Serving Cell Change With Parallel Random Access
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Solution Overview
Problem
The existing Conditional Handover (CHO) and Conditional PSCell Change (CPC) procedures in telecommunication networks experience delays and interruptions due to sequential execution of handovers to secondary target cells, leading to radio link failures and increased interruption times.
Innovation Solution
A method and apparatus that enable a user equipment (UE) to perform simultaneous or sequential random access procedures to multiple candidate target cells during a serving cell change procedure, allowing access to a target cell after the completion of the change, thereby reducing interruption time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sequential handover execution to candidate target cells is performed, then device complexity is reduced, but handover interruption time increases and reliability decreases
Solution Approach 1:
The UE performs random access procedures to multiple candidate target cells in advance before the actual handover is triggered. By pre-establishing connections to candidate cells, the handover execution time is significantly reduced when the handover condition is met, as the UE can immediately switch to the prepared target cell without performing random access at that moment.
Solution Approach 2:
The patent enables dynamic selection of target cell from multiple candidates based on real-time conditions. The UE maintains multiple active protocol stacks simultaneously and can dynamically switch between them based on which candidate cell is most suitable, making the handover process adaptive and flexible rather than following a fixed sequential order.
2Device complexity
If sequential handover execution to candidate target cells is performed, then device complexity is reduced, but handover reliability decreases
Solution Approach 1:
The UE prepares multiple candidate target cells in advance with full protocol stacks configured and ready. This creates a buffer or cushion against handover failures - if the first candidate cell handover fails, the UE already has alternative target cells prepared and can immediately attempt handover to the next candidate without returning to the source cell, thus preventing radio link failure.
Solution Approach 2:
The patent changes the state parameter of candidate target cells from 'inactive/sequential' to 'active/simultaneous'. By activating multiple protocol stacks simultaneously and maintaining them in a ready state, the system transforms the handover mechanism from a sequential trial-and-error process to a parallel preparedness model, significantly improving handover success probability.
3Loss of time
If simultaneous random access to multiple candidate target cells is performed, then handover interruption time is reduced, but device complexity increases
Solution Approach 1:
The patent segments the handover process into independent parallel random access procedures for each candidate target cell. Each random access procedure operates independently with its own protocol stack, allowing them to execute simultaneously without interfering with each other. This segmentation makes the complex simultaneous operations manageable and implementable.
Solution Approach 2:
The UE implements a universal protocol stack structure that can serve multiple candidate target cells simultaneously. Each protocol stack is designed to be multi-functional, capable of handling communication with any candidate target cell, which reduces the overall complexity compared to having separate dedicated stacks for each cell.
4Loss of time
If simultaneous random access to multiple candidate target cells is performed, then handover interruption time is reduced, but device resource requirements increase
Solution Approach 1:
The UE performs partial random access procedures simultaneously to multiple candidate cells rather than completing full handover sequences. By performing only the necessary random access phase in parallel and then selecting the successful target, the UE achieves the time reduction benefit without the excessive energy consumption of completing multiple full handover procedures.
Data Source
AI summary
Embodiments of the present disclosure relate to device, method, apparatus and computer readable storage medium of serving cell change procedure utilizing the multiple candidate target cells. The method comprises receiving, from a second device, configuration information associated with a serving cell change procedure of the first device, the configuration information indicating at least a first candidate cell managed by a third device and a second candidate cell managed by a fourth device available for the serving cell change procedure; performing, during the serving cell change procedure, a first random access procedure to access the first candidate cell and a second random access procedure to access the second candidate cell; and accessing to a target cell determined from the first candidate cell and the second candidate cell after the serving cell change procedure is completed. In this way, the interruption time corresponding to CHO or CPC procedure when multiple candidates are available can be reduced.