Early Synchronization in 5G LTM Cell Switch
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Solution Overview
Problem
Current 5G wireless communication systems face challenges in achieving early synchronization, particularly in layer 1/layer 2 triggered mobility (LTM) scenarios, which can lead to latency and complexity issues, especially when handling dual connectivity and cell switch procedures.
Innovation Solution
The implementation of a method that performs early downlink and uplink synchronization before triggering LTM cell switch execution, including specific bandwidth part (BWP) handling and power ramping procedures to optimize random access procedures, thereby reducing latency and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If early synchronization is performed before LTM cell switch execution, then latency is reduced and synchronization accuracy is improved, but device complexity and procedure complexity increase
Solution Approach 1:
The patent performs downlink and uplink synchronization procedures in advance before the LTM cell switch execution is triggered. Specifically, the UE performs downlink synchronization with the target cell and acquires uplink timing advance information before the actual cell switch occurs, ensuring that when the switch happens, synchronization is already established, thereby reducing latency.
Solution Approach 2:
The synchronization process is divided into separate downlink synchronization and uplink synchronization stages. Downlink synchronization involves receiving synchronization signals and system information from the target cell, while uplink synchronization involves acquiring timing advance information through random access procedures. This segmentation allows each synchronization aspect to be handled independently and efficiently.
2Adaptability or versatility
If bandwidth part operation is performed during random access procedure for LTM candidate cell, then communication flexibility is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts the bandwidth part operation from the random access procedure for LTM candidate cells. Specifically, it is determined that BWP operation should not be performed during the random access procedure on the LTM candidate cell, thereby simplifying the overall procedure and reducing device complexity while maintaining necessary communication flexibility through other means.
3Measurement precision
If early downlink and uplink synchronization is performed before LTM cell switch, then synchronization accuracy is improved, but user plane data loss increases
Solution Approach 1:
The patent performs downlink synchronization by receiving synchronization signals and system information from the target cell before the LTM cell switch. This preliminary downlink synchronization ensures that the UE is properly synchronized with the target cell's downlink timing and frequency, improving synchronization accuracy while minimizing data loss through proper buffer management during the transition.
Data Source
AI summary
The disclosure relates to a fifth-generation (5G) or sixth-generation (6G) communication system for supporting a higher data transmission rate. A method performed by a user equipment (UE) in a wireless communication system is provided. The method comprises receiving, from a base station, a physical downlink control channel (PDCCH) order for a random access procedure on a layer 1/layer 2 triggered mobility (LTM) candidate cell, transmitting a random access preamble for an early timing advance (TA) acquisition for the LTM candidate cell, based on the PDCCH order and receiving, from the base station, a cell switch command including a TA value of the LTM candidate cell, wherein a bandwidth part (BWP) operation is not performed for the LTM candidate cell based on the random access procedure being initiated by the PDCCH order.