human: Given a node-centered hypergraph: <hypergraph>, where nodes represent papers and hyperedges represent sets of papers co-cited by a source paper.

Details of the hypergraph:
Center node: "energy efficient low power circuits for wireless energy and data transfer in iot sensor nodes"
  Abstract: In this paper, we present techniques and examples to reduce power consumption and increase energy efficiency of autonomous Wireless Sensor Nodes (WSNs) for the Internet of Things. We focus on the RF Energy Harvester (RFEH), the data receiver and the transmitter, all of which have a large impact on the device cost, lifetime and functionality. Co-design of the antenna and the electronics is explored to boost the power conversion efficiency of the RF-DC converter. As a proof of principle, a charge pump rectifier is designed, and its measurement results are presented. To boost the rectifier output voltage, a DC-DC converter that employs maximum power point tracking has been designed. A prototype circuit is also presented that can accommodate an input power level range of 1 {\mu}W to 1 mW and offers peak efficiencies of 76.3% and 82% at 1 {\mu}W and 1 mW, respectively. The co-design principle is also used at the receiver side where the antenna-electronics interface is optimized. It is shown how this technique allows improving the noise figure of the Low Noise Amplifier (LNA) without sacrificing power consumption. As a low power alternative to narrow-band wireless transmission, sub-GHz ultra-wideband is proposed. As a proof of principle, the design of a novel low-power sub-GHz Ultra-Wide-Bandwidth (UWB) transmitter which consumes only 0.28 mW is presented. Its working principle is verified by means of circuit simulations and measurements. The low power nature of the transmitter and receiver principles, combined with the power efficient RF-DC converter paves the way towards the continuous operation of a WSN.

Connected through hyperedge HE-1 (induced by source paper "spectral and energy efficient wireless powered iot networks noma or tdma"):
  with members:
    - "wireless powered cooperative jamming for secure ofdm system"
    - "fundamental green tradeoffs progresses challenges and impacts on 5g networks"
    - "wireless powered communications with non orthogonal multiple access"
    - "an overview of sustainable green 5g networks"
    - "wireless powered communication networks an overview"
    - "energy efficient resource allocation for wireless powered communication networks"
    - "on the performance of non orthogonal multiple access in 5g systems with randomly deployed users"
    - "throughput maximization in wireless powered communication networks"

Question: Please tell me which class the center node belongs to. The 40 classes are: cs.NA(Numerical Analysis), cs.MM(Multimedia), cs.LO(Logic in Computer Science), cs.CY(Computers and Society), cs.CR(Cryptography and Security), cs.DC(Distributed, Parallel, and Cluster Computing), cs.HC(Human-Computer Interaction), cs.CE(Computational Engineering, Finance, and Science), cs.NI(Networking and Internet Architecture), cs.CC(Computational Complexity), cs.AI(Artificial Intelligence), cs.MA(Multiagent Systems), cs.GL(General Literature), cs.NE(Neural and Evolutionary Computing), cs.SC(Symbolic Computation), cs.AR(Hardware Architecture), cs.CV(Computer Vision and Pattern Recognition), cs.GR(Graphics), cs.ET(Emerging Technologies), cs.SY(Systems and Control), cs.CG(Computational Geometry), cs.OH(Other Computer Science), cs.PL(Programming Languages), cs.SE(Software Engineering), cs.LG(Machine Learning), cs.SD(Sound), cs.SI(Social and Information Networks), cs.RO(Robotics), cs.IT(Information Theory), cs.PF(Performance), cs.CL(Computation and Language), cs.IR(Information Retrieval), cs.MS(Mathematical Software), cs.FL(Formal Languages and Automata Theory), cs.DS(Data Structures and Algorithms), cs.OS(Operating Systems), cs.GT(Computer Science and Game Theory), cs.DB(Databases), cs.DL(Digital Libraries), cs.DM(Discrete Mathematics). Directly output the class name.

gpt: cs.ET(Emerging Technologies)