5G UE Congestion Control Timer Management
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Solution Overview
Problem
In 5G systems, the processes for congestion control in network slices and how terminals handle rejection responses in session management are not clearly defined, especially when multiple congestion controls are activated, leading to confusion in identifying the targeted timer for session management requests.
Innovation Solution
A mechanism and communication control method are implemented to manage congestion control for each network slice, allowing terminal apparatuses and core network apparatuses to perform congestion control initiated by either the terminal or the network, enabling effective management of PDU sessions and session management across different network slices and access networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If congestion control mechanisms are implemented for both EPS and network slices simultaneously, then congestion control coverage is improved, but the complexity of identifying and managing multiple congestion control timers increases
Solution Approach 1:
The patent segments congestion control management by introducing separate timer structures for EPS-level congestion control (T3346) and network slice-level congestion control (T3354). This segmentation allows independent management of each congestion control mechanism, resolving the complexity of simultaneously handling multiple congestion controls by treating them as distinct, manageable units rather than a monolithic system.
Solution Approach 2:
The patent adds a new dimension to congestion control by introducing slice-specific timer management alongside existing EPS-level timers. This dimensional expansion allows the system to track congestion control states at multiple levels (EPS and network slice) simultaneously, improving reliability while maintaining clarity through structured, multi-layered timer management.
2Reliability
If multiple congestion control timers are activated simultaneously, then comprehensive congestion control is achieved, but the difficulty of identifying the targeted timer for session management requests increases
Solution Approach 1:
The patent implements feedback mechanisms where the network includes explicit timer identification information in rejection responses (indicating whether T3346 or T3354 is activated). This feedback allows the terminal to accurately identify which timer is targeted without ambiguity, resolving the difficulty of detecting and measuring the correct timer state among multiple activated congestion control mechanisms.
Solution Approach 2:
The patent uses distinct identification markers (analogous to color coding) for different timer types - T3346 for EPS-level congestion control and T3354 for network slice-level congestion control. This clear differentiation through unique identifiers enables the terminal to easily distinguish and respond to the appropriate timer based on the rejection cause and included identification information.
3Measurement precision
If congestion control is managed at both EPS and network slice levels, then congestion control precision is improved, but the loss of information regarding which congestion control is targeted increases
Solution Approach 1:
The patent applies preliminary action by having the network pre-identify and indicate the targeted congestion control timer in the rejection response before the terminal needs to make decisions. This preliminary indication of timer identity (T3346 or T3354) prevents information loss by providing the terminal with explicit guidance on which congestion control mechanism is active, eliminating ambiguity in subsequent timer management actions.
Data Source
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AI summary
In a case that a network (NW) applies a plurality of congestion controls, various kinds of congestion control identification information along with a back-off timer (Session Management (SM) timer) are notified such that a terminal apparatus (UE) can apply a congestion control expected by the NW. Alternatively, in a case that the UE receives an NW-initiated SM request with the back-off timer activated, the UE is allowed to identify an SM timer intended by the NW-initiated SM request. Alternatively, in a case that the UE receives the NW-initiated SM request with the back-off timer activated, the UE is allowed to modify the association of the activated back-off timer and the congestion control to be applied. Thus, a communication control method for the terminal to apply the congestion control expected by the NW in the congestion controls applied by the NW in 5G congestion control that applies a plurality of congestion controls is provided.