IMS UE Context Recovery Before SIP Retry Delays
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Solution Overview
Problem
The loss of UE context information during internet protocol multimedia subsystem (IMS) procedures results in prolonged time and significant power consumption due to repeated transmissions of IMS session initiation protocol (SIP) messages when the core network entity fails to maintain accurate UE context, leading to connection drops.
Innovation Solution
A user equipment (UE) proactively performs a non-access stratum (NAS) procedure when a synchronization timer associated with the connection is running and an IMS response is not received within the IMS Procedure Failure Reset Timer, reestablishing the UE context to facilitate timely receipt of response messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE repeatedly transmits IMS SIP messages when context is lost, then the UE attempts to maintain service continuity, but the time and power consumption increase significantly
Solution Approach 1:
The UE performs a NAS procedure proactively before the IMS procedure completely fails, when the synchronization timer is still running. This preliminary action reestablishes the UE context at the core network entity, preventing the need for repeated SIP message transmissions and reducing the time to complete the IMS procedure.
2Reliability
If the UE repeatedly transmits IMS SIP messages when context is lost, then the UE attempts to maintain service continuity, but the power consumption increases significantly
Solution Approach 1:
The UE performs a NAS procedure proactively before the IMS procedure completely fails, when the synchronization timer is still running. This preliminary action reestablishes the UE context at the core network entity, preventing the need for repeated SIP message transmissions and reducing power consumption.
3Loss of time
If the UE performs a NAS procedure to reestablish context, then the time and power consumption are reduced, but the device complexity increases
Solution Approach 1:
The UE monitors the state of the synchronization timer as a parameter to decide when to perform the NAS procedure. By changing the operational parameter (timer state) rather than the fundamental procedure structure, the solution reduces time loss without significantly increasing device complexity.
Data Source
AI summary
Certain aspects of the present disclosure provide techniques for managing loss of user equipment (UE) context information during internet protocol multimedia subsystem (IMS) procedures. An example method includes starting an internet protocol multimedia subsystem (IMS) procedure failure reset timer, transmitting, while the IMS Procedure Failure Reset Timer is running, one or more IMS session initiation protocol (SIP) messages to a network entity, detecting that the IMS Procedure Failure Reset Timer has expired without receiving an IMS response message from the network entity responding to the one or more IMS SIP messages, determining, in response to detecting that the IMS Procedure Failure Reset Timer has expired without receiving an IMS response message, that a synchronization timer associated with a connection between the UE and the network entity is running, and performing, based on the determination that the synchronization timer is running, a non-access stratum (NAS) procedure with the network entity.