NLOS Detection and Mitigation Based on Confidence Metric and EKF

C. Gentner, S. Sand

Abstract:	This paper presents a novel non-line-of-sight (NLOS) detection algorithm for GNSS signals. It adapts the confidence metric, which was derived for ultra wide-band scenarios and is based on multipath propagation effects, to GNSS. The confidence metric indicates NLOS scenarios by comparing the signal power of the multipath components to the propagation time. Instead of considering the whole propagation time, we consider only the additionally propagation time of the multipath signals. This adapted algorithm is more stable against varying signal to noise ratio and outputs the probability whether the received signal is LOS or NLOS. Because the metric is based on the received GNSS multipath signal, a multipath mitigation algorithm is necessary to use the NLOS detection algorithm. Hence, this paper derives additionally the Cramer-Rao lower bound (CRLB) for a channel estimator with the estimation errors in the amplitudes and delays. Simulation results show the benefit using this metric in the position estimation by an extended Kalman filter. Additionally, we consider different scenarios with GPS only, GPS + Galileo and GPS + Galileo + LTE. Especially, if less than 4 LOS satellites are available, the LTE signals can improve the position estimation significantly.
Published in:	Proceedings of the 2011 International Technical Meeting of The Institute of Navigation January 24 - 26, 2011 Catamaran Resort Hotel San Diego, CA
Pages:	606 - 611
Cite this article:	Gentner, C., Sand, S., "NLOS Detection and Mitigation Based on Confidence Metric and EKF," Proceedings of the 2011 International Technical Meeting of The Institute of Navigation, San Diego, CA, January 2011, pp. 606-611.
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