Random Access Preamble Detection With Wide-to-Narrow Beam Search
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Solution Overview
Problem
In mmW systems, the complexity of baseband processing for hundreds of narrow beams is excessive, and uncoordinated UE access can lead to preamble collisions, complicating the random access procedure.
Innovation Solution
A method involving digital beamforming of incoming signals into wide beams to identify candidate preambles, followed by narrow beamforming and threshold comparison to resolve collisions, reducing computational complexity and enabling simultaneous serving of multiple UEs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If narrow beamforming is applied to detect preambles in mmW systems, then measurement precision is improved, but device complexity increases excessively
Solution Approach 1:
The patent divides the beam detection process into two stages: first using wide beams to perform initial preamble detection and identify candidate preambles, then using narrow beams only for selected candidate preambles. This segmentation reduces the overall computational complexity while maintaining detection precision for the final selected preambles.
Solution Approach 2:
The patent performs preliminary wide beam detection to identify candidate preambles before conducting narrow beam detection. This preliminary action filters out non-candidate preambles, so that computationally intensive narrow beam processing is only applied to a small subset of candidates, significantly reducing total processing complexity.
2Adaptability or versatility
If uncoordinated UE access is allowed, then adaptability is improved, but loss of information increases due to preamble collisions
Solution Approach 1:
The patent implements a feedback mechanism where the access point detects preamble collisions through wide beam detection, identifies the colliding preambles, and provides feedback information to guide UEs in selecting different preambles or beams for retransmission. This feedback loop resolves collisions while maintaining UE access flexibility.
Solution Approach 2:
The patent uses wide beams as an intermediary layer between uncoordinated UE access and collision-free detection. Wide beams provide a coarse-grained detection mechanism that can identify multiple candidate preambles simultaneously, serving as a mediator that manages uncoordinated access without requiring strict coordination among UEs.
Data Source
AI summary
A RAP detection procedure that can be used to find the best narrow beam in an efficient manner. In a first step, an access point correlates an incoming signal with appropriate RAPs and then selects at least one candidate RAP for further processing in at least one set of narrow beams that all reside within the coverage area of a wide beam with which the candidate preamble is associated. For each candidate RAP, a second step is executed including narrow beamforming and a PRACH receiver chain including threshold comparison.