Performance of time-difference-of-arrival ultra wideband indoor localisation

Ultra wideband (UWB) is a good candidate for indoor positioning, thanks to its ability to resolve multipath and penetrate through walls. This study investigates the performance of UWB-based time difference of arrival (TDOA) positioning for indoor environment, where one or more blind nodes are to be localised with the aid of a number of anchor nodes. The positions of the blind nodes are estimated using the previously proposed iterative localisation method. The achievable positioning accuracy is analysed in terms of Cramer–Rao lower bound (CRLB), which is a theoretical lower bound on the variance of the positions of blind nodes. The range errors are modelled as distance independent (DI) and distance dependent (DD) for line-of-sight (LOS) and non-line-of-sight (NLOS) cases. Closed-form expressions of CRLB for TDOA localisation are derived and the theoretical analyses have been verified by experimental results.