Iterative B-spline channel estimation for space-time block coded systems in fast flat fading channels

A novel iterative B-spline channel estimation technique for space-time block coded (STBC) systems over fast flat fading channels is proposed. The optimal linear minimum mean square error (LMMSE) multiple-input and multiple-output (MIMO) channel estimator can be decoupled into a simplified maximum likelihood (ML) estimator over a block period, by taking advantage of the orthogonal property in the STBC, and a subsequent Wiener filter. The Wiener filter can then be replaced by a B-spline estimator for complexity reduction. Both local linear and parabolic splines are considered. Comparisons between the Wiener filtering and B-spline approaches in mean square error (MSE), bit error rate (BER) and complexity are given. The BER performance of the iterative receiver with the B-spline estimators is nearly the same as that of the Wiener filter for a fast fading channel. However, the complexity of the proposed estimators is much lower than that of the Wiener filter.