Energy-Efficient D2D Communications Underlaying NOMA-Based Networks With Energy Harvesting

This letter investigates the resource allocation problem in device-to-device (D2D) communications underlaying a nonorthogonal multiple access based cellular network, where both cellular users (CUs) and D2D users harvest energy from the hybrid access point in the downlink and transmit information in the uplink. We propose a low-complexity iterative algorithm to maximize the energy efficiency of the D2D pair while guaranteeing the quality of service of CUs. In each iteration, by analyzing the Karush-Kuhn-Tucker conditions, the globally optimal solution can be derived in the closed form despite the nonconvexity. Simulation results validate the superiority of the proposed scheme over the existing schemes.