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: "3d channel model in 3gpp"
  Abstract: Multi-antenna techniques capable of exploiting the elevation dimension are anticipated to be an important air-interface enhancement targeted to handle the expected growth in mobile traffic. In order to enable the development and evaluation of such multi-antenna techniques, the 3rd Generation Partnership Project (3GPP) has recently developed a three-dimensional (3D) channel model. The existing two-dimensional (2D) channel models do not capture the elevation channel characteristics, making them insufficient for such studies. This article describes the main components of the newly developed 3D channel model and the motivations behind introducing them. One key factor is the ability to model channels for users located on different floors of a building (at different heights). This is achieved by capturing a user height dependency in modelling some channel characteristics including pathloss, lineof- sight (LOS) probability, etc. In general, this 3D channel model follows the framework of WINNERII/WINNER+ while also extending the applicability and the accuracy of the model by introducing some height dependent and distance dependent elevation related parameters.

Connected through hyperedge HE-1 (induced by source paper "elevation beamforming with full dimension mimo architectures in 5g systems a tutorial"):
  with members:
    - "asymptotic analysis of rzf over double scattering channels with mmse estimation"
    - "distributed fd mimo cellular evolution for 5g and beyond"
    - "overview of full dimension mimo in lte advanced pro"
    - "an effective limited feedback scheme for fd mimo based on noncoherent detection and kronecker product codebook"
    - "hybrid digital and analog beamforming design for large scale antenna arrays"
    - "3d massive mimo systems modeling and performance analysis"
    - "a generalized spatial correlation model for 3d mimo channels based on the fourier coefficients of power spectrums"
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"

Connected through hyperedge HE-2 (induced by source paper "optimization of massive full dimensional mimo for positioning and communication"):
  with members:
    - "channel estimation and performance analysis of one bit massive mimo systems"
    - "a pessimistic approximation for the fisher information measure"
    - "sectoring in multi cell massive mimo systems"
    - "layered downlink precoding for c ran systems with full dimensional mimo"
    - "positioning for the internet of things a 3gpp perspective"
    - "downlink achievable rate analysis in massive mimo systems with one bit dacs"
    - "optimal fronthaul quantization for cloud radio positioning"
    - "parallel and distributed methods for nonconvex optimization part ii applications"

Connected through hyperedge HE-3 (induced by source paper "wireless link capacity under shadowing and fading"):
  with members:
    - "beyond geometry towards fully realistic wireless models"
    - "approximation algorithms for wireless link scheduling with flexible data rates"
    - "a fully distributed algorithm for throughput performance in wireless networks"
    - "dynamic packet scheduling in wireless networks"
    - "algorithms for wireless capacity"
    - "secondary spectrum auctions for symmetric and submodular bidders"
    - "wireless connectivity and capacity"
    - "wireless capacity with oblivious power in general metrics"

Connected through hyperedge HE-4 (induced by source paper "layered downlink precoding for c ran systems with full dimensional mimo"):
  with members:
    - "fronthaul compression and precoding design for c rans over ergodic fading channels"
    - "kronecker product correlation model and limited feedback codebook design in a 3d channel model"

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)