  In this paper, we study Full Duplex (FD) Multiple-Input Multiple-Output
(MIMO) radios for simultaneous data communication and control information
exchange. Capitalizing on a recently proposed FD MIMO architecture combining
digital transmit and receive beamforming with reduced complexity multi-tap
analog Self-Interference (SI) cancellation, we propose a novel transmission
scheme exploiting channel reciprocity for joint downlink beamformed information
data communication and uplink channel estimation through training data
transmission. We adopt a general model for pilot-assisted channel estimation
and present a unified optimization framework for all involved FD MIMO design
parameters. Our representative Monte Carlo simulation results for an example
algorithmic solution for the beamformers as well as for the analog and digital
SI cancellation demonstrate that the proposed FD-based joint communication and
control scheme provides 1.4x the downlink rate of its half duplex counterpart.
This performance improvement is achieved with 50% reduction in the hardware
complexity for the analog canceller than conventional FD MIMO architectures
with fully connected analog cancellation.
