High Resolution Time Of Arrival Estimation for OFDM-Based Transceivers

This letter presents a novel algorithm for Time Of Arrival (TOA) estimation for Orthogonal Frequency Division Multiplexing (OFDM) based transceivers. 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) 802.11g 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 (LOS) environment for ranges of 1-7 m.