Orthogonal procrustes-based semi-blind channel estimation for MIMO-OFDM systems

This paper introduces a novel semi-blind channel estimation algorithm based on Orthogonal Procrustes (OP) approach for Multiple Input Multiple Output (MIMO) systems using Orthogonal Frequency Division Multiplexing (OFDM) modulation. The presented joint estimator is based on decomposition of channel matrix H as a whitening matrix R and a unitary rotation matrix Q. The whitening matrix R can be estimated blindly based on the eigenvalue decomposition (EVD) of the received signal correlation matrix, while Q has to be fed by using the properties of the constrained OP estimator for an orthogonal pilot sequence. The estimation gain is obtained by the power method with low complexity as it offers such optimum rotation matrices which are parameterized a fewer number of parameters. Various numerical examples are conducted to support the algorithms and analysis, and they demonstrate improved performance up to 3-5 dB compared to exclusively training-based estimation.