Improved line-of-sight/non-line-of-sight classification methods for pulsed ultrawideband localisation

Classification of line-of-sight (LOS) or non-LOS (NLOS) propagation is critical for most pulsed ultrawideband localisation systems. In this letter, first, the authors propose a two-dimensional (2D) LOS/NLOS classification scheme that uses skewness of the channel impulse/pulse response, which has not been used by existing work. The log-likelihood ratio of the 2D LOS/NLOS classification is used to determine the weights for localisation. Then, the authors derive an iterative Gauss-Newton method to solve the location of the target, which provides a higher accuracy than the Gauss-Newton method used in existing work. Finally, they investigate improved localisation by incorporating the statistics of NLOS bias as a result of LOS/NLOS classification into the cost function, and derive the statistics of the corresponding errors of location estimates. The proposed 2D LOS/NLOS classification scheme is compared with an existing 3D scheme to demonstrate its effectiveness.