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: "holographic mimo surfaces for 6g wireless networks opportunities challenges and trends"
  Abstract: Future wireless networks are expected to evolve towards an intelligent and software reconfigurable functionality paradigm enabling ubiquitous communication between humans and mobile devices, but also being capable of sensing, controlling, and optimizing the wireless environment to fulfill the visions of low powered, high throughput, massive connectivity, and low latency communications. A key conceptual enabler that is recently gaining increasing popularity is the Holographic Multiple Input Multiple Output Surface (HMIMOS) that refers to a low cost transformative wireless planar structure comprising of sub-wavelength metallic or dielectric scattering particles, which is capable of impacting electromagnetic waves according to desired objectives. In this article, we provide an overview of HMIMOS communications by introducing the available hardware architectures for reconfigurable metasurfaces and their main characteristics, as well as highlighting the opportunities and key design challenges when multiple HMIMOS are considered.

Connected through hyperedge HE-1 (induced by source paper "overhead aware design of reconfigurable intelligent surfaces in smart radio environments"):
  with members:
    - "over the air computation via intelligent reflecting surfaces"
    - "intelligent reflecting surface with discrete phase shifts channel estimation and passive beamforming"
    - "miso wireless communication systems via intelligent reflecting surfaces"
    - "secure wireless communication via intelligent reflecting surface"
    - "joint active and passive beamforming for intelligent reflecting surface assisted massive mimo systems"
    - "rfocus practical beamforming for small devices"
    - "cascaded channel estimation for large intelligent metasurface assisted massive mimo"
    - "intelligent reflecting surface irs enabled covert communications in wireless networks"

Connected through hyperedge HE-2 (induced by source paper "exploiting randomly located blockages for large scale deployment of intelligent surfaces"):
  with members:
    - "intelligent reflecting surface versus decode and forward how large surfaces are needed to beat relaying"
    - "joint active and passive beamforming optimization for intelligent reflecting surface assisted swipt under qos constraints"
    - "a novel communication paradigm for high capacity and security via programmable indoor wireless environments in next generation wireless systems"
    - "large intelligent surface antennas lisa making reflective radios smart"
    - "secure wireless communication via intelligent reflecting surface"
    - "reflection probability in wireless networks with metasurface coated environmental objects an approach based on random spatial processes"
    - "resource allocation for secure irs assisted multiuser miso systems"
    - "a mathematical justification for exponentially distributed nlos bias"

Connected through hyperedge HE-3 (induced by source paper "joint power control and passive beamforming in irs assisted spectrum sharing"):
  with members:
    - "intelligent reflecting surface assisted multiple access with user pairing noma or oma"
    - "joint active and passive beamforming optimization for intelligent reflecting surface assisted swipt under qos constraints"
    - "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"
    - "enabling secure wireless communications via intelligent reflecting surfaces"
    - "intelligent reflecting surface assisted secrecy communication is artificial noise helpful or not"
    - "beamforming optimization for wireless network aided by intelligent reflecting surface with discrete phase shifts"

Connected through hyperedge HE-4 (induced by source paper "parallel factor decomposition channel estimation in ris assisted multi user miso communication"):
  with members:
    - "large intelligent surface antennas lisa making reflective radios smart"
    - "passive beamforming and information transfer via large intelligent surface"
    - "indoor signal focusing with deep learning designed reconfigurable intelligent surfaces"
    - "intelligent reflecting surface design for mimo system by maximizing sum path gains"
    - "enabling large intelligent surfaces with compressive sensing and deep learning"
    - "towards smart and reconfigurable environment intelligent reflecting surface aided wireless network"
    - "intelligent reflecting surface enhanced ofdm channel estimation and reflection optimization"
    - "energy efficient multi user miso communication using low resolution large intelligent surfaces"

Connected through hyperedge HE-5 (induced by source paper "deep reinforcement learning for intelligent reflecting surfaces towards standalone operation"):
  with members:
    - "reconfigurable intelligent surface empowered 6g wireless communications challenges and opportunities"
    - "deep reinforcement learning for 5g networks joint beamforming power control and interference coordination"
    - "deep learning for massive mimo with 1 bit adcs when more antennas need fewer pilots"
    - "large intelligent surface antennas lisa making reflective radios smart"
    - "indoor signal focusing with deep learning designed reconfigurable intelligent surfaces"
    - "deepmimo a generic deep learning dataset for millimeter wave and massive mimo applications"
    - "enabling large intelligent surfaces with compressive sensing and deep learning"
    - "deep learning for direct hybrid precoding in millimeter wave 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)