Closed-form blind channel estimation in orthogonally coded MIMO-OFDM systems

Two closed-form blind channel estimators for orthogonally coded multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems are proposed. The key idea of our approaches is to estimate the channel parameters in the time domain instead of doing this in the frequency domain. Our first approach is based on the maximum likelihood (ML) technique with the relaxed finite alphabet constraint, while the second approach uses the generalized Capon estimator to obtain the channel parameters. The proposed techniques amount to solving eigenvector problems.