An Energy-Efficient Resource Allocation Scheme for SWIPT-NOMA Based Femtocells Users with Imperfect CSI

In this paper, we propose, an energy-efficient resource allocation scheme for simultaneous wireless information and power transfer (SWIPT)-Non-orthogonal multiple access (NOMA) based femtocell users with imperfect channel state information. SWIPT enhances the transmission power of Femto users and NOMA improves the spectral efficiency. Therefore, SWIPT and NOMA at Femto base station are integrated to improve the energy efficiency and spectral efficiency of femtocells. The formulated resource allocation problem is divided into subchannel allocation and power control. The preference list of Femto users and macro users is developed on the basis of their energy harvested from the Femto base station and macro base station, respectively. Then, to optimize the power of a Femto base station, a successive convex approximation low complexity technique at each Femto base station is used. Also, Dinkelbach method is used to convert the non-liner fractional problem into a subtractive problem and Lagrangian duality is used for power computation of Femto base station. Finally, the simulation results demonstrate that our proposed scheme provides 0.2% and 31.25% higher energy-efficiency in comparison to the existing EH-NOMA and EH-OFDMA schemes