UE Session Continuity During Intersystem Change
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communication systems, particularly during intersystem changes from S1 mode to N1 mode or vice versa, user equipment (UE) faces challenges in managing session continuity due to running non-congestion back-off timers, which are not effectively handled, leading to potential re-registration or detach issues.
Innovation Solution
The UE method involves stopping all relevant non-congestion back-off timers upon receiving specific NAS signaling messages during intersystem changes, considering RATC and EPLMNC indicators to ensure seamless re-registration or re-attach procedures, thereby enhancing session continuity by managing timers appropriately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE stops all non-congestion back-off timers during intersystem change, then session continuity is improved, but timer management complexity increases
Solution Approach 1:
The UE proactively stops all non-congestion back-off timers (both 5GSM and ESM timers) before or during the intersystem change process, rather than waiting for potential conflicts to arise. This preliminary action ensures that timer expiration events cannot interfere with the re-registration or re-attach procedures, thereby guaranteeing session continuity while the timer management logic itself remains straightforward.
2Reliability
If the UE handles both 5GSM and ESM timers during intersystem change, then session continuity is improved, but the processing overhead increases
Solution Approach 1:
The UE merges the handling of 5GSM and ESM non-congestion back-off timers into a single unified process. Instead of managing these timer types separately with distinct logic paths, the UE applies a common stopping mechanism to both timer types simultaneously during intersystem change. This consolidation reduces processing overhead and energy consumption while ensuring comprehensive timer management for session continuity.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A method of enhancing session continuity for system interworking is proposed. Upon intersystem change from S1 mode to N1 mode, a UE may perform deregistration when reregistration is required. The UE stops all 5GSM non-congestion back-off timers (501, 504). In addition to the 5GSM non-congestion back-off timers, there may be ESM non-congestion back-off timers running (501). The UE may take the RATC and the EPLMNC indicators in the Re-attempt indicator IE into consideration, and stops all ESM non-congestion timers (504). Upon intersystem change from N1 mode to S1 mode, the UE may perform detach procedure when re-attach is required. The UE stops all ESM non-congestion back-off timers (501, 504). In addition to the ESM non-congestion back-off timers, there may be 5GSM non-congestion back-off timers running (501). The UE may take the RATC and the EPLMNC indicators in the Re-attempt indicator IE into consideration, and stops all 5GSM non-congestion timers (504).