L1 Channel State Based Conditional Handover Mechanism
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Solution Overview
Problem
Current 5G/NR wireless communication systems face challenges in reducing handover delay and service interruption time due to the reliance on Layer 3 measurement results for conditional handover (CHO) decisions, which can lead to frequent and inefficient handovers when using only the latest Layer 1 measurement results without considering past measurements.
Innovation Solution
Implementing a Layer 1 channel state/quality based CHO mechanism that uses both current and past channel state information (CSI) reports to determine when to execute a handover, with a counter-based approach to ensure that handovers are only executed when a candidate cell's CSI is consistently better than the serving cell's CSI for a predetermined number of reporting times, thereby reducing unnecessary handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If Layer 1 measurement results are used for conditional handover decisions, then handover speed is improved, but handover frequency increases causing unnecessary handovers
Solution Approach 1:
The system performs preliminary filtering of Layer 1 measurement results by comparing current measurements with past measurements. Only when the current Layer 1 measurement exceeds the past measurement by a threshold value is the result considered valid for handover decision, preventing premature or unnecessary handovers while maintaining fast response to genuine channel improvements
Solution Approach 2:
The system uses feedback from past measurement results to validate current Layer 1 measurements. By comparing current CSI reports with historical data and applying threshold-based validation, the system ensures that handover decisions are based on consistent channel state improvements rather than transient fluctuations, thereby reducing unnecessary handovers
2Reliability
If Layer 3 measurement results are used for conditional handover decisions, then handover stability is improved, but handover delay increases
Solution Approach 1:
The system merges Layer 1 channel state information with Layer 3 measurement results to make handover decisions. By combining the speed advantages of Layer 1 measurements with the stability of Layer 3 measurements, the system achieves both fast and reliable handover execution, eliminating the need to choose between speed and stability
Solution Approach 2:
The system performs preliminary validation of Layer 1 measurements against Layer 3 results and historical data before executing handover. This preliminary check ensures that only genuine channel state improvements trigger handover, maintaining stability while utilizing the fast Layer 1 measurement capability
Data Source
AI summary
Methods and apparatuses for an L1 channel state/quality based CHO in a wireless communication system. A method of a UE comprises: receiving configuration information for a CHO; generating a CSI report indicating that a channel state associated with a candidate cell is better than a channel state associated with a serving cell; transmitting the CSI report; determining, based on the CSI report transmitted, whether a value of a counter reaches a number of reporting times N for the CHO; and executing the CHO based on a determination that the value of the counter reaches the number of reporting times N for the CHO.