Training sequences design for symbol timing estimation in MIMO correlated fading channels

In This work, the problem of training sequence design for symbol timing estimation in MIMO channels is addressed. In particular, we consider correlated fading between antennas. The optimal training sequences are derived by minimizing the modified Cramer-Rao bound (MCRB) with respect to the training data. It is found that when the transmit pulse is a root raised cosine pulse and there is no correlation among antennas, the optimal training sequences resemble the Walsh sequences. Furthermore, it is also found that the the impact of not knowing the antenna correlations when designing training sequences is very small.