Uplink Synchronization Using Pre-Acquired TA for Cell Switching
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Solution Overview
Problem
Existing methods for uplink synchronization during cell switching in wireless communication result in significant latency due to the time required for acquiring Timing Advance (TA) information, especially during frequent cell-to-cell switching.
Innovation Solution
A method and apparatus that enable a terminal device to send an uplink reference signal to a network device of a candidate cell to determine TA information, which is then indicated by the network device of the serving cell, allowing the terminal device to perform uplink synchronization based on this pre-acquired TA information before switching cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the terminal device switches from serving cell to target cell first, then performs uplink access to obtain TA information, then the cell switching process is completed, but the uplink synchronization is delayed due to the time required for TA information acquisition
Solution Approach 1:
The terminal device sends uplink reference signals to candidate cells before switching occurs. The network device determines TA information for candidate cells in advance and includes it in the cell switching command. This preliminary acquisition of TA information eliminates the time delay that would otherwise occur after cell switching, resolving the contradiction between switching speed and synchronization timeliness.
2Measurement precision
If the terminal device performs uplink access in the target cell to obtain TA information after switching, then the TA information is accurate for the target cell, but the overall process efficiency is reduced due to sequential operations
Solution Approach 1:
TA information for candidate cells is determined in advance by the network device before the terminal device switches cells. The switching command includes pre-calculated TA information for the target cell, ensuring both accuracy and efficiency. This eliminates the need for post-switching uplink access while maintaining precise TA values.
Solution Approach 2:
The network device acts as an intermediary that pre-processes and determines TA information for multiple candidate cells. Instead of the terminal device performing sequential uplink access after switching, the network device provides the necessary TA information through the switching command itself, streamlining the process.
Data Source
AI summary
An uplink synchronization method is performed by a terminal device, and includes: sending an uplink reference signal to a network device of at least one candidate cell, wherein the uplink reference signal is configured by a network device of a serving cell where the terminal device is located, and is used to determine timing advance (TA) information by the network device of the at least one candidate cell; receiving TA indication information sent by the network device of the serving cell where the terminal device is located, wherein the TA indication information sent by the network device of the serving cell at least comprises: TA information of a target cell to be switched to by the terminal device among the at least one candidate cell; and performing uplink synchronization according to the TA information of the target call, based on the network device of the serving cell instructing the terminal device to switch to the target cell.