Beam Failure Recovery Updates After CBRA in 5G NR
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Solution Overview
Problem
Fifth Generation (5G) New Radio (NR) systems face challenges with beam failure recovery due to rapid channel variations and high latency in beam management operations, particularly in scenarios where highly directional antennas require precise alignment, which can affect initial access, handover, and beam tracking.
Innovation Solution
Implementing a contention-based random access (CBRA) procedure for beam failure recovery (BFR) in wireless devices, enabling them to update beam information, such as control resource sets, physical channels, and power control parameters, even when resources for contention-free access are unavailable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If highly directional antennas are used to achieve sufficient link budget, then communication reliability is improved, but beam management latency increases
Solution Approach 1:
The system performs preliminary beam failure detection by monitoring downlink reference signals before complete link failure occurs. The wireless device proactively identifies beam failures and initiates recovery procedures in advance, reducing the overall latency of beam management operations while maintaining communication reliability through early intervention.
Solution Approach 2:
The patent implements a feedback mechanism where the wireless device monitors beam quality through downlink reference signals and provides feedback to the network about beam failures. This feedback loop enables the system to adaptively manage beams, triggering recovery procedures only when necessary, thus reducing unnecessary latency while maintaining reliable communication through continuous monitoring and response.
2Reliability
If beam management operations are performed frequently to maintain precise alignment, then communication quality is improved, but control layer procedure latency increases
Solution Approach 1:
The system performs preliminary monitoring of beam quality using downlink reference signals configured by the network. By detecting beam failures in advance through this preliminary monitoring mechanism, the system can initiate recovery procedures only when necessary, avoiding frequent unnecessary beam management operations that would increase control layer latency while still maintaining communication quality through proactive detection.
Solution Approach 2:
The wireless device autonomously monitors beam quality and detects beam failures without requiring continuous network intervention. The device independently determines when beam recovery is needed and initiates the appropriate recovery procedure, reducing the overhead and latency associated with frequent network-controlled beam management operations while maintaining communication quality through self-monitoring.
3Speed
If contention-free random access resources are configured for BFR, then BFR speed is improved, but resource availability is reduced when CBRA is needed
Solution Approach 1:
The patent enables the wireless device to use contention-based random access resources for beam failure recovery when contention-free resources are not configured or unavailable. This multi-functionality allows the same random access resources to serve both initial access and beam failure recovery purposes, ensuring resource availability is maintained across different scenarios while still providing fast BFR through contention-free resources when they are configured.
Solution Approach 2:
The system dynamically adapts the beam failure recovery procedure based on the configuration and availability of random access resources. When contention-free resources are available, the device uses them for faster recovery; when they are not available or when CBRA is needed, the device transitions to using contention-based resources. This dynamic adaptation ensures optimal performance across varying conditions while maintaining resource availability flexibility.
Data Source
AI summary
In various embodiments, methods that may be performed by a processor of a wireless device for managing beam failure recovery may include determining that a contention based random access (CBRA)-based beam failure recovery (BFR) procedure has been completed, determining whether a new candidate beam reference signal identifier was identified and included in a BFR media access control-control element (MAC-CE), updating beam information based on the new candidate beam reference signal identifier in response to determining that the new candidate beam reference signal identifier (RS ID) was identified and included in a BFR MAC-CE in a message to the base station, and updating the beam information based on a synchronization signal block selected during the CBRA-based BFR procedure in response to determining that the new candidate beam RS ID was not identified and included in the BFR MAC-CE in the message to the base station.