Adaptive blind channel identification and equalization for OFDM-MIMO wireless communication systems

Wireless systems employing multiple-input multiple-output (MIMO) structure at the transmitter and the receiver have recently been shown to have the potential of achieving extraordinary bit rates. Orthogonal frequency division multiplexing (OFDM) significantly reduces receiver complexity in broadband systems. In this paper, we investigate a blind algorithm for channel identification and equalization of OFDM-MIMO systems. We exploit the second-order cyclostationarity inherent in OFDM with cyclic prefix and the characteristics of the phased antenna, construct a practical HIPERLAN/2 standard based MIMO-OFDM simulator with the sufficient considerations of statistical correlations between the multiple antenna channels under wireless wideband multipath fading environment, and formulate a new two-stage adaptive blind algorithm using rank reduced subspace channel matrix approximation and CMA (constant modulus algorithm) criteria. The performance of the new method has been justified theoretically and validated through extensive simulations over various common wireless and mobile communication links.