UWB Nodes Auto-Calibration through a Bias-Aware Two-Stage Methodology*

Ultra-wideband (UWB) technology is gaining acceptance in short to medium-range wireless positioning applications for indoor and GNSS-denied environments due to the accuracy that can be achieved. For this to happen, UWB-based localization requires some knowledge about the underlying infrastructure of network nodes: if the nodes positions are known, one can apply triangulation techniques to self-localize inside the operation area by means of several range measurements with the network nodes. This paper describes a novel two-stage methodology aiming at estimating the localization of the UWB nodes by means of a collection of ranges gathered during an initialization/calibration stage. For enhanced calibration accuracy, the methodology models ranges considering both multiplicative and additive biases. The experiments performed have resulted in estimation errors of the nodes positions of around 11–12 cm under non-line-of-sight (NLOS) conditions.