Multiuser and Multipath Interference Mitigation in UWB TOA Estimation

In this paper we consider the impact of MUI (multiuser interference) on coherent TOA (time of arrival) estimation. We consider TH-PPM (time-hopping pulse position modulation). We propose estimators based on the ML (maximum likelihood) criterion together with interference cancellation. We propose algorithms for SP (single-path) and MP (multipath) communication channels. We report simulation results and we conclude that the proposed estimators obtain smaller variance than the per-user ML estimator. Moreover, with well-chosen signature parameters, it is possible to reach the CRB (Cramer-Rao bound) when multiple sources are transmitting in SP channels and values close to the CRB in MP channels. We also show that the interference cancellation technique makes the estimation robust against near-far situations.