  The joint design of spatial channel assignment and power allocation in
Multiple Input Multiple Output (MIMO) systems capable of Simultaneous Wireless
Information and Power Transfer (SWIPT) is studied. Assuming availability of
channel state information at both communications ends, we maximize the
harvested energy at the multi-antenna receiver, while satisfying a minimum
information rate requirement for the MIMO link. We first derive the globally
optimal eigenchannel assignment and power allocation design, and then present a
practically motivated tight closed-form approximation for the optimal design
parameters. Selected numerical results verify the validity of the optimal
solution and provide useful insights on the proposed designs as well as the
pareto-optimal rate-energy tradeoff.
