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: "relay beamforming strategies for physical layer security"
  Abstract: In this paper, collaborative use of relays to form a beamforming system and provide physical-layer security is investigated. In particular, amplify-and-forward (AF) relay beamforming designs under total and individual relay power constraints are studied with the goal of maximizing the secrecy rates when perfect channel state information (CSI) is available. In the AF scheme, not having analytical solutions for the optimal beamforming design under both total and individual power constraints, an iterative algorithm is proposed to numerically obtain the optimal beamforming structure and maximize the secrecy rates. Robust beamforming designs in the presence of imperfect CSI are investigated for decode-and-forward (DF) based relay beamforming, and optimization frameworks are provided.

Connected through hyperedge HE-1 (induced by source paper "joint relay and jammer selection improves the physical layer security in the face of csi feedback delays"):
  with members:
    - "security versus reliability analysis of opportunistic relaying"
    - "wireless physical layer security with imperfect channel state information a survey"
    - "optimal relay selection for physical layer security in cooperative wireless networks"
    - "joint relay and jammer selection for secure two way relay networks"
    - "rethinking the secrecy outage formulation a secure transmission design perspective"
    - "cooperative jamming for secure communications in mimo relay networks"
    - "robust beamforming for security in mimo wiretap channels with imperfect csi"
    - "on the throughput of secure hybrid arq protocols for gaussian block fading channels"

Connected through hyperedge HE-2 (induced by source paper "network simplification for secure af relaying"):
  with members:
    - "secure transmission in amplify and forward diamond networks with a single eavesdropper"
    - "analog network coding in general snr regime"
    - "wireless network simplification the gaussian n relay diamond network"
    - "collaborative relay beamforming for secrecy"
    - "discrete memoryless interference and broadcast channels with confidential messages secrecy rate regions"
    - "a simple cooperative diversity method based on network path selection"

Connected through hyperedge HE-3 (induced by source paper "secure analog network coding in layered networks"):
  with members:
    - "secure transmission in amplify and forward diamond networks with a single eavesdropper"
    - "analog network coding in general snr regime"

Connected through hyperedge HE-4 (induced by source paper "to harvest and jam a paradigm of self sustaining friendly jammers for secure af relaying"):
  with members:
    - "secrecy wireless information and power transfer in fading wiretap channel"
    - "multipair full duplex relaying with massive arrays and linear processing"
    - "robust beamforming for secure communication in systems with wireless information and power transfer"
    - "secrecy wireless information and power transfer with miso beamforming"
    - "multiuser miso beamforming for simultaneous wireless information and power transfer"
    - "secure communication with a wireless powered friendly jammer"
    - "throughput maximization in wireless powered communication networks"
    - "wireless physical layer security with imperfect channel state information a survey"

Connected through hyperedge HE-5 (induced by source paper "wireless powered cooperative jamming for secrecy multi af relaying networks"):
  with members:
    - "secrecy wireless information and power transfer in fading wiretap channel"
    - "to harvest and jam a paradigm of self sustaining friendly jammers for secure af relaying"
    - "wireless powered communication opportunities and challenges"
    - "joint power splitting and secure beamforming design in the multiple non regenerative wireless powered relay networks"
    - "robust beamforming for secure communication in systems with wireless information and power transfer"
    - "wireless networks with rf energy harvesting a contemporary survey"
    - "power allocation strategies in energy harvesting wireless cooperative networks"
    - "secrecy wireless information and power transfer with miso beamforming"

Connected through hyperedge HE-6 (induced by source paper "secure transmission in amplify and forward diamond networks with a single eavesdropper"):
  with members:
    - "optimal amplify and forward schemes for relay channels with correlated relay noise"
    - "the approximate capacity of the gaussian n relay diamond network"
    - "amplify and forward in wireless relay networks"
    - "discrete memoryless interference and broadcast channels with confidential messages secrecy rate regions"
    - "network beamforming using relays with perfect channel information"

Connected through hyperedge HE-7 (induced by source paper "secrecy capacity of two hop relay assisted wiretap channels"):
  with members:
    - "principles of physical layer security in multiuser wireless networks a survey"
    - "on cooperative relaying schemes for wireless physical layer security"
    - "joint relay and jammer selection for secure two way relay networks"
    - "optimal and robust transmit designs for miso channel secrecy by semidefinite programming"
    - "cooperation with an untrusted relay a secrecy perspective"
    - "secure transmission with multiple antennas ii the mimome wiretap channel"
    - "the secrecy capacity region of the gaussian mimo multi receiver wiretap channel"
    - "the secrecy capacity of the mimo wiretap channel"

Connected through hyperedge HE-8 (induced by source paper "secure relay beamforming over cognitive radio channels"):
  with members:
    - "collaborative relay beamforming for secrecy"

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)