Conditional Handover Timer for Radio Link Failure Reporting
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Solution Overview
Problem
In ultra-dense 5G networks, the complex and frequent cell handovers due to dense micro base station deployment lead to inaccurate handover failure reporting, making it difficult for base stations to adjust and improve mobility performance effectively.
Innovation Solution
A method where user equipment (UE) receives a conditional handover command from a base station, determines handover decision parameters for target cells, starts a timer and executes handover only when the target cell meets specific conditions, and records detailed handover information in a radio link failure-report to accurately pinpoint and address handover failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If immediate handover execution is implemented upon receiving handover command, then handover speed is improved, but handover failure reporting accuracy deteriorates
Solution Approach 1:
The patent applies preliminary action by starting a handover timer T304 immediately upon receiving the handover command, before the actual handover execution. This timer records the timing information in advance, which can be used later to accurately determine whether a radio link failure occurred during handover or before handover, thereby improving failure reporting accuracy without delaying handover execution
Solution Approach 2:
The patent implements feedback by using the handover timer T304 to provide timing information back to the network side. When a radio link failure occurs, the UE can report the T304 timer status to help the network accurately identify whether the failure happened during conditional handover evaluation or before handover, enabling precise failure analysis and reporting
2Measurement precision
If conditional handover with timer evaluation is implemented, then handover failure reporting accuracy is improved, but handover execution time increases
Solution Approach 1:
The handover timer T304 is started in advance upon receiving the handover command, preparing the timing information before handover execution is needed. This preliminary timing setup enables accurate failure reporting without adding evaluation delays during the actual handover process
Solution Approach 2:
The handover timer T304 automatically tracks the handover process timing without requiring additional network commands or UE processing. The timer self-manages the timing recording and can be reported to the network when needed, eliminating the need for separate timing measurement mechanisms
3Difficulty of detecting and measuring
If detailed handover information recording is implemented, then failure analysis capability is improved, but signaling overhead increases
Solution Approach 1:
The patent extracts only the essential timing information (handover timer T304 status) from the complex handover process and reports it separately when radio link failure occurs. This extraction approach provides critical failure analysis data without requiring the UE to report all handover-related parameters, thereby reducing signaling overhead while maintaining failure analysis capability
Solution Approach 2:
The handover timer T304 acts as an intermediary that automatically records timing information during the handover process. Instead of requiring the UE to manually track and report multiple timing parameters, the T304 timer serves as a pre-configured intermediary that captures the necessary timing data, simplifying the reporting process and reducing signaling overhead
Data Source
Figure 1A~1B
Figure 2
Figure 3~5
AI summary
A method and an apparatus for cell handover and user equipment are disclosed. method of cell handover includes: when receiving a preset handover command transmitted by a base station for indicating a conditional handover command, determining a handover decision parameter corresponding to each target cell; when determining a target cell that meets a handover condition based on the handover decision parameter corresponding to each target cell, starting a preset timer and executing a cell handover operation from a current serving cell to the target cell that meets the handover condition; and when unsuccessfully executing the cell handover operation, recording first handover information in a radio link failure-report for reporting to the base station. The technical solution of the present disclosure can enable the UE to start the preset timer when receiving the conditional handover command and starting to execute the cell handover operation, so as to ensure that the UE can trigger a handover process and avoid occurrence of a radio link failure, thereby improving mobility performance of the UE.