP SN_1加1，PDCP SN_1为数据包#1的PDCP SN，数据包#1为源接入网设备缓存的该第一多播广播业务的数据包中PDCP SN的值最大的一个数据包。目标接入网设备通过SN状态信息可以确定gNB应该发送或缓存的下一个数据包的标识信息。
可选地，该方法还可以包括S820，终端设备向T-gNB(MB-gNB)发送切换确认信息，指示切换完成。
S830，T-gNB(MB-gNB)根据SN状态信息确定gNB传输第一MBS业务数据的数据传输进度慢于MB-gNB传输第一MBS业务数据的数据传输进度。
具体地，MB-gNB根据SN状态信息确定第一序列号，MB-gNB确定第一序列号的值小于第二序列号，该步骤与S730中类似。即第二序列号对应的数据包为MB-gNB中缓存的多个第一MBS业务的数据包中序列号最小的一个数据包，MB-gNB确定第一序列号的值小于第二序列号的值，即为确定gNB传输第一MBS业务数据的数据传输进度慢于MB-gNB。
S840，MB-gNB通过路径切换流程中向MB-UPF发送第一信息，相应地，MB-UPF接收该第一信息。
具体地，MB-gNB在路径切换流程中，通过MB-gNB和MB-UPF之间的信令交互向MB-UPF发送该第一信息。其中，该第一信息包括第三序列号和第四序列号，第三序列号、第四序列号分别与第一序列号和第二序列号具有映射关系，该步骤与S740类似。
S850a，MB-UPF向MB-gNB发送第二数据包，相应地，MB-gNB接收第二数据包。
MB-UPF通过第一信息确定第一多播广播业务的数据中第五序列号对应数据包为第二数据包。该第五序列号的值大于等于第三序列号，且小于第四序列号。MB-UPF向MB-gNB发送该第二数据包，以使得MB-gNB以单播方式向终端设备发送该第二数据包，该步骤与S760类似。
可选地，该方法还可以包括S850b，MB-UPF向gNB发送该第二数据包，该步骤与S770类似。
可选地，在MB-gNB接收MB-UPF发送的后续的第一MBS业务的数据之前，该方法还可以包括S860，MB-gNB向gNB发送UE上下文释放消息。
可选地，该方法还可以包括S851，数据前传(data forwarding)过程。通过该过程，gNB可以向MB-gNB发送S850b中接收的第二数据包。
S870和S880，MB-gNB接收MB-UPF发送的后续的第一MBS业务的数据，并向该 终端设备发送后续的第一MBS业务的数据。
根据本申请实施例的方案，在终端设备从S-gNB(不支持多播广播业务的接入网设备)接收第一多播广播业务的数据，且由S-gNB切换至T-gNB(支持多播广播业务的接入网设备)的过程中，核心网设备可以通过接收来自T-gNB的第一信息，确定向T-gNB发送的第二数据包，即因S-gNB和T-gNB传输进度差异而产生的“gap数据”，避免了终端设备在切换过程中接收第一多播广播业务的数据的丢包等问题，保证了该终端设备在切换过程中多播广播数据传输的可靠性。
图9示出了本申请实施例提供的多播广播业务的传输切换方法的另一示例性流程图，该方法可应用于终端设备从不支持MBS业务的接入网设备切换至支持MBS业务的接入网设备的场景中，该方法至少包括以下步骤。
S910，S-gNB向T-gNB发送切换请求消息，相应地，T-gNB接收该切换请求消息。
其中，该S-gNB为不支持MBS业务的接入网设备，并且该S-gNB通过UPF接收核心网设备(MB-UPF)发送的第一MBS业务的数据，且以单播方式向终端设备发送该第一MBS业务的第一数据包。该步骤和S710类似。
S920，T-gNB向核心网设备发送第一信息，相应地，核心网设备接收该第一信息。
应理解，该过程可以发生在，该终端设备断开与S-gNB的上行或下行数据传输之后的时刻，例如，该过程可以是S-gNB向T-gNB发送序列号状态信息(SN status transfer)之后。其次，预设S-gNB和T-gNB中，第一MBS业务数据的标识信息到PDCP SN的映射关系一致，该步骤和S401类似。
具体地，T-gNB向核心网设备发送第一信息，该第一信息包括第四序列号。该第四序列号与第二序列号之间具有映射关系，其中，第二序列号可以是T-gNB缓存的多个第三数据包的序列号中最小的序列号，或者，该第二序列号也可以为T-gNB即将发送的数据包(第三数据包的一例)的序列号。该第四序列号可以为QFI SN或GTP-U SN，第二序列号可以为PDCP SN。也就是说，该第四序列指示T-gNB传输该第一MBS业务的进度信息。T-gNB向核心网设备发送该第一信息具体过程和S740中类似，在此不再赘述。
S930，核心网设备确定第四序列号的值大于第六序列号。
核心网设备根据第一信息确定第四序列号的值，并确定第四序列号的值大于第六序列号，其中，该第六序列号为核心网设备已经向S-gNB发送的多个第四数据包的序列号中最大的序列号，或者，该第六序列号可以是该核心网设备即将向S-gNB发送的该第一MBS业务的数据包的序列号。核心网设备通过确定第四序列号的值大于第六序列号，从而确定S-gNB传输第一MBS业务数据的进度慢于T-gNB。
S940，核心网设备向T-gNB发送第二数据包，以使得T-gNB以单播方式向该终端设备发送该第二数据包，该第二数据包为第一MBS业务的数据包。
应理解，该第二数据包括第七序列号对应的数据包，该第七序列号的值大于等于第六序列号，且小于第四序列号的值。即该第七序列号对应的数据包(第二数据包)为，因S-gNB和T-gNB传输该第一MBS业务数据的进度不同而产生的“gap数据”。
