Optimization for DF Relaying Cognitive Radio Networks with Multiple Energy Access Points

Cognitive radio (CR) has been advocated to improve the network spectrum efficiency for decades, and the cooperation between the primary and secondary systems has become a new paradigm to further improve the spectrum utilization. However, in practice, secondary transmitters (STs) are usually power constrained, which limits the application of cooperative cognitive radio networks (CCRN). In this paper, to tackle this, we consider a novel spectrum sharing CCRN powered by energy access points (EAPs) that can charge users wirelessly, in which a multi-antenna secondary user (SU) solely powered by its harvested energy seeks cooperation with a single-antenna primary user (PU) by serving as a deocde-and-forward (DF) relay. We investigate a payoff maximization problem from the SU's perspective, who gets paid by offering data relaying service for PU but has to pay for WEH, and obtain its optimal DF relay and WEH strategy. A greedy-based algorithm that can assign the ST to right EAPs is also proposed for the ease of implementation. The proposed scheme is shown to be effective by simulations with a negligible gap to the optimal solution