NLOS Identification and Mitigation for UWB Localization Systems

Non-line-of-sight (NLOS) identification and mitigation carries significant importance in wireless positioning systems. In this paper, the authors propose a novel NLOS identification technique based on the multipath channel statistics such as the kurtosis, the mean excess delay spread, and the root mean square delay spread. In particular, the IEEE 802.15.4a ultrawideband channel models are used as examples and the above statistics are found to be well modeled by log-normal random variables. Subsequently, a joint likelihood ratio test is developed for LOS/NLOS identification. Simulation results show that correct identification can be achieved with over 90% of the realizations for most channel models. A weighted least squares localization algorithm is also developed using the NLOS information, and accuracy gains with respect to a conventional least squares algorithm are demonstrated via Monte-Carlo simulations.