Users' grouping algorithm for fairness improvement of NOMA-based multi-beams satellite networks intended for 5G

Non-Orthogonal Multiple-Access (NOMA)-based Multibeam Satellite Networks (MBSNs) are intended for 5G implementation, and 5G networks set the requirement for both high system capacity as well as high system reliability to all users, which is achieved via high system's fairness. The NOMA network requires a user grouping algorithm (UGA), and most existing UGAs for 2-users NOMA-MBSNs, favor the system's capacity maximization with little regard to the system's fairness. Thus, this paper proposes a UGA that maximizes the fairness of 2-users NOMA-MBSNs. The algorithm seeks to group 2M users into M-pairs satisfying three requirements, (i) a minimum channel-gain margin; (ii) high channel-correlation coefficients; and (iii) there is high fairness amongst the resulting pairs, in term of their respective channel-correlation coefficients, to increase the users' fairness of the system. To achieve this, the 2M users are split into two sets of M-far and M-near users based on users' channel gains for pairing far and near users with high channel-correlation coefficients. It will turn it into a maximization Bipartite Matching problem (BPMP) of channel-correlation coefficients. The BPMP is addressed by means of the Hungarian Method (HM) to ensure high fairness amongst resulting pairs regarding their channel-correlation coefficients. The proposed UGA demonstrates superior fairness compared to existing UGAs.