User Equipment Handover Failure Handling via Target Cell Context
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Solution Overview
Problem
In existing handover mechanisms, handover failures in 5G New Radio (NR) systems lead to unnecessary delays due to the reliance on source cell context data for re-establishing connections, especially when the user equipment remains within the target cell's service coverage, as in high-speed train or non-terrestrial scenarios, or during conditional handovers.
Innovation Solution
The proposed solution involves a user equipment (UE) that performs a cell selection procedure to determine if the selected cell is a configured target cell, allowing direct continuation of the connection re-establishment procedure using target cell configuration information, thereby avoiding immediate reliance on source cell context data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the user equipment reverts to source cell configuration for connection re-establishment, then the connection can be re-established through source cell context data, but unnecessary delays occur when the user equipment remains within target cell coverage
Solution Approach 1:
The target cell is pre-configured with the user equipment's context data during the handover preparation stage. When handover failure occurs and the user equipment selects the target cell for re-establishment, the connection can be immediately restored using the pre-stored context data, eliminating the delay of retrieving data from the source cell.
2Ease of operation
If the user equipment always uses source cell context data for re-establishment, then the procedure is standardized, but signaling overhead and delays increase when target cell still has valid context
Solution Approach 1:
The target cell autonomously identifies itself as a configured target cell and determines whether to use its locally stored context data for connection re-establishment. This self-service mechanism allows the system to bypass source cell data retrieval when unnecessary, reducing signaling overhead while maintaining procedural simplicity through clear conditional logic.
Data Source
AI summary
A user equipment (UE), a communication system, and a handling method for handover failure are provided. The handover procedure of the UE from a source cell to one or more configured target cells fail. In the method, in response to the handover procedure failing, a cell selection procedure to select a suitable cell is performed, where the cell selection procedure is configured to perform a connection re-establishment procedure. Whether to continue the connection re-establishment procedure is determined according to a determining result of whether a suitable cell is one configured target cell.