Energy-efficient transmission for wireless powerec D2D communication networks

This paper studies resource allocation for energy-efficient device-to-device (D2D) communications in an overlay wireless cellular networks, where a D2D transmitter first harvests energy from a base station (BS) and then communicates with a D2D receiver. The resource allocation algorithm design is formulated as a non-convex optimization problem for the maximization of the energy efficiency (bits/Joule) of the D2D system. The proposed problem formulation takes into account the minimum required harvested energy, maximum duration of signal transmission, and minimum required system throughput. Exploiting fractional programming theory, we transform the non-convex problem into a standard convex optimization problem. This allows us to characterize the optimal solution structure of joint time, frequency, and power allocation and to derive an efficient iterative algorithm for obtaining the optimal solution. We reveal that the optimal energy-efficient D2D communication in this framework should occur if the D2D transmitter consumes all the harvested energy from the BS. Simulation results demonstrate the energy efficiency improvement brought by the proposed optimal resource allocation compared to two baseline schemes.