A Maximum-Likelihood Channel Estimator in MIMO Full-Duplex Systems

This paper focuses on the channel estimation for residual self-interference cancellation at the baseband in a full-duplex transceiver. In particular, we analyze and develop a semi-blind maximum-likelihood algorithm to jointly estimate both the residual self-interference channel and intended signal channel based on the perfectly known transmitted symbols from its own transmitter, and both known pilot and unknown data symbols sent from the other intended transmitter. We first derive a closed-form solution for the channel estimate, and subsequently develop an iterative procedure to improve the estimation performance of the closed- form approach at high SNR. The iterative algorithm is guaranteed to converge to the ML solution when properly initiated. Simulation results show that, with a modest complexity, the proposed algorithm can offer good channel estimation MSE that follows well the Cramer-Rao bound (CRB), and good cancellation performance for a large SNR range.