Performance Analysis of NOMA in 5G Systems with HPA Nonlinearities

• Published in: IEEE access 2020-01, Vol.8, p.1-1
• Main Authors: Belkacem, O. B. Haj, Ammari, M. L., Dinis, Rui
• Format: Article
• Language: English
• Subjects: Distortion; Downlink; Ergodic processes; ergodic sum rate; Fading channels; high-power amplifiers (HPA); Interference; Lower bounds; Mathematical analysis; Monte Carlo simulation; NOMA; non-orthogonal multiple access (NOMA); Nonlinear distortion; nonlinear polynomial model; Nonorthogonal multiple access; outage probability (OP); Performance assessment; Performance evaluation; Polynomials; Power amplifiers; Signal to noise ratio
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2020.3020372

In this paper, we provide an analytical performance assessment of downlink non-orthogonal multiple access (NOMA) systems over Nakagami-m fading channels in the presence of nonlinear high-power amplifiers (HPAs). By modeling the distortion of the HPA by a nonlinear polynomial model, we evaluate the performance the NOMA scheme in terms of outage probability (OP) and ergodic sum rate. Hence, we derive a new closed-form expression for the exact OP, taking into account the undesirable effects of HPA. Furthermore, to characterize the diversity order of the considered system, the asymptotic OP in the high signal-to-noise (SNR) regime is derived. Moreover, the ergodic sum rate is investigated, resulting in new upper and lower bounds. Our numerical results demonstrate that the performance loss in presence of nonlinear distortions is very substantial at high data rates. In particular, it is proved that in presence of HPA distortion, the ergodic sum rate cannot exceed a determined threshold which limits its performance compared to the ideal hardware case. Monte-Carlo simulations are conducted and their results agree well with the analytical results.