Phase Roll Estimation for Accurate Wireless Distance Measurement
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Solution Overview
Problem
Accurate symbol boundary estimation is crucial for precise distance and position measurement between wireless network devices, but existing methods face challenges due to impairments like fading, thermal noise, and channel noise, which affect the accuracy of symbol timing and phase roll estimation.
Innovation Solution
A receiver module comprising a channel estimation module and a phase roll estimation module calculates channel estimates on multiple tones, computes phase roll differences, and applies timing advances to correct symbol timing errors, enhancing the accuracy of symbol boundary estimation and distance measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing symbol timing estimation methods are used, then the basic communication function is maintained, but the measurement precision of distance and position is degraded due to fading, thermal noise, and channel noise
Solution Approach 1:
The patent introduces phase roll estimation as an intermediary step between channel estimation and symbol timing correction. By calculating the phase roll from channel estimates on multiple tones and using this intermediate value to adjust symbol timing, the system effectively mediates the impact of noise and fading, improving both reliability and measurement precision simultaneously
Solution Approach 2:
The patent implements a feedback mechanism where the estimated phase roll is used to correct the symbol timing in subsequent processing stages. This feedback loop continuously refines the timing estimation by using the phase roll information to adjust the symbol boundaries, thereby improving measurement precision while maintaining reliability under noisy conditions
2Measurement precision
If higher resolution distance measurement is achieved, then the timing resolution requirement increases, but the accuracy of symbol boundary estimation becomes more difficult to maintain
Solution Approach 1:
The patent segments the timing estimation process into distinct stages: channel estimation on multiple tones, phase roll calculation from the channel estimates, and finally symbol timing correction using the phase roll information. This segmentation allows each stage to be optimized independently, making the overall system more robust to noise and fading while achieving high resolution measurements
Solution Approach 2:
The patent changes the parameter used for timing estimation from direct symbol boundary detection to phase roll-based correction. By transforming the estimation problem into the phase roll domain and then converting back to timing adjustments, the system achieves higher measurement precision while reducing the difficulty of accurate symbol boundary estimation under noisy conditions
Data Source
AI summary
A receiver for a wireless device. A channel estimation module is configured to calculate a first channel estimate on a first tone of a data packet and calculate a second channel estimate on a second tone of the data packet. A phase roll estimation module is configured to calculate a conjugate of the second channel estimate and calculate, using the first channel estimate and the conjugate of the second channel estimate, an estimate of a phase roll caused by an error in symbol timing of the data packet. The phase roll corresponds to a difference between phases across adjacent tones of the data packet. The phase roll estimation module is further configured to calculate, based on the estimate of the phase roll, a timing advance to be applied to the symbol timing of the data packet. The timing advance corresponds to a number of samples of the data packet.