Beam Failure Recovery With Candidate Beams and PRACH Preambles
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Solution Overview
Problem
In high-frequency wireless communication systems, beam failures can occur due to deteriorating signal quality, leading to ineffective communication between user equipment and base stations, and existing recovery mechanisms are inefficient or unreliable.
Innovation Solution
A method and user equipment (UE) are developed to perform beam quality measurements, initiating either contention-free or contention-based beam recovery processes, utilizing dedicated PRACH preambles for contention-free recovery and shared PRACH preambles for contention-based recovery, with timers and counters to manage the processes, and macro-cell assistance for fallback connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If beamforming schemes are employed to focus transmitted signals in high frequency bands, then system capacity is increased, but beam failures occur more frequently due to deteriorating signal quality
Solution Approach 1:
The system performs preliminary actions by monitoring signal quality of candidate beams before the serving beam fails. The UE identifies and prepares candidate beams in advance, so when beam failure occurs, recovery can immediately switch to a pre-identified candidate beam, reducing interruption time and maintaining system capacity while improving reliability.
Solution Approach 2:
The patent implements beforehand cushioning by maintaining a set of candidate beams with pre-measured signal qualities. These candidate beams serve as a buffer or cushion that can be immediately activated when the serving beam fails, preventing complete communication breakdown and ensuring continuous system operation despite beam failures in high-frequency environments.
2Reliability
If existing beam recovery mechanisms are used, then beam failure can be addressed, but recovery efficiency is poor and communication disruptions are prolonged
Solution Approach 1:
The UE continuously monitors and identifies candidate beams before failure occurs, performing preliminary beam selection and quality assessment. When beam failure is detected, the UE can immediately initiate recovery using the pre-identified candidate beam, eliminating the need for time-consuming beam search and significantly improving recovery efficiency while maintaining reliable communication.
Solution Approach 2:
The UE autonomously performs beam failure detection, candidate beam identification, and recovery initiation without requiring extensive network intervention. The self-service mechanism allows the UE to independently manage beam recovery, reducing signaling overhead and acceleration the recovery process, thereby improving both reliability and productivity.
3Productivity
If multiple beams are used to cover serving area, then system capacity increases, but complexity of beam management and failure detection increases
Solution Approach 1:
The patent segments beam management into distinct functional modules: serving beam monitoring, candidate beam identification, signal quality measurement, and recovery decision-making. This segmentation allows each module to handle specific tasks independently, reducing overall system complexity while maintaining the ability to manage multiple beams for high system capacity.
Solution Approach 2:
The beam management system implements multi-functionality by using the same measurement and evaluation mechanisms for both serving beam monitoring and candidate beam assessment. This universal approach reduces the need for separate complex procedures, simplifying beam management while enabling effective handling of multiple beams to maintain high system capacity.
Data Source
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AI summary
Aspects of the disclosure provide a method of beam failure handling. The method can include performing beam quality measurement of one or more beams transmitted from a base station (BS) at a user equipment (UE) in a beamformed wireless communication system, determining a beam failure occurs based on the beam quality measurement, and performing a beam recovery process that includes at least one of a contention-free beam recovery process or a contention-based beam recovery process. The one or more beams are used for transmitting physical downlink control channels (PDCCHs).