Abstract
Non-orthogonal multiple access (NOMA) has been seen as a promising technology for 5G communication. The performance optimization of NOMA systems depends on both power allocation (PA) and user pairing (UP). Most existing researches provide sub-optimal solutions with high computational complexity for PA problem and mainly focuses on maximizing the sum rate (capacity) without considering the fairness performance. Also, the joint optimization of PA and UP needs an exhaustive search. The main contribution of this paper is the proposing of a novel capacity maximization-based fair power allocation (CMFPA) with low-complexity in downlink NOMA. Extensive investigation and analysis of the joint impact of signal to noise ratio (SNR) per subcarrier and the channel gains of the paired users on the performance of NOMA in terms of the capacity and the user fairness is presented. Next, a closed-form equation for the power allocation coefficient of CMFPA as a function of SNR, and the channel gains of the paired users is provided. In addition, to jointly optimize UP and PA in NOMA systems an efficient low-complexity UP (ELCUP) method is proposed to be incorporated with the proposed CMFPA to compromise the proposed joint resource allocation (JRA). Simulation results demonstrate that the proposed CMFPA can improve the capacity and fairness performance of existing UP methods, such as conventional UP, and random UP methods. Furthermore, the simulation results show that the proposed JRA significantly outperforms the existing schemes and gives a near-optimal performance.
Highlights
Non-orthogonal multiple access (NOMA) arises as the reliable multiple access technique for the fifth-generation (5G) communication systems to provide the required high data rates and massive connectivity [1,2]
In capacity maximizationbased fair power allocation (CMFPA), a closed-form equation is proposed for the power allocation coefficient as a function of signal to noise ratio (SNR) per subcarrier and the channel gains of the paired users
3) In addition, efficient low-complexity user pairing (UP) (ELCUP) method is proposed to be incorporated with the proposed CMFPA to compromise the proposed joint resource allocation (JRA) for the optimization of capacity and fairness performance of NOMA systems with a significantly low computational complexity
Summary
Non-orthogonal multiple access (NOMA) arises as the reliable multiple access technique for the fifth-generation (5G) communication systems to provide the required high data rates and massive connectivity [1,2]. The resource allocation for downlink NOMA systems is investigated with a focus on PA which is based on SNR per subcarrier and the channel gains of the paired users for optimization of both the sum rate and fairness performance. The main contributions of this paper are as follows: 1) Extensive investigation and analysis of the joint impact of SNR per subcarrier and the paired users’ channel gains on the performance of NOMA is presented. 3) In addition, efficient low-complexity UP (ELCUP) method is proposed to be incorporated with the proposed CMFPA to compromise the proposed joint resource allocation (JRA) for the optimization of capacity and fairness performance of NOMA systems with a significantly low computational complexity.
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