  This paper considers a multiple-input multiple-output (MIMO) relay system
with an energy harvesting relay node. All nodes are equipped with multiple
antennas, and the relay node depends on the harvested energy from the received
signal to support information forwarding. In particular, the relay node deploys
power splitting based energy harvesting scheme. The capacity maximization
problem subject to power constraints at both the source and relay nodes is
considered for both fixed source covariance matrix and optimal source
covariance matrix cases. Instead of using existing software solvers, iterative
approaches using dual decomposition technique are developed based on the
structures of the optimal relay precoding and source covariance matrices.
Simulation results demonstrate the performance gain of the joint optimization
against the fixed source covariance matrix case.
