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: "green cell less design for rf wireless power transfer networks"
  Abstract: This paper studies a new concept so-called green cell-less radio frequency (RF) wireless power transfer (WPT) networks. We consider a scenario in which multiple indoor access points (APs) equipped with outdoor energy harvesters are connected with a central control unit via backhaul links. Further, such APs exploit the harnessed green energy to recharge wirelessly indoor devices under the coordination of the control unit. Considering the network, we focus on AP selection and beamforming optimization to maximize the total energy harvesting (EH) rate. The resulting mathematical problem has the form of mixed-integer optimization that is intractable to solve. Thus, we propose an algorithm to tackle this difficulty. Through numerical results, we show the advantages of the cell-less design over the conventional small-cell one to validate our ideas. In particular, the issue on safety requirements of human exposure to RF radiation is discussed. Finally, potential future research is provided.

Connected through hyperedge HE-1 (induced by source paper "joint power control and lsfd for wireless powered cell free massive mimo"):
  with members:
    - "max min fair wireless powered cell free massive mimo for uncorrelated rician fading channels"
    - "optimal downlink transmission for cell free swipt massive mimo systems with active eavesdropping"
    - "scalability aspects of cell free massive mimo"
    - "scalable cell free massive mimo systems"
    - "massive mimo with spatially correlated rician fading channels"
    - "performance of cell free massive mimo with rician fading and phase shifts"
    - "multiple antenna technologies for beyond 5g"
    - "making cell free massive mimo competitive with mmse processing and centralized implementation"

Connected through hyperedge HE-2 (induced by source paper "max min fair wireless powered cell free massive mimo for uncorrelated rician fading channels"):
  with members:
    - "optimal downlink transmission for cell free swipt massive mimo systems with active eavesdropping"
    - "scalability aspects of cell free massive mimo"
    - "massive mimo with spatially correlated rician fading channels"
    - "performance of cell free massive mimo with rician fading and phase shifts"
    - "multiple antenna technologies for beyond 5g"
    - "making cell free massive mimo competitive with mmse processing and centralized implementation"
    - "optimization of power transfer efficiency and energy efficiency for wireless powered systems with massive mimo"
    - "performance of cell free massive mimo systems with mmse and lsfd receivers"

Connected through hyperedge HE-3 (induced by source paper "ultra small cell networks with collaborative rf and lightwave power transfer"):
  with members:
    - "robust design of ac computing enabled receiver architecture for swipt networks"
    - "fundamentals of wireless information and power transfer from rf energy harvester models to signal and system designs"
    - "rf wireless power transfer regreening future networks"
    - "coverage and rate analysis for co existing rf vlc downlink cellular networks"
    - "robust resource allocation for mimo wireless powered communication networks based on a non linear eh model"
    - "waveform design for wireless power transfer"
    - "practical non linear energy harvesting model and resource allocation for swipt systems"
    - "5g cellular key enabling technologies and research challenges"

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.NI(Networking and Internet Architecture)