可选地，该方法还可以包括S950，核心网设备向S-gNB发送该第二数据包，相应地，S-gNB接收该第二数据包。
可选地，该方法还可以包括S960，数据前传(data forwarding)过程。即S-gNB将未 发送成功的该第一MBS业务的数据转发到T-gNB。同时，在数据前传的过程中，S-gNB向T-gNB发送该第二数据包，以使得T-gNB以单播方式向该终端设备发送该第二数据包。
根据本申请实施例的方案，在终端设备从S-gNB接收第一MBS业务的数据，且将该终端设备由S-gNB切换至T-gNB的过程中，核心网设备可以通过接收来自T-gNB的第一信息，确定向该T-gNB发送的第二数据包，即因S-gNB和T-gNB传输该第一MBS业务数据的进度不同而产生的“gap数据”，避免了终端设备在切换过程中接收该第一MBS业务的数据的丢包等问题，进而保证了该终端设备在切换过程中MBS数据传输的可靠性。
图10示出了本申请实施例提供的多播广播业务的传输切换方法的另一示例性流程图，该方法可应用于终端设备从不支持MBS业务的接入网设备切换至支持MBS业务的接入网设备的场景中，该方法为图9中方法900的详细过程。下面结合图10详细说明该方法。
在S1010之前，该方法还包括步骤S1001至S1006。
S1001和S1002，S-gNB(gNB)经由UPF接收MB-UPF发送的第一MBS业务的数据，gNB向终端设备发送该第一MBS业务的数据。
预设MB-gNB和gNB中第一MBS业务的数据的标识信息到PDCP SN的映射关系一致。在该过程中，gNB可以根据该终端设备的测量报告，确定将该终端设备切换至T-gNB(MB-gNB)。
在终端设备指示切换完成之前，该方法还可以包括S1003至S1005。
其中，S1003为切换准备；S1004，S-gNB向终端设备发送该切换命令，该过程可以是在S-gNB向T-gNB发送该切换请求(与S910中类似)之后，终端设备接收该切换命令之后，断开与gNB的数据传输后，启动与MB-gNB的下行同步过程；可选地，该方法还可以包括S1005，S-gNB向T-gNB发送序列号状态信息。
S1006，终端设备向T-gNB(MB-gNB)发送切换确认信息，指示切换完成。
S1010，MB-gNB通过路径切换流程中向MB-UPF发送第一信息，相应地，MB-UPF接收该第一信息。
具体地，该第一信息包括第四序列号。该第四序列号与第二序列号具有映射关系，该第二序列号为MB-gNB缓存的多个第三数据包的序列号中最小的序列号。也就是说，该第四序列号用于表示MB-gNB传输第一多播广播业务的进度信息。
MB-gNB在路径切换流程中向MB-UPF发送第一信息，可以是通过MB-gNB和MB-UPF之间的信令交互传输该第一信息。该步骤与S920类似。
S1020，MB-UPF确定第四序列号的值大于第六序列号。
具体地，该第六序列号为MB-UPF已经向gNB发送的多个第四数据包的序列号中最大的序列号。MB-UPF通过确定第四序列号的值大于第六序列号，从而确定gNB传输第一多播广播业务的数据进度慢于MB-gNB。即MB-UPF确定第七序列号对应的数据包(第二数据包)为因gNB和MB-gNB传输进度差异而产生的“gap数据”。
S1030a，MB-UPF向MB-gNB发送第二数据包，相应地，MB-gNB接收第二数据包。
可以理解的是，该第二数据包为上述“gap数据”。MB-UPF向MB-gNB发送该第二数据包，以使得MB-gNB以单播方式向终端设备发送该第二数据包。
可选地，该方法还可以包括S1030b，MB-UPF向gNB发送该第二数据包，相应地， gNB接收该第二数据包。
S1040，MB-gNB向gNB发送UE上下文释放消息。
可选地，该方法还可以包括S1031，数据前传(data forwarding)过程。即gNB将第一序列号之前、没有成功发送给终端设备的第一多播广播业务的数据转发到MB-gNB。同时，在数据前传的过程中，gNB向MB-gNB发送该第二数据包。
S1050和S1060，MB-gNB接收MB-UPF发送的后续的第一MBS业务的数据，并向该终端设备发送后续的第一MBS业务的数据。
根据本申请实施例的方案，在终端设备从S-gNB(不支持多播广播业务的接入网设备)接收第一多播广播业务的数据，且由S-gNB切换至T-gNB(支持多播广播业务的接入网设备)的过程中，核心网设备可以通过接收来自T-gNB的第一信息，确定向T-gNB发送的第二数据包，即因S-gNB和T-gNB传输进度差异而产生的“gap数据”，避免了终端设备在切换过程中接收第一多播广播业务的数据的丢包等问题，最终保证了该终端设备在切换过程中多播广播数据传输的可靠性。
应理解，上述实施例中，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。
以上，结合图4和图10详细说明了本申请实施例提供的方法。以下，结合图11至图15详细说明本申请实施例提供的装置。
图11示出了本申请实施例提供的通信装置的示意性框图。如图11所示，该装置1100包括发送单元1110，接收单元1120。
在一种可能的设计中，该通信装置1100可对应于根据本申请实施例的方法400、500和600中的源接入网设备。该通信装置1100可以包括用于执行图4中的方法400、图5中的方法500、图6中的方法600中源接入网设备执行的方法的单元。并且，该通信装置1100中的单元和上述其他操作和/或功能分别为了实现图4中的方法400、图5中的方法500、图6中的方法600的相应流程。
