Multicast service transmission method and apparatus

A multicast/broadcast service transmission system, comprising:

• an access network device;
• and
• a session management network element in communication with the access network device, the session management network element is configured to:
• receive a second message, the second message updating a protocol data unit (PDU) session of a terminal device, and the PDU session is associated with a multicast/broadcast service;
• determine, based on a multicast/broadcast capability information of the access network device, a delivery mode of the multicast/broadcast service, the multicast/broadcast capability information of the access network device indicating whether the access network device supports multicast/broadcast, and the access network device is currently accessed by the terminal device or by a target access network device of the terminal device;
• and
• map a multicast/broadcast quality of service (QOS) flow of the multicast/broadcast service to a unicast QoS flow of the PDU session, the unicast QoS flow being used to transmit the multicast/broadcast data, the unicast QoS Flow Identifier (QFI) of the unicast QoS flow comprising an unused QFI of the PDU session.

A multicast service transmission apparatus comprising:

• a memory, configured to store instructions;
• and
• at least one processor, configured to execute the instructions stored in the memory to perform the following steps:
• receive a second message, the second message updating a protocol data unit (PDU) session of a terminal device, and the PDU session is associated with a multicast/broadcast service;
• determine, based on multicast/broadcast capability information of an access network device, a delivery mode of the multicast/broadcast service, the multicast/broadcast capability information of the access network device indicating whether the access network device supports multicast/broadcast, and the access network device is currently accessed by the terminal device or by a target access network device of the terminal device;
• and
• mapping a multicast/broadcast quality of service (QOS) flow of the multicast/broadcast service to a unicast QoS flow of the PDU session, the unicast QoS flow being used to transmit the multicast/broadcast data, the unicast QoS Flow Identifier (QFI) of the unicast QoS flow comprising an unused QFI of the PDU session.