Localization of mobile equipment in radio environments with no line-of-sight path

In recent years, radio positioning has received increasing attention and found many applications in various areas. However, the existence of non-line-of-sight (NLOS) paths introduces considerable positioning errors. In this paper, we propose a two-step approach in order to deal with pure NLOS scenarios based on a simple assumption regarding the propagation environment. A nonlinear least squares (NLS) method is proposed for the initial estimation, followed by a Kalman filter-based method to track subsequent movements. Compared with previous studies, fewer measurements are required to be made. Simulation results are provided to show the performance of both methods.