LOS/NLOS Detection in UWB Localization System with Anchors Deployment Along a Narrow Path

Recently, the ultra-wideband (UWB) localization technology has been widely used in outdoor scenarios with high accuracy, fast refresh rate and non-sensitive to multipath fading. However, the deployment of UWB anchors along a narrow path has a large condition number of the observation matrix formed by the coordinates of UWB anchors and thus quite sensitive to the non-line-of-sight (NLOS) ranging error. In this paper, a LOS/NLOS detection algorithm is proposed to identify the NLOS from LOS propagation with UWB anchors deployment along a narrow path. Firstly, a ranging error correction model is constructed to estimate the NLOS ranging error under the blocking of single path between one anchor and the tag. Secondly, an iterative algorithm for ranging error estimation is proposed in the case of the multi-path blocked. Finally, a detection method based on the tetrahedron volume is combined to improve the detection accuracy. The simulation results show that the proposed algorithm outperforms the maximum likelihood method. When the average NLOS error is 20 cm, the probability of detection achieves an improvement of about 12% with 5 anchors, compared with other algorithms. When the NLOS error increases to 50 cm, the improvement is about 3% and the probability of detection reaches 90%.