DRU Pilot Tone Distribution for Phase Tracking
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Solution Overview
Problem
The existing approach for designing a distributed tone resource unit (dRU) tone plan results in clustered pilot tones, leading to reduced phase tracking accuracy and system performance degradation due to insufficient frequency diversity.
Innovation Solution
A new dRU tone plan design that distributes pilot tones across the distribution bandwidth while maintaining the same number and locations as the corresponding rRU tone plan, allowing for improved phase tracking and frequency diversity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a round-robin distribution approach is used to design dRU tone plan from rRU tone plan, then the dRU structure can be easily constructed, but the pilot tones become clustered into local areas resulting in reduced phase tracking accuracy
Solution Approach 1:
The patent segments the pilot tones from their clustered positions and redistributes them individually across the distribution bandwidth. Each pilot tone is placed at a distinct subcarrier index calculated to ensure uniform distribution, breaking the clustering effect while maintaining the overall dRU structure.
Solution Approach 2:
The patent transforms the one-dimensional round-robin distribution pattern into a two-dimensional distribution pattern by calculating specific subcarrier indices based on both the tone index and distribution bandwidth. This creates a more uniform spatial distribution of pilot tones across the frequency spectrum.
2Device complexity
If pilot tones are clustered into local areas, then the dRU structure is simpler to implement, but the frequency diversity is insufficient leading to system performance degradation
Solution Approach 1:
The patent applies local quality by ensuring that pilot tones are uniformly distributed across different frequency regions rather than clustered. Each local area (frequency region) contains an appropriate number of pilot tones, providing localized frequency diversity while maintaining overall system simplicity.
Solution Approach 2:
The patent changes the distribution parameter from round-robin sequential assignment to a calculated index-based assignment. The subcarrier index for each pilot tone is determined by a formula that distributes them uniformly across the distribution bandwidth, improving frequency diversity without significantly increasing complexity.
3Adaptability or versatility
If the existing dRU tone plan is used, then backwards compatibility is maintained, but transmit power must be limited due to clustered pilot tones
Solution Approach 1:
The patent maintains universality by preserving the same number of pilot tones and their relative positioning relationships as the original rRU tone plan. This allows legacy devices to continue operating while enabling improved transmit power for dRU-based transmissions through better pilot tone distribution.
Data Source
AI summary
A method performed by an access point (AP) to receive uplink trigger-based physical layer protocol data units (PPDUs) from stations (STAs) in accordance with a distributed tone resource unit (dRU) tone plan for a distribution bandwidth. The method includes assigning dRUs to the STAs in the distribution bandwidth, wherein the dRU tone plan for the distribution bandwidth specifies a set of non-contiguous data tones for each of the dRUs, wherein the dRU tone plan for the distribution bandwidth further specifies pilot tones that are located at the same subcarrier indices as pilot tones specified by a regular non-distributed tone resource unit (rRU) tone plan for the distribution bandwidth. The method further includes soliciting the uplink trigger-based PPDUs from the STAs in accordance with the assignment and receiving the uplink trigger-based PPDUs from the STAs in the dRUs assigned to the STAs in accordance with the dRU tone plan for the distribution bandwidth.