Efficient user pairing algorithm for enhancement of spectral efficiency and interference cancelation in downlink NOMA sy
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Efficient user pairing algorithm for enhancement of spectral efficiency and interference cancelation in downlink NOMA system Mohammed Abd-Elnaby1,2 • Germien G. Sedhom1,3 • Nagy W. Messiha1 • Mohamed Elwekeil1 Accepted: 31 October 2020 Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract A new subcarrier-user allocation algorithm for the downlink non-orthogonal multiple access system is presented in this paper. The proposed algorithm aims to enhance the spectral efficiency of the system and the successive interference cancelation performance by guaranteeing a high difference in channel-gain between the paired users per subcarrier. To enhance the spectral efficiency, the proposed algorithm provides a higher priority to the subcarrier that has a higher best (maximum) channel gain value rather than that has a lower best channel gain value. Also, it pairs the strong user with the second minimum channel-gain user rather than the minimum channel gain user. Besides, the proposed algorithm divides the subcarriers into two groups according to the standard deviation of the channel gain of each subcarrier. Then, it gives the priority to the group with low standard deviation values during subcarrier-user allocation to guarantee a high difference in channel-gain between the paired users per subcarrier. Later, fractional transmit power allocation is applied to distribute the subcarrier power between the paired users. Simulation results prove that the proposed algorithm improves the spectral efficiency of the system, and guarantees a significantly higher difference in channel-gain between the paired users per subcarrier compared to the conventional algorithms. Keywords NOMA SIC FTPA OMA
1 Introduction
& Germien G. Sedhom [email protected] Mohammed Abd-Elnaby [email protected] Nagy W. Messiha [email protected] Mohamed Elwekeil [email protected] 1
Electronics and Electrical Communication Department, Faculty of Electronic Engineering, Menoufia University, Menouf 32952, Egypt
2
Department of Computer Engineering, College of Computers and Information Technology, Taif University, Al-Hawiya 21974, Kingdom of Saudi Arabia
3
Electronics and Electrical Communication Department, Delta Higher Institute for Engineering and Technology, Talkha 35111, Egypt
The growth of the Internet-of-things (IoT) and mobile Internet applications prompt the benefits of 5G and beyond-5G communication systems [1]. Non-orthogonal multiple access (NOMA) is a technology that has promising potentials in future wireless networks, because of its high spectral efficiency, low transmission latency, and massive connectivity. Specifically, NOMA permits different users to share the same radio resources [2–7]. In NOMA, several users can be multiplexed in the powerdomain or code-domain [4]. We concentrate on the downlink power-domain NOMA in this paper, wherein several users can utilize the same time, frequency, and code resources. This can be achieved by emp
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