Throughput enhancement for cognitive radio networks with energy harvesting and non orthogonal multiple access

In this article, users’ powers, harvesting, and sensing durations are optimized for interweave cognitive radio networks using Non-Orthogonal Multiple Access (NOMA). In the first slot, the secondary source harvests energy using the received signal from node H during βT\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\beta T$$\end{document} seconds where 0<β<1\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$0<\beta <1$$\end{document} is the harvesting duration percentage and T is frame duration. In the second slot, the secondary source senses the channel during (1-β)νT\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(1-\beta )\nu T$$\end{document} seconds to detect primary source activity using the energy detector. When the primary node is idle, the secondary source transmits data to N NOMA secondary users during (1-β)(1-ν)T\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$(1-\beta )(1-\nu ) T$$\end{document} seconds. Users’ powers, harvesting β\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\beta $$\end{document} and sensing durations ν\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\nu $$\end{document} were not yet optimized for interweave cognitive radio networks using NOMA to maximize the throughput. We derive the outage probability at each user in order to compute and optimize the throughput using the alternating maximization algorithm. Two strategies are considered for users’ ranking based on the instantaneous or the average power of channel gains. Optimal harvesting and sensing durations with optimal power allocation offer up to 7.8 dB gain with respect to using the same durations for energy harvesting and spectrum sensing. Joint optimization of harvesting and sensing durations offers up to 5 dB gain with respect to optimizing either the sensing or the harvesting durations as proposed in the literature.