Energy-Efficient Power Allocation in Non-Linear Energy Harvesting Multiple Relay Systems

In this paper, to maximize the energy efficiency (EE) in two-hop multi-relay cooperative decoding and forwarding (DF) system for simultaneous wireless information power transmission (SWIPT), an optimal allocation algorithm is proposed, which relay harvesting (EH) adopts a nonlinear model. Under constraints, including causality, minimum quality of total at relays, optimization problem constructed jointly optimize transmit power-splitting (PS) ratios multiple relays. Although fractional programming problem, iterative developed obtain allocation. particular, joint relays first decoupled into single allocation, then single-relay performed by Dinkelbach iteration algorithm, can be proven that it convex problem. Its closed form solutions different polylines EH models are obtained using mathematical methods, such as monotonicity, Lagrange multipliers, KKT condition Cardan formula. The simulation results show superiority proposed paper terms EE.