Bounds on the accuracy of Ultra-wideband based positioning

Time of arrival (TOA) and position estimation in harsh environments has drawn considerable attention. The ineffectiveness of Global Navigation Satellite System systems in such environments has given rise to new technologies providing localization services for costumer, medical, logistics, and more applications. Ultra-wideband (UWB) is an appealing technology for short range and high accuracy positioning that can potentially satisfy these needs. In this dissertation, we focus on estimators and lower bounds for UWB based ranging and localization. In the first part of the thesis, we investigate cancellation techniques for both multiuser and multipath (MP) interference. The techniques are based on the per-user maximum-likelihood estimation (MLE). We propose algorithms for both single-path (SP) and MP channels. We show simulation results for different signature parameters. In the second part of the thesis, we study the performance of TOA estimation in the presence of signal model mismatch. A fundamental lower bound accounting for signal model inaccuracies is derived. The bound is extended to assess the presence of one or several interfering pulses (MP case). Also, we study a lower bound on the TOA estimation computed by means of the probability density function (pdf) of the interference. The bounds are afterward validated by means of simulations with UWB signals. In last section, we consider the positioning aspect of UWB systems. We investigate small and large-error bounds for the conventional two steps estimation approach and the alternative direct position estimation (DPE) approach. The bounds are derived for both SP and MP channels, and compared with the performance of conventional and direct position estimators.(FSA - Sciences de l) -- UCL, 201