Hierarchical Pilot Mapping for 6 GHz Distributed RUs to Avoid Clustering
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Solution Overview
Problem
Current pilot tone designs for distributed-tone resource units (dRUs) in 6 GHz low-power indoor (LPI) systems result in clustered pilot tones, leading to narrowband interference issues due to stringent Federal Communications Commission (FCC) regulations and inefficient distribution of pilot tones.
Innovation Solution
A hierarchical structure-based pilot tone design is proposed, distributing pilot tones over an entire bandwidth with no adjacent tones, maintaining regular RU pilot tone hierarchies, and ensuring even or near-even distribution across dRUs, using subcarrier distribution and reusing regular RU pilot tone values and mapping rules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pilot tones are assigned in dRUs using conventional methods, then the hierarchical structure for regular RU pilot tones is maintained, but pilot tones become clustered and cause narrowband interference
Solution Approach 1:
The patent segments the pilot tone assignment by treating each 26-tone dRU as an independent unit with its own pilot tone pattern. This segmentation prevents clustering by ensuring that pilot tones from different 26-tone dRUs are distributed across the entire bandwidth rather than concentrated in specific frequency regions.
Solution Approach 2:
The patent applies local quality by assigning different pilot tone offsets to different 26-tone dRUs. Specifically, odd-numbered 26-tone dRUs use one offset pattern while even-numbered ones use another, creating a staggered distribution that eliminates clustering while maintaining the hierarchical structure within each local dRU unit.
2Object-generated harmful factors
If pilot tones are distributed over wider bandwidth to avoid clustering, then narrowband interference is reduced, but the hierarchical structure for regular RU pilot tones may be compromised
Solution Approach 1:
The patent implements a nested structure where the overall pilot tone distribution pattern contains within it smaller hierarchical units. Each 26-tone dRU maintains its own internal pilot tone hierarchy, while the collection of these nested units creates the broader distributed pattern across the entire bandwidth, satisfying both requirements simultaneously.
Solution Approach 2:
The patent resolves the contradiction by introducing a new dimension - the dRU index dimension. Instead of only varying pilot tone frequencies within a single dRU, the solution varies the frequency offset based on the dRU's position in the sequence, creating a two-dimensional distribution pattern that maintains local hierarchy while achieving global dispersion.
3Power
If dRUs are used to spread subcarriers over wider bandwidth, then transmit power is boosted and coverage range is extended, but pilot tones from multiple dRUs cluster at the receiver
Solution Approach 1:
The patent changes the frequency offset parameter dynamically based on the dRU index. By making the offset a function of the dRU position (odd vs. even indexing), the system transforms the static pilot tone assignment into a dynamic one that adapts to the distributed nature of dRUs, preventing receiver-side clustering while preserving the power boosting benefits of dRU spreading.
Data Source
AI summary
Various schemes pertaining to pilot tone design for distributed-tone resource units (dRUs) in 6 GHz low-power indoor (LPI) systems are described. A communication entity generates a plurality of pilot tones of a dRU based on a hierarchical structure of pilot tones that is used for a regular RU (rRU). The communication entity then communicates with another communication entity using the dRU.