  In this paper, we deal with the deployment of full-duplex relaying in
amplify-and-forward (AF) cooperative networks with multiple-antenna terminals.
In contrast to previous studies, which focus on the spatial mitigation of the
loopback interference (LI) at the relay node, a joint precoding/decoding design
that maximizes the end-to-end (e2e) performance is investigated. The proposed
precoding incorporates rank-1 zero-forcing (ZF) LI suppression at the relay
node and is derived in closed-form by solving appropriate optimization
problems. In order to further reduce system complexity, the antenna selection
(AS) problem for full-duplex AF cooperative systems is discussed. We
investigate different AS schemes to select a single transmit antenna at both
the source and the relay, as well as a single receive antenna at both the relay
and the destination. To facilitate comparison, exact outage probability
expressions and asymptotic approximations of the proposed AS schemes are
provided. In order to overcome zero-diversity effects associated with the AS
operation, a simple power allocation scheme at the relay node is also
investigated and its optimal value is analytically derived. Numerical and
simulation results show that the joint ZF-based precoding significantly
improves e2e performance, while AS schemes are efficient solutions for
scenarios with strict computational constraints.
