UWB TDoA Error Correction using Transformers: Patching and Positional Encoding Strategies

TL;DR

This paper introduces a transformer-based method for correcting UWB TDoA localization errors in NLOS-rich environments, significantly improving accuracy by leveraging raw CIR data with novel encoding and patching strategies.

Contribution

It presents a novel transformer-based approach that utilizes raw CIRs and new encoding strategies for TDoA error correction in challenging environments.

Findings

Achieves up to 0.39 m accuracy in NLOS environments

Improves TDoA localization accuracy by 73.6% over baseline

Demonstrates scalability and effectiveness of proposed techniques

Abstract

Despite their high accuracy, UWB-based localization systems suffer inaccuracies when deployed in industrial locations with many obstacles due to multipath effects and non-line-of-sight (NLOS) conditions. In such environments, current error mitigation approaches for time difference of arrival (TDoA) localization typically exclude NLOS links. However, this exclusion approach leads to geometric dilution of precision problems and this approach is infeasible when the majority of links are NLOS. To address these limitations, we propose a transformer-based TDoA position correction method that uses raw channel impulse responses (CIRs) from all available anchor nodes to compute position corrections. We introduce different CIR ordering, patching and positional encoding strategies for the transformer, and analyze each proposed technique's scalability and performance gains. Based on experiments on real-world UWB measurements, our approach can provide accuracies of up to 0.39 m in a complex environment consisting of (almost) only NLOS signals, which is an improvement of 73.6 % compared to the TDoA baseline.