Optimal Resource Allocation in Wireless Powered Relay Networks with Nonlinear Energy Harvesters

This letter investigates a multiple-relay decode-and-forward (DF) network with simultaneous wireless information and power transfer (SWIPT). The relays use the power splitting (PS) technique to receive radio frequency (RF) energy and information simultaneously from the source. To characterize nonlinearity of energy harvesters at the relays, two existing models are adopted, which are the logistic function model and the constant-linear-constant (CLC) model. We target end-to-end throughput maximization by optimizing the power and bandwidth assignment for every source-relay-destination link and the PS ratio at every relay node. The formulated problems are demonstrated to be nonconvex. Through a series of analysis and transformations, we find global optimal solutions for the formulated problems. Numerical results verify the effectiveness of our proposed methods.