其中，当该通信装置1100用于执行图4中的方法400，发送单元1110可用于执行方法400中的S410、S420，S430a或S430b，以及S460。当该通信装置1100用于执行图5中的方法500，发送单元1110可用于执行方法500中的S502至S505，S510a或S510b，以及S5110；接收单元1120可用于执行方法500中的S501a或S501b，以及S570。当该通信装置1100用于执行图6中的方法600，发送单元1110可用于执行方法600中的S602至S610，以及S690；接收单元1120可用于执行方法600中的S601a或S601b、S660。应理解，各单元执行上述相应步骤的具体过程在上述方法实施例中已经详细说明，为了简洁，在此不再赘述。
图12示出了本申请实施例提供的通信装置的示意性框图。如图12所示，该装置1200包括发送单元1210，接收单元1220。
在一种可能的设计中，该通信装置1200可对应于根据本申请实施例的方法400、500和600中的核心网设备。该通信装置1200可以包括用于执行图4中的方法400、图5中的方法500、图6中的方法600中核心网设备执行的方法的单元。并且，该通信装置1200中的单元和上述其他操作和/或功能分别为了实现图4中的方法400、图5中的方法500、图6中的方法600的相应流程。
其中，当该通信装置1200用于执行图4中的方法400，发送单元1210可用于执行方法400中的S450和S470。当该通信装置1200用于执行图5中的方法500，发送单元1210可用于执行方法500中的S520b和S580；接收单元1220可用于执行方法500中的S540a、S510b，以及S540b。当该通信装置1200用于执行图6中的方法600，发送单元1210可用于执行方法600中的S601a或S601b，以及S670；接收单元1220可用于执行方法600中的S640。应理解，各单元执行上述相应步骤的具体过程在上述方法实施例中已经详细说明，为了简洁，在此不再赘述。
图13是本申请实施例提供的通信装置的示意性框图。如图13所示，该通信装置1300可以包括发送单元1310，接收单元1320和处理单元1330。
在一种可能的设计中，该通信装置1300可对应于根据本申请实施例的方法700、800、900和1000中的目标接入网设备。该通信装置1300可以包括用于执行图7中的方法700、图9中的方法900、图8中的方法800，以及图10中的方法1000中目标接入网设备执行的方法的单元。并且，该通信装置1300中的各单元和上述其他操作和/或功能分别为了实现图7中的方法700、图8中的方法800、图9中的方法900和图10中的方法1000的相应流程。
其中，当该通信装置1300用于执行图7中的方法700时，发送单元1310可用于执行方法700中的S740；接收单元1320可用于执行方法700中的S710、S720、S760和S780；处理单元1330可用于执行方法700中的S730。当该通信装置1300用于执行图9中的方法900，发送单元1310可用于执行方法900中的S920；接收单元1320可用于执行方法900中的S910、S960。应理解，各单元执行上述相应步骤的具体过程在上述方法实施例中已经详细说明，为了简洁，在此不再赘述。
图14是本申请实施例提供的通信装置的示意性框图。如图14所示，该通信装置1400可以包括发送单元1410，接收单元1420和处理单元1430。
在一种可能的设计中，该通信装置1400可对应于根据本申请实施例的方法700、800、900和1000中的核心网设备。该通信装置1400可以包括用于执行图7中的方法700、图8中的方法800、图9中的方法900，以及图10中的方法1000中核心网网设备执行的方法的单元。并且，该通信装置1400中的各单元和上述其他操作和/或功能分别为了实现图7中的方法700、图8中的方法800、图9中的方法900和图10中的方法1000的相应流程。
其中，当该通信装置1400用于执行图7中的方法700时，发送单元1410可用于执行方法700中的S760和S770；接收单元1420可用于执行方法700中的S740；处理单元1430可用于执行方法700中的S750。当该通信装置1400用于执行图9中的方法900，发送单元1410可用于执行方法900中的S940和S950；接收单元1420可用于执行方法900中的S920；处理单元1430可用于执行方法900中的S930。应理解，各单元执行上述相应步骤的具体过程在上述方法实施例中已经详细说明，为了简洁，在此不再赘述。
图15是根据本申请实施例提供的通信装置1500的结构框图。图15所示的通信装置1500包括：处理器1510、存储器1520和收发器1530。该处理器1510与存储器1520耦合，用于执行存储器1520中存储的指令，以控制收发器1530发送信号和/或接收信号。
应理解，上述处理器1510和存储器1520可以合成一个处理装置，处理器1510用于 执行存储器1520中存储的程序代码来实现上述功能。具体实现时，该存储器1520也可以集成在处理器1510中，或者独立于处理器1510。应理解，处理器1510也可以和前面通信装置中的各个处理单元相对应，收发器1530可以和前面通信装置中的各个接收单元和发送单元相对应。
