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: "beamspace channel estimation for millimeter wave massive mimo systems with lens antenna array"
  Abstract: By employing the lens antenna array, beamspace MIMO can utilize beam selection to reduce the number of required RF chains in mmWave massive MIMO systems without obvious performance loss. However, to achieve the capacityapproaching performance, beam selection requires the accurate information of beamspace channel of large size, which is challenging, especially when the number of RF chains is limited. To solve this problem, in this paper we propose a reliable support detection (SD)-based channel estimation scheme. Specifically, we propose to decompose the total beamspace channel estimation problem into a series of sub-problems, each of which only considers one sparse channel component. For each channel component, we first reliably detect its support by utilizing the structural characteristics of mmWave beamspace channel. Then, the influence of this channel component is removed from the total beamspace channel estimation problem. After the supports of all channel components have been detected, the nonzero elements of the sparse beamspace channel can be estimated with low pilot overhead. Simulation results show that the proposed SD-based channel estimation outperforms conventional schemes and enjoys satisfying accuracy, even in the low SNR region.

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 "millimeter wave systems for wireless cellular communications"):
  with members:
    - "coverage analysis for millimeter wave networks the impact of directional antenna arrays"
    - "coverage and rate analysis for millimeter wave cellular networks"

Connected through hyperedge HE-3 (induced by source paper "beamspace channel estimation in mmwave systems via cosparse image reconstruction technique"):
  with members:
    - "multi user millimeter wave mimo with full dimensional lens antenna array"
    - "scampi a robust approximate message passing framework for compressive imaging"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "channel estimation in broadband millimeter wave mimo systems with few bit adcs"
    - "compressed sensing based multi user millimeter wave systems how many measurements are needed"
    - "millimeter wave mimo with lens antenna array a new path division multiplexing paradigm"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"
    - "distributed compressive csit estimation and feedback for fdd multi user massive mimo systems"

Connected through hyperedge HE-4 (induced by source paper "2d unitary esprit based super resolution channel estimation for millimeter wave massive mimo with hybrid precoding"):
  with members:
    - "millimeter wave mimo channel estimation based on adaptive compressed sensing"
    - "millimeter wave mimo channel estimation using overlapped beam patterns and rate adaptation"
    - "a lse and sparse message passing based channel estimation for mmwave mimo systems"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "subspace estimation and decomposition for large millimeter wave mimo systems"
    - "hybrid mimo architectures for millimeter wave communications phase shifters or switches"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"

Connected through hyperedge HE-5 (induced by source paper "iterative channel estimation using lse and sparse message passing for mmwave mimo systems"):
  with members:
    - "low complexity sparse bayesian learning using combined belief propagation and mean field with a stretched factor graph"
    - "a lse and sparse message passing based channel estimation for mmwave mimo systems"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "low rf complexity technologies to enable millimeter wave mimo with large antenna array for 5g wireless communications"
    - "channel estimation for hybrid architecture based wideband millimeter wave systems"
    - "convergence analysis and assurance for gaussian message passing iterative detector in massive mu mimo systems"
    - "frequency selective hybrid precoding for limited feedback millimeter wave systems"
    - "gaussian message passing iterative detection for mimo noma systems with massive access"

Connected through hyperedge HE-6 (induced by source paper "multi user millimeter wave mimo with full dimensional lens antenna array"):
  with members:
    - "rf lens embedded massive mimo systems fabrication issues and codebook design"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "low rf complexity technologies to enable millimeter wave mimo with large antenna array for 5g wireless communications"
    - "cost effective millimeter wave communications with lens antenna array"
    - "hybrid digital and analog beamforming design for large scale antenna arrays"
    - "frequency selective hybrid precoding for limited feedback millimeter wave systems"
    - "limited feedback hybrid precoding for multi user millimeter wave systems"
    - "near optimal hybrid processing for massive mimo systems via matrix decomposition"

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)