Beam Failure Detection Recovery Coordination
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Solution Overview
Problem
The challenge in New Radio (NR) is efficiently handling beam failure detection and recovery procedures among multiple cells, particularly when carrier aggregation is involved, as existing methods struggle to coordinate these processes effectively within a single Medium Access Control (MAC) entity, leading to potential duplication of random access procedures.
Innovation Solution
A conditional random access procedure is implemented by the user equipment (UE) to manage beam failure recovery, where the UE configures multiple bandwidth parts (BWPs) and resets or disables beam failure detection timers and counters to prevent duplicate triggers, allowing for efficient coordination and prioritization of beam failure recovery processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If beam failure recovery procedure is implemented in both PCell and SCell for carrier aggregation, then coverage and reliability are improved, but complexity of coordinating multiple random access procedures increases
Solution Approach 1:
The patent divides the beam failure recovery coordination into cell-specific states (first state for PCell, second state for SCell) and uses separate counters (first counter, second counter) to track recovery procedures in each cell independently. This segmentation allows the MAC entity to manage multiple cells without creating a single complex coordination system, resolving the contradiction between improved reliability through multi-cell support and the resulting coordination complexity.
Solution Approach 2:
The patent introduces a counter as an intermediary mechanism that tracks the state of beam failure recovery procedures. The counter increments when a random access procedure is triggered and decrements when it completes, providing a simple intermediary state tracker that enables reliable coordination across multiple cells without requiring complex inter-cell signaling or management logic.
2Speed
If multiple random access procedures are allowed to trigger simultaneously in multiple cells, then beam failure recovery responsiveness is improved, but duplication of procedures increases
Solution Approach 1:
The patent implements feedback through the counter mechanism that tracks the state of random access procedures. When a procedure is triggered, the counter increments; when it completes, the counter decrements. This feedback loop allows the MAC entity to detect when a procedure is already ongoing and prevent duplicate triggers, maintaining high responsiveness while eliminating harmful procedure duplication across multiple cells.
Solution Approach 2:
The patent performs preliminary tracking of procedure states using counters before actual random access procedures execute. By incrementing the counter when a procedure is triggered and checking its state before allowing new procedures, the system prevents duplication in advance. This preliminary state management enables multiple cells to respond simultaneously to beam failures without generating duplicate procedures.
Data Source
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AI summary
A user equipment (UE) is configured with at least one bandwidth part (BWP) specific configuration information. The UE receives a configuration information specific to the bandwidth part (BWP). The configuration information configures an initial value of a beam failure detection (BFD) timer and a beam failure indication (BFI) count threshold. The UE starts or re-starts the BFD timer from the initial value when receiving a beam failure indication (BFI) from a lower sublayer, and counts a number of the received BFIs using a BFI counter. The UE resets the BFI counter to zero when receiving a reconfiguration information. The reconfiguration information, that is specific to the BWP, re-configures at least one of the initial value of the BFD timer and the BFI count threshold.