Efficient Minimum Variance receivers for MC-CDMA systems using transmit diversity

The issues of blind channel estimation and information symbol detection for the downlink of Space-Frequency Block Coded Multi-Carrier Code Division Multiple Access (SFBC MC-CDMA) schemes are revisited. Specifically, we first formulate blind channel estimation and detection algorithms based on the Second-Order Statistics (SOS) of the frequency-domain received signal using a Minimum Variance (MV) criterion. Then, we identify the unique structure of the input covariance matrix based on which we propose modifications of the presented algorithms that are computationally efficient and offer enhanced performance in practical cases where only an estimate of the received signal covariance matrix is available. The effectiveness of the new algorithms utilizing the special structure of the received signal covariance matrix is demonstrated through the comparison with the corresponding conventional approaches.