Cell Switch Command Synchronization Timing
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Solution Overview
Problem
Current cell change procedures in wireless communication systems result in significant data interruption and delay due to the need for UE L1/L2/L3 processing before downlink synchronization on the target cell, which includes time waiting for reference signals, leading to inefficiencies in handover processes.
Innovation Solution
Performing downlink synchronization on the target cell before initiating UE L1/L2/L3 processing procedures, such as L2 reconfiguration, RF retuning, and security updates, to reduce interruption time and improve handover efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If UE performs L1/L2/L3 processing before downlink synchronization on target cell, then processing can be completed systematically, but data interruption time increases due to waiting for reference signals
Solution Approach 1:
The patent applies preliminary action by performing downlink synchronization on the target cell before executing L1/L2/L3 processing procedures. Specifically, the UE performs downlink synchronization including obtaining downlink timing and frequency information, and performing random access procedure on the target cell prior to completing L2 reconfiguration, L3 reconfiguration, RF retuning, and baseband retuning. This reordering reduces data interruption time by eliminating the waiting period for reference signals during processing.
2Productivity
If downlink synchronization is performed before L1/L2/L3 processing, then data interruption time is reduced, but the system must coordinate multiple procedures in a new sequence
Solution Approach 1:
The patent applies dynamics by making the cell change procedure adaptive and flexible. The UE dynamically adjusts the execution sequence based on received commands and conditions. The method supports both RACH-based and RACH-less cell switch procedures, and can handle conditional handover commands where the UE performs downlink synchronization when specific handover conditions are met. This dynamic approach improves handover efficiency while managing coordination complexity through standardized procedures.
Data Source
AI summary
Apparatus and methods are provided for enhanced cell change procedure. In one novel aspect, downlink synchronization on the target cell is performed before performing one or more UE L1/L2/L3 processing procedures. In one embodiment, the command for cell change is a cell switch command. In one embodiment, the cell switch command is carried by a MAC control element (CE). In one embodiment, the command for cell change is a conditional handover command, and wherein the UE performs downlink synchronization on the target cell when at least one handover condition is met. In one embodiment, the cell switch procedure is a random access channel (RACH) based cell switch. In another embodiment, the cell switch procedure is a RACH-less cell switch procedure.