Joint User Grouping and Resource Allocation for NOMA Enhanced D2D Communications

To mitigate the interference caused by frequency reuse between inter-layer and intra-layer users for Non-Orthogonal Multiple Access (NOMA) based device-to-device (D2D) communication underlaying cellular systems, this paper proposes a joint optimization strategy that combines user grouping resource allocation. Specifically, problem is formulated to maximize sum rate while ensuring minimum of users, considering three parameters: grouping, sub channel allocation power However, mixed integer nonlinear programming (MINLP) hard solve directly. address issue, we divide into two sub-problems: First, classify D2D pairs or NOMA groups on greedy algorithm. Then, in terms allocation, allocate sub-channel swap matching algorithm reduce co-channel interference, optimize transmission local search Simulation results show that, compared other schemes, proposed significantly improves system spectral utilization.