Scattering-model-based methods for TOA location in NLOS environments

In this paper, we address methods of mitigating one of the major issues affecting wireless location accuracy in land mobile terrestrial environments: nonline-of-sight (NLOS) propagation. In order to improve location accuracy under such conditions, we propose a novel methodology for NLOS environments based on the use of scattering models to classify propagation environments. The scattering models allow modeling of the NLOS error so that the NLOS effect can be incorporated into a location algorithm. Through the use of the scattering models, we develop three novel location techniques based on the statistics of measured ranges via moment matching, the expectation maximization algorithm, and a Bayesian algorithm. Simulation results and discussion are given to illustrate the performance in typical NLOS environments. The results show that the algorithms provide improvement over traditional location algorithms.