Energy Efficiency of Uplink and Downlink Non-Orthogonal Multiple-Access Channels Under Gaussian-Mixture Interference

• Published in: IEEE transactions on green communications and networking 2020-09, Vol.4 (3), p.657-668
• Main Authors: Ranjbar, Mohammad, Tran, Nghi H., Nguyen-Le, Hung, Karacolak, Tutku
• Format: Article
• Language: English
• Subjects: Broadband; Cellular communication; Cellular networks; Channels; Closed form solutions; Divergence; Downlink; downlink and uplink channels; Downlinking; Energy efficiency; energy per bit; Evaluation; Exact solutions; Interchannel interference; Interference; Mathematical analysis; NOMA; non-orthogonal multiple access; Nonorthogonal multiple access; Signal to noise ratio; Silicon carbide; Taylor series; Uplink; Upper bounds; Wideband; wideband slope
• ISSN: 2473-2400; 2473-2400
• DOI: 10.1109/TGCN.2020.2982835

In this paper, we analyze the energy efficiency (EE) of uplink and downlink non-orthogonal multiple access (NOMA) channels with successive interference cancellation under Gaussian-mixture aggregate interference. The adopted non-Gaussian model is a realistic noise plus interference model to capture the asynchronism in a heterogeneous cellular network. The considered EE is measured via the minimum energy per bit \frac {E_{b}}{N_{0}}_{\min } for reliable communication and the wideband slope of the spectral efficiency as a function of energy per bit \frac {E_{b}}{N_{0}} . For completeness, both Gaussian signaling schemes and practical finite alphabet inputs are examined. To this end, our approach is to calculate \frac {E_{b}}{N_{0}}_{\min } and the wideband slope region via the Kullback-Leibler divergence. Due to the presence of mixture of multiple Gaussian distributions, the Kullback-Leibler divergence cannot be expressed in closed-form. As an alternative, we exploit upper bounds on the divergence, and we show that the bounds are achievable at the limit points, i.e., when the signal-to-noise-ratio (SNR) approaches zero. As a result, \frac {E_{b}}{N_{0}}_{\min } of each user can be established in closed-form. Next, we apply Taylor series expressions and exploit the achievability in the previous step to evaluate the second derivative of the rates when SNR goes to zero. It is then shown that the wideband slope region can be found effectively. The proposed method can serve as an important tool for making more accurate throughput and EE evaluation of important wireless/cellular networks.