A robust UWB array localization scheme through passive anchor assistance

Ultra-Wide Bandwidth (UWB) localization based on time of arrival (TOA) and angle of arrival (AOA) has attracted increasing interest owing to its high accuracy and low cost. However, existing localization methods often fail to achieve satisfactory accuracy in realistic environments due to multipath effects and non-line-of-sight (NLOS) propagation. In this paper, we propose a passive anchor assisted localization (PAAL) scheme, where the active anchor obtains TOA/AOA measurements to the agent while the passive anchors capture the signals from the active anchor and agent. The proposed method fully exploits the time-difference-of-arrival (TDOA) information from the measurements at the passive anchors to complement single-anchor joint TOA/AOA localization. The performance limits of the PAAL system are derived as a benchmark via the information inequality. Moreover, we implement the PAAL system on a low-cost UWB platform, which can achieve 20 cm localization accuracy in NLOS environments.