NAS-Level Congestion Control Timer Management Across 5GS and EPS Networks
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Solution Overview
Problem
Current 3GPP specifications do not clearly define the applicability and derivation of NAS-level congestion control timers during intersystem changes between 5G and EPS networks, leading to ambiguity in mobility management procedures.
Innovation Solution
A method and apparatus for a user equipment (UE) to manage NAS-level congestion control timers by starting and maintaining timers across different wireless networks, including deriving timer values when performing intersystem changes from 5GS to EPS or vice versa, using common or separate timers based on network equivalency and access types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE uses separate NAS-level congestion control timers for 5GS and EPS networks, then the congestion control can be optimized for each specific network type, but the device complexity and difficulty of timer management increase
Solution Approach 1:
The patent applies universality by making the NAS-level congestion control timer (T3346) applicable to both 5GS and EPS networks. The timer is started based on congestion indications from either network type and continues to run across intersystem changes, providing a unified congestion control mechanism that reduces complexity while maintaining effectiveness for both network types.
Solution Approach 2:
The patent merges the congestion control timer functionality for 5GS and EPS into a single shared timer T3346. Instead of maintaining separate timers for each network type, the same timer is used to control congestion back-off behavior across both 5GS and EPS, simplifying the timer management architecture.
2Ease of operation
If the UE stops the congestion control timer when changing PLMN, then the timer management follows current 3GPP specifications, but congestion control effectiveness is reduced during mobility procedures
Solution Approach 1:
The patent applies preliminary action by starting the congestion control timer T3346 in advance when a congestion indication is received from either 5GS or EPS network. The timer is started before any potential intersystem change occurs, ensuring that congestion control is already in effect when mobility procedures happen, thereby preventing congestion-related service disruptions during transitions.
Solution Approach 2:
The patent ensures continuity of the congestion control timer across intersystem changes between 5GS and EPS. The timer continues to run without being stopped when the UE performs mobility procedures or network type changes, maintaining continuous congestion control effectiveness throughout the mobility process rather than interrupting it.
3Productivity
If the UE derives timer values from running timers during intersystem change, then seamless mobility is achieved, but the precision of timer value derivation becomes critical
Solution Approach 1:
The patent applies copying by deriving the T3346 timer value from the remaining value of a running 5GMM congestion control timer during intersystem change from 5GS to EPS. The UE copies the remaining time from the source timer to initialize the target timer, enabling seamless continuity of congestion control without requiring precise recalculation or re-measurement of timer values.
Data Source
AI summary
Various examples pertaining to application of non-access stratum (NAS)-level congestion control timer values at intersystem change in mobile communications are described. A user equipment (UE) receives an indication of a NAS-level congestion control from a first type of wireless network. The UE starts a timer responsive to the receiving of the indication of the NAS-level congestion control. The UE then performs an intersystem change from the first type of wireless network to a second type of wireless network different from the first type by utilizing the timer.