还应理解，收发器1530可以包括接收器(或者称，接收机)和发射器(或者称，发射机)。收发器还可以进一步包括天线，天线的数量可以为一个或多个。收发器还可以是通信接口或者接口电路。
具体地，该通信装置1500可对应于根据本申请实施例的方法400、500和600中的核心网设备，方法700、800中的目标接入网设备，或者，方法900、1000中的核心网设备。该通信装置1500可以包括方法400、500和600中的核心网设备执行的方法的单元，执行方法700、800中的目标接入网设备执行的方法的单元，或者，方法900、1000中的核心网设备执行的方法的单元。应理解，各单元执行上述相应步骤的具体过程在上述方法实施例中已经详细说明，为了简洁，在此不再赘述。
当该通信装置1500为芯片时，该芯片包括收发单元和处理单元。其中，收发单元可以是输入输出电路或通信接口；处理单元可以为该芯片上集成的处理器或者微处理器或者集成电路。
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。
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4至图10所示实施例中任意一个实施例的方法。
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介质，该计算机可读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3至图9所示实施例中任意一个实施例的方法。
根据本申请实施例提供的方法，本申请还提供一种系统，其包括前述的装置或设备。
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2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。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的系统、装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
在本申请所提供的几个实施例中，应该理解到，所揭露的系统、装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，所述单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
所述作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。
所述功能如果以软件功能单元的形式实现并作为独立的产品销售或使用时，可以存储在一个计算机可读取存储介质中。基于这样的理解，本申请的技术方案本质上或者说对现有技术做出贡献的部分或者该技术方案的部分可以以软件产品的形式体现出来，该计算机软件产品存储在一个存储介质中，包括若干指令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)执行本申请各个实施例所述方法的全部或部分步骤。而前述的存储介质包括：U盘、移动硬盘、只读存储器(Read-Only Memory，ROM)、随机存取存储器(Random Access Memory，RAM)、磁碟或者光盘等各种可以存储程序代码的介质。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (77)

  1. 一种多播广播业务的传输切换方法，其特征在于，所述方法包括：
    源接入网设备向终端设备发送第一数据包，所述第一数据包为第一多播广播业务的数据包；
    所述源接入网设备向所述终端设备发送切换命令，所述切换命令用于指示所述终端设备从所述源接入网设备向目标接入网设备切换；
    所述源接入网设备向核心网设备发送第一信息，所述第一信息包括所述第一数据包的标识信息，所述第一数据包的标识信息用于所述核心网设备确定向所述目标接入网设备发送的第二数据包，所述第二数据包为所述第一多播广播业务的数据包。
  2. 根据权利要求1所述的方法，其特征在于，所述第一数据包为所述源接入网设备向所述终端设备发送的最后一个数据包。
  3. 根据权利要求1或2所述的方法，其特征在于，所述第一数据包的标识信息包括以下序列号中的至少一种：
    所述第一数据包的服务质量流标识和所述第一数据包的服务质量流标识序列号，所述第一数据包的数据的分组数据汇聚协议序列号，所述第一数据包的用户面通用分组无线业务隧道协议序列号。
  4. 根据权利要求1至3中任一项所述的方法，其特征在于，所述第一信息还包括：
    所述终端设备的标识信息，所述目标接入网设备的标识信息。
  5. 根据权利要求4所述的方法，其特征在于，所述第一信息还包括所述第一多播广播业务的会话标识信息。
  6. 根据权利要求1至5中任一项所述的方法，其特征在于，所述源接入网设备向核心网设备发送第一信息，包括：
    所述源接入网设备向所述核心网设备发送下行数据传输状态信息，所述下行数据传输状态信息携带所述第一信息。
  7. 根据权利要求1至5中任一项所述的方法，其特征在于，所述源接入网设备向核心网设备发送第一信息，包括：
    所述源接入网设备通过所述目标接入网设备向所述核心网设备发送所述第一信息。
  8. 根据权利要求7所述的方法，其特征在于，所述源接入网设备通过所述目标接入网设备向所述核心网设备发送所述第一信息，包括：
