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: "massive mimo and millimeter wave for 5g wireless hetnet potentials and challenges"
  Abstract: There have been active research activities worldwide in developing the next-generation 5G wireless network. The 5G network is expected to support significantly large amount of mobile data traffic and huge number of wireless connections, achieve better cost- and energy-efficiency as well as quality of service (QoS) in terms of communication delay, reliability and security. To this end, the 5G wireless network should exploit potential gains in different network dimensions including super dense and heterogeneous deployment of cells and massive antenna arrays (i.e., massive multiple input multiple output (MIMO) technologies) and utilization of higher frequencies, in particular millimeter wave (mmWave) frequencies. This article discusses potentials and challenges of the 5G heterogeneous wireless network (HetNet) which incorporates massive MIMO and mmWave technologies. We will first provide the typical requirements of the 5G wireless network. Then, the significance of massive MIMO and mmWave in engineering the future 5G HetNet is discussed in detail. Potential challenges associated with the design of such 5G HetNet are discussed. Finally, we provide some case studies, which illustrate the potential benefits of the considered technologies.

Connected through hyperedge HE-1 (induced by source paper "multi cell hybrid millimeter wave systems pilot contamination and interference mitigation"):
  with members:
    - "a multi beam noma framework for hybrid mmwave systems"
    - "massive mimo has unlimited capacity"
    - "optimal resource allocation for power efficient mc noma with imperfect channel state information"
    - "massive mimo performance tdd versus fdd what do measurements say"
    - "coverage analysis for millimeter wave networks the impact of directional antenna arrays"
    - "where when and how mmwave is used in 5g and beyon"
    - "multi user precoding and channel estimation for hybrid millimeter wave systems"
    - "small scale local area and transitional millimeter wave propagation for 5g communications"

Connected through hyperedge HE-2 (induced by source paper "multi user precoding and channel estimation for hybrid millimeter wave systems"):
  with members:
    - "modeling and analyzing millimeter wave cellular systems"
    - "millimeter wave mimo channel estimation using overlapped beam patterns and rate adaptation"
    - "doubly massive mmwave mimo systems using very large antenna arrays at both transmitter and receiver"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "hybrid digital and analog beamforming design for large scale antenna arrays"
    - "achievable rate of rician large scale mimo channels with transceiver hardware impairments"
    - "massive mimo ten myths and one critical question"
    - "limited feedback hybrid precoding for multi user millimeter wave 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)