Power-Allocation Algorithm for Fairness Maximisation of Non-Orthogonal Multiple Access-Based Multibeam Satellite Networks

Abstract

5G networks and beyond set a critical requirement for both massive capacity and seamless connectivity to all users. This implies that, the network must have both very high capacity and users' fairness. Non-Orthogonal Multiple-Access (NOMA)-based Multibeam Satellite Networks (MBSNs) are designed for 5G networks, and are thus, required to provide both high capacity and high users' fairness. Most existing power-allocation (PA) algorithms for NOMA-MBSNs focus on maximising the network's throughput alone, with not much attention on user's fairness. This leaves a critical requirement of 5G networks unaddressed. As an attempt to close this gap, this paper, proposes a PA algorithm that maximises the users' fairness of a 2Users NOMA-MBSN. To do so, the maximisation request is formulated as an optimisation problem. The original problem being NP-hard, it is decomposed into two sub-problems; namely, the intra-beam and the inter-beam fairness maximisation. Each of these problem is independently solved by means of numerical search methods. In this regards, the concept of converging the Offered-Capacity to Traffic-Request (OCTR) ratios of respective users, in order to maximise the system's fairness, is employed. Thus, based on the OCTR-ratios convergence concept, the fairness maximisations power-allocation algorithms, which respectively solve the two sub-problems, are designed. The two algorithms include the intra-beam and the inter-beam power-allocation algorithms. A global power-allocation algorithm (PAA-1) combines the two algorithm, to yield a solution to the original problem. Numerical results confirm that, the algorithm makes all the OCTR-ratios of all user converge; thus maximising the network's users-fairness. Results also demonstrate the superiority of the proposed PAA-1 with respect to achieved system's fairness, compared to some other existing PA algorithms.