Early Uplink Synchronization for Cell Switch Latency Reduction
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Solution Overview
Problem
Current cell switch procedures in the new radio standard involve complete L2 and L1 resets, leading to higher overhead and longer interruption times, which can be improved by reducing mobility latency through mechanisms like L1/L2-triggered mobility and early RA, but these introduce scheduling gaps that need to be minimized.
Innovation Solution
Implementing an early-uplink synchronization (EUS) procedure where user equipment (UE) performs synchronization with a target cell before receiving a cell switch command, allowing for reduced interruption times and minimizing scheduling gaps by acquiring a timing advance value prior to the cell switch command.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If early RA is implemented to shorten interruption time, then interruption time is reduced, but a scheduling gap is introduced where the serving cell cannot schedule the UE
Solution Approach 1:
The UE performs random access procedure to the target cell before receiving the cell switch command, acquiring timing advance value in advance. This preliminary action allows the UE to be ready for uplink transmission immediately upon receiving the cell switch command, eliminating the need for scheduling gap while maintaining short interruption time.
2Reliability
If complete L2 and L1 resets are performed during cell switch, then mobility reliability is improved, but overhead increases and interruption time lengthens
Solution Approach 1:
The patent extracts the essential synchronization function from the complete L1/L2 reset procedure. By performing only the necessary random access procedure to acquire timing advance value before cell switch, the patent eliminates unnecessary L1/L2 resets while maintaining uplink synchronization capability, thereby reducing interruption time without compromising mobility reliability.
Data Source
AI summary
The embodiments of the disclosure provide a method for implementing a cell switch procedure and a user equipment (UE). The method includes: receiving a cell switch configuration for the cell switch procedure from a source cell, wherein the cell switch configuration comprises an early-uplink synchronization (EUS) configuration for an EUS procedure; performing the EUS procedure based on the EUS configuration to obtain a timing advance (TA) value associated with a target cell and a cell switch command from the source cell; in response to receiving the cell switch command, performing the cell switch procedure to the target cell based on the TA value; and transmitting a cell switch complete information to the target cell after completing the cell switch procedure.