Distributed localization of a non-cooperative RF target in NLOS environments

We propose a novel distributed generalized expectation maximization (EM) method for non-cooperative target localization using a wireless sensor network. We consider the scenario where few or no sensors receive line-of-sight signals from the target. Each sensor is able to measure the time difference of arrival of the target's signal with respect to a reference node, as well as the angle of arrival of the target's signal. We show that our distributed algorithm converges, and simulation results suggest that our method achieves an accuracy close to the centralized EM algorithm. We apply the distributed EM algorithm to a set of experimental measurements, which confirm that the algorithm is able to localize a RF target in a realistic non-line-of-sight scenario.