Resource Allocation for Energy-Efficient Transmission in D2D Underlaid Cellular Networks

In this paper, we consider the problem of maximizing the weighted sum energy efficiency (WS-EE) of device- to-device (D2D) pairs while guaranteeing the minimum throughput of cellular links in a D2D underlaid cellular network. To increase the spectral efficiency, D2D users (DUs) are allowed to reuse all the uplink cellular subchannels. A novel iterative algorithm is proposed, which consists of solving two subproblems: the channel allocation subproblem for cellular users (CUs) and the power control subproblem for DUs. We model the former subproblem by an assignment problem, which can be optimally solved with low complexity. The latter subproblem is a sum-of-ratios optimization, and the numerator of each summation term is non-concave. Therefore, we first express it in an equivalent form, and then apply a parametric algorithm to solve it. By iteratively solving these two subproblems, the WS-EE of DUs converges to a suboptimal solution. Simulation results show that the proposed algorithm converges rapidly and outperforms the existing algorithm significantly in terms of the WS-EE of DUs.