    所述源接入网设备向所述目标接入网设备发送序列号状态转移信息，所述序列号状态转移信息携带所述第一信息。
  9. 根据权利要求1至8中任一项所述的方法，其特征在于，所述源接入网设备和所述目标接入网中所述第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，
    所述第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
  10. 根据权利要求2所述的方法，其特征在于，所述第一信息还包括第二标识信息， 所述第二标识信息用于指示第三数据包，所述第三数据包包括所述源接入网设备向所述终端设备未发送成功的所述第一多播广播业务的数据包。
  11. 一种多播广播业务的传输切换方法，其特征在于，所述方法包括：
    核心网设备接收来自源接入网设备的第一信息，所述第一信息包括第一数据包的标识信息，所述第一数据包为终端设备的第一多播广播业务的数据包；
    所述核心网设备根据所述第一信息确定向目标接入网设备发送的第二数据包，所述第二数据包为所述第一多播广播业务的数据包。
  12. 根据权利要求11所述的方法，其特征在于，所述第一数据包为所述源接入网设备向所述终端设备发送的最后一个数据包。
  13. 根据权利要求11或12所述的方法，其特征在于，所述第一数据包的标识信息包括以下序列号中的至少一种：
    所述第一数据包的服务质量流标识和所述第一数据包的服务质量流标识序列号，所述第一数据包的数据的分组数据汇聚协议序列号，所述第一数据包的用户面通用分组无线业务隧道协议序列号。
  14. 根据权利要求11至13中任一项所述的方法，其特征在于，所述第一信息还包括：
    所述终端设备的标识信息，所述目标接入网设备的标识信息。
  15. 根据权利要求14所述的方法，其特征在于，所述第一信息还包括所述第一多播广播业务的会话标识信息。
  16. 根据权利要求11至15中任一项所述的方法，其特征在于，所述源接入网设备和所述目标接入网中所述第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，
    所述第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
  17. 根据权利要求11至15中任一项所述的方法，其特征在于，所述第一信息还包括第二标识信息，所述第二标识信息用于指示第三数据包，所述第三数据包包括所述源接入网设备向所述终端设备未发送成功的所述第一多播广播业务的数据包，所述方法还包括：
    所述核心网设备向所述目标接入网设备发送所述第三数据包。
  18. 一种多播广播业务的传输切换方法，其特征在于，所述方法包括：
    目标接入网设备接收来自源接入网设备的切换请求消息，所述切换请求消息用于请求将终端设备从所述源接入网设备切换到所述目标接入网设备；
    所述目标接入网设备接收来自源接入网设备的序列号状态信息，所述序列号状态信息包括第一数据包的标识信息，所述第一数据包为第一多播广播业务的数据包；
    所述目标接入网设备根据所述序列号状态信息向核心网设备发送第一信息，所述第一信息用于确定第二数据包，所述第二数据包为所述第一多播广播业务的数据包；
    所述目标接入网设备接收所述第二数据包。
  19. 根据权利要求18所述的方法，其特征在于，包括：
    所述序列号状态信息指示第一序列号的值，所述第一序列号的值为所述源接入网设备缓存的多个所述第一数据包的序列号中最大的序列号的值加1。
  20. 根据权利要求19所述的方法，其特征在于，所述目标接入网设备根据所述序列 号状态信息向核心网设备发送第一信息，包括：
    所述目标接入网设备确定所述第一序列号的值小于第二序列号的值，所述第二序列号为所述目标接入网设备缓存的多个第三数据包的序列号中最小的序列号，所述第三数据包为所述第一多播广播业务的数据包；
    所述目标接入网向所述核心网设备发送所述第一信息。
  21. 根据权利要求18至20中任一项所述的方法，其特征在于，所述源接入网设备和所述目标接入网中所述第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，
    所述第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
  22. 根据权利要求18至21中任一项所述的方法，其特征在于，所述第一信息包括第三序列号和第四序列号，所述第三序列号与所述第一序列号存在映射关系，所述第四序列号与所述第二序列号存在映射关系。
  23. 根据权利要求22所述的方法，其特征在于，所述第一序列号和所述第二序列号为分组数据汇聚协议序列号，所述第三序列号和所述第四序列号为服务质量流标识序列号或者用户面通用分组无线业务隧道协议序列号。
  24. 根据权利要求18至23中任一项所述的方法，其特征在于，所述第一信息承载于第一消息，所述第一消息为路径切换流程中的消息。
  25. 一种多播广播业务的传输切换方法，其特征在于，所述方法包括：
    目标接入网设备接收来自源接入网设备的切换请求信息，所述切换请求信息用于请求将终端设备从所述源接入网设备切换到所述目标接入网设备；
    所述目标接入网设备向核心网设备发送第一信息，所述第一信息用于确定第二数据包，所述第二数据包为所述第一多播广播业务的数据包；
