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: "physical layer security in uav systems challenges and opportunities"
  Abstract: Unmanned aerial vehicle (UAV) wireless communications have experienced an upsurge of interest in both military and civilian applications, due to its high mobility, low cost, on-demand deployment, and inherent line-of-sight (LoS) air-to-ground channels. However, these benefits also make UAV wireless communication systems vulnerable to malicious eavesdropping attacks. In this article, we aim to examine the physical layer security issues in UAV systems. In particular, passive and active eavesdroppings are two primary attacks in UAV systems. We provide an overview on emerging techniques, such as trajectory design, resource allocation, and cooperative UAVs, to fight against both types of eavesdroppings in UAV wireless communication systems. Moreover, the applications of non-orthogonal multiple access, multiple-input and multiple-output, and millimeter wave in UAV systems are also proposed to improve the system spectral efficiency and to guarantee security simultaneously. Finally, we discuss some potential research directions and challenges in terms of physical layer security in UAV systems.

Connected through hyperedge HE-1 (induced by source paper "resource allocation for secure multi uav communication systems with multi eavesdropper"):
  with members:
    - "robust trajectory and resource allocation design for secure uav aided communications"
    - "safeguarding wireless network with uavs a physical layer security perspective"
    - "energy efficient resource allocation for secure uav communication systems"
    - "cognitive uav communication via joint maneuver and power control"
    - "secrecy energy efficiency maximization for uav enabled mobile relaying"
    - "joint altitude beamwidth location and bandwidth optimization for uav enabled communications"
    - "optimal 3d trajectory design and resource allocation for solar powered uav communication systems"
    - "securing uav communications via joint trajectory and power control"

Connected through hyperedge HE-2 (induced by source paper "angle aware user cooperation for secure massive mimo in rician fading channel"):
  with members:
    - "machine intelligence at the edge with learning centric power allocation"
    - "robust and secure wireless communications via intelligent reflecting surfaces"
    - "vulnerabilities of massive mimo systems to pilot contamination attacks"
    - "resource allocation for secure irs assisted multiuser miso systems"
    - "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"
    - "on low resolution adcs in practical 5g millimeter wave massive mimo systems"
    - "a survey of physical layer security techniques for 5g wireless networks and challenges ahead"
    - "performance analysis of mixed adc massive mimo systems over rician fading channels"

Connected through hyperedge HE-3 (induced by source paper "multiple antenna technologies for beyond 5g"):
  with members:
    - "intelligent reflecting surface versus decode and forward how large surfaces are needed to beat relaying"
    - "robust trajectory and resource allocation design for secure uav aided communications"
    - "a new look at cell free massive mimo making it practical with dynamic cooperation"
    - "scalability aspects of cell free massive mimo"
    - "cascaded channel estimation for large intelligent metasurface assisted massive mimo"
    - "robust and secure wireless communications via intelligent reflecting surfaces"
    - "channel estimation for intelligent reflecting surface assisted multiuser communications framework algorithms and analysis"
    - "resource allocation for secure irs assisted multiuser miso systems"

Connected through hyperedge HE-4 (induced by source paper "improving phy security of uav enabled transmission with wireless energy harvesting robust trajectory design and power allocation"):
  with members:
    - "on the performance of low altitude uav enabled secure af relaying with cooperative jamming and swipt"
    - "uav communications for 5g and beyond recent advances and future trends"
    - "securing uav communications via joint trajectory and power control"
    - "a tutorial on uavs for wireless networks applications challenges and open problems"
    - "robust trajectory and transmit power design for secure uav communications"
    - "secure uav communication with cooperative jamming and trajectory control"
    - "securing uav communications via trajectory optimization"
    - "wireless communications with unmanned aerial vehicles opportunities and challenges"

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)