Communication method and communication apparatus

1 . A communication method, comprising:

determining, by a first access network device, that a first terminal device is a last terminal device that receives data of a first multicast service via the first access network device in response to the first terminal device being in a handover preparation phase in which the first terminal device is handed over from the first access network device to a second access network device; and

sending, by the first access network device, a message to an access and mobility management function network element, wherein the message includes first information, wherein the first information includes identification information of the first multicast service, a request usable to release a first tunnel, and information about the first tunnel, wherein the information about the first tunnel includes a tunnel endpoint identifier TEID) uniquely identifying the first tunnel, and the first tunnel is useable for transmitting the data of the first multicast service between the first access network device and a multicast user plane function network element.

2 . The method according to claim 1 , further comprising:

updating, by the first access network device, a quantity of terminal devices that have joined the first multicast service via the first access network device.

3 . The method according to claim 1 , wherein the first information includes identification information of the first multicast service-uniquely identifying the first multicast service, wherein the identification information uniquely identifying the first multicast service includes a multicast service ID, a multicast service name, a multicast address, or a multicast group ID.

4 . The method according to claim 1 , wherein the first tunnel is a multicast session tunnel which is shared by terminal devices.

5 . The communication method according to claim 1 further comprising preparing by the first access network device for the first terminal device, a resource for the handover, wherein the resource includes a forwarding tunnel, radio bearer configuration information needed by the first terminal device to receive service data via the first access network device, or an air interface resource configured by the first access network device for the first terminal device.

6 . A communication method, comprising:

determining, by a first access network device, that a first terminal device is a last terminal device that receives data of a first multicast service via the first access network device in response to the first terminal device being in a handover preparation phase in which the first terminal device is handed over from the first access network device to a second access network device;

sending, by the first access network device, a message to an access and mobility management function network element, wherein the message includes first information, wherein the first information includes identification information of the first multicast service, a request usable to release a first tunnel, and information about the first tunnel, wherein the information about the first tunnel includes a tunnel endpoint identifier (TEID) uniquely identifying the first tunnel, and the first tunnel is usable for transmitting the data of the first multicast service between the first access network device and a multicast user plane function network element;

receiving, by the multicast user plane function network element, the first information; and

releasing, by the multicast user plane function network element, the first tunnel based on the receiving the first information.

7 . The method according to claim 6 , wherein the receiving the first information further includes:

updating, by the first access network device, a quantity of terminal devices that have joined the first multicast service via the first access network device.

8 . The method according to claim 6 , wherein the first information includes identification information of the first multicast service uniquely identifying the first multicast service, wherein the identification information uniquely identifying the first multicast service includes a multicast service ID, a multicast service name, a multicast address, or a multicast group ID.

9 . The method according to claim 6 , wherein the first tunnel is a multicast session tunnel which is shared by terminal devices.

10 . The method according to claim 6 further comprising preparing by the first access network device for the first terminal device, a resource for the handover, wherein the resource includes a forwarding tunnel, radio bearer configuration information needed by the first terminal device to receive service data via the first access network device, or an air interface resource configured by the first access network device for the first terminal device.

11 . The method according to claim 6 further comprising receiving by the first access network device, for preparing the first terminal device for the handover preparation phase, a measurement report of the first terminal device, and making a handover decision on the first terminal device based on the measurement report, where a decision result is handover; and the first access network device sends a handover request to the second access network device, and receives a handover request acknowledgement sent by the second access network device.

12 . A communication system, comprising:

a first access network device configured to determine that a first terminal device is a last terminal device that receives data of a first multicast service via the first access network device in response to the first terminal device being in a handover preparation phase in which the first terminal device is handed over from the first access network device to a second access network device, and send a message to an access and mobility management function network element, wherein the message includes first information, wherein the first information includes identification information of the first multicast service, a request usable to release a first tunnel, and information about the first tunnel, wherein the information about the first tunnel includes a tunnel endpoint identifier (TEID) uniquely identifying the first tunnel, and the first tunnel is usable for transmitting the data of the first multicast service between the first access network device and a multicast user plane function network element.

13 . The communication system according to claim 12 , wherein the first access network device is further configured to update a quantity of terminal devices that have joined the first multicast service via the first access network device.

14 . The communication system according to claim 12 , wherein the first information includes identification information of the first multicast service uniquely identifying-the first multicast service, wherein the identification information uniquely identifying the first multicast service includes a multicast service ID, a multicast service name, a multicast address, or a multicast group ID.

15 . The communication system according to claim 12 , wherein the first tunnel is a multicast session tunnel which is shared by terminal devices.

16 . A communication apparatus, comprising:

a memory storing computer-readable instructions; and

at least one processor connected to the memory, wherein the at least one processor is configured to execute the computer-readable instructions to perform operations including:

determining that a first terminal device is a last terminal device that receives data of a first multicast service via a first access network device in response to the first terminal device being in a handover preparation phase in which the first terminal device is handed over from the first access network device to a second access network device; and

sending a message to an access and mobility management function network element, wherein the message includes first information, wherein the first information includes identification information of the first multicast service, a request usable to release a first tunnel, and information about the first tunnel, wherein the request includes information about the first tunnel including a tunnel endpoint identifier (TEID) uniquely identifying the first tunnel, and the first tunnel is useable for transmitting the data of the first multicast service between the first access network device and a multicast user plane function network element.

17 . The communication apparatus according to claim 16 , wherein the at least one processor is further configured to update a quantity of terminal devices that have joined the first multicast service via the first access network device.

18 . The communication apparatus according to claim 16 , wherein the first information includes identification information of the first multicast service uniquely identifying-the first multicast service, wherein the identification information uniquely identifying the first multicast service includes a multicast service ID, a multicast service name, a multicast address, or a multicast group ID.

19 . The communication apparatus according to claim 16 , wherein the first tunnel is a multicast session tunnel which is shared by terminal devices.

20 . The communication apparatus according to claim 16 , wherein the at least one processor is further configured to send a message to an access and mobility management function network element, wherein the message includes the first information.