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: "degrees of freedom of holographic mimo channels"
  Abstract: This paper focuses on physically large spatially-continuous apertures, called holographic MIMO. Given the area limitation of the aperture, the limit on the available spatial degrees of freedom (DoF) is derived under isotropic propagation of electromagnetic waves. A linear-system theoretic interpretation of wave propagations reveals that the channel has a bandlimited spectrum. This is used in [1, 2] to approximate it with a Fourier plane-wave series representation that provides a simple and intuitive way to compute the DoF.

Connected through hyperedge HE-1 (induced by source paper "spatial characterization of holographic mimo channels"):
  with members:
    - "large system analysis of massive mimo with optimal m mmse processing"
    - "beyond massive mimo the potential of data transmission with large intelligent surfaces"
    - "massive mimo has unlimited capacity"
    - "optimal pilot and payload power control in single cell massive mimo systems"
    - "space constrained massive mimo hitting the wall of favorable propagation"
    - "a generalized spatial correlation model for 3d mimo channels based on the fourier coefficients of power spectrums"
    - "on landau s eigenvalue theorem and information cut sets"
    - "optimal design of energy efficient multi user mimo systems is massive mimo the answer"

Connected through hyperedge HE-2 (induced by source paper "spatially stationary model for holographic mimo small scale fading"):
  with members:
    - "beyond massive mimo the potential of data transmission with large intelligent surfaces"
    - "massive mimo has unlimited capacity"
    - "ns 3 implementation of the 3gpp mimo channel model for frequency spectrum above 6 ghz"
    - "optimal pilot and payload power control in single cell massive mimo systems"
    - "a generalized spatial correlation model for 3d mimo channels based on the fourier coefficients of power spectrums"
    - "on landau s eigenvalue theorem and information cut sets"
    - "optimal design of energy efficient multi user mimo systems is massive mimo the answer"
    - "energy and spectral efficiency of very large multiuser mimo systems"

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)