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: "cascaded channel estimation for large intelligent metasurface assisted massive mimo"
  Abstract: In this letter, we consider the problem of channel estimation for large intelligent metasurface (LIM) assisted massive multiple-input multiple-output (MIMO) systems. The main challenge of this problem is that the LIM integrated with a large number of low-cost metamaterial antennas can only passively reflect the incident signal by a certain phase shift, and does not have any signal processing capability. To deal with this, we introduce a general framework for the estimation of the transmitter-LIM and LIM-receiver cascaded channel, and propose a two-stage algorithm that includes a sparse matrix factorization stage and a matrix completion stage. Simulation results illustrate that the proposed method can achieve accurate channel estimation for LIM-assisted massive MIMO systems.

Connected through hyperedge HE-1 (induced by source paper "overhead aware design of reconfigurable intelligent surfaces in smart radio environments"):
  with members:
    - "over the air computation via intelligent reflecting surfaces"
    - "holographic mimo surfaces for 6g wireless networks opportunities challenges and trends"
    - "intelligent reflecting surface with discrete phase shifts channel estimation and passive beamforming"
    - "miso wireless communication systems via intelligent reflecting surfaces"
    - "secure wireless communication via intelligent reflecting surface"
    - "joint active and passive beamforming for intelligent reflecting surface assisted massive mimo systems"
    - "rfocus practical beamforming for small devices"
    - "intelligent reflecting surface irs enabled covert communications in wireless networks"

Connected through hyperedge HE-2 (induced by source paper "intelligent reflecting surface assisted multi user ofdma channel estimation and training design"):
  with members:
    - "intelligent reflecting surface assisted multiple access with user pairing noma or oma"
    - "parallel factor decomposition channel estimation in ris assisted multi user miso communication"
    - "intelligent reflecting surface with discrete phase shifts channel estimation and passive beamforming"
    - "secure wireless communication via intelligent reflecting surface"
    - "channel estimation for intelligent reflecting surface assisted multiuser communications framework algorithms and analysis"
    - "capacity characterization for intelligent reflecting surface aided mimo communication"
    - "progressive channel estimation and passive beamforming for intelligent reflecting surface with discrete phase shifts"
    - "intelligent reflecting surface meets ofdm protocol design and rate maximization"

Connected through hyperedge HE-3 (induced by source paper "gmd based hybrid beamforming for large reconfigurable intelligent surface assisted millimeter wave massive mimo"):
  with members:
    - "joint active and passive beamforming optimization for intelligent reflecting surface assisted swipt under qos constraints"
    - "closed loop sparse channel estimation for wideband millimeter wave full dimensional mimo systems"
    - "principal component analysis based broadband hybrid precoding for millimeter wave massive mimo systems"
    - "passive beamforming and information transfer via large intelligent surface"
    - "compressive sensing based channel estimation for millimeter wave full dimensional mimo with lens array"
    - "intelligent reflecting surface enhanced ofdm channel estimation and reflection optimization"
    - "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"
    - "spatial and frequency wideband effects in millimeter wave massive mimo systems"

Connected through hyperedge HE-4 (induced by source paper "analysis and optimization of an intelligent reflecting surface assisted system with interference"):
  with members:
    - "analysis and optimization of outage probability in multi intelligent reflecting surface assisted systems"
    - "enabling secure wireless communications via intelligent reflecting surfaces"
    - "intelligent reflecting surface assisted non orthogonal multiple access"
    - "weighted sum power maximization for intelligent reflecting surface aided swipt"
    - "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"
    - "reconfigurable intelligent surfaces for energy efficiency in wireless communication"
    - "large intelligent surface assisted wireless communication exploiting statistical csi"
    - "power efficient multi quality multicast beamforming based on scalable video coding and superposition coding"

Connected through hyperedge HE-5 (induced by source paper "broadband channel estimation for intelligent reflecting surface aided mmwave massive mimo systems"):
  with members:
    - "closed loop sparse channel estimation for wideband millimeter wave full dimensional mimo systems"
    - "compressive sensing based channel estimation for millimeter wave full dimensional mimo with lens array"
    - "enabling large intelligent surfaces with compressive sensing and deep learning"
    - "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"
    - "compressive sensing techniques for next generation wireless communications"
    - "channel estimation for millimeter wave massive mimo with hybrid precoding over frequency selective fading channels"
    - "compressed sensing for wireless communications useful tips and tricks"
    - "spatially common sparsity based adaptive channel estimation and feedback for fdd massive mimo"

Connected through hyperedge HE-6 (induced by source paper "reconfigurable intelligent surface empowered 6g wireless communications challenges and opportunities"):
  with members:
    - "channel estimation for intelligent reflecting surface assisted multiuser communications"
    - "enabling large intelligent surfaces with compressive sensing and deep learning"
    - "the roadmap to 6g ai empowered wireless networks"
    - "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"
    - "reconfigurable intelligent surfaces for energy efficiency in wireless communication"
    - "large intelligent surface assisted wireless communication exploiting statistical csi"
    - "user assignment with distributed large intelligent surface lis systems"

Connected through hyperedge HE-7 (induced by source paper "beamforming optimization for intelligent reflecting surface assisted mimo a sum path gain maximization approach"):
  with members:
    - "beamforming optimization for wireless network aided by intelligent reflecting surface with discrete phase shifts"
    - "towards smart and reconfigurable environment intelligent reflecting surface aided wireless network"
    - "fundamental green tradeoffs progresses challenges and impacts on 5g networks"

Connected through hyperedge HE-8 (induced by source paper "intelligent reflecting surface versus decode and forward how large surfaces are needed to beat relaying"):
  with members:
    - "towards smart and reconfigurable environment intelligent reflecting surface aided wireless network"
    - "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"
    - "reconfigurable intelligent surfaces for energy efficiency in wireless communication"

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)