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: "designing wireless broadband access for energy efficiency are small cells the only answer"
  Abstract: The main usage of cellular networks has changed from voice to data traffic, mostly requested by static users. In this paper, we analyze how a cellular network should be designed to provide such wireless broadband access with maximal energy efficiency (EE). Using stochastic geometry and a detailed power consumption model, we optimize the density of access points (APs), number of antennas and users per AP, and transmission power for maximal EE. Small cells are of course a key technology in this direction, but the analysis shows that the EE improvement of a small-cell network saturates quickly with the AP density and then "massive MIMO" techniques can further improve the EE.

Connected through hyperedge HE-1 (induced by source paper "network deployment for maximal energy efficiency in uplink with multislope path loss"):
  with members:
    - "massive mimo has unlimited capacity"
    - "performance limits of network densification"
    - "cell free massive mimo versus small cells"
    - "deploying dense networks for maximal energy efficiency small cells meet massive mimo"
    - "downlink cellular network analysis with multi slope path loss models"
    - "what will 5g be"
    - "optimal design of energy efficient multi user mimo systems is massive mimo the answer"
    - "downlink mimo hetnets modeling ordering results and performance analysis"

Connected through hyperedge HE-2 (induced by source paper "deploying dense networks for maximal energy efficiency small cells meet massive mimo"):
  with members:
    - "energy efficient future wireless networks a marriage between massive mimo and small cells"
    - "interference management in 5g reverse tdd hetnets with wireless backhaul a large system analysis"
    - "massive mimo performance evaluation based on measured propagation data"
    - "massive mimo with non ideal arbitrary arrays hardware scaling laws and circuit aware design"
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"
    - "multiobjective signal processing optimization the way to balance conflicting metrics in 5g systems"
    - "impact of transceiver power consumption on the energy efficiency of zero forcing detector in massive mimo systems"
    - "massive mimo for next generation wireless systems"

Connected through hyperedge HE-3 (induced by source paper "energy efficient future wireless networks a marriage between massive mimo and small cells"):
  with members:
    - "deploying dense networks for maximal energy efficiency small cells meet massive mimo"
    - "multiobjective signal processing optimization the way to balance conflicting metrics in 5g systems"
    - "impact of transceiver power consumption on the energy efficiency of zero forcing detector in massive mimo systems"
    - "massive mimo for next generation wireless systems"
    - "what will 5g be"
    - "optimal design of energy efficient multi user mimo systems is massive mimo the answer"
    - "transmission capacity of wireless networks"
    - "a tractable approach to coverage and rate in cellular 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.IT(Information Theory)