Session establishment method and system, and device

1. A session establishment method, comprising:

obtaining, by a mobility management entity, group identification information of a group to which a terminal belongs, the group being a communication group in which a plurality of terminals communicate with each other;

determining, by the mobility management entity based on the group identification information, a session management entity that serves the group to which the terminal belongs;

sending, by the mobility management entity, the group identification information to the session management entity;

receiving, by the session management entity, the group identification information;

determining, by the session management entity based on the group identification information, a user plane function entity that serves the group to which the terminal belong, so that the same used plane function entity is selected for the plurality of terminals in the group for group communication between the plurality of terminals;

sending, by the session management entity, path information to the user plane function entity, wherein the path information is used to establish a user plane path of the terminal.

2. The method according to claim 1 , wherein the determining, by the mobility management entity based on the group identification information, a session management entity that serves the group to which the terminal belongs comprises:

sending, by the mobility management entity, a session management entity request message to a database entity, wherein the session management entity request message requests information about the session management entity that serves the group to which the terminal belongs; and

receiving, by the mobility management entity, a session management entity response message from the database entity, wherein the session management entity response message carries the information about the session management entity that serves the group to which the terminal belongs.

3. The method according to claim 1 , wherein the determining, by the mobility management entity based on the group identification information, a session management entity that serves the group to which the terminal belongs comprises:

determining, by the mobility management entity based on the group identification information and information about the session management entity that serves the group to which the terminal belongs.

4. The method according to claim 1 , wherein the obtaining, by a mobility management entity, group identification information of a group to which a terminal belongs comprises:

obtaining, by the mobility management entity, a context of the terminal, wherein the context of the terminal comprises the group identification information.

5. The method according to claim 4 , wherein before the obtaining, by the mobility management entity, the context of the terminal, the method further comprises:

receiving, by the mobility management entity, a registration request from the terminal, wherein the registration request carries an identity of the terminal;

obtaining, by the mobility management entity, subscription data of the terminal from a database entity based on the identity of the terminal, wherein the subscription data comprises the group identification information; and

storing, by the mobility management entity, the group identification information into the context of the terminal.

6. A session establishment method, comprising:

receiving, by a session management entity, a first session establishment request of a first terminal from a mobility management entity, wherein the first session establishment request comprises group identification information of a group to which the first terminal belongs, the group being a communication group in which a plurality of terminals communicate with each other;

determining, by the session management entity based on the group identification information, a user plane function entity that serves the group to which the first terminal belong, so that the same user plane function entity is selected for the plurality of terminals in the group for group communication between the plurality of terminals; and

sending, by the session management entity, path information to the user plane function entity, wherein the path information is used to establish a user plane path of the first terminal.

7. The method according to claim 6 , wherein the first terminal is not the first to initiate a session establishment procedure in the group, the determining of the user plane function entity comprises:

determining, by the session management entity, the user plane function entity according to a stored correspondence between the group identification information and the user plane function entity.

8. The method according to claim 7 , before the determining of the user plane function entity, the method further comprises:

receiving, by the session management entity, a second session establishment request of a second terminal from the mobility management entity, wherein the second session establishment request comprises the group identification information, wherein the second terminal belongs to the group;

determining, by the session management entity, the user plane function entity based on the group identification information; and

storing, by the session management entity, the correspondence between the group identification information and the user plane function entity.

9. The method according to claim 6 , wherein the determining of the user plane function entity comprises:

determining, by the session management entity, based on a location of the first terminal, load of the user plane function entity, or a capability of the user plane function entity, the user plane function entity that serves the group to which the first terminal belongs.

10. The method according to claim 6 , wherein the path information comprises: an endpoint address or an endpoint identifier of an access device connected to the first terminal, or an address of the access device.

11. A communication system, comprising:

a mobility management entity and a session management entity;

wherein the mobility management entity is configured to:

obtain, group identification information of a group to which a terminal belongs, the group being a communication group in which a plurality of terminals communicate with each other;

determine, based on the group identification information, a session management entity that serves the group to which the terminal belongs; and

send, the group identification information to the session management entity, wherein the group identification information determines a user plane function entity that serves the group to which the terminal belongs, so that the same user plane function entity is selected for the plurality of terminals in the group for group communication between the plurality of terminals;

wherein the session management entity is configured to:

receive the group identification information;

determine based on the group identification information, a user plane function entity that serves the group to which the terminal belong, so that the same user plane function entity is selected for the plurality of terminals in the group for group communication between the plurality of terminals, and

send path informaton to the user plane function entity, wherein the path information is used to establish a user plane path of the terminal.

12. The communication system according to claim 11 , wherein the mobility management entity is further configured to:

send a session management entity request message to a database entity, wherein the session management entity request message requests information about the session management entity that serves the group to which the terminal belongs;

and

receive a session management entity response message sent from the database entity, wherein the session management entity response message carries the information about the session management entity that serves the group to which the terminal belongs.

13. The communication system according to claim 11 , wherein the mobility management entity is further configured to:

determine, based on the group identification information and information about the session management entity that serves the group to which the terminal belongs, the session management entity that serves the group to which the terminal belongs, wherein the context of the terminal comprises.

14. The communication system according to claim 11 , wherein the mobility management entity is further configured to:

obtain a context of the terminal, wherein the context of the terminal comprises the group identification information.

15. The communication system according to claim 14 , wherein before the obtaining the context of the terminal, the mobility management entity is further configured to:

receive a registration request from the terminal, wherein the registration request carries an identity of the terminal;

obtain subscription data of the terminal from a database entity based on the identity of the terminal, wherein the subscription data comprises the group identification information; and

store the group identification information into the context of the terminal.

16. A network device that serves as a session management entity, comprising:

a processor; and

a memory storing instructions that, when executed by the processor, cause the processor to:

receive a first session establishment request of a first terminal from a mobility management entity, wherein the first session establishment request comprises group identification information of a group to which the first terminal belongs, the group being a communication group in which a plurality of terminals communicate with each other;

determine based on the group identification information, a user plane function entity that serves the group to which the first terminal belong, so that the same user plane function entity is selected for the plurality of terminals in the group for group communication between the plurality of terminals; and

send path information to the user plane function entity, wherein the path information is used to establish a user plane path of the first terminal.

17. The network device according to claim 16 , wherein the first terminal is not the first to initiate a session establishment procedure in the group, and the processor is further caused to:

determine the user plane function entity according to a stored correspondence between the group identification information and the user plane function entity.

18. The network device according to claim 17 , before the determining of the user plane function entity, the processor is further caused to:

receive a second session establishment request of a second terminal from the mobility management entity, wherein the second session establishment request comprises the group identification information, and the second terminal belongs to the group;

determine the user plane function entity based on the group identification information; and

store the correspondence between the group identification information and the user plane function entity.

19. The network device according to claim 16 , wherein the processor is further caused to:

determine, based on a location of the first terminal, load of the user plane function entity, or a capability of the user plane function entity, and the user plane function entity that serves the group to which the first terminal belongs.

20. The network device according to claim 16 , wherein the path information comprises: an endpoint address or an endpoint identifier of an access device connected to the first terminal, or an address of the access device.