Decision Feedback Channel Estimation for Alamouti coded OFDM-MIMO Systems

In this paper, we propose a new channel estimation algorithm for orthogonal frequency division multiplexing (OFDM) systems. For fast fading environment, we introduce a new method which is extended to the Alamouti Coded OFDM case. At the first stage of this algorithm, the channel response is estimated for pilot sub-carriers and then, the channel response for data sub-carriers are interpolated by Gaussian Radial Basis function as it is an efficient nonlinear interpolator. The post-processing and filtering on the estimated channel taps energy are proposed to improve the estimation performance and reduce the noise effects of primary estimation, which is caused by LS estimation at pilot data. The accuracy of our channel estimation algorithm is improved by using iterative decision feedback. The decision feedback method is used to update channel parameters in each OFDM symbol. The effectiveness of new techniques is demonstrated through the simulation of an Alamouti coded OFDM system with two-transmit and two-receive antennas. Finally, the results are analyzed and compared with previous algorithms which show performance enhancement.