A Succinct Method for Non-Line-of-Sight Mitigation for Ultra-Wideband Indoor Positioning System

Ultra-wideband (UWB) is a promising indoor position technology with centimetre-level positioning accuracy in line-of-sight (LOS) situations. However, walls and other obstacles are common in an indoor environment, which can introduce non-line-of-sight (NLOS) and deteriorate UWB positioning accuracy t...

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Bibliographic Details
Published in:Sensors (Basel, Switzerland) Switzerland), 2022-10, Vol.22 (21), p.8247
Main Authors: Liu, Ang, Lin, Shiwei, Wang, Jianguo, Kong, Xiaoying
Format: Article
Language:English
Subjects:
Accuracy
Algorithms
Analysis
Delay
delay model
Distance measurement
Identification methods
Indentation
Indoor environments
Internet of Things
Learning strategies
Line of sight
Machine learning
Methods
NLOS
Ultrasonic imaging
Ultrawideband
UWB
WLS
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Summary:Ultra-wideband (UWB) is a promising indoor position technology with centimetre-level positioning accuracy in line-of-sight (LOS) situations. However, walls and other obstacles are common in an indoor environment, which can introduce non-line-of-sight (NLOS) and deteriorate UWB positioning accuracy to the meter level. This paper proposed a succinct method to identify NLOS induced by walls and mitigate the error for improved UWB positioning with NLOS. First, NLOS is detected by a sliding window method, which can identify approximately 90% of NLOS cases in a harsh indoor environment. Then, a delay model is designed to mitigate the error of the UWB signal propagating through a wall. Finally, all the distance measurements, including LOS and NLOS, are used to calculate the mobile UWB tag position with ordinary least squares (OLS) or weighted least squares (WLS). Experiment results show that with correct NLOS indentation and delay model, the proposed method can achieve positioning accuracy in NLOS environments close to the level of LOS. Compared with OLS, WLS can further optimise the positioning results. Correct NLOS indentation, accurate delay model and proper weights in the WLS are the keys to accurate UWB positioning in NLOS environments.
ISSN:1424-8220
1424-8220
DOI:10.3390/s22218247