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: "multi user millimeter wave mimo with full dimensional lens antenna array"
  Abstract: Millimeter wave (mmWave) communication by utilizing lens antenna arrays is a promising technique for realizing cost-effective 5G wireless systems with large MIMO (multiple-input multiple-output) but only limited radio frequency (RF) chains. This paper studies an uplink multi-user mmWave single-sided lens MIMO system, where only the base station (BS) is equipped with a full-dimensional (FD) lens antenna array with both elevation and azimuth angle resolution capabilities, and each mobile station (MS) employs the conventional uniform planar array (UPA) without the lens. By exploiting the angle-dependent energy focusing property of the lens antenna array at the BS as well as the multi-path sparsity of mmWave channels, we propose a low-complexity path division multiple access (PDMA) scheme, which enables virtually interference-free multi-user communications when the angle of arrivals (AoAs) of all MS multi-path signals are sufficiently separable at the BS. To this end, a new technique called path delay compensation is proposed at the BS to effectively transform the multi-user frequency-selective MIMO channels to parallel frequency-flat small-size MIMO channels for different MSs, for each of which the low-complexity single-carrier(SC) transmission is applied. For general scenarios with insufficient AoA separations, analog beamforming at the MSs and digital combining at the BS are jointly designed to maximize the achievable sum-rate of the MSs based on their effective MIMO channels resulting from path delay compensation. In addition, we propose a new and efficient channel estimation scheme tailored for PDMA, which requires negligible training overhead in practical mmWave systems and yet leads to comparable performance as that based on perfect channel state information (CSI).

Connected through hyperedge HE-1 (induced by source paper "intelligent reflecting and transmitting surface aided millimeter wave massive mimo"):
  with members:
    - "a novel communication paradigm for high capacity and security via programmable indoor wireless environments in next generation wireless systems"
    - "intelligent reflecting surfaces for free space optical communications"
    - "feedback aware precoding for millimeter wave massive mimo systems"
    - "energy efficiency of mmwave massive mimo precoding with low resolution dacs"
    - "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"
    - "scalable and energy efficient millimeter massive mimo architectures reflect array and transmit array antennas"
    - "intelligent reflecting surface enhanced wireless network joint active and passive beamforming design"
    - "c ran with hybrid rf fso fronthaul links joint optimization of rf time allocation and fronthaul compression"

Connected through hyperedge HE-2 (induced by source paper "compressive sensing based channel estimation for millimeter wave full dimensional mimo with lens array"):
  with members:
    - "deep learning based channel estimation for beamspace mmwave massive mimo systems"
    - "compressive sensing techniques for next generation wireless communications"
    - "beamspace channel estimation in mmwave systems via cosparse image reconstruction technique"
    - "millimeter wave vehicular communication to support massive automotive sensing"
    - "compressed sensing for wireless communications useful tips and tricks"
    - "spatially common sparsity based adaptive channel estimation and feedback for fdd massive mimo"
    - "millimeter wave mimo with lens antenna array a new path division multiplexing paradigm"

Connected through hyperedge HE-3 (induced by source paper "tracking position and orientation through millimeter wave lens mimo in 5g systems"):
  with members:
    - "optimal precoders for tracking the aod and aoa of a mmwave path"
    - "direct localization for massive mimo"
    - "error bounds for uplink and downlink 3d localization in 5g mmwave systems"
    - "compressive channel estimation and tracking for large arrays in mm wave picocells"
    - "joint device positioning and clock synchronization in 5g ultra dense networks"
    - "frequency selective hybrid precoding for limited feedback millimeter wave systems"
    - "tracking angles of departure and arrival in a mobile millimeter wave channel"
    - "fingerprinting based positioning in distributed massive mimo systems"

Connected through hyperedge HE-4 (induced by source paper "uplink channel estimation and data transmission in millimeter wave cran with lens antenna arrays"):
  with members:
    - "fronthaul limited uplink ofdma in ultra dense cran with hybrid decoding"
    - "joint millimeter wave fronthaul and ofdma resource allocation in ultra dense cran"
    - "rf lens embedded massive mimo systems fabrication issues and codebook design"
    - "channel estimation for hybrid architecture based wideband millimeter wave systems"
    - "cost effective millimeter wave communications with lens antenna array"
    - "millimeter wave mimo with lens antenna array a new path division multiplexing paradigm"
    - "optimized uplink transmission in multi antenna c ran with spatial compression and forward"
    - "optimized backhaul compression for uplink cloud radio access network"

Connected through hyperedge HE-5 (induced by source paper "beamspace channel estimation in mmwave systems via cosparse image reconstruction technique"):
  with members:
    - "beamspace channel estimation for millimeter wave massive mimo systems with 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"

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)