Timing Advance Maintenance for Low-Latency L1/L2 Mobility
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing wireless communication systems, particularly 5G NR, face challenges in improving latency and efficiency during L1/L2 inter-cell mobility due to the need for frequent timing advance (TA) updates when switching between cells, which increases activation latency.
Innovation Solution
A UE maintains timing advance (TA) for deactivated cells based on reception time differences, allowing autonomous application upon activation without additional signaling, thereby reducing the need for real-time updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If frequent timing advance updates are performed during cell switching, then timing synchronization is maintained, but activation latency increases
Solution Approach 1:
The UE derives and maintains TA values for deactivated cells in advance based on Rx time differences measured from downlink signals. When a deactivated cell is activated, the pre-computed TA can be immediately applied without waiting for network signaling, thus reducing activation latency while maintaining timing synchronization.
Solution Approach 2:
The UE autonomously derives TA values for deactivated cells using its own measurements of Rx time differences from downlink reference signals. This self-service approach eliminates the need for continuous network-provided TA updates, reducing signaling overhead and activation latency while maintaining reliable timing synchronization.
2Measurement precision
If real-time TA updates are requested for activated cells, then timing accuracy is maintained, but signaling overhead increases
Solution Approach 1:
The UE independently derives TA values by measuring Rx time differences from downlink signals and applying appropriate offsets. This self-service mechanism maintains timing accuracy without requiring continuous real-time TA updates from the network, thereby reducing signaling overhead and information loss.
Solution Approach 2:
The UE uses feedback from downlink signal measurements (Rx time differences) to autonomously adjust and maintain TA values. This feedback-based approach allows the UE to maintain timing accuracy using locally available information rather than relying on continuous network feedback, reducing signaling overhead.
Data Source
AI summary
Aspects presented herein may improve the latency and efficiency of L1/L2 inter-cell mobility by providing an improved TA management for a UE. In one aspect, a UE derives a TA for a set of deactivated cells based on an Rx time difference between an active cell and the set of deactivated cells. The UE maintains the TA for the set of deactivated cells prior to an activation of the set of deactivated cells. The UE applies the TA to the set of deactivated cells or to an initial Tx to the set of deactivated cells in response to the activation of the set of deactivated cells. The set of deactivated cells may correspond to one deactivated cell or a deactivated TAG that includes multiple deactivated cells.