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: "hierarchical codebook design for beamforming training in millimeter wave communication"
  Abstract: In millimeter-wave communication, large antenna arrays are required to achieve high power gain by steering toward each other with narrow beams, which poses the problem to efficiently search the best beam direction in the angle domain at both Tx and Rx sides. As the exhaustive search is time consuming, hierarchical search has been widely accepted to reduce the complexity, and its performance is highly dependent on the codebook design. In this paper, we propose two basic criteria for the hierarchical codebook design, and devise an efficient hierarchical codebook by jointly exploiting sub-array and deactivation (turning-off) antenna processing techniques, where closed-form expressions are provided to generate the codebook. Performance evaluations are conducted under different system and channel models. Results show superiority of the proposed codebook over the existing alternatives.

Connected through hyperedge HE-1 (induced by source paper "edge cache assisted secure low latency millimeter wave transmission"):
  with members:
    - "securing downlink massive mimo noma networks with artificial noise"
    - "hybrid precoder design for cache enabled millimeter wave radio access networks"
    - "secure and energy efficient transmissions in cache enabled heterogeneous cellular networks performance analysis and optimization"
    - "two level transmission scheme for cache enabled fog radio access networks"
    - "optimized base station cache allocation for cloud radio access network with multicast backhaul"
    - "exploiting physical layer security for multiuser multicarrier computation offloading"
    - "content placement in cache enabled sub 6 ghz and millimeter wave multi antenna dense small cell networks"
    - "random caching based cooperative transmission in heterogeneous wireless networks"

Connected through hyperedge HE-2 (induced by source paper "channel estimation and hybrid beamforming for reconfigurable intelligent surfaces assisted thz communications"):
  with members:
    - "secure wireless communication via intelligent reflecting surface"
    - "capacity characterization for intelligent reflecting surface aided mimo communication"
    - "intelligent reflecting surface meets ofdm protocol design and rate maximization"
    - "intelligent reflecting surface design for mimo system by maximizing sum path gains"
    - "channel estimation and transmission for intelligent reflecting surface assisted thz communications"
    - "energy efficient multi user miso communication using low resolution large intelligent surfaces"
    - "achievable rate maximization by passive intelligent mirrors"
    - "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"

Connected through hyperedge HE-3 (induced by source paper "a new codebook design for analog beamforming in millimeter wave communication"):
  with members:
    - "investigating robustness and interpretability of link prediction via adversarial modifications"
    - "partition pruning parallelization aware pruning for deep neural networks"
    - "age of information in multiple sensing"
    - "on the age of information in erasure channels with feedback"
    - "generating user friendly explanations for loan denials using gans"
    - "hybrid precoder and combiner design with low resolution phase shifters in mmwave mimo systems"
    - "embedding multimodal relational data for knowledge base completion"
    - "on the performance of mrc receiver with unknown timing mismatch a large scale analysis"

Connected through hyperedge HE-4 (induced by source paper "optimal link scheduling in millimeter wave multi hop networks with mu mimo radios"):
  with members:
    - "integrated access and backhaul in 5g mmwave networks potentials and challenges"
    - "distributed path selection strategies for integrated access and backhaul at mmwaves"
    - "understanding noise and interference regimes in 5g millimeter wave cellular networks"
    - "codebook design for millimeter wave channel estimation with hybrid precoding structure"
    - "hybrid architectures with few bit adc receivers achievable rates and energy rate tradeoffs"
    - "towards an appropriate receiver beamforming scheme for millimeter wave communication a power consumption based comparison"
    - "massive mimo ten myths and one critical question"
    - "low power analog to digital conversion in millimeter wave systems impact of resolution and bandwidth on performance"

Connected through hyperedge HE-5 (induced by source paper "swift link a compressive beam alignment algorithm for practical mmwave radios"):
  with members:
    - "partially blind handovers for mmwave new radio aided by sub 6 ghz lte signaling"
    - "a novel millimeter wave channel simulator and applications for 5g wireless communications"
    - "a compressive channel estimation technique robust to synchronization impairments"
    - "compressive channel estimation and tracking for large arrays in mm wave picocells"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "hybrid architectures with few bit adc receivers achievable rates and energy rate tradeoffs"
    - "channel estimation in broadband millimeter wave mimo systems with few bit adcs"
    - "self calibration and biconvex compressive sensing"

Connected through hyperedge HE-6 (induced by source paper "closed loop sparse channel estimation for wideband millimeter wave full dimensional mimo systems"):
  with members:
    - "wideband hybrid precoding for next generation backhaul fronthaul based on mmwave fd mimo"
    - "over sampling codebook based hybrid minimum sum mean square error precoding for millimeter wave 3d mimo"
    - "stochastic successive convex optimization for two timescale hybrid precoding in massive mimo"
    - "multi user precoding and channel estimation for hybrid millimeter wave systems"
    - "compressive sensing techniques for next generation wireless communications"
    - "millimeter wave mimo channel estimation using overlapped beam patterns and rate adaptation"
    - "channel estimation for millimeter wave multiuser mimo systems via parafac decomposition"
    - "an overview of signal processing techniques for millimeter wave mimo systems"

Connected through hyperedge HE-7 (induced by source paper "beam codebook design for 5g mmwave terminals"):
  with members:
    - "statistical blockage modeling and robustness of beamforming in millimeter wave systems"
    - "over sampling codebook based hybrid minimum sum mean square error precoding for millimeter wave 3d mimo"
    - "millimeter wave mimo prototype measurements and experimental results"
    - "codebook design for millimeter wave channel estimation with hybrid precoding structure"
    - "beamforming tradeoffs for initial ue discovery in millimeter wave mimo systems"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"
    - "what will 5g be"
    - "designing unimodular codes via quadratic optimization"

Connected through hyperedge HE-8 (induced by source paper "channel estimation and transmission for intelligent reflecting surface assisted thz communications"):
  with members:
    - "intelligent reflecting surface design for mimo system by maximizing sum path gains"
    - "achievable rate maximization by passive intelligent mirrors"
    - "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"
    - "reconfigurable intelligent surfaces for energy efficiency in wireless communication"
    - "limited feedback hybrid precoding for multi user millimeter wave systems"
    - "iterative joint beamforming training with constant amplitude phased arrays in millimeter wave communications"
    - "channel estimation and hybrid precoding for millimeter wave cellular 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)