SMF Session Context Deletion via UDM Trigger in 5G
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Solution Overview
Problem
In 5G mobile communications systems, there is a challenge in deleting the session context from the Session Management Function (SMF) after a terminal is abnormally deregistered, as the context remains stored, preventing the establishment of a new session context.
Innovation Solution
A method where the Unified Data Management (UDM) triggers the old Session Management Function (SMF) to delete the PDU session context by sending a PDU session release request, ensuring that the session context is properly deleted after abnormal deregistration, allowing for the reestablishment of a new session context when the terminal reconnects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE is abnormally deregistered from the network, then the MM context can be deleted from the AMF, but the SM context remains stored in the SMF, preventing new session establishment
Solution Approach 1:
The patent introduces the UDM (Unified Data Management) as an intermediary entity that coordinates the deletion of SM context from the SMF during abnormal deregistration. The UDM receives the deregistration request from the AMF, validates the UE identity, and then triggers the SMF to delete the associated SM context, ensuring complete deregistration while maintaining system reliability
Solution Approach 2:
The patent implements preliminary action by having the AMF send a delete request message to the UDM before the actual SM context deletion occurs. This preliminary coordination ensures that the SM context is properly identified and marked for deletion, allowing the SMF to accurately remove the correct context and enabling subsequent new session establishment
2Stability of the object's composition
If the SM context is not deleted after abnormal deregistration, then the network maintains connection state for potential recovery, but the terminal cannot establish a new session context
Solution Approach 1:
The patent extracts the SM context deletion function from the normal deregistration flow by introducing a separate delete request message mechanism. The AMF sends this delete request to the UDM, which then triggers the SMF to extract and remove the SM context, separating the maintenance of MM context from the deletion of SM context to resolve the contradiction between stability and productivity
3Reliability
If the AMF sends a delete request message to the UDM, then the SM context can be deleted from the SMF, but additional signaling messages are required
Solution Approach 1:
The patent applies multi-functionality by having the UDM serve multiple purposes: it acts as both the authentication server and the coordinator for SM context deletion. The UDM receives the delete request from the AMF, validates the UE identity using its authentication functions, and then triggers the SMF to delete the context, consolidating multiple functions into a single entity to reduce overall system complexity
Data Source
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AI summary
A method and an apparatus for deleting a session context are provided, to resolve a technical problem of how to delete an SM context from an SMF after abnormal network disconnection. The method includes: receiving, by a session management function entity, a packet data unit PDU session release request; and deleting, by the session management function entity based on the PDU session release request, a PDU session context that is stored in the session management function entity and that is of a terminal, where the PDU session context is a PDU session context that is not deleted after the terminal is abnormally deregistered.