Power Allocation-Based NOMA and Underlay D2D Communication for Public Safety Users in the 5G Cellular Network

Abstract

Cellular networks (CNs) continue to evolve by implementing several technologies such as nonorthogonal multiple access and device-to-device communication, accommodating thereby the high data traffic demand. By leveraging these technologies, in this article, we propose a novel scheme to integrate public safety (PS) networks in CNs. This integration enhances the performance of PS users (PSUs) that rely on low-rate technologies. We formulate a mixed integer nonlinear programming problem for sum throughput maximization, to optimize the channel allocation and achieve the required rate of PSUs. This optimization takes into account power budget, users required rates, and successful interference cancellation constraints. Since the maximization problem is computationally challenging, we design a heuristic algorithm that selects the appropriate cellular users to share their resources with PS clusters. Then, given this selection, we compute the optimal power allocation in each PS cluster using the Lagrange multiplier method. Evaluation results demonstrate that our approach improves spectral efficiency and provides higher sum throughput compared to other works in the literature. We also conduct extensive simulations to compare our throughput maximization approach with the fairness maximization approach. Finally, we compute the outage probability to reassign PSUs groups to new resource blocks if necessary.