UL HARQ Buffer Retention During Beam Recovery in 5G UE
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Solution Overview
Problem
In 5G wireless communication systems, the reliability of beamforming at higher frequencies is challenged by increased sensitivity to time and space variations, leading to rapid degradation of signal quality and reduced coverage area, necessitating effective beam tracking and recovery mechanisms to maintain connectivity during UE mobility.
Innovation Solution
A method for user equipment (UE) to initiate a beam recovery procedure when a serving beam becomes invalid, involving transmitting a scheduling request and retransmitting data stored in the UL HARQ buffer via a new beam found during the recovery process, without flushing the UL HARQ buffer, to ensure continuous communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If beamforming is used at higher frequencies to improve signal directionality and coverage, then the signal can be focused more precisely, but the system becomes more sensitive to time and space variations causing rapid signal degradation
Solution Approach 1:
The system performs preliminary beam tracking and monitoring before complete beam failure occurs. The UE continuously monitors beam quality metrics and triggers beam recovery procedures proactively when degradation thresholds are approached, preventing complete communication failure and maintaining service continuity.
Solution Approach 2:
The patent implements continuous feedback mechanisms where the UE monitors beam quality and reports to the network. When beam degradation is detected, the feedback loop triggers beam recovery procedures including beam switching and reconfiguration, allowing the system to adapt dynamically to changing channel conditions at higher frequencies.
2Reliability
If beam tracking is performed continuously to maintain beam validity, then connectivity can be maintained during UE mobility, but power consumption and system complexity increase
Solution Approach 1:
Instead of continuous beam tracking, the system employs periodic beam monitoring and validation. The UE performs beam quality measurements at scheduled intervals and triggers recovery procedures only when necessary, reducing power consumption while maintaining connectivity during UE mobility through event-driven beam management.
Solution Approach 2:
The UE autonomously performs beam validity checks and triggers beam recovery procedures without requiring continuous network control. The device self-manages beam tracking state machine, autonomously detecting beam failure and initiating recovery actions, which reduces overall system complexity and power consumption compared to network-controlled continuous tracking.
3Ease of manufacture
If the UL HARQ buffer is flushed when beam failure occurs, then the system can clear invalid data, but data loss occurs and retransmission efficiency decreases
Solution Approach 1:
The system performs preliminary beam recovery attempts before declaring complete buffer invalidation. The UE maintains the UL HARQ buffer and attempts beam switching and recovery procedures first, only flushing the buffer as a last resort when recovery fails, thereby minimizing data loss while maintaining system simplicity through hierarchical recovery strategies.
4Reliability
If fast beam recovery procedures are implemented to maintain connectivity during beam tracking failures, then communication reliability improves, but device complexity and processing overhead increase
Solution Approach 1:
The beam recovery mechanism is segmented into distinct operational states and procedures: beam monitoring state, beam failure detection state, beam recovery execution state, and buffer management state. Each state has specific, simplified actions, reducing overall device complexity while maintaining fast recovery capability through structured state transitions.
Solution Approach 2:
The system selectively discards and recovers beam configurations based on failure severity. Instead of complete system reset, the UE discards only the failed beam configuration and recovers communication by switching to alternative beams or triggering reconfiguration, maintaining reliability while reducing complexity through targeted rather than comprehensive recovery actions.
Data Source
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AI summary
A method for a wireless communications system is disclosed. In one example, user equipment (UE) maintains at least one serving beam (1202), and uses a serving beam to perform an uplink (UL) transmission of data (1204). The data is stored in an uplink hybrid automatic repeat request (UL HARQ) buffer. When there is a failure to track the serving beam, a beam recovery procedure is initialized (1206). After successful completion of the beam recovery procedure, the UE retransmits the data stored in the UL HARQ buffer (1208). The UE prevents the data from being flushed from the UL HARQ buffer when the failure to track the serving beam occurs, so that the data can be retransmitted.