Performance analysis of directional beacon based position location algorithm for UWB systems

Abstract

We propose an enhanced directional beacon based position location procedure for UWB systems. Unlike previous work that relies on strongest return and therefore prone to errors in obstructed line of sight (OLOS) environments, our procedure identifies the LOS return by detecting the earliest arrival. To overcome synchronization problems, we propose a correlation based window algorithm to detect the earliest arrival and hence the LOS component across a 360 deg rotation of directional beacon. We performed a detailed and exact analysis of the algorithm that has not yet reported in the literature. The analysis quantifies the dependence of the algorithm on the variance of noise and the beam pattern. The analysis also motivated us to mitigate the effect of noise. We, therefore, propose an improved algorithm and implement it in a computationally efficient way. To improve position estimation we perform a three point search around the estimated time index n and selects the point that minimizes l2 norm of a performance measure vector. From simulation results we claim position location accuracy of around 30 cm with a pragmatic 4-element antenna array using 2.4 GHz UWB pulses and 4-bit A/D converter at 28 dB SNR