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: "planning of cellular networks enhanced by energy harvesting"
  Abstract: We pose a novel cellular network planning problem, considering the use of renewable energy sources and a fundamentally new concept of energy balancing, and propose a novel algorithm to solve it. In terms of the network capital and operational expenditure we conclude that savings can be made by enriching cellular infrastructure with energy harvesting sources, in comparison to traditional deployment methods.

Connected through hyperedge HE-1 (induced by source paper "comp meets smart grid a new communication and energy cooperation paradigm"):
  with members:
    - "information and energy cooperation in cognitive radio networks"
    - "base station sleeping and resource allocation in renewable energy powered cellular networks"
    - "energy cooperation in energy harvesting communications"
    - "throughput maximization for the gaussian relay channel with energy harvesting constraints"
    - "energy cooperation in cellular networks with renewable powered base stations"
    - "throughput optimal policies for energy harvesting wireless transmitters with non ideal circuit power"
    - "delay aware bs discontinuous transmission control and user scheduling for energy harvesting downlink coordinated mimo systems"
    - "optimal save then transmit protocol for energy harvesting wireless transmitters"

Connected through hyperedge HE-2 (induced by source paper "base station sleeping and resource allocation in renewable energy powered cellular networks"):
  with members:
    - "finite horizon online lazy scheduling with energy harvesting transmitters over fading channels"
    - "optimal power allocation for energy harvesting and power grid coexisting wireless communication systems"
    - "on the precoder design of a wireless energy harvesting node in linear vector gaussian channels with arbitrary input distribution"
    - "delay aware bs discontinuous transmission control and user scheduling for energy harvesting downlink coordinated mimo systems"
    - "broadcasting with an energy harvesting rechargeable transmitter"
    - "optimal utilization of a cognitive shared channel with a rechargeable primary source node"
    - "transmission with energy harvesting nodes in fading wireless channels optimal policies"
    - "optimal packet scheduling on an energy harvesting broadcast link"

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)