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: "intelligent reflecting surface design for mimo system by maximizing sum path gains"
  Abstract: Intelligent reflecting surface (IRS) serves as an emerging paradigm to enhance the wireless transmission with a low hardware cost and a reduced power consumption. In this letter, we investigate the IRS-assisted downlink multi-input multi-output (MIMO) system, where an Alice-Bob pair wishes to communicate with the assist of IRS. Our goal is to maximize the spectral efficiency by designing the active beamformer at Alice and the passive reflecting phase shifters (PSs) at the IRS, which turns out to be an intractable mixed integer non-convex optimization problem. To tackle this problem, we propose an efficient algorithm to obtain an effective solution. Specifically, the PSs at the IRS are optimized to maximize the sum of gains of different paths. Such a criterion is also referred to as the maximizing the sum of gains (MSG) principle. Then, an alternating direction method of multipliers (ADMM) algorithm is developed to solve the MSG-based optimization problem. With the obtained PSs, the beamformer at Alice is obtained by classic singular value decomposition (SVD) and water-filling (WF) solutions.

Connected through hyperedge HE-1 (induced by source paper "resource allocation in intelligent reflecting surface assisted noma systems"):
  with members:
    - "joint active and passive beamforming optimization for intelligent reflecting surface assisted swipt under qos constraints"
    - "capacity characterization for intelligent reflecting surface aided mimo communication"
    - "power efficient irs assisted noma"
    - "intelligent reflecting surface meets ofdm protocol design and rate maximization"
    - "intelligent reflecting surface assisted non orthogonal multiple access"
    - "a simple design of irs noma transmission"
    - "towards smart radio environment for wireless communications via intelligent reflecting surfaces a comprehensive survey"
    - "joint beamforming design in multi cluster miso noma intelligent reflecting surface aided downlink communication networks"

Connected through hyperedge HE-2 (induced by source paper "parallel factor decomposition channel estimation in ris assisted multi user miso communication"):
  with members:
    - "holographic mimo surfaces for 6g wireless networks opportunities challenges and trends"
    - "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"
    - "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-3 (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"
    - "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"
    - "beyond massive mimo the potential of data transmission with large intelligent surfaces"

Connected through hyperedge HE-4 (induced by source paper "channel estimation and transmission for intelligent reflecting surface assisted thz communications"):
  with members:
    - "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"
    - "hierarchical codebook design for beamforming training in millimeter wave 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)