Session establishment method and system, and device

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.

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.

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.