Outage Minimization for Energy-Harvesting Multi-Antenna Multi-Relay Networks

In this paper, we consider an energy-harvesting (EH) decode-and-forward (DF) relay system consisting of a source, a destination and multiple EH relays each equipped with multiple antennas. We first propose an optimal power splitting and relay selection (OPS-RS) scheme for our considered EH multi-antenna multi-relay system, where a closed-form solution to the optimal power-splitting ratio is obtained for maximizing an instantaneous channel capacity from the source via an EH relay to the destination. For the purpose of comparison, we also take into account the equal power splitting and relay selection (EPS-RS) scheme as a benchmark. Then, we derive closed-form expressions of the outage probability for both the OPS-RS and EPS-RS schemes over Rayleigh fading channels. Numerical results demonstrate that as the number of EH multi-antenna relays increases, the outage probabilities of both OPS-RS and EPS-RS decrease significantly. In addition, the proposed OPSRS scheme outperforms the traditional EPS-RS method in terms of outage probability.