Energy efficient transceiver design for SWIPT systems with non-orthogonal multiple access and power splitting

Abstract

This paper studies the energy efficient (EE) optimization for the simultaneous wireless information and power transfer (SWIPT) systems combined with non-orthogonal multiple access for multi-user support. Power splitting at receiver is adopted with nonlinear energy harvesting (EH) model. Our goal is to pursue high EE for information transmission by jointly design the transmit beamforming and power splitting coefficients while satisfying quality of service requirements, such as maximum transmit power budget, minimum data rate, and minimum harvested energy per terminal. The coupling of variables make it the non-convex even with linear EH models, which is difficult to solve. Firstly, after approximating the nonlinear EH model in the optimization objective by linear one, the nonlinear fractional function is transformed into a linear subtractive form with two groups of coupled variables. After transformations, the original problem is approximately solved in an alternate way. Through the iterative procedure, semi-definite relaxation and arithmetic–geometric mean inequality are adopted to deal with the non-convex constraints. Simulation results reveal that our proposed method has a faster convergence speed and a higher energy efficiency than the benchmarks.