Ergodic capacity analysis and transmission power optimization in D2D underlaying cellular communication

Abstract

In this paper, we consider a non-cooperative deployment of Long Term Evolution (LTE) and Device-to-Device (D2D) links, for which we derive approximations for Signal-to-Interference and Noise Ratio (SINR) distributions plus ergodic capacity expressions. We show that the capacities of D2D and cellular LTE systems w.r.t. their transmitted power ratios are concave and convex, respectively. We then propose two optimization approaches for the power allocation mechanism. In the particular case of major interference links, the convex concave procedure (CCCP) is proposed to obtain the optimal power ratio that satisfies the target quality of service. In an environment with multiple D2D links, we firstly generalize the CCCP approach and propose a resource association and power allocation algorithm. We then propose a lower complexity optimization approach that exploits the spatial statistics and correlation of the D2D and cellular links based on the Kriging interpolator to estimate the SINR distributions at each location. Finally, we present analytical and numerical results that demonstrate the effectiveness of the introduced algorithms, and we show that there exists an optimal power ratio that satisfies the transmission constraints in both D2D and cellular systems.