Low complexity power allocation for device-to-device communication underlaying cellular networks

Device-to-device (D2D) communication, which underlays a cellular network to improve the reuse of spectrum resources, is a promising technique that can increase system capacity, enhance cell coverage and extend battery lifetime of user equipments. In this paper, we study the power allocation for a D2D underlaying cellular network. Our optimization task is to maximize the sum rate of the cellular network subject to the maximum power budgets of both the cellular link and the D2D link. The formulated problem is nonconvex which is generally difficult to obtain the global optimum. We propose a low complexity iterative algorithm to work out promising solutions with reasonable complexity. We develop a linear complexity barrier method to get a concave lower bound of the sum rate, and prove that an improved solution can be obtained after each iteration until the proposed algorithm converges, when the lower bound is tight. Simulation results validate the effectiveness and the efficiency of our proposed algorithm.