Throughput analysis of energy harvesting MIMO relay systems over Nakagami-m fading channels

In this paper, we consider two-hop multi-input multi-output (MIMO) relay wireless systems with energy harvesting. In each hop, transmit antenna selection (TAS)/receive antenna selection (RAS), TAS/maximum ratio combining (MRC), or maximum ratio transmission (MRT)/RAS is employed. Also, a relay harvests energy from the source via either a time switching-based relaying protocol (TSR) or a power splitting-based relaying protocol (PSR). We perform unified analysis of the resulting eighteen system configurations over Nakagami-m fading channels. Specifically, we derive exact and approximated closed-form expressions for ergodic capacity and throughput. Moreover, optimal energy-harvesting time (in TSR-based system) and optimal power-splitting ratio (in PSR-based system) to achieve maximum throughput at high signal-to-noise-ratio (SNR) are analyzed. Impacts of various MIMO processing schemes and energy harvesting mechanisms on the system performance are also examined and discussed. The theoretical analysis is corroborated by simulations.