Blind identification of MIMO channels with periodic modulation

We propose a method for blind identification of MIMO FIR channels with periodic modulation. The method exploits the linear relation between the covariance matrix of the received data and the "product matrices" of the channel. The proposed algorithm requires solving linear equations and computing eigenvalues and eigenvectors of a Hermitian matrix. We show that the identifiability condition depends on the modulating sequences alone and the method is robust with respect to channel order overestimation. A method for optimal selection of modulating sequences is proposed, which takes into account the effect of noise and the numerical error in estimating the covariance matrix of the received data. Simulations are used to demonstrate the performance of the proposed algorithm.