Dynamic T400 Timer Configuration for NR Sidelink PC5-RRC Stability
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Solution Overview
Problem
Existing technologies face challenges in efficiently monitoring and managing the PC5-RRC configuration procedure in NR SL mode 1, particularly due to radio link problems on the Uu interface, which can lead to premature release of the PC5 link and disruption of V2X services.
Innovation Solution
The method involves configuring a SL UE to handle and monitor PC5 RRC procedures and related timers based on the status of the Uu interface. This includes configuring different timer values or extending the T400 timer under specific conditions such as physical layer problems, connection reestablishment, or handover procedures, to ensure accurate monitoring of the PC5 RRC configuration procedure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single fixed timer value is used for monitoring PC5 RRC configuration procedure, then the configuration is simple, but the timer may expire prematurely due to Uu interface issues causing unnecessary PC5 link release
Solution Approach 1:
The patent implements dynamic timer adjustment by configuring multiple timer values (first timer value for normal operation, second timer value for exceptional conditions) and selecting appropriate values based on Uu interface status. When exceptional conditions are detected (physical layer problems, connection reestablishment, handover), the system switches to the second timer value which extends the monitoring period, preventing premature PC5 link release while maintaining simple configuration structure.
2Reliability
If the timer is extended to account for Uu interface issues, then PC5 link stability improves, but the monitoring time increases causing service disruption
Solution Approach 1:
The patent applies local quality by differentiating timer values based on specific operational conditions rather than using a uniform extension. The second timer value is specifically configured for exceptional conditions (physical layer problems, connection reestablishment, handover procedures), while the first timer value remains applicable for normal operation. This condition-specific approach ensures timer extension only when necessary, minimizing overall service disruption while maintaining PC5 link stability during critical Uu interface issues.
3Measurement precision
If multiple timer values are configured based on Uu interface status, then accurate monitoring is achieved, but the device complexity increases
Solution Approach 1:
The patent implements parameter changes by configuring multiple timer values (first and second timer values) with different durations based on Uu interface operational status. The system monitors specific parameters (physical layer status, connection state, handover procedures) and adjusts the timer parameter accordingly. This approach enables accurate monitoring differentiation between normal and exceptional conditions while maintaining manageable complexity through structured parameter configuration.
Data Source
AI summary
Systems, methods, apparatuses, and computer program products for monitoring PC5 interface to radio resource control (PC5-RRC) configuration procedure, e.g., in new radio (NR) sidelink (SL) mode 1, are provided. One method may include configuring a SL user equipment (UE) with behaviors for handling and monitoring PC5-RRC procedures and one or more related timers by taking into account a status of an interface between the SL UE and the network node.