Improved residual weighting for NLOS mitigation in TDOA-based UWB positioning systems

This paper presents an improved algorithm for mitigating non-line-of-sight (NLOS) error in time-difference-of-arrival (TDOA) positioning applications employing ultra wideband (UWB) signals. The main idea of the algorithm is based on calculating the residuals for the different subsets formed by the reference nodes. The final estimate is a linear summation of the estimate from the different sets weighted by the inverse of the residual to eliminate the effect of NLOS nodes. The algorithm performance is thoroughly analyzed using various statistical channel models based on the IEEE 802.15.4a standard. The impact of changing parameters like SNR, cell size, number of sensors and propagation environment types, on the accuracy of the algorithm is also investigated. The improved residual weighting algorithm is compared with a previously published algorithm and shows a better accuracy for TDOA positioning.