Energy efficient power control for device to device communication in 5G networks

Next generation cellular networks require high capacity, enhanced efficiency of energy and guaranteed quality of service (QoS). To reach these goals, device-to device (D2D) communication is a candidate technologie for future 5th Generation especially applications that require the reuse, the hop and the proximity gain. The present paper studies the energy efficient power control for the uplink of an OFDMA (orthogonal frequency-division multiple access) system composed of both regular cellular users and device-to-device (D2D) pairs. First, we analyze and model mathematically the prerequisites for D2D communications and classical cellular links in terms of minimum rate and maximum power requirement. Second, we use fractional programming in order to convert the initial problem into a concave one and we apply non-cooperative game theory in order to characterize the equilibrium. Then, we got the solution of the problem from the results of a water-filling power allocation. Moreover, we employ a distributed design for power allocation by means of three methods: a) Theory of fractional programming b) Closed form expression (the novelty is the use of Wright Omega function). c) Inverse water filling. Finally, simulations in both static and dynamic channel setting are realized to demontrate the enhanced gain in term of EE, SE (spectral efficiency) and time of execution of the iterative algorithm (Dinkelbach) than the closed form algorithms