An EM-based channel estimation algorithm for OFDM with transmitter diversity

We study channel estimation for OFDM systems utilizing transmitter diversity and operating over multipath fading channels. An expectation-maximization (EM) based estimation algorithm is introduced and compared to least-squares based estimation algorithms. At each iteration and for every OFDM link, the EM algorithm partitions the problem of estimating a multi-input channel into independent channel estimations for each transmit-receive antenna pair. It is shown that the EM algorithm is more robust to multipath channel delay profile variations and can be implemented more efficiently compared to a previously proposed algorithm