Apparatus and method are provided for estimating the shortest time of arrival or the shortest round-trip time (RTT) of radio signals between communication devices in a wireless network. Filtering is performed by adaptive filters with suppressed side lobes adjustable in the time domain and widths of main lobes adjustable in the frequency domain to improve detection of signals on the shortest path of arrival or line-of-sight (LOS) path while mitigating the effects signals received from longer paths of arrival or non-line-of-sight (NLOS) paths.