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: "structured compressive sensing based superimposed pilot design in downlink large scale mimo systems"
  Abstract: Large-scale multiple-input multiple-output (MIMO) with high spectrum and energy efficiency is a very promising key technology for future 5G wireless communications. For large-scale MIMO systems, accurate channel state information (CSI) acquisition is a challenging problem, especially when each user has to distinguish and estimate numerous channels coming from a large number of transmit antennas in the downlink. Unlike the conventional orthogonal pilots whose pilot overhead prohibitively increases with the number of transmit antennas, we propose a spectrum-efficient superimposed pilot design for downlink large-scale MIMO scenarios, where frequency-domain pilots of different transmit antennas occupy the completely same subcarriers in the freqency domain. Meanwhile, spatial-temporal common sparsity of large-scale MIMO channels motivates us to exploit the emerging theory of structured compressive sensing (CS) for reliable MIMO channel estimation, which is realized by the proposed structured subspace pursuit (SSP) algorithm to simultaneously recover multiple channels with low pilot overhead. Simulation results demonstrate that the proposed scheme performs well and can approach the performance bound.

Connected through hyperedge HE-1 (induced by source paper "an overview of transmission theory and techniques of large scale antenna systems for 5g wireless communications"):
  with members:
    - "channel acquisition for massive mimo ofdm with adjustable phase shift pilots"
    - "mixed adc massive mimo detectors performance analysis and design optimization"
    - "performance analysis and location optimization for massive mimo systems with circularly distributed antennas"
    - "uplink achievable rate for massive mimo systems with low resolution adc"
    - "spatially common sparsity based adaptive channel estimation and feedback for fdd massive mimo"
    - "a stochastic geometry framework for analyzing pairwise cooperative cellular networks"
    - "fractional pilot reuse in massive mimo systems"
    - "pilot reuse for massive mimo transmission over spatially correlated rayleigh fading channels"

Connected through hyperedge HE-2 (induced by source paper "structured compressive sensing based spatio temporal joint channel estimation for fdd massive mimo"):
  with members:
    - "joint csit acquisition based on low rank matrix completion for fdd massive mimo systems"
    - "asymptotic orthogonality analysis of time domain sparse massive mimo channels"
    - "spatially common sparsity based adaptive channel estimation and feedback for fdd massive mimo"
    - "priori information aided iterative hard threshold a low complexity high accuracy compressive sensing based channel estimation for tds ofdm"
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"
    - "super resolution sparse mimo ofdm channel estimation based on spatial and temporal correlations"
    - "massive mimo for next generation wireless systems"
    - "downlink training techniques for fdd massive mimo systems open loop and closed loop training with memory"

Connected through hyperedge HE-3 (induced by source paper "a scalable framework for csi feedback in fdd massive mimo via dl path aligning"):
  with members:
    - "pilot decontamination via pdp alignment"
    - "channel acquisition for massive mimo ofdm with adjustable phase shift pilots"
    - "flexible pilot contamination mitigation with doppler psd alignment"
    - "achievable rates of fdd massive mimo systems with spatial channel correlation"
    - "pilot beam pattern design for channel estimation in massive mimo systems"
    - "distributed compressive csit estimation and feedback for fdd multi user massive mimo systems"
    - "downlink training techniques for fdd massive mimo systems open loop and closed loop training with memory"
    - "on gridless sparse methods for line spectral estimation from complete and incomplete data"

Connected through hyperedge HE-4 (induced by source paper "design and analysis of downlink channel estimation based on parametric model for massive mimo in fdd systems"):
  with members:
    - "massive mimo for next generation wireless systems"
    - "downlink training techniques for fdd massive mimo systems open loop and closed loop training with memory"
    - "closed loop beam alignment for massive mimo channel estimation"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "energy and spectral efficiency of very large multiuser mimo systems"

Connected through hyperedge HE-5 (induced by source paper "a novel antenna selection scheme for spatially correlated massive mimo uplinks with imperfect channel estimation"):
  with members:
    - "massive mimo for next generation wireless systems"
    - "five disruptive technology directions for 5g"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "on capacity of large scale mimo multiple access channels with distributed sets of correlated antennas"
    - "large system analysis of linear precoding in correlated miso broadcast channels under limited feedback"
    - "mimo interference alignment over correlated channels with imperfect csi"

Connected through hyperedge HE-6 (induced by source paper "near optimal hybrid analog and digital precoding for downlink mmwave massive mimo systems"):
  with members:
    - "low complexity near optimal signal detection for uplink large scale mimo systems"
    - "spatially sparse precoding in millimeter wave mimo systems"
    - "suboptimal spatial diversity scheme for 60 ghz millimeter wave wlan"
    - "energy and spectral efficiency of very large multiuser mimo systems"

Connected through hyperedge HE-7 (induced by source paper "turbo like beamforming based on tabu search algorithm for millimeter wave massive mimo systems"):
  with members:
    - "on the number of rf chains and phase shifters and scheduling design with hybrid analog digital beamforming"
    - "spatially sparse precoding in millimeter wave mimo systems"
    - "millimeter wave beamforming for wireless backhaul and access in small cell networks"

Connected through hyperedge HE-8 (induced by source paper "robust preamble design for synchronization signaling transmission and channel estimation"):
  with members:
    - "priori information aided iterative hard threshold a low complexity high accuracy compressive sensing based channel estimation for tds ofdm"
    - "frequency domain response based timing synchronization a near optimal sampling phase criterion for tds ofdm"
    - "super resolution sparse mimo ofdm channel estimation based on spatial and temporal correlations"

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)