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: "superimposed pilots are superior for mitigating pilot contamination in massive mimo part i theory and channel estimation"
  Abstract: Superimposed pilots are introduced, in this two-part paper, as an alternative to time-multiplexed pilot and data symbols for mitigating pilot contamination in massive multiple-input multiple-output (MIMO) systems. In this part of the two-part paper, a non-iterative scheme for uplink channel estimation based on superimposed pilots is first proposed and an expression for the uplink signal-to-interference-plus-noise ratio (SINR), at the output of a matched filter employing this channel estimate, is derived. Based on this expression, it is observed that the quality of the channel estimate can be improved by reducing the interference that results from transmitting data alongside the pilots, and an iterative data-aided scheme is also proposed that reduces this component of interference. Approximate expressions for the uplink SINR are provided for the iterative data-aided method as well. In addition, it is shown that a hybrid system with users utilizing both time-multiplexed and superimposed pilots is superior to an optimally designed system that employs only time-multiplexed pilots. Numerical simulations demonstrating the superiority of the proposed channel estimation schemes based on superimposed pilots and the accuracy of the approximations are also given in this part.

Connected through hyperedge HE-1 (induced by source paper "locally orthogonal training design for cloud rans based on graph coloring"):
  with members:
    - "rrh based massive mimo with on the fly pilot contamination control"
    - "cell free massive mimo versus small cells"
    - "selective uplink training for massive mimo systems"
    - "fundamental limits of training based multiuser mimo systems"
    - "training design and channel estimation in uplink cloud radio access networks"
    - "joint power and antenna selection optimization in large cloud radio access networks"
    - "dynamic nested clustering for parallel phy layer processing in cloud rans"
    - "blind pilot decontamination"

Connected through hyperedge HE-2 (induced by source paper "on hybrid pilot for channel estimation in massive mimo uplink"):
  with members:
    - "pilot beam pattern design for channel estimation in massive mimo systems"
    - "massive mimo with optimal power and training duration allocation"
    - "massive mimo for next generation wireless systems"
    - "what will 5g be"
    - "blind pilot decontamination"
    - "massive mimo for maximal spectral efficiency how many users and pilots should be allocated"
    - "five disruptive technology directions for 5g"
    - "scaling up mimo opportunities and challenges with very large arrays"

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)