A novel algorithm for semi-blind estimation in MIMO systems

A novel semi-blind orthogonal procrustes based channel estimation technique is developed for Multiple Input Multiple Output (MIMO) systems operating in the presence over Rayleigh flat-fading channels. We propose to implement the channel matrix via a QR factorization based algorithm, which is suitable for operating in conjunction with the orthogonal procrustes (OP) estimator. The presented estimator is based on Cholesky decomposition of the down-triangular matrix blindly from the received signals, which can be directly applied when exploiting the unitary matrix exclusively from the pilot data. The estimation gain is obtained by the powerful method while ensuring low complexity as it offers such optimum rotation matrices which are parameterized a fewer number of parameters. Numerical examples show that the proposed schemes outperform conventional ML channel estimator, and 2–5 dB improvement of mean squared error (MSE) would result if the same length of training sequence is used.