Semi-Blind Channel Estimation in MIMO Systems With Discrete Priors on Data Symbols

In this work, we addressthe MIMO semi-blindchannel estimation problem. We propose an eigenvalue decomposition based technique to significantly reduce the dimensionality of the EM based algorithm when the imposed prior on the data is Gaussian, greatly lowering the computational complexity. In addition to that, we apply the Minimum Power Distortionless Response (MPDR) decoupling principle to derive a tractable EM algorithm that uses the actual discrete prior of the data symbols. Our results show that the proposed MPDR based algorithm has superior performance over other EM based algorithms in both low and high SNR regions. The results also show that a faster version of the algorithm can be obtained by initializing it using the eigenvalue decomposition based Gaussian algorithm.