A simple channel estimator for OFDM with transmit diversity in rapid fading channels

This paper presents a simple channel estimator for orthogonal frequency division multiplexing (OFDM) systems with transmit diversity in rapid fading channels. The channels at the training bauds are estimated using the EM (expectation-maximization) algorithm, while the channels at the data bauds are estimated based on the method that the time-varying channel can be modelled as the linear combination of several time-invariant "Doppler channels". Computer simulations show that this estimator outperforms the decision-directed tracking in rapid fading channels and the performance of this method can be improved by iteration.