    所述目标接入网设备接收所述第二数据包。
  26. 根据权利要求25所述的方法，其特征在于，包括：
    所述第一信息包括第四序列号，所述第四序列号与第二序列号存在映射关系，所述第二序列号为所述目标接入网设备缓存的多个第三数据包的序列号中最小的序列号，所述第三数据包为所述第一多播广播业务的数据包。
  27. 根据权利要求26所述的方法，其特征在于，所述第二序列号为分组数据汇聚协议序列号，所述第四序列号为服务质量流标识序列号或者用户面通用分组无线业务隧道协议序列号。
  28. 根据权利要求25至27中任一项所述的方法，其特征在于，所述源接入网设备和所述目标接入网中所述第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，
    所述第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
  29. 根据权利要求25至28中任一项所述的方法，其特征在于，所述第一信息承载于第一消息，所述第一消息为路径切换流程中的消息。
  30. 一种多播广播业务的传输切换方法，其特征在于，所述方法包括：
    核心网设备接收来自目标接入网设备的第一信息；
    所述核心网设备根据所述第一信息确定第二数据包，所述第二数据包为终端设备的第一多播广播业务的数据包；
    所述核心网设备向所述目标接入网设备发送所述第二数据包。
  31. 根据权利要求30所述的方法，其特征在于，
    所述第一信息包括第四序列号，所述第四序列号与第二序列号存在映射关系，所述第二序列号为所述目标接入网设备缓存的多个第三数据包的序列号中最小的序列号，所述第三数据包为所述第一多播广播业务的数据包。
  32. 根据权利要求31所述的方法，其特征在于，所述核心网设备根据所述第一信息确定第二数据包，包括：
    所述核心网设备确定所述第四序列号的值大于第六序列号的值，所述第六序列号为所述核心网设备向所述源接入网设备发送的多个第四数据包的序列号中最大的序列号；
    所述核心网设备确定所述第二数据包包括第七序列号对应的数据包，所述第七序列号的值大于等于所述第六序列号的值，且小于所述第四序列号的值。
  33. 根据权利要求31所述的方法，其特征在于，
    所述第一信息还包括第三序列号，所述第三序列号与第一序列号存在映射关系，所述第一序列号的值为所述源接入网设备缓存的多个所述第一数据包的序列号中最大的序列号的值加1，所述第三序列号的值小于所述第四序列号的值。
  34. 根据权利要求33所述的方法，其特征在于，所述核心网设备根据所述第一信息确定第二数据包，包括：
    所述核心网设备确定所述第二数据包包括第五序列号对应的数据包，所述第五序列号的值大于等于所述第三序列号的值，且小于所述第四序列号的值。
  35. 根据权利要求30至34中任一项所述的方法，其特征在于，所述第一序列号和所述第二序列号为分组数据汇聚协议序列号，所述第三序列号、所述第四序列号和所述第六序列号为服务质量流标识序列号或用户面通用分组无线业务隧道协议序列号。
  36. 根据权利要求30至35中任一项所述的方法，其特征在于，所述源接入网设备和所述目标接入网中所述第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，
    所述第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
  37. 根据权利要求30至36中任一项所述的方法，其特征在于，所述第一信息承载于第一消息，所述第一消息为路径切换流程中的消息。
  38. 一种通信装置，其特征在于，包括：
    发送单元，用于向终端设备发送第一数据包，所述第一数据包为第一多播广播业务的数据包；
    所述发送单元还用于，向所述终端设备发送切换命令，所述切换命令用于指示所述终端设备从所述源接入网设备向目标接入网设备切换；
    所述发送单元还用于，向核心网设备发送第一信息，所述第一信息包括所述第一数据包的标识信息，所述第一数据包的标识信息用于所述核心网设备确定向所述目标接入网设 备发送的第二数据包，所述第二数据包为所述第一多播广播业务的数据包。
  39. 根据权利要求38所述的通信装置，其特征在于，所述第一数据包为所述发送单元向所述终端设备发送的最后一个数据包。
  40. 根据权利要求38或39所述的通信装置，其特征在于，所述第一数据包的标识信息包括以下序列号中的至少一种：
    所述第一数据包的服务质量流标识和所述第一数据包的服务质量流标识序列号，所述第一数据包的数据的分组数据汇聚协议序列号，所述第一数据包的用户面通用分组无线业务隧道协议序列号。
  41. 根据权利要求38至40中任一项所述的通信装置，其特征在于，所述第一信息还包括：
    所述终端设备的标识信息，所述目标接入网设备的标识信息。
  42. 根据权利要求41所述的通信装置，其特征在于，所述第一信息还包括所述第一多播广播业务的会话标识信息。
  43. 根据权利要求38至42中任一项所述的通信装置，其特征在于，
    所述发送单元具体用于，向所述核心网设备发送下行数据传输状态信息，所述下行数据传输状态信息携带所述第一信息。
  44. 根据权利要求38至42中任一项所述的通信装置，其特征在于，
