A Robust UWB Indoor Positioning System for Highly Complex Environments

Ultra-Wideband (UWB) has a high interest in research and industry for accurate indoor positioning. This technology comprises signals with a bandwidth of at least 500 MHz at a power decay of -10dB. This large bandwidth conferes the capability of resolving multipath, penetrating through obstacles and accurate ranging. However, NLOS (Non-Line-Of-Sight) conditions produced by obstacles in indoor environments severely degrade performance, as they introduce a positive bias in ranging estimation. In this paper we present a robust UWB indoor positioning which is able to accurately operate in a highly complex indoor scenario, where NLOS condition is predominant. For that purpose, the system uses a NLOS detection algorithm based on the skewness of the estimated channel impulse response and it mitigates NLOS by using an Extended Kalman Filter. The use of this detection/mitigation algorithm shows an improvement of the RMSE in positioning about 67%.