NOMA grouping in 5G intelligent transportation system for high spectral efficiency

In recent years, the increasing number of cellular users and smart devices necessitates the use of efficient network access techniques. The Non-Orthogonal Multiple Access (NOMA) technique is one of the best methods for ensuring efficient network accessibility. However, grouping and power allocation are the two main factors that affect the performance of NOMA. In most studies, users with high channel gain differences (CGD) are selected as the grouped users. Or, a threshold is defined for the users’ CGD in a group to increase the number of users. In this paper, a user grouping method is proposed for the cellular users and vehicles at the intersections of an intelligent transportation system. The goal of the grouping method is to increase the number of users that use NOMA while controlling the users’ interference, and so, increasing the system throughput. The performance of the proposed method is evaluated by the simulations that show improvements in the throughput, spectrum efficiency, and Energy efficiency of the system compared to the previous studies.