Relay selection and power allocation for cooperative communication networks with energy harvesting

Abstract

This paper addresses the joint relay, power splitting ratio, and transmission power selection problem for an energy harvesting (EH) cooperative network, where the source and the relays can harvest energy from natural sources (e.g., solar) and radio frequency (RF) signals, respectively. To effectively use the harvested energy of the source, the relays are designed to employ the power splitting technique to scavenge energy from RF signals radiated by the source. The addressed problem is considered in both offline and online settings, with the objective to maximize system payoff, which is defined as the difference between system transmission benefit and system energy cost, and meanwhile to minimize system outage probability. In particular, direct transmission is considered in our study and relay transmission is selected dynamically based on the network channel conditions and the available energy of EH nodes. Our simulation results reveal that it is necessary to consider direct transmission and select relay transmission and power splitting ratio dynamically in some cases, which can greatly improve system performance. Besides, simulations also verify that considering system energy consumption is also meaningful for EH relaying systems, which can lead to a desired system performance by choosing some related parameters appropriately. In addition, we also show that the resource allocation models and the corresponding resource allocation schemes proposed can be extended to more general communication scenarios, e.g., when some relays scavenge energy from natural sources and others from RF signals.