Enhanced position location with UWB in obstructed LOS and NLOS multipath environments

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) and non-LOS (NLOS) 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° rotation of directional beacon. We extend the algorithm to non-LOS (NLOS) case and estimate position by minimizing the norm between the sets of measurements. To assess the performance over realistic UWB channels, we modify the UWB channel model to incorporate the effect of directional transmitting antennas. From simulation results we claim position location accuracy of around 34 cm with a pragmatic 4-element antenna array using 2.4GHz UWB pulses and 4-bit A/D converter at 24dB SNR.