Joint TDOA and DOA Single Site Localization in NLOS Environment Using Virtual Stations

Non-line of sight (NLOS) propagation is usually considered undesirable in localization problems, so that researchers try to mitigate the effect to enhance the positioning performance, but from another point of view, NLOS propagation can be considered beneficial making it possible to find the position of a source using a single-site. This article presents a geometrical-based single-site localization method using direction of arrival (DOA) and time difference of arrival (TDOA) estimates in a multiple reflection NLOS environment. In this method, NLOS reflection paths are converted to line of sight (LOS) paths by setting up some virtual stations (VSs). The method works in two steps. In the first step, VSs are constructed to make an initial estimation of the source position (SP) alongside a termination condition (TC) to end up the search for this initial position. In the second step, by using the position estimate of the first step, linearizing the TDOA/DOA equations, and developing a two-step weighted least square (TSWLS) estimator, the SP is estimated more accurately. Simulation results show that the proposed method is efficient attaining the Cramer-Rao lower bound (CRLB).