Message Passing-Based Robust Asynchronous Multistatic Localization Using Differential Time Delays With Unknown Transmitter Position

Abstract

This article addresses the problem of target localization in mixed line-of-sight (LOS) and non-LOS (NLOS) environments using differential time-delay (DTD) measurements from signals of opportunity emitted by a noncooperative transmitter with unknown position. The system operates without time synchronization among the transmitter and receivers, making it suitable for asynchronous multistatic localization. To mitigate the impact of outliers caused by NLOS propagation, the localization task is formulated as a least absolute deviation (LAD) optimization problem, and we then develop an efficient iterative message passing algorithm to solve it. Different from conventional methods, our proposed method circumvents the coupling issue between measurements and noises, making it suitable for dealing with outliers. Simulation results demonstrate that the proposed method outperforms state-of-the-art approaches under mixed LOS/NLOS conditions, exhibiting strong robustness and high accuracy even at high noise levels and with a limited number of sensors.