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: "on the fundamental characteristics of ultra dense small cell networks"
  Abstract: In order to cope with the forecasted 1000x increase in wireless capacity demands by 2030, network operators will aggressively densify their network infrastructure to reuse the spectrum as much as possible. However, it is important to realise that these new ultra-dense small cell networks are fundamentally different from the traditional macrocell or sparse small cell networks, and thus ultra-dense networks (UDNs) cannot be deployed and operated in the same way as in the last 25 years. In this paper, we systematically investigate and visualise the performance impacts of several fundamental characteristics of UDNs, that mobile operators and vendors should consider when deploying UDNs. Moreover, we also provide new deployment and management guidelines to address the main challenges brought by UDNs in the future.

Connected through hyperedge HE-1 (induced by source paper "smart radio environments empowered by ai reconfigurable meta surfaces an idea whose time has come"):
  with members:
    - "a novel communication paradigm for high capacity and security via programmable indoor wireless environments in next generation wireless systems"
    - "reflection probability in wireless networks with metasurface coated environmental objects an approach based on random spatial processes"
    - "a tractable analysis of the blind spot probability in localization networks under correlated blocking"
    - "using any surface to realize a new paradigm for wireless communications"
    - "wireless network intelligence at the edge"
    - "medium access control in wireless network on chip a context analysis"
    - "beyond massive mimo the potential of positioning with large intelligent surfaces"
    - "realizing wireless communication through software defined hypersurface environments"

Connected through hyperedge HE-2 (induced by source paper "survey on uav cellular communications practical aspects standardization advancements regulation and security challenges"):
  with members:
    - "understanding uav cellular communications from existing networks to massive mimo"
    - "supporting uav cellular communications through massive mimo"
    - "uav aided offloading for cellular hotspot"
    - "the essential guide to realizing 5g connected uavs with massive mimo"
    - "performance analysis for practical unmanned aerial vehicle networks with los nlos transmissions"
    - "promises and caveats of uplink iot ultra dense networks"
    - "the sky is not the limit lte for unmanned aerial vehicles"
    - "cellular enabled uav communication a connectivity constrained trajectory optimization perspective"

Connected through hyperedge HE-3 (induced by source paper "promises and caveats of uplink iot ultra dense networks"):
  with members:
    - "performance impact of base station antenna heights in dense cellular networks"
    - "microscopic analysis of the uplink interference in fdma small cell networks"
    - "performance impact of idle mode capability on dense small cell networks"
    - "performance impact of idle mode capability on dense small cell networks with los and nlos transmissions"
    - "performance impact of los and nlos transmissions in dense cellular networks"
    - "uplink performance analysis of dense cellular networks with los and nlos transmissions"
    - "towards 1 gbps ue in cellular systems understanding ultra dense small cell deployments"
    - "downlink cellular network analysis with multi slope path loss models"

Connected through hyperedge HE-4 (induced by source paper "reshaping cellular networks for the sky the major factors and feasibility"):
  with members:
    - "ultra reliable uav communication using altitude and cooperation diversity"
    - "maximizing indoor wireless coverage using uavs equipped with directional antennas"
    - "coverage analysis for low altitude uav networks in urban environments"
    - "modeling and analysis of cellular networks using stochastic geometry a tutorial"
    - "a stochastic geometry model of backhaul and user coverage in urban uav networks"
    - "backhaul aware robust 3d drone placement in 5g wireless networks"
    - "efficient deployment of multiple unmanned aerial vehicles for optimal wireless coverage"
    - "wireless communications with unmanned aerial vehicles opportunities and 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)