    所述发送单元具体用于，通过所述目标接入网设备向所述核心网设备发送所述第一信息。
  45. 根据权利要求44所述的通信装置，其特征在于，
    所述发送单元具体用于，向所述目标接入网设备发送序列号状态转移信息，所述序列号状态转移信息携带所述第一信息。
  46. 根据权利要求38至45中任一项所述的通信装置，其特征在于，所述通信装置和所述目标接入网中所述第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，
    所述第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
  47. 根据权利要求39所述的通信装置，其特征在于，所述第一信息还包括第二标识信息，所述第二标识信息用于指示第三数据包，所述第三数据包包括所述通信装置向所述终端设备未发送成功的所述第一多播广播业务的数据包。
  48. 一种通信装置，其特征在于，包括：
    接收单元，用于接收来自源接入网设备的第一信息，所述第一信息包括第一数据包的标识信息，所述第一数据包为终端设备的第一多播广播业务的数据包；
    处理单元，用于根据所述第一信息确定向目标接入网设备发送的第二数据包，所述第二数据包为所述第一多播广播业务的数据包。
  49. 根据权利要求48所述的通信装置，其特征在于，所述第一数据包为所述源接入网设备向所述终端设备发送的最后一个数据包。
  50. 根据权利要求48或49所述的通信装置，其特征在于，所述第一数据包的标识信息包括以下序列号中的至少一种：
    所述第一数据包的服务质量流标识和所述第一数据包的服务质量流标识序列号，所述第一数据包的数据的分组数据汇聚协议序列号，所述第一数据包的用户面通用分组无线业务隧道协议序列号。
  51. 根据权利要求48至50中任一项所述的通信装置，其特征在于，所述第一信息还包括：
    所述终端设备的标识信息，所述目标接入网设备的标识信息。
  52. 根据权利要求51所述的通信装置，其特征在于，所述第一信息还包括所述第一多播广播业务的会话标识信息。
  53. 根据权利要求48至52中任一项所述的通信装置，其特征在于，所述源接入网设备和所述目标接入网中所述第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，
    所述第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
  54. 根据权利要求48至52中任一项所述的通信装置，其特征在于，所述第一信息还包括第二标识信息，所述第二标识信息用于指示第三数据包，所述第三数据包包括所述源接入网设备向所述终端设备未发送成功的所述第一多播广播业务的数据包，所述通信装置还包括：
    发送单元，用于向所述目标接入网设备发送所述第三数据包。
  55. 一种通信装置，其特征在于，包括：
    接收单元，接收来自源接入网设备的切换请求消息，所述切换请求消息用于请求将终端设备从所述源接入网设备切换到所述通信装置；
    所述接收单元还用于，接收来自源接入网设备的序列号状态信息，所述序列号状态信息包括第一数据包的标识信息，所述第一数据包为第一多播广播业务的数据包；
    处理单元，用于根据所述序列号状态信息向核心网设备发送第一信息，所述第一信息用于确定第二数据包，所述第二数据包为所述第一多播广播业务的数据包；
    所述接收单元还用于，接收所述第二数据包。
  56. 根据权利要求55所述的通信装置，其特征在于，
    所述序列号状态信息指示第一序列号的值，所述第一序列号的值为所述源接入网设备缓存的多个所述第一数据包的序列号中最大的序列号的值加1。
  57. 根据权利要求56所述的通信装置，其特征在于，所述处理单元具体用于，确定所述第一序列号的值小于第二序列号的值，所述第二序列号为所述目标接入网设备缓存的多个第三数据包的序列号中最小的序列号，所述第三数据包为所述第一多播广播业务的数据包，所述通信装置还包括：
    发送单元，用于向所述核心网设备发送所述第一信息。
  58. 根据权利要求55至57中任一项所述的通信装置，其特征在于，所述源接入网设备和通信装置中所述第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，
    所述第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
  59. 根据权利要求55至58中任一项所述的通信装置，其特征在于，所述第一信息包括第三序列号和第四序列号，所述第三序列号与所述第一序列号存在映射关系，所述第四序列号与所述第二序列号存在映射关系。
  60. 根据权利要求59所述的通信装置，其特征在于，所述第一序列号和所述第二序列号为分组数据汇聚协议序列号，所述第三序列号和所述第四序列号为服务质量流标识序列号或者用户面通用分组无线业务隧道协议序列号。
  61. 根据权利要求55至60中任一项所述的通信装置，其特征在于，所述第一信息承载于第一消息，所述第一消息为路径切换流程中的消息。
  62. 一种通信装置，其特征在于，包括：
    接收单元，用于接收来自源接入网设备的切换请求信息，所述切换请求信息用于请求将终端设备从所述源接入网设备切换到所述通信装置；
    发送单元，用于向核心网设备发送第一信息，所述第一信息用于确定第二数据包，所述第二数据包为所述第一多播广播业务的数据包；
