Perturbation analysis of whitening-rotation-based semi-blind MIMO channel estimation

The whitening-rotation (WR)-based semi-blind methods have been shown to achieve much better channel estimation performance than the conventional training-based methods for MIMO systems. In this paper, the performance analysis is conducted for an ideal WR-based method, in which the knowledge of the ideal whitening matrix is known a priori. This analysis is a valuable study since the ideal WR-based method provides the upper bound of the channel estimation performance for WR-based methods. First, the expression of the error of the rotation matrix is derived by using a perturbation analysis. This result is then utilized to derive a closed-form expression of mean square error (MSE) of the ideal WR-based method. The simulation studies have shown that the theoretical MSE values are consistent with the simulation results, confirming the high accuracy of the derivation of the MSE expression.