Steady-State Beam Scanning for Latency Reduction in mmWave Systems
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Solution Overview
Problem
In mmWave wireless communication systems, blind codebook-based beam scanning increases latency due to frequent measurements for beam evaluation, and beam paths/clusters can be blocked or change due to environmental factors, leading to incoherent beams and radio link failures.
Innovation Solution
A user equipment (UE) employs a steady-state approach for beam scanning, prioritizing serving-subarray scanning based on a timescale and dynamically updating the codebook, switching to alternate-subarray scanning when necessary, to maintain coherent communication by selecting beams with better coherence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If blind codebook-based beam scanning is performed to evaluate beams based on channel measurements, then beam selection accuracy is improved, but latency increases due to frequent measurements
Solution Approach 1:
The system performs preliminary beam scanning and evaluation to build a codebook of beam candidates in advance. This pre-computed codebook is then used for rapid beam selection without requiring frequent full measurements, thus reducing latency while maintaining selection accuracy through the pre-established beam information
Solution Approach 2:
The beam scanning approach transitions from static blind scanning to dynamic steady-state scanning. The system adapts the scanning behavior based on channel conditions and mobility states, performing comprehensive measurements only when necessary and using lighter-weight procedures during stable conditions, thereby reducing overall measurement frequency and latency
2Loss of time
If steady-state beam scanning is performed to quickly select beams, then latency is reduced, but reliability decreases when environmental conditions change causing beam blocking
Solution Approach 1:
The system implements feedback mechanisms that continuously monitor channel conditions, beam quality metrics, and link stability. When degradation or blocking is detected, the feedback triggers a switch from steady-state scanning to more comprehensive beam evaluation, ensuring reliable beam selection adapts to changing environmental conditions while maintaining low latency during stable operation
Solution Approach 2:
The system dynamically changes operational parameters such as scanning frequency, measurement depth, and codebook update intervals based on detected environmental conditions. During stable conditions, parameters are optimized for low latency; when changes or blockings are detected, parameters shift to prioritize reliability and comprehensive beam evaluation
3Adaptability or versatility
If frequent beam measurements are performed to track changing channel conditions, then adaptability to environmental changes is improved, but device complexity and processing load increase
Solution Approach 1:
The beam measurement and tracking process is segmented into different operational modes or stages. Rather than performing full comprehensive measurements continuously, the system divides tracking into periodic comprehensive updates and interstitial lightweight monitoring, reducing processing complexity while maintaining adaptability to channel changes through this hierarchical measurement approach
Data Source
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AI summary
A method, an apparatus, and a computer-readable medium may be described in the present disclosure. The apparatus may be a user equipment. The apparatus may determine whether a number of unsuccessful repetitions associated with performance of a first type of scanning exceeds a repetition threshold. The apparatus may perform a second type of beam scanning based on the determination that the number of unsuccessful repetitions exceeded the repetition threshold.