In this paper, an energy harvesting (EH) based cooperative non-orthogonalmultiple access (NOMA) system is considered, where node S simultaneously sendsindependent signals to a stronger node R and a weaker node D. We focus on thescenario that the direct link between S and D is too weak to meet the qualityof service (QoS) of D. Based on the NOMA principle, node R, the stronger user,has prior knowledge about the information of the weaker user, node D. Tosatisfy the targeted rate of D, R also serves as an EH decode-and-forward (DF)relay to forward the traffic from S to D. In the sense of equivalent cognitiveradio concept, node R viewed as a secondary user assists to boost theperformance of D, in exchange for receiving its own information from S.Specifically, transmitter beamforming design, power splitting ratiooptimization and receiver filter design to maximize node R rate are studiedwith the predefined QoS constraint of D and the power constraint of S. Sincethe problem is non-convex, we propose an iterative approach to solve it.Moreover, to reduce the computational complexity, a zero- forcing (ZF) basedsolution is also presented. Simulation results demonstrate that, both twoproposed schemes have better performance than the direction transmission.
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