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 indicate and manage congestion control are not clearly defined, especially in cases of session management requests and timer management across multiple congestion controls.
Innovation Solution
A User Equipment (UE) includes a controller that stops a timer for Single Network Slice Selection Assistance information (S-NSSAI) upon receiving a PDU session modification command and provides S-NSSAI during session establishment, enabling effective congestion control management for each network slice.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If congestion control is applied for both EPS and network slices simultaneously, then congestion control coverage is improved, but process clarity and identification reliability deteriorate
Solution Approach 1:
The patent segments congestion control into two distinct parts: EPS-level congestion control and network slice-level congestion control. Each level has its own timer management rules and rejection response formats. The UE and network separately manage timers for each congestion control type, allowing both to coexist without confusion. This segmentation resolves the contradiction by maintaining clear, separate processes for each congestion control mechanism while providing comprehensive coverage.
Solution Approach 2:
The patent introduces a new dimension of congestion control by adding network slice-specific timers and rejection responses to the existing EPS congestion control framework. Instead of mixing both controls in a single process, the patent creates a hierarchical structure where EPS-level controls operate at one dimension and slice-level controls operate at another dimension, each with its own timer management rules. This dimensional separation maintains process clarity while achieving comprehensive congestion control coverage.
2Reliability
If multiple congestion control timers are activated simultaneously, then congestion control capability is improved, but timer identification accuracy deteriorates
Solution Approach 1:
The patent segments timer management by creating distinct timer types: T3346 for EPS-level congestion control and slice-specific timers for network slice congestion control. Each timer type has unique identification rules and management procedures. When multiple timers are activated, the UE and network can precisely identify which timer corresponds to which congestion control level through these segmentation rules, maintaining high identification accuracy while supporting multiple simultaneous timers.
Solution Approach 2:
The patent introduces rejection response messages as intermediaries that carry explicit timer identification information. When the network applies congestion control, it sends rejection responses that specify which timer should be activated and which congestion control level applies. This intermediary mechanism ensures accurate timer identification even when multiple congestion control timers are simultaneously active, resolving the contradiction between enhanced capability and identification precision.
3Loss of information
If rejection response includes detailed congestion control information, then information completeness is improved, but message complexity increases
Solution Approach 1:
The patent segments rejection response information into EPS-level fields and network slice-level fields. Each rejection response contains only the relevant congestion control information for its specific level, avoiding the need to include all possible congestion control details in every message. This segmentation reduces message complexity while maintaining information completeness for the applicable congestion control scenario.
Solution Approach 2:
The patent applies partial action by including only the necessary congestion control information in each rejection response based on the specific scenario. Rather than always including complete congestion control details for both EPS and network slice levels, the message includes only the relevant portion needed for that particular rejection case, reducing overall message complexity while maintaining sufficient information completeness.
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.