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: "technical rate of substitution of spectrum in future mobile broadband provisioning"
  Abstract: Dense deployment of base stations (BSs) and multi-antenna techniques are considered key enablers for future mobile networks. Meanwhile, spectrum sharing techniques and utilization of higher frequency bands make more bandwidth available. An important question for future system design is which element is more effective than others. In this paper, we introduce the concept of technical rate of substitution (TRS) from microeconomics and study the TRS of spectrum in terms of BS density and antenna number per BS. Numerical results show that TRS becomes higher with increasing user data rate requirement, suggesting that spectrum is the most effective means of provisioning extremely fast mobile broadband.

Connected through hyperedge HE-1 (induced by source paper "joint transmission with dummy symbols for dynamic tdd in ultra dense deployments"):
  with members:
    - "interference management in 5g reverse tdd hetnets with wireless backhaul a large system analysis"
    - "asymptotic behavior of ultra dense cellular networks and its economic impact"

Connected through hyperedge HE-2 (induced by source paper "radio access network and spectrum sharing in mobile networks a stochastic geometry perspective"):
  with members:
    - "a primer on cellular network analysis using stochastic geometry"
    - "resource sharing in 5g mmwave cellular networks"
    - "on spectrum and infrastructure sharing in multi operator cellular networks"
    - "poisson hole process theory and applications to wireless networks"
    - "gains of restricted secondary licensing in millimeter wave cellular systems"
    - "co primary multi operator resource sharing for small cell networks"
    - "on the feasibility of sharing spectrum licenses in mmwave cellular systems"
    - "effect of los nlos propagation on area spectral efficiency and energy efficiency of small cells"

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)