Test measurements of improved UWB localization technique for precision automobile parking

Ultra-Wideband (UWB) communication system provides high accurate localization due to the high multipath resolution capacity. For Ultra-Wideband (UWB) localization systems, time-based schemes namely Time of Arrival (TOA) and Time Difference of Arrival (TDOA) provide very good accuracy due to the high time resolution (large bandwidth) of UWB signals. Due to the inherent suitability and accuracy of time-based approaches for UWB systems, particularly the TDOA technique, it is proposed as the appropriate UWB localization technique for the precision automobile parking system. UWB pulse of 0.5 ns pulse width is simulated. Tests measurements are conducted using Impulse Radio UWB transceiver test setup. The TDOA values are measured for different positions of tag and reference nodes. Time-delay estimation is obtained by generalized cross correlation method and position estimation is obtained by direct method (DM) using hyperbolic navigation. The precision of the obtained position estimation is improved by an iterative Davidon-Fletcher-Powell (DFP) algorithm. The performance of the technique is analysed by determining the mean square error for various reference nodes densities. The proposed system is composed of UWB nodes, UWB tags and an UWB location server. With UWB tags, equipped only with transmitters, on targets and UWB nodes with both transmitters and receivers, installed on infrastructure, the system calculates the position of the tags precisely.