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: "fundamental tradeoffs on green wireless networks"
  Abstract: Traditional design of mobile wireless networks mainly focuses on ubiquitous access and large capacity. However, as energy saving and environmental protection become a global demand and inevitable trend, wireless researchers and engineers need to shift their focus to energy-efficiency oriented design, that is, green radio. In this paper, we propose a framework for green radio research and integrate the fundamental issues that are currently scattered. The skeleton of the framework consists of four fundamental tradeoffs: deployment efficiency - energy efficiency tradeoff, spectrum efficiency - energy efficiency tradeoff, bandwidth - power tradeoff, and delay - power tradeoff. With the help of the four fundamental tradeoffs, we demonstrate that key network performance/cost indicators are all stringed together.

Connected through hyperedge HE-1 (induced by source paper "optimal linear precoding in multi user mimo systems a large system analysis"):
  with members:
    - "interference management in 5g reverse tdd hetnets with wireless backhaul a large system analysis"
    - "large system analysis of the energy consumption distribution in multi user mimo systems with mobility"
    - "optimal multiuser transmit beamforming a difficult problem with a simple solution structure"
    - "optimal power allocation and user loading for multiuser miso channels with regularized channel inversion"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "large system analysis of linear precoding in correlated miso broadcast channels under limited feedback"
    - "robust monotonic optimization framework for multicell miso systems"
    - "base station cooperation on the downlink large system analysis"

Connected through hyperedge HE-2 (induced by source paper "power allocation for energy harvesting transmitter with causal information"):
  with members:
    - "iterative dynamic water filling for fading multiple access channels with energy harvesting"
    - "a learning theoretic approach to energy harvesting communication system optimization"
    - "optimal energy allocation for wireless communications with energy harvesting constraints"
    - "transmission with energy harvesting nodes in fading wireless channels optimal policies"
    - "optimum transmission policies for battery limited energy harvesting nodes"
    - "optimal packet scheduling in an energy harvesting communication system"
    - "a survey of green networking research"

Connected through hyperedge HE-3 (induced by source paper "green communication via type i arq finite block length analysis"):
  with members:
    - "green communication via power optimized harq protocols"
    - "on noisy arq in block fading channels"
    - "finite block length analysis of the incremental redundancy harq"
    - "quasi static simo fading channels at finite blocklength"
    - "quasi static multiple antenna fading channels at finite blocklength"
    - "performance of hybrid arq in block fading channels a fixed outage probability analysis"

Connected through hyperedge HE-4 (induced by source paper "dimensioning of pa for massive mimo system with load adaptive number of antennas"):
  with members:
    - "multiobjective signal processing optimization the way to balance conflicting metrics in 5g systems"
    - "optimal design of energy efficient multi user mimo systems is massive mimo the answer"
    - "designing multi user mimo for energy efficiency when is massive mimo the answer"
    - "energy and spectral efficiency of very large multiuser mimo systems"
    - "miso capacity with per antenna power constraint"

Connected through hyperedge HE-5 (induced by source paper "on optimizing energy efficiency in multi radio multi channel wireless networks"):
  with members:
    - "throughput maximization in wireless powered communication networks"
    - "energy efficient resource allocation in wireless networks with quality of service constraints"

Connected through hyperedge HE-6 (induced by source paper "distributed power control over interference channels using ack nack feedback"):
  with members:
    - "joint scheduling and resource allocation in ofdma downlink systems via ack nak feedback"

Connected through hyperedge HE-7 (induced by source paper "energy efficient coordinated beamforming for multi cell miso systems"):
  with members:
    - "energy efficiency optimization for mimo broadcast channels"
    - "framework for link level energy efficiency optimization with informed transmitter"
    - "optimal distributed beamforming for miso interference channels"
    - "cooperative interference management with miso beamforming"

Connected through hyperedge HE-8 (induced by source paper "a cross layer perspective on energy harvesting aided green communications over fading channels"):
  with members:
    - "throughput optimal policies for energy harvesting wireless transmitters with non ideal circuit power"
    - "optimal energy allocation for wireless communications with energy harvesting constraints"
    - "information capacity of energy harvesting sensor nodes"
    - "optimal energy management policies for energy harvesting sensor nodes"

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.IT(Information Theory)