Power-Domain Non-Orthogonal Multiple Access for Distributed Non-Terrestrial Networks: A Semi-Analytical Throughput Estimation

This paper analyzes the application of power-domain non-orthogonal multiple access (PD-NOMA) techniques in contention-based aerial and spatial contexts, by specifically focusing on the many-to-one scenario. The proposed work moves from the derivation of closed-form expressions for the statistic of the power received by a common destination from a single source, subsequently extending the investigation to the performance evaluation of the whole network. More precisely, Nakagami fading in drone swarms characterized by random waypoint mobility and scintillation effects in space subnets with uniformly located satellites are addressed by analytically calculating the power distribution and then numerically determining the achievable throughput. Moreover, the success probability for the single packet reception attempt is calculated by considering, beside the usually adopted Shannon bound, also a more realistic code-modulation scheme relying on a combination of fixed quadrature phase-shift keying modulation and efficient coding. The presented semi-analytical model is then exploited to examine the influence of these latter elements and of the propagation parameters on the behavior of distributed non-terrestrial PD-NOMA networks.