High‐resolution time of arrival estimation for OFDM‐based transceivers

A novel algorithm for time of arrival (TOA) estimation for OFDM‐based transceivers is presented. The algorithm processes the sampled baseband signal to obtain a high‐resolution estimate of the TOA of the OFDM symbol. In the first step, the algorithm obtains a sample‐resolution estimate of the TOA by finding the peak of the absolute value of the cross‐correlation of the in‐phase and quadrature received signals with the known transmitted symbol. In the second step, the algorithm refines this estimate to sub‐sample resolution by estimating the phase delay of the received signal based on the gradient of a linear fit to the phase difference between the transmitted and received sub‐carriers (in the frequency domain). The algorithm was applied to the long training sequence (LTS) symbol of the IEEE wireless local area network (WLAN) 802.11 g preamble. In real‐world experiments, the algorithm was found to achieve a mean TOA estimation error of 49 cm in a low multi‐path line‐of‐sight environment for ranges of 1–7 m.