Beam Failure Recovery Using Timer-Based Cell Selection
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Solution Overview
Problem
Current wireless network technologies face challenges in reliably and robustly recovering from beam failures during handovers, particularly in high-frequency environments, leading to potential service disruptions and inefficiencies in handover procedures.
Innovation Solution
A method is introduced where user equipment determines whether a timer is running upon detecting beam failure, and if so, initiates a beam failure recovery procedure with a target non-serving cell, or if the timer is not running, performs the recovery with the serving cell, ensuring stable handover and minimizing false alarms and service disruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If beam failure recovery is performed with the serving cell, then the recovery procedure is simple, but the reliability is reduced when the serving cell's radio link quality is poor
Solution Approach 1:
The patent implements dynamic selection of the recovery target cell based on real-time timer status and radio link quality conditions. The UE adapts its recovery procedure by choosing between serving cell and non-serving cell dynamically, rather than using a fixed recovery mechanism. This dynamic approach resolves the contradiction by allowing simple recovery when conditions permit while enabling more complex but reliable recovery paths when necessary.
Solution Approach 2:
The patent changes the parameter of recovery target selection based on timer status and radio link quality measurements. By monitoring whether the timer is running and evaluating radio link conditions, the system adjusts which cell becomes the recovery target. This parameter-based adaptation allows the system to optimize between simplicity and reliability depending on current network conditions.
2Speed
If handover is triggered quickly upon beam failure detection, then the response speed is fast, but false alarms increase when radio link quality fluctuates
Solution Approach 1:
The patent implements preliminary monitoring of radio link quality and timer status before triggering handover. By checking whether the timer is already running and evaluating radio link conditions in advance, the system avoids premature handover decisions. This preliminary action filters out false alarms caused by transient quality fluctuations while maintaining fast response to genuine beam failures.
Solution Approach 2:
The system uses feedback from radio link quality measurements and timer status to control the handover triggering decision. The continuous monitoring of link quality and timer state provides feedback that prevents false handover triggers while enabling rapid response when conditions genuinely warrant handover. This feedback mechanism resolves the contradiction between speed and stability.
3Ease of operation
If beam failure recovery uses only the serving cell, then the procedure is straightforward, but service disruptions occur when the serving cell cannot be recovered
Solution Approach 1:
The patent introduces a non-serving cell as an intermediary recovery target when the serving cell recovery is not viable. By selecting a different cell (non-serving cell) as the recovery target based on timer status and radio link conditions, the system maintains service continuity when the original serving cell cannot be recovered. This intermediary approach preserves simplicity when possible while ensuring reliability when needed.
Data Source
AI summary
A UE, in response to a beam failure being detected for a serving cell that serves the user equipment, determines whether a timer is running. One of the following is performed by the UE: in response to the timer running, a beam failure recovery procedure with a target non-serving cell; or in response to the timer not running, a beam failure recovery procedure with the serving cell. Methods, apparatus, computer programs, and computer program products are disclosed.