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 reuse for massive mimo transmission over spatially correlated rayleigh fading channels"
  Abstract: We propose pilot reuse (PR) in single cell for massive multiuser multiple-input multiple-output (MIMO) transmission to reduce the pilot overhead. For spatially correlated Rayleigh fading channels, we establish a relationship between channel spatial correlations and channel power angle spectrum when the base station antenna number tends to infinity. With this channel model, we show that sum mean square error (MSE) of channel estimation can be minimized provided that channel angle of arrival intervals of the user terminals reusing the pilots are non-overlapping, which shows feasibility of PR over spatially correlated massive MIMO channels with constrained channel angular spreads. Since channel estimation performance might degrade due to PR, we also develop the closed-form robust multiuser uplink receiver and downlink precoder that minimize sum MSE of signal detection, and reveal a duality between them. Subsequently, we investigate pilot scheduling, which determines the PR pattern, under two minimum MSE related criteria, and propose a low complexity pilot scheduling algorithm, which relies on the channel statistics only. Simulation results show that the proposed PR scheme provides significant performance gains over the conventional orthogonal training scheme in terms of net spectral efficiency.

Connected through hyperedge HE-1 (induced by source paper "energy efficiency optimization for downlink massive mimo with statistical csit"):
  with members:
    - "beam domain secure transmission for massive mimo communications"
    - "fractional programming for communication systems part i power control and beamforming"
    - "energy efficient multicell multigroup multicasting with joint beamforming and antenna selection"
    - "fdd massive mimo via ul dl channel covariance extrapolation and active channel sparsification"
    - "network deployment for maximal energy efficiency in uplink with multislope path loss"
    - "energy efficient beam coordination strategies with rate dependent processing power"
    - "bdma for millimeter wave terahertz massive mimo transmission with per beam synchronization"
    - "free deterministic equivalents for the analysis of mimo multiple access channel"

Connected through hyperedge HE-2 (induced by source paper "covariance aided csi acquisition with non orthogonal pilots in massive mimo a large system performance analysis"):
  with members:
    - "massive mimo has unlimited capacity"
    - "pilot length optimization for spatially correlated multi user mimo channel estimation"
    - "snops short non orthogonal pilot sequences for downlink channel state estimation in fdd massive mimo"
    - "dealing with interference in distributed large scale mimo systems a statistical approach"
    - "achievable rates of fdd massive mimo systems with spatial channel correlation"
    - "massive mimo for next generation wireless systems"
    - "five disruptive technology directions for 5g"
    - "scaling up mimo opportunities and challenges with very large arrays"

Connected through hyperedge HE-3 (induced by source paper "statistical beamforming for fdd downlink massive mimo via spatial information extraction and beam selection"):
  with members:
    - "semi blind channel and signal estimation for uplink massive mimo with channel sparsity"
    - "multi band covariance interpolation with applications in massive mimo"
    - "structured turbo compressed sensing for downlink massive mimo ofdm channel estimation"
    - "fdd massive mimo via ul dl channel covariance extrapolation and active channel sparsification"
    - "channel estimation for tdd fdd massive mimo systems with channel covariance computing"
    - "dictionary learning based sparse channel representation and estimation for fdd massive mimo systems"
    - "massive mimo for next generation wireless systems"
    - "statistical beamforming on the grassmann manifold for the two user broadcast channel"

Connected through hyperedge HE-4 (induced by source paper "massive mimo transmission for leo satellite communications"):
  with members:
    - "architectures and key technical challenges for 5g systems incorporating satellites"
    - "fdd massive mimo via ul dl channel covariance extrapolation and active channel sparsification"
    - "channel acquisition for massive mimo ofdm with adjustable phase shift pilots"
    - "statistical eigenmode transmission over jointly correlated mimo channels"

Connected through hyperedge HE-5 (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"
    - "enhancing the estimation of mm wave large array channels by exploiting spatio temporal correlation and sparse scattering"
    - "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"

Connected through hyperedge HE-6 (induced by source paper "design of non orthogonal beamspace multiple access for cellular internet of things"):
  with members:
    - "beam design and user scheduling for nonorthogonal multiple access with multiple antennas based on pareto optimality"
    - "non orthogonal multiple access common myths and critical questions"
    - "optimal user scheduling and power allocation for millimeter wave noma systems"
    - "performance analysis of noma in training based multiuser mimo systems"
    - "a survey on non orthogonal multiple access for 5g networks research challenges and future trends"
    - "design of massive mimo noma with limited feedback"
    - "a general mimo framework for noma downlink and uplink transmission based on signal alignment"
    - "why does the kronecker model result in misleading capacity estimates"

Connected through hyperedge HE-7 (induced by source paper "the effect of spatial correlation on the performance of uplink and downlink single carrier massive mimo systems"):
  with members:
    - "average sep optimal precoding for correlated massive mimo with zf detection an asymptotic analysis"
    - "uplink massive mimo for channels with spatial correlation"
    - "waveforms for the massive mimo downlink amplifier efficiency distortion and performance"
    - "mimo channel modeling and capacity analysis for 5g millimeter wave wireless systems"
    - "massive mimo for next generation wireless systems"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "diversity of mimo linear precoding"

Connected through hyperedge HE-8 (induced by source paper "performance of high mobility mimo communications with doppler diversity"):
  with members:
    - "bdma for millimeter wave terahertz massive mimo transmission with per beam synchronization"
    - "channel acquisition for massive mimo ofdm with adjustable phase shift pilots"
    - "an overview of transmission theory and techniques of large scale antenna systems for 5g wireless communications"
    - "large system analysis of linear precoding in correlated miso broadcast channels under limited feedback"

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)