Sum Rate Maximization for Cooperative NOMA with Hardware Impairments

Xiao-yu WAN  Rui-fei CHANG  Zheng-qiang WANG  Zi-fu FAN  

IEICE TRANSACTIONS on Information and Systems   Vol.E104-D    No.9    pp.1399-1405
Publication Date: 2021/09/01
Publicized: 2021/05/28
Online ISSN: 1745-1361
DOI: 10.1587/transinf.2020EDP7204
Type of Manuscript: PAPER
Category: Fundamentals of Information Systems
cooperative non-orthogonal multiple access,  sum rate,  resource allocation,  hardware impairments,  interior-point,  

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This paper investigates the sum rate (SR) maximization problem for downlink cooperative non-orthogonal multiple access (C-NOMA) systems with hardware impairments (HIs). The source node communicates with users via a half-duplex amplified-and-forward (HD-AF) relay with HIs. First, we derive the SR expression of the systems under HIs. Then, SR maximization problem is formulated under maximum power of the source, relay, and the minimum rate constraint of each user. As the original SR maximization problem is a non-convex problem, it is difficult to find the optimal resource allocation directly by tractional convex optimization method. We use variable substitution method to convert the non-convex SR maximization problem to an equivalent convex optimization problem. Finally, a joint power and rate allocation based on interior point method is proposed to maximize the SR of the systems. Simulation results show that the algorithm can improve the SR of the C-NOMA compared with the cooperative orthogonal multiple access (C-OMA) scheme.