  We consider a bidirectional in-band full-duplex (FD) multiple-input
multiple-output (MIMO) system subject to imperfect channel state information
(CSI), hardware distortion, and limited analog cancellation capability as well
as the self-interference (SI) power requirement at the receiver analog domain
so as to avoid the saturation of low noise amplifier (LNA). A novel minimum
mean square error (MMSE)-based joint design of digital precoder and combiner
for SI cancellation is offered, which combines the well-known gradient
projection method and non-monotonicity considered in recent machine-learning
literature in order to tackle the non-convexity of the optimization problem
formulated in this article. Simulation results illustrate the effectiveness of
the proposed SI cancellation algorithm.
