Channel Estimation for Alamouti Coded OFDM over Time Variant Channel with Different Receivers

In this paper, we investigate a semi-blind maximum a posteriori probability-based channel estimator for Alamouti coded OFDM system over time varying Rayleigh channels. This channel estimation is used to handle rapid variations of channel within a transmission block. With the estimate of the channel matrix for the Alamouti symbol interval, a zero-forcing (ZF) receiver can be applied to detect this symbol. Linear and Minimum Mean Square Error (MMSE) decoding algorithms are also introduced in this paper. These receivers take into consideration the variation of channel over two consecutive OFDM symbols, i.e., over Alamouti symbol. The performance of this estimator is compared with Least Square (LS) channel estimator via simulation. Moreover it is shown that using MMSE as a decoding algorithm provides better performance than conventional, linear or ZF decoding methods.