Detector for Alamouti space-time coding in Rayleigh fading MIMO channels with randomly distributed timing drift

We analyze the properties of a robust timing error detector for n _T = 2 orthogonal space-time block coded M-PSK systems with an arbitrary number of receive antennas. The algorithm uses maximum-likelihood detection variables to estimate the timing error by examining the difference in threshold crossings. The S-curve of the detector is shown to be independent of the channel state, thus making it very robust in poor channel conditions. Furthermore, we derive a closed form expression for the variance of the estimator, and show that the estimation SNR peaks in the timing error region the receiver usually operates in. We evaluate the tracking performance in 1-, 2- and 4-receive antenna systems with randomly distributed timing drift. Complete channel state estimation is assumed throughout the paper