Optimal Resource Block Assignment and Power Allocation for D2D-Enabled NOMA Communication

A novel joint optimization framework for device-to-device (D2D)-enabled non-orthogonal multiple access (NOMA) networks is proposed. Our objective is to maximize the performance of the D2D communication by jointly optimizing the resource block (RB) assignment and the power allocation, by considering the SIC decoding order of the NOMA-based cellular user equipments (CUEs). We invoke the distributed decision making (DDM) framework to decouple the formulated problem into two sub-problems. For the RB assignment sub-problem with integer variables, we propose a differential evolution (DE) algorithm to obtain the optimal NOMA CUE group and RB assignment for D2D pairs. For power allocation sub-problem with continuous variables and decoding order variables, we first use a heuristic algorithm to optimize the power allocation for NOMA-based CUEs with given D2D power allocation. We prove that the power allocation for the NOMA-based CUEs is the optimal solution. We then invoke the successive convex approximation (SCA) and DE to find the sub-optimal power allocation of the D2D pairs. The numerical results validate the feasibility, fast convergence, and flexibility of the proposed algorithm, and the performance with our algorithm outperforms the conventional OMA technology in terms of energy efficiency and sum rate.