Data-aided maximum likelihood symbol timing estimation in MIMO correlated fading channels

In this paper, the maximum likelihood (ML) symbol timing estimator in a MIMO correlated channel, based on training data, is derived. It is shown that the approximated ML algorithm in (A. F. Naguib et al, IEEE J Select. Areas in Commun., vol.16, p.1459-1478, 1998) and (Y. C. Wu et al, IEEE Trans. on Wireless Comm., 2003) is just a special case of the proposed algorithm. Furthermore, the modified Cramer-Rao bound (MCRB) is also derived for comparison. Simulation results under different operating conditions (e.g., number of antennas and correlation between antennas) are given to assess the performances of the ML estimator and it is found that the mean square errors (MSE)s of the ML estimator: i) are close to the MCRBs; ii) are approximately independent of the number of transmit antennas; iii) are inversely proportional to the number of receive antennas; and iv) correlation between antennas has no effect on the MSE performance.