Method, Apparatus, and System for Establishing Session

A system, comprising:

• a session management function (SMF) entity configured to:
• establish a first Protocol Data Unit (PDU) session, wherein the first PDU session is served by a second user plane function (UPF);
• determine that the second UPF needs to be changed;
• and
• send a first request message indicating a PDU session re-establishment;
• and
• an access and mobility management function (AMF) configured to:
• receive the first request message from the SMF entity;
• send a first message to a terminal in response to the first request message, wherein the first message comprises PDU session release time information associated with the first PDU session;
• receive a second message comprising a PDU session establishment request and a first PDU session identifier (ID) from the terminal, wherein the first PDU session ID is associated with the first PDU session;
• and
• send the second message to the SMF entity based on an association between the first PDU session ID and an SMF ID associated with the SMF entity stored in the AMF entity, and
• wherein the SMF entity is further configured to:
• establish a new PDU session, wherein the new PDU session is served by a first UPF;
• and
• release the first PDU session according to the PDU session release time information.

An apparatus, comprising:

• at least one processor;
• and
• a memory coupled to the at least one processor and configured to store programming instructions that, when executed by the at least one processor, cause the apparatus to:
• establish a first Protocol Data Unit (PDU) session using a session management function (SMF) entity;
• receive a first message indicating a PDU session re-establishment from an access and mobility management function (AMF) entity, wherein the first message comprises a PDU session release time information associated with the first PDU session;
• and
• transmit a second message comprising a PDU session establishment request and a first PDU session identifier (ID) to the AMF entity, wherein the first PDU session ID is associated with the first PDU session, wherein the AMF entity stores an association between the first PDU session ID and an SMF ID associated with the SMF entity, and wherein the first PDU session ID indicates that the AMF entity selects the SMF entity for establishing a new PDU session;
• and
• release the first PDU session according to the PDU session release time information.

A network apparatus, comprising:

• at least one processor;
• and
• a memory coupled to the at least one processor and configured to store programming instructions that, when executed by the at least one processor, cause the network apparatus to:
• send a first message indicating a Packet Data Unit (PDU) session re-establishment to a terminal, wherein the first message comprises a PDU session release time information associated with the first PDU session;
• receive a second message comprising a PDU session establishment request and a first PDU session identifier (ID) from the terminal, wherein the first PDU session ID is associated with a first PDU session;
• and
• send the second message to a session management function (SMF) entity based on an association between the first PDU session ID and an SMF ID associated with the SMF entity.