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: "pilot contamination is not a fundamental asymptotic limitation in massive mimo"
  Abstract: Massive MIMO (multiple-input multiple-output) provides great improvements in spectral efficiency over legacy cellular networks, by coherent combining of the signals over a large antenna array and by spatial multiplexing of many users. Since its inception, the coherent interference caused by pilot contamination has been believed to be an impairment that does not vanish, even with an unlimited number of antennas. In this work, we show that this belief is incorrect and an artifact from using simplistic channel models and suboptimal signal processing schemes. We focus on the uplink and prove that with multicell MMSE combining, the spectral efficiency grows without bound as the number of antennas increases, even under pilot contamination, under a condition of linear independence between the channel covariance matrices. This condition is generally satisfied, except in special cases that are hardly found in practice.

Connected through hyperedge HE-1 (induced by source paper "machine learning for geometrically consistent angular spread function estimation in massive mimo"):
  with members:
    - "learning to optimize training deep neural networks for interference management"
    - "deep learning based channel estimation for beamspace mmwave massive mimo systems"
    - "deep learning methods for improved decoding of linear codes"
    - "fdd massive mimo via ul dl channel covariance extrapolation and active channel sparsification"
    - "deep learning for joint source channel coding of text"
    - "massive mimo pilot decontamination and channel interpolation via wideband sparse channel estimation"
    - "power of deep learning for channel estimation and signal detection in ofdm systems"
    - "on deep learning based channel decoding"

Connected through hyperedge HE-2 (induced by source paper "theoretical performance limits of massive mimo with uncorrelated rician fading channels"):
  with members:
    - "massive mimo with spatially correlated rician fading channels"
    - "massive mimo has unlimited capacity"
    - "performance analysis of mixed adc massive mimo systems over rician fading channels"
    - "on the spectral efficiency of massive mimo systems with low resolution adcs"
    - "asymptotic analysis of multicell massive mimo over rician fading channels"
    - "achievable rate of rician large scale mimo channels with transceiver hardware impairments"
    - "massive mimo ten myths and one critical question"
    - "massive mimo with multi cell mmse processing exploiting all pilots for interference suppression"

Connected through hyperedge HE-3 (induced by source paper "massive mimo has unlimited capacity"):
  with members:
    - "massive mimo pilot decontamination and channel interpolation via wideband sparse channel estimation"
    - "massive mimo with imperfect channel covariance information"
    - "robust pilot decontamination based on joint angle and power domain discrimination"
    - "massive mimo with multi cell mmse processing exploiting all pilots for interference suppression"
    - "massive mimo in real propagation environments do all antennas contribute equally"
    - "massive mimo performance evaluation based on measured propagation data"
    - "pilot reuse for massive mimo transmission over spatially correlated rayleigh fading channels"
    - "optimal multiuser transmit beamforming a difficult problem with a simple solution structure"

Connected through hyperedge HE-4 (induced by source paper "covariance matrix estimation for massive mimo"):
  with members:
    - "massive mimo has unlimited capacity"
    - "superimposed pilots are superior for mitigating pilot contamination in massive mimo"
    - "massive mimo pilot decontamination and channel interpolation via wideband sparse channel estimation"
    - "massive mimo with imperfect channel covariance information"
    - "downlink performance of superimposed pilots in massive mimo systems"
    - "superimposed pilots are superior for mitigating pilot contamination in massive mimo part ii performance analysis and hybrid system design"
    - "massive mimo for next generation wireless systems"
    - "blind pilot decontamination"

Connected through hyperedge HE-5 (induced by source paper "supporting uav cellular communications through massive mimo"):
  with members:
    - "reshaping cellular networks for the sky the major factors and feasibility"
    - "massive mimo for communications with drone swarms"
    - "cell edge aware precoding for downlink massive mimo cellular networks"
    - "massive mimo unlicensed a new approach to dynamic spectrum access"
    - "uplink sounding reference signal coordination to combat pilot contamination in 5g massive mimo"
    - "a stochastic geometry model of backhaul and user coverage in urban uav networks"
    - "wireless communications with unmanned aerial vehicles opportunities and challenges"
    - "operating massive mimo in unlicensed bands for enhanced coexistence and spatial reuse"

Connected through hyperedge HE-6 (induced by source paper "large system analysis of power normalization techniques in massive mimo"):
  with members:
    - "massive mimo has unlimited capacity"
    - "reducing the computational complexity of multicasting in large scale antenna systems"
    - "energy efficient downlink transmission for multicell massive das with pilot contamination"
    - "joint power allocation and user association optimization for massive mimo systems"
    - "convergence analysis and assurance for gaussian message passing iterative detector in massive mu mimo systems"
    - "massive mimo ten myths and one critical question"
    - "performance analysis of massive mimo for cell boundary users"
    - "power allocation schemes for multicell massive mimo systems"

Connected through hyperedge HE-7 (induced by source paper "massive mimo pilot decontamination and channel interpolation via wideband sparse channel estimation"):
  with members:
    - "low complexity massive mimo subspace estimation and tracking from low dimensional projections"
    - "robust pilot decontamination based on joint angle and power domain discrimination"
    - "channel acquisition for massive mimo ofdm with adjustable phase shift pilots"
    - "rrh based massive mimo with on the fly pilot contamination control"
    - "cell free massive mimo uniformly great service for everyone"
    - "linear precoding based on polynomial expansion large scale multi cell mimo systems"
    - "massive mimo for next generation wireless systems"
    - "low complexity polynomial channel estimation in large scale mimo with arbitrary statistics"

Connected through hyperedge HE-8 (induced by source paper "jamming resistant receivers for the massive mimo uplink"):
  with members:
    - "jamming resistant receivers for massive mimo"
    - "subverting massive mimo by smart jamming"
    - "secure massive mimo transmission with an active eavesdropper"
    - "jamming aided secure communication in massive mimo rician channels"
    - "physical layer security for massive mimo an overview on passive eavesdropping and active attacks"
    - "worst case jamming on mimo gaussian channels"
    - "securing massive mimo at the physical layer"
    - "interference reduction in multi cell massive mimo systems i large scale fading precoding and decoding"

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)