Distributed-Tone RU Pilot Tone Shifting for Wireless Communications
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In wireless communications, particularly in 6 GHz low-power indoor systems, distributed-tone RU (dRU) pilot tones face a pilot nulling problem due to the close ratio of pilot tone spacing to cyclic shift delay (CSD) periodicity, especially in smaller dRUs like dRU26 and dRU52, which affects transmission efficiency.
Innovation Solution
The optimization of dRU pilot tone designs involves shifting the positions of pilot tones in 20 MHz or 40 MHz bandwidths to avoid pilot nulling, ensuring the ratio of pilot tone spacing to CSD nulling spacing is close to a non-integer real number, while maintaining the hierarchical structure and maximizing the minimum distance between pilot tones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pilot tones are placed at regular intervals in dRU, then the structure is simple and easy to implement, but pilot nulling occurs when the ratio of pilot tone spacing to CSD periodicity is close to an integer
Solution Approach 1:
The patent changes the spacing parameter of pilot tones from regular intervals to non-uniform intervals. Specifically, it adjusts the spacing between adjacent pilot tones so that the ratio of pilot tone spacing to CSD periodicity is not close to an integer, thereby avoiding pilot nulling while maintaining a relatively simple structure.
Solution Approach 2:
The patent applies different spacing characteristics to different segments of the frequency spectrum. By making the pilot tone spacing non-uniform across the bandwidth, it locally optimizes each pilot tone position to avoid nulling conditions while maintaining overall structural simplicity.
2Measurement precision
If pilot tone spacing is reduced to increase pilot density, then measurement precision improves, but the ratio of pilot tone spacing to CSD periodicity approaches an integer causing pilot nulling
Solution Approach 1:
The patent optimizes the pilot tone spacing parameter to achieve a balance between density and nulling avoidance. By carefully selecting non-uniform spacing values, it increases pilot density for better channel estimation while ensuring the spacing-to-CSD-periodicity ratio remains away from integer values.
3Productivity
If dRU size is reduced for better spectral efficiency, then bandwidth utilization improves, but the pilot nulling problem becomes more serious due to limited pilot tones
Solution Approach 1:
The patent applies non-uniform spacing optimization to small dRUs (dRU26, dRU52) to compensate for their limited number of pilot tones. By strategically positioning each pilot tone with non-uniform spacing, it maximizes the effectiveness of each pilot while avoiding nulling, thereby maintaining reliability in spectrally efficient small RU configurations.
Data Source
AI summary
Techniques pertaining to optimization of distributed-tone resource unit (RU) pilot tone designs in wireless communications are described. An apparatus (e.g., station (STA)) generates a distributed-tone RU (dRU) with a respective position of each of one or more pilot tones shifted with a respective position of each of one or more other pilot tones kept unchanged. The apparatus then performs a wireless communication in a 20 MHz or 40 MHz bandwidth with the dRU.