MIMO Decode-and-Forward Relay Systems With an Energy-Constrained Antenna-Switching Relay

We study a multiple-input multiple-output (MIMO) relay system composed of a source, a relay, and a destination, in which the decode-and-forward relay delivers the decoded symbols from the source to the destination by harvesting energy from the source. Each antenna in the relay has capability of both information decoding (ID) and energy harvesting (EH), each of which is opportunistically selected to be used for either ID or EH at each time. Under this configuration, we propose antenna assignment algorithms at the relay and the corresponding optimal beamforming design at the source and relay that maximize the end-to-end transmission rate. Specifically, we propose suboptimal antenna assignment algorithms that give performance close to the exhaustive search with significantly reduced complexity.