LOS-NLOS Situation Tracking for Positioning Systems

The position estimation accuracy is severely impaired by the non-line of sight (NLOS) effect present in urban scenarios. When estimating the position of a Mobile Terminal (MT) using some base stations (BS), it is of vital importance to know which ones are in NLOS with the MT. The present document shows a dual tracker system to follow the LOS-NLOS situations and the position of a MT. The first tracker provides an estimation of the probability of being at each situation. This information is used by the second tracker, an improved Unscented Kalman Filter, to weight the information from each BS to enhance the final positioning accuracy. The approach is tested under a real scenario with severe NLOS conditions and with a limited number of available BS.