Designing orthogonal pilot scheme for semi-blind channel estimation in MIMO systems

This paper presents a least square based semi-blind channel estimation using the new orthogonal pilot scheme for multiple-input multiple-output (MIMO) wireless communications. In practice, knowledge of the wireless unknown channel is often estimated by sending known training symbols to the receiver. We determine the optimal training sequence aiming to minimize the mean square error (MSE) of the channel estimator under a total transmit power constraint. In order to reduce the training overhead, this semi-blind algorithm only use fewer number of training symbols for decomposed channel matrices. Combining the advantage of semi-blind approach with designed pilot scheme addresses the improvement of the total bandwidth efficiency. In addition, the problem of power allocation between the pure data and the training symbols is also calculated. Experimental studies are carried out to study and validate the optimal performance of the proposed scheme.