Threshold-Based Time-of-Arrival Estimators in UWB Dense Multipath Channels

In this paper we put forth a simple threshold-based time-of-arrival (ToA) estimator and analyze its performance in ultra-wide bandwidth (UWB) dense multipath channels. Closed-from expressions for the estimator bias and mean square error are derived as a function of signal-to-noise ratio (SNR), overcoming the limitation of conventional asymptotic analysis valid only for high SNR. A comparison with results based on Monte Carlo simulation as well as those based on experimental measurements in an office environment confirms the validity of our analytical approach. Our analysis enables us to determine the threshold value that minimizes the mean-square error, critical parameter for optimal estimator design. It is shown that the estimation accuracy mainly depends on large estimation errors due to peak ambiguities at the output of the correlator and on the fading statistics of the first path.