General selection criteria to mitigate the impact of NLoS errors in RTT measurements for mobile positioning

Abstract

In this contribution, a new Mobile Station (MS) localization method is provided using Round Trip Time (RTT) measurements in the UMTS-FDD [I]. Three or more base stations (BS) performing RTT measurements of a signal from a mobile station (MS) are necessary for its localization. However, when some of the measurements are from Non-Line-Of-Sight (NLoS) paths, the location errors can be very large. We propose a method that takes into account possible large RTT error measurements caused by NLoS. To this end, the new method measures the best coherence between the RTT estimates and allows the mobile to select the three most reliable measures among the whole available RTT measurements. This method does not depend on a particular distribution of the NLoS error. Realistic simulations show the gain of positioning accuracy provided by the proposed algorithm. © 2007 IEEE.