Match-filtering based TOA estimation for IR-UWB ranging systems

Accurate geolocation techniques using IR-UWB (impulse radio ultra-wideband) signals have gained more and more interests recently. To exploit the fine time resolution of IR-UWB most, TOA (time of arrival) based ranging is the most appropriate technique. Considering the challenges for the design of TOA estimation algorithms in many aspects, a three-step match-filtering detection based algorithm is proposed. First, the search region for DP (direct path) detection is determined; then, a rough detection of DP is made by threshold comparison; last, a refined search process is carried out to obtain the precise location of DP. The threshold-factor in the second step is dynamically set using a joint-metric in terms of kurtosis and RMS (root mean square) delay spread of the match-filtering output. Performance comparisons with other algorithms prove that the proposed three-step algorithm can achieve a good trade-off between computation efficiency and estimation accuracy. The reliability of TOA estimation result is also discussed. Three levels of reliability are defined and the probability density functions for TOA estimation errors in each level are modeled. It is expected to improve the final location estimation accuracy further by properly incorporating the reliability information into the positioning algorithms.