A time-of-arrival estimation algorithm for OFDM signals in indoor multipath environments

摘要

Time-of-arrival (TOA) estimation of OFDM signals in multipath channels is challenging, especially when the signal bandwidth is limited, such as is the case of WIFI. In this paper, a novel low complexity TOA estimation algorithm is developed for OFDM signals that is robust to various multipath environments. We approximate the received signal as Gaussian with an autocorrelation that can be predetermined by the environment characteristics, and then derive the Maximum Likelihood estimator with an efficient implementation algorithm. The estimator performance was tested with a measurement system that was developed based on off-the-shelf WIFI 802.11g routers. The measurement system enabled the evaluation of the estimator performance in real-life indoor environments, and with real-life OFDM transmitter and receiver imperfections. The results show that the novel TOA estimator outperforms other known reference methods over various indoor environments.