    所述接收单元还用于，接收所述第二数据包。
  63. 根据权利要求62所述的通信装置，其特征在于，
    所述第一信息包括第四序列号，所述第四序列号与第二序列号存在映射关系，所述第二序列号为所述通信装置缓存的多个第三数据包的序列号中最小的序列号，所述第三数据包为所述第一多播广播业务的数据包。
  64. 根据权利要求63所述的通信装置，其特征在于，所述第二序列号为分组数据汇聚协议序列号，所述第四序列号为服务质量流标识序列号或者用户面通用分组无线业务隧道协议序列号。
  65. 根据权利要求62至64中任一项所述的通信装置，其特征在于，所述源接入网设备和所述通信装置中所述第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，
    所述第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
  66. 根据权利要求62至65中任一项所述的通信装置，其特征在于，所述第一信息承载于第一消息，所述第一消息为路径切换流程中的消息。
  67. 一种通信装置，其特征在于，包括：
    接收单元，用于接收来自目标接入网设备的第一信息；
    处理单元，用于根据所述第一信息确定第二数据包，所述第二数据包为终端设备的第一多播广播业务的数据包；
    发送单元，用于向所述目标接入网设备发送所述第二数据包。
  68. 根据权利要求67所述的通信装置，其特征在于，
    所述第一信息包括第四序列号，所述第四序列号与第二序列号存在映射关系，所述第二序列号为所述目标接入网设备缓存的多个第三数据包的序列号中最小的序列号，所述第三数据包为所述第一多播广播业务的数据包。
  69. 根据权利要求68所述的通信装置，其特征在于，
    所述处理单元具体用于，确定所述第四序列号的值大于第六序列号的值，所述第六序 列号为所述通信装置向所述源接入网设备发送的多个第四数据包的序列号中最大的序列号；
    所述处理单元还用于，确定所述第二数据包包括第七序列号对应的数据包，所述第七序列号的值大于等于所述第六序列号的值，且小于所述第四序列号的值。
  70. 根据权利要求68所述的通信装置，其特征在于，
    所述第一信息还包括第三序列号，所述第三序列号与第一序列号存在映射关系，所述第一序列号的值为所述源接入网设备缓存的多个所述第一数据包的序列号中最大的序列号的值加1，所述第三序列号的值小于所述第四序列号的值。
  71. 根据权利要求70所述的通信装置，其特征在于，
    所述处理单元具体用于，确定所述第二数据包包括第五序列号对应的数据包，所述第五序列号的值大于等于所述第三序列号的值，且小于所述第四序列号的值。
  72. 根据权利要求67至71中任一项所述的通信装置，其特征在于，所述第一序列号和所述第二序列号为分组数据汇聚协议序列号，所述第三序列号、所述第四序列号和所述第六序列号为服务质量流标识序列号或用户面通用分组无线业务隧道协议序列号。
  73. 根据权利要求67至72中任一项所述的通信装置，其特征在于，所述源接入网设备和所述目标接入网中所述第一多播广播业务的服务质量流标识序列号到分组数据汇聚协议序列号的映射关系相同；或者，
    所述第一多播广播业务的用户面通用分组无线业务隧道协议序列号到所述分组数据汇聚协议序列号的映射关系相同。
  74. 根据权利要求67至72中任一项所述的通信装置，其特征在于，所述第一信息承载于第一消息，所述第一消息为路径切换流程中的消息。
  75. 一种通信装置，其特征在于，包括：
    存储器，用于存储计算机指令；
    处理器，用于执行所述存储器中存储的计算机指令，使得所述装置执行如权利要求1至10中任一项所述的方法，或如权利要求11至17中任一项所述的方法，或如权利要求18至24中任一项所述的方法，或如权利要25至29中任一项所述的方法，或如权利要30至37中任一项所述的方法。
  76. 一种计算机可读存储介质，其特征在于，其上存储有计算机程序，所述计算机程序用于执行如权利要求1至10中任一项所述的方法，或如权利要求11至17中任一项所述的方法，或如权利要求18至24中任一项所述的方法，或如权利要求25至29中任一项所述的方法，或如权利要求30至37中任一项所述的方法。
  77. 一种芯片系统，其特征在于，包括：处理器，所述处理器用于执行存储的计算机程序，所述计算机程序用于执行如权利要求1至10中任一项所述的方法，或如权利要求11至17中任一项所述的方法，或如权利要求18至24中任一项所述的方法，或如权利要求25至29中任一项所述的方法，或如权利要求30至37中任一项所述的方法。
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ERICSSON: "Conditional Handover for NR - Data Forwarding", 3GPP DRAFT; R3-193041 - CONDITIONAL HANDOVER FOR NR - DATA FORWARDING, vol. RAN WG3, 4 May 2019 (2019-05-04), Reno, NV, USA, pages 1 - 3, XP051713228 *

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