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: "a survey of physical layer security techniques for 5g wireless networks and challenges ahead"
  Abstract: Physical layer security which safeguards data confidentiality based on the information-theoretic approaches has received significant research interest recently. The key idea behind physical layer security is to utilize the intrinsic randomness of the transmission channel to guarantee the security in physical layer. The evolution towards 5G wireless communications poses new challenges for physical layer security research. This paper provides a latest survey of the physical layer security research on various promising 5G technologies, including physical layer security coding, massive multiple-input multiple-output, millimeter wave communications, heterogeneous networks, non-orthogonal multiple access, full duplex technology, etc. Technical challenges which remain unresolved at the time of writing are summarized and the future trends of physical layer security in 5G and beyond are discussed.

Connected through hyperedge HE-1 (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"
    - "physical layer security in uav systems challenges and opportunities"
    - "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"
    - "on low resolution adcs in practical 5g millimeter wave massive mimo systems"
    - "performance analysis of mixed adc massive mimo systems over rician fading channels"

Connected through hyperedge HE-2 (induced by source paper "physical layer security in the finite blocklength regime over fading channels"):
  with members:
    - "secure and energy efficient transmissions in cache enabled heterogeneous cellular networks performance analysis and optimization"
    - "safeguarding decentralized wireless networks using full duplex jamming receivers"
    - "artificial noise aided secure transmission in large scale spectrum sharing networks"
    - "on the spectral efficiency and security enhancements of noma assisted multicast unicast streaming"
    - "finite blocklength bounds for wiretap channels"
    - "a survey on wireless security technical challenges recent advances and future trends"
    - "enhancing the physical layer security of non orthogonal multiple access in large scale networks"
    - "finite block length analysis of the incremental redundancy harq"

Connected through hyperedge HE-3 (induced by source paper "a survey on the security and the evolution of osmotic and catalytic computing for 5g networks"):
  with members:
    - "5g nr jamming spoofing and sniffing threat assessment and mitigation"
    - "a framework for mitigating zero day attacks in iot"
    - "nhad neuro fuzzy based horizontal anomaly detection in online social networks"
    - "multi radio 5g architecture for connected and autonomous vehicles application and design insights"
    - "rehand secure region based fast handover with user anonymity for small cell networks in 5g"
    - "robust physical layer security for power domain non orthogonal multiple access based hetnets and hudns sic avoidance at eavesdroppers"
    - "a survey on the security of pervasive online social networks posns"
    - "self enforcing game theory based resource allocation for lorawan assisted public safety communications"

Connected through hyperedge HE-4 (induced by source paper "data aided secure massive mimo transmission under the pilot contamination attack"):
  with members:
    - "pilot spoofing attack by multiple eavesdroppers"
    - "multiple antennas secure transmission under pilot spoofing and jamming attack"
    - "secure transmission with large numbers of antennas and finite alphabet inputs"
    - "massive mimo pilot decontamination and channel interpolation via wideband sparse channel estimation"
    - "analysis and design of secure massive mimo systems in the presence of hardware impairments"
    - "performance limits of massive mimo systems based on bayes optimal inference"
    - "secure massive mimo transmission with an active eavesdropper"
    - "large scale mimo relaying techniques for physical layer security af or df"

Connected through hyperedge HE-5 (induced by source paper "secure communication for spatially sparse millimeter wave massive mimo channels via hybrid precoding"):
  with members:
    - "secure massive mimo communication with low resolution dacs"
    - "secure users oriented downlink miso noma"
    - "a hardware efficient analog network structure for hybrid precoding in millimeter wave systems"
    - "performance analysis of multi cell millimeter wave massive mimo networks with low precision adcs"
    - "low complexity reconfigurable mimo for millimeter wave communications"
    - "millimeter wave communications with reconfigurable antennas"
    - "millimeter wave mimo channel estimation using overlapped beam patterns and rate adaptation"
    - "analysis of one bit quantized precoding for the multiuser massive mimo downlink"

Connected through hyperedge HE-6 (induced by source paper "two way physical layer security protocol for gaussian channels"):
  with members:
    - "semi finite length analysis for information theoretic tasks"
    - "physical layer security for rf satellite channels in the finite length regime"
    - "wiretap channels nonasymptotic fundamental limits"
    - "quantum inspired secure wireless communication protocol under spatial and local gaussian noise assumptions"
    - "secure wireless communication under spatial and local gaussian noise assumptions"
    - "numerical study on secrecy capacity and code length dependence of the performances in optical wiretap channels"
    - "the wiretap channel with generalized feedback secure communication and key generation"
    - "secret key agreement general capacity and second order asymptotics"

Connected through hyperedge HE-7 (induced by source paper "security of 5g mobile backhaul networks a survey"):
  with members:
    - "bandwidth partitioning and downlink analysis in mmwave integrated access and backhaul for 5g"
    - "cross layer authentication protocol design for ultra dense 5g hetnets"
    - "formal analysis of 5g authentication"
    - "massive multiple input massive multiple output for 5g wireless backhauling"
    - "the 5g cellular backhaul management dilemma to cache or to serve"
    - "optimal joint routing and scheduling in millimeter wave cellular networks"
    - "a survey on low latency towards 5g ran core network and caching solutions"
    - "fso based vertical backhaul fronthaul framework for 5g wireless networks"

Connected through hyperedge HE-8 (induced by source paper "fixed region beamforming using frequency diverse subarray for secure mmwave wireless communications"):
  with members:
    - "safeguarding millimeter wave communications against randomly located eavesdroppers"
    - "a survey on wireless security technical challenges recent advances and future trends"
    - "secure communications in millimeter wave ad hoc networks"
    - "multi antenna relay aided wireless physical layer security"
    - "robust beamforming for secure communication in systems with wireless information and power transfer"
    - "millimeter wave channel modeling and cellular capacity evaluation"

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)