Multicast service transmission method and apparatus
This application provides a multicast service transmission method and apparatus, to deliver a multicast service regardless of whether there is a device supporting multicast in a system, so as to improve flexibility and reliability of the multicast service transmission. The method performed by a session management network element includes: receiving a first message or a second message, where the first message requests to add a terminal device to a multicast service, the second message is used to update a PDU session of the terminal device, and the PDU session is associated with the multicast service; and determining, based on multicast capability information of the terminal device and/or multicast capability information of an access network device, a delivery mode of the multicast service, where the access network device is an access network device currently accessed by the terminal device or a target access network device of the terminal device.
1. A multicast/broadcast service transmission method, comprising:
receiving, by a session management network element, 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;
determining, by the session management network element 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, by the session management network element, 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.
2. The method according to claim 1 , wherein the second message is a Nsmf_PDUSession_UpdateSMContext Request.
3. The method according to claim 1 , wherein the delivery mode comprises a multicast/broadcast mode and/or a unicast mode.
4. The method according to claim 3 , wherein the multicast/broadcast mode comprises a 5GC shared multicast broadcast service (MBS) traffic delivery method, and the unicast mode comprises a 5GC individual MBS traffic delivery method.
5. The method according to claim 3 , wherein in the multicast/broadcast mode, a user plane function (UPF) delivers multicast/broadcast data of the multicast/broadcast service to the access network device using a multicast session tunnel, and the access network device delivers the multicast/broadcast data to the terminal device in a point to multi-point (PTM) manner; and
the unicast mode delivers the multicast/broadcast data to the terminal device using a PDU session, the PDU session relating to the multicast/broadcast service.
6. The method according to claim 1 , further comprising:
determining, by the session management network element based on multicast/broadcast QoS information of the multicast/broadcast service, the unicast QoS flow corresponding to the multicast/broadcast service; and
adding, by the session management network element, the unicast QoS flow to the PDU session of the terminal device, wherein the unicast QoS flow is used to deliver the multicast/broadcast data.
7. The method according to claim 1 , further comprising:
sending, by the session management network element, a correspondence between a multicast/broadcast QoS flow identifier (QFI) of the multicast/broadcast QoS flow and a unicast QFI of the unicast QoS flow to the access network device.
8. The method according to claim 1 , further comprising:
receiving, by the session management network element, the multicast/broadcast capability information of the access network device from an access and mobility management network element.
9. 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.
10. The system according to claim 9 , further comprising an access and mobility management network element, wherein:
the access network device is configured to send the multicast/broadcast capability information of the access network device to the access and mobility management network element; and
the access and mobility management network element is configured to send the multicast/broadcast capability information of the access network device to the session management network element.
11. The system according to claim 9 , wherein the second message is a Nsmf_PDUSession_UpdateSMContext Request.
12. The system according to claim 9 , wherein the delivery mode comprises a multicast/broadcast mode and/or a unicast mode.
13. The system according to claim 12 , wherein the multicast/broadcast mode comprises a 5GC shared multicast broadcast service (MBS) traffic delivery method, and the unicast mode comprises a 5GC individual MBS traffic delivery method.
14. The system according to claim 12 , wherein in the multicast/broadcast mode, a user plane function (UPF) delivers multicast/broadcast data of the multicast/broadcast service to the access network device using a multicast session tunnel, and the access network device delivers the multicast/broadcast data to the terminal device in a point to multi-point (PTM) manner; and
the unicast mode delivers the multicast/broadcast data to the terminal device using a PDU session, the PDU session relating to the multicast/broadcast service.
15. The system according to claim 9 , wherein the session management network element is further configured to:
send a correspondence between a multicast/broadcast QoS flow identifier (QFI) of the multicast/broadcast QoS flow and a unicast QFI of the unicast QoS flow to the access network device.
16. 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.
17. The apparatus according to claim 16 , wherein the second message is a Nsmf_PDUSession_UpdateSMContext Request.
18. The apparatus according to claim 16 , wherein the delivery mode comprises a multicast/broadcast mode and/or a unicast mode.
19. The apparatus according to claim 18 , wherein the multicast/broadcast mode comprises a 5GC shared multicast broadcast service (MBS) traffic delivery method, and the unicast mode comprises a 5GC individual MBS traffic delivery method.
20. The apparatus according to claim 16 , wherein the at least one processor is further configured to:
determine, based on multicast/broadcast QoS information of the multicast/broadcast service, the unicast QoS flow corresponding to the multicast/broadcast service; and
add the unicast QoS flow to the PDU session of the terminal device, wherein the unicast QoS flow is used to deliver the multicast/broadcast data.