Blind Separation for Precoding-Based Blind Channel Estimation for MIMO-OFDM Systems

In this paper, the problem of blind channel separation for precoding-based blind channel estimation is considered in multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems. In the new scheme, blind separation is achieved by implicitly "marking" the respective signal sent by each transmitter with a unique (known) circular time-shift during even-valued time slots. Separation of the blindly obtained channel mixtures is achieved through a combination of subspace alignment followed by SVD based computation of the intersection of two subspaces. Separability conditions required for the proposed precoding-based blind channel estimation are established. Numerical results are presented demonstrating the efficacy of the proposed algorithm.