Performance analysis for device-to-device communications with optimal power control

Power control is an effective method to guarantee the resource sharing between cellular and D2D links for D2D (device-to-device) communications. In this work, we study the power optimization to maximize the sum rate of all coexistent links. We explicitly put priority for cellular link to guarantee QoS (quality of service) of cellular service. The power optimization problem can be characterized as a D.C. (difference of convex functions) programming problem, which can be solved with a branch and bound algorithm. In the bounding step, the optimal lower bound is obtained via a Lagrangian decomposition. Numerical results show that optimal power control provides significant sum rate improvement with cellular service well protected.