Temporal autocorrelation estimation for OFDM with application to spatial interpolation

Due to the prolonged symbol duration of OFDM frequency-selective channels are utilized for high-data-rate transmission easily. Unfortunately, OFDM becomes vulnerable to large Doppler spread, since subcarriers lose their orthogonality giving rise for so-called intercarrier interference. Among previous proposals to cope with this problem was the use of multiple receive antennas. These are positioned in the moving direction of the receiver such that the individual antennas are receiving delayed replica of the transmit signal via identical paths. By means of interpolation this enables to fabric virtual non-moving antennas which seemingly experience no Doppler spread. However, knowledge of the temporal channel autocorrelation function is required to perform this interpolation. This paper presents a method to estimate the autocorrelation function in time domain based on the cylic OFDM signaling structure.