Quality-Balanced User Clustering Schemes for Non-Orthogonal Multiple Access Systems

Abstract

Non-orthogonal multiple access (NOMA) is a promising technology aimed at improving the bandwidth efficiency of wireless transmissions. In this letter, we focus on the optimization of user clustering and power allocation for an NOMA system under a service rate constraint, where the goal is to maximize the total sum rate. Based on the optimal power allocation in a cluster, we propose a suboptimal solution-the quality-balanced clustering approach to optimize the total sum rate in a system. According to the simulations, the proposed user clustering and power allocation schemes can achieve the maximum total sum rate obtained via exhaustive search optimization. The proposed schemes have very low computational complexity, and thus are suitable for real-time NOMA transmissions.