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: "enhancing the estimation of mm wave large array channels by exploiting spatio temporal correlation and sparse scattering"
  Abstract: In order to cope with the large path-loss exponent of mm-Wave channels, a high beamforming gain is needed. This can be achieved with small hardware complexity and high hardware power efficiency by Hybrid Digital-Analog (HDA) beamforming, where a very large number $M\gg 1$ of antenna array elements requires only a relatively small $m\ll M$ number of A/D converters and modulators/demodulators. As such, the estimation of mm-Wave MIMO channels must deal with two specific problems: 1) high Doppler, due to the large carrier frequency; 2) impossibility of observing directly the M-dimensional channel vector at the antenna array elements, due to the mentioned HDA implementation. In this paper, we consider a novel scheme inspired by recent results on gridless multiple measurement vectors problem in compressed sensing, that is able to exploit the inherent mm-Wave channel sparsity in the angular domain in order to cope with both the above problems simultaneously. Our scheme uses past pilot-symbol observations in a window of length $T$ in order to estimate a low-dimensional subspace that approximately contains the channel vector at the current time. This subspace information can be used directly, in order to separate users in the spatial domain, or indirectly, in order to improve the estimate of the user channel vector from the current pilot-symbol observation.

Connected through hyperedge HE-1 (induced by source paper "an efficient beam and channel acquisition via sparsity map and joint angle delay power profile estimation for wideband massive mimo systems"):
  with members:
    - "spatial channel covariance estimation for the hybrid mimo architecture a compressive sensing based approach"
    - "channel estimation for tdd fdd massive mimo systems with channel covariance computing"
    - "low complexity massive mimo subspace estimation and tracking from low dimensional projections"
    - "channel acquisition for massive mimo ofdm with adjustable phase shift pilots"
    - "a generalized framework on beamformer design and csi acquisition for single carrier massive mimo systems in millimeter wave channels"
    - "hybrid beamforming for massive mimo a survey"
    - "spatially common sparsity based adaptive channel estimation and feedback for fdd massive mimo"
    - "pilot reuse for massive mimo transmission over spatially correlated rayleigh fading channels"

Connected through hyperedge HE-2 (induced by source paper "subspace tracking and least squares approaches to channel estimation in millimeter wave multiuser mimo"):
  with members:
    - "massive mimo in sub 6 ghz and mmwave physical practical and use case differences"
    - "cell free and user centric massive mimo at millimeter wave frequencies"
    - "subspace tracking algorithms for millimeter wave mimo channel estimation with hybrid beamforming"
    - "millimeter wave mimo channel estimation using overlapped beam patterns and rate adaptation"
    - "low complexity massive mimo subspace estimation and tracking from low dimensional projections"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "subspace estimation and decomposition for large millimeter wave mimo systems"
    - "hybrid architectures with few bit adc receivers achievable rates and energy rate tradeoffs"

Connected through hyperedge HE-3 (induced by source paper "energy efficiency and asymptotic performance evaluation of beamforming structures in doubly massive mimo mmwave systems"):
  with members:
    - "doubly massive mmwave mimo systems using very large antenna arrays at both transmitter and receiver"
    - "multi user massive mimo communication systems based on irregular antenna arrays"
    - "energy efficiency optimization of 5g radio frequency chain systems"
    - "on clustered statistical mimo millimeter wave channel simulation"
    - "hybrid digital and analog beamforming design for large scale antenna arrays"
    - "a survey of energy efficient techniques for 5g networks and challenges ahead"
    - "massive mimo combining with switches"
    - "limited feedback hybrid precoding for multi user millimeter wave systems"

Connected through hyperedge HE-4 (induced by source paper "multiuser millimeter wave beamforming strategies with quantized and statistical csit"):
  with members:
    - "sum rate maximization for linearly precoded downlink multiuser miso systems with partial csit a rate splitting approach"
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "achievable dof regions of mimo networks with imperfect csit"
    - "miso networks with imperfect csit a topological rate splitting approach"
    - "hierarchical codebook design for beamforming training in millimeter wave communication"
    - "robust transmission in downlink multiuser miso systems a rate splitting approach"
    - "a rate splitting strategy for max min fair multigroup multicasting"
    - "rate splitting for mimo wireless networks a promising phy layer strategy for lte evolution"

Connected through hyperedge HE-5 (induced by source paper "a generalized framework on beamformer design and csi acquisition for single carrier massive mimo systems in millimeter wave channels"):
  with members:
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "channel acquisition for massive mimo ofdm with adjustable phase shift pilots"
    - "two stage beamformer design for massive mimo downlink by trace quotient formulation"
    - "spatially common sparsity based adaptive channel estimation and feedback for fdd massive mimo"
    - "pilot reuse for massive mimo transmission over spatially correlated rayleigh fading channels"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"
    - "pilot beam pattern design for channel estimation in massive mimo systems"
    - "distributed compressive csit estimation and feedback for fdd multi user massive mimo systems"

Connected through hyperedge HE-6 (induced by source paper "doubly massive mmwave mimo systems using very large antenna arrays at both transmitter and receiver"):
  with members:
    - "spectral efficiency of mimo millimeter wave links with single carrier modulation for 5g networks"
    - "on clustered statistical mimo millimeter wave channel simulation"
    - "a survey of energy efficient techniques for 5g networks and challenges ahead"
    - "hybrid mimo architectures for millimeter wave communications phase shifters or switches"
    - "subspace estimation and decomposition for hybrid analog digital millimetre wave mimo systems"
    - "massive antenna arrays with low front end hardware complexity an enabling technology for the emerging small cell and distributed network architectures"
    - "massive mimo for next generation wireless systems"
    - "what will 5g be"

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)