Unified analysis of energy harvesting-based MIMO relay wireless systems over Nakagami-m fading channels

In this paper, we consider two-hop multi-input multi-output relay wireless systems with energy harvesting. In each hop, transmit antenna selection/receive antenna selection, transmit antenna selection/maximum ratio combining, or maximum ratio transmission/receive antenna selection is used. Also, an energy-constrained relay harvests energy from the source via either a time switching–based relaying protocol or a power splitting–based relaying protocol. We perform unified analysis of the systems over Nakagami-m fading channels. Specifically, we derive exact closed form expressions for ergodic capacity and throughput (for delay-tolerant transmission mode) and outage probability and throughput (for delay-limited transmission). Optimal energy-harvesting time (in time switching–based relaying protocol–based system) and optimal power-splitting ratio (in power splitting–based relaying protocol–based system) to achieve maximum throughput at high signal-to-noise-ratio are also determined. Moreover, we derive an exact closed form expression for the bit error rate, which facilitates the evaluation of the system performance. Impacts of various multi-input multi-output processing schemes, numbers of equipped antennas, energy-harvesting mechanisms, and transmission modes on the system performance are also examined and discussed. All theoretical analyses are corroborated by simulations.