TOA Estimation for MB-OFDM UWB Signals
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Solution Overview
Problem
Existing TOA estimation algorithms for MB-OFDM UWB signals are limited by discrete time sampled-spaced models, which constrain resolution and require channel delay profile information, and often converge to suboptimal solutions or perform poorly in multipath-rich environments.
Innovation Solution
A two-step TOA estimation algorithm using a least squares method to recover the channel impulse response from an equally-spaced model with a tap interval set to the inverse of the signal bandwidth, allowing for continuous delay variation and minimizing energy leakage from the first path, enabling higher resolution without requiring channel delay profile information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If discrete time sampled-spaced models are used for TOA estimation, then the estimation process is simplified, but the resolution is constrained by the sampling interval
Solution Approach 1:
The patent changes the fundamental parameter of the estimation model from discrete time sampling to continuous frequency-domain representation. By estimating channel coefficients at N equally spaced frequencies and transforming to time domain, the system achieves resolution determined by frequency spacing (inverse of observation interval) rather than time sampling interval, thereby improving measurement precision while maintaining computational tractability through FFT-based implementation.
2Productivity
If traditional channel estimation algorithms are used, then the process is computationally efficient, but they require channel delay profile information and converge to suboptimal solutions in multipath-rich environments
Solution Approach 1:
The patent performs preliminary action by explicitly removing the effect of the first path (direct path or dominant path) from the received signal before channel estimation. This preliminary subtraction of the known first path component eliminates interference and energy leakage from the first path, allowing the estimation algorithm to focus on estimating the remaining multipath components without contamination, thereby improving reliability in multipath-rich environments while maintaining computational efficiency.
3Measurement precision
If maximum-likelihood based methods are used for TOA estimation, then measurement precision is improved, but computational complexity increases significantly
Solution Approach 1:
The patent segments the channel estimation problem into two independent stages: first estimating the channel impulse response using a simplified least-squares approach based on frequency-domain samples, then separately estimating the TOA from the recovered CIR. This segmentation avoids the need for joint maximum-likelihood optimization of all parameters simultaneously, significantly reducing computational complexity while maintaining good measurement precision through the two-step estimation procedure.
Data Source
AI summary
A time-of-arrival (TOA) estimation method for multi-band orthogonal frequency division multiplexing (MB-OFDM) signals uses a simple equally-spaced channel model to recover the impulse response of the wireless channel, and locates the delay of the first channel path by minimizing the energy leakage from the first channel path. The TOA is estimated based on the delay. Such a method does not require channel information for TOA estimation at the receiver and does not require modification of the receiver structure. The method also avoids a sub-optimal solution known to occur in maximum likelihood (ML) estimation.