A Novel Energy-Efficient Power Allocation for D2D Communications Underlaying Cellular Network

This paper investigates an uplink D2D communications underlaying cellular network. An optimal problem is proposed to maximize the energy efficiency of all the D2D pairs while the quality of service (QoS) of the cellular user(CU) is also taken into consideration. Firstly, we reformulate the fractional programming problem as an equivalent form by using the quadratic transformation. Then, after applying the Lagrangian relaxation (LR) method and the Dinkelbach method successively, a closed form solution to the relaxed problem is obtained. Finally, a novel iterative algorithm is proposed to solve the optimal power allocation problem. The results from this study demonstrate that the proposed algorithm has a good performance in terms of both energy efficiency and convergence.