Optimal design of amplify-and-forward helper stations for cellular networks with device-to-device links

Abstract

In this thesis, device-to-device (D2D) communication underlaying cellular communication system is considered. The Amplify-and-Forward (AF) helper station is proposed for this model, and the optimization problem to design the filter of helper station is presented. The interference allowance constraint is proposed to limit interference to cellular user. First, the worst D2D user rate maximization problem with controlling the interference to cellular user is considered. The Pareto boundary problem is proposed and problems of outer boundary of rate region are shown when the D2D usersusers cooperate with each other or not. It is shown that the all proposed problems can be reformulated as semi-definite program (SDP) problem. In addition, we show that the number of optimization variables is reduced by using interference neutralization techniques. Numerical results show the effectiveness of the allowed power of helper station, the allowed power of D2D transmitter, and interference allowance factor respectively.