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: "hybrid analog digital channel estimation and beamforming training throughput tradeoff"
  Abstract: This paper develops hybrid analog-digital channel estimation and beamforming techniques for multiuser massive multiple-input multiple-output (MIMO) systems with limited number of radio frequency (RF) chains. For these systems, first, we design novel minimum-mean-squared error (MMSE) hybrid analog-digital channel estimator by considering both cases with perfect and imperfect channel covariance matrix knowledge. Then, we utilize the estimated channels to enable beamforming for data transmission. When the channel covariance matrices of all user equipments (UEs) are known perfectly, we show that there is a tradeoff between the training duration and throughput. Specifically, we exploit the fact that the optimal training duration that maximizes the throughput depends on the covariance matrices of all UEs, number of RF chains, and channel coherence time (  $T_c$  ). We also show that the training time optimization problem can be formulated as a concave maximization problem where its global optimal solution can be obtained efficiently using existing tools. The analytical expressions are validated by performing extensive Monte Carlo simulations.

Connected through hyperedge HE-1 (induced by source paper "wirelessly powered sensor networks power allocation for channel estimation and energy beamforming"):
  with members:
    - "cluster based wireless energy transfer for low complex energy receivers"
    - "wireless energy beamforming using received signal strength indicator feedback"
    - "on the beneficial roles of fading and transmit diversity in wireless power transfer with nonlinear energy harvesting"
    - "waveform design for wireless power transfer with limited feedback"
    - "distributed wireless power transfer with energy feedback"
    - "robust resource allocation for mimo wireless powered communication networks based on a non linear eh model"
    - "on the feasibility of wireless energy transfer using massive antenna arrays"
    - "waveform design for wireless power transfer"

Connected through hyperedge HE-2 (induced by source paper "beam squint and channel estimation for wideband mmwave massive mimo ofdm systems"):
  with members:
    - "spatial and frequency wideband effects in millimeter wave massive mimo systems"
    - "beamforming codebook compensation for beam squint with channel capacity constraint"
    - "a new view of multi user hybrid massive mimo non orthogonal angle division multiple access"
    - "multi user precoding and channel estimation for hybrid millimeter wave systems"
    - "millimeter wave channel estimation via exploiting joint sparse and low rank structures"
    - "effect of wideband beam squint on codebook design in phased array wireless systems"
    - "channel estimation for millimeter wave multiuser mimo systems via parafac decomposition"
    - "channel estimation for hybrid architecture based wideband millimeter wave systems"

Connected through hyperedge HE-3 (induced by source paper "optimal channel estimation for hybrid energy beamforming under phase shifter impairments"):
  with members:
    - "sensitive and nonlinear far field rf energy harvesting in wireless communications"
    - "wireless energy beamforming using received signal strength indicator feedback"
    - "multiuser millimeter wave beamforming strategies with quantized and statistical csit"
    - "on the feasibility of wireless energy transfer using massive antenna arrays"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "channel estimation for hybrid architecture based wideband millimeter wave systems"
    - "on the number of rf chains and phase shifters and scheduling design with hybrid analog digital beamforming"
    - "i q imbalance aware widely linear receiver for uplink multi cell massive mimo systems design and sum rate analysis"

Connected through hyperedge HE-4 (induced by source paper "matrix completion based channel estimation for mmwave communication systems with array inherent impairments"):
  with members:
    - "millimeter wave channel estimation via exploiting joint sparse and low rank structures"
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "channel estimation for millimeter wave multiuser mimo systems via parafac decomposition"
    - "channel estimation for hybrid architecture based wideband millimeter wave systems"
    - "subspace estimation and decomposition for large millimeter wave mimo systems"
    - "codebook design for millimeter wave channel estimation with hybrid precoding structure"
    - "channel estimation for mmwave massive mimo based access and backhaul in ultra dense network"
    - "joint csit acquisition based on low rank matrix completion for fdd massive mimo systems"

Connected through hyperedge HE-5 (induced by source paper "interleaved training and training based transmission design for hybrid massive antenna downlink"):
  with members:
    - "millimeter wave beam alignment large deviations analysis and design insights"
    - "codebook based hybrid precoding for millimeter wave multiuser systems"
    - "performance scaling law for multi cell multi user massive mimo"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "hybrid digital and analog beamforming design for large scale antenna arrays"
    - "beam searching and transmission scheduling in millimeter wave communications"
    - "limited feedback hybrid precoding for multi user millimeter wave systems"
    - "turbo like beamforming based on tabu search algorithm for millimeter wave massive mimo systems"

Connected through hyperedge HE-6 (induced by source paper "optimal precoders for tracking the aod and aoa of a mmwave path"):
  with members:
    - "fast channel estimation for millimetre wave wireless systems using overlapped beam patterns"
    - "robust location aided beam alignment in millimeter wave massive mimo"
    - "modeling and analyzing millimeter wave cellular systems"
    - "error bounds for uplink and downlink 3d localization in 5g mmwave systems"
    - "transmitter beam selection in millimeter wave mimo with in band position aiding"
    - "hierarchical codebook design for beamforming training in millimeter wave communication"
    - "millimeter wave vehicular communication to support massive automotive sensing"
    - "channel estimation for hybrid architecture based wideband millimeter wave systems"

Connected through hyperedge HE-7 (induced by source paper "joint state estimation and communication over a state dependent gaussian multiple access channel"):
  with members:
    - "broadcasting information subject to state masking"
    - "causal state communication"
    - "state amplification subject to masking constraints"
    - "hybrid digital analog codes for source channel broadcast of gaussian sources over gaussian channels"

Connected through hyperedge HE-8 (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"
    - "enhancing the estimation of mm wave large array channels by exploiting spatio temporal correlation and sparse scattering"
    - "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"

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)