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 heterogeneous cellular networks"
  Abstract: The heterogeneous cellular network (HCN) is a promising approach to the deployment of 5G cellular networks. This paper comprehensively studies physical layer security in a multi-tier HCN where base stations (BSs), authorized users and eavesdroppers are all randomly located. We first propose an access threshold based secrecy mobile association policy that associates each user with the BS providing the maximum \emph{truncated average received signal power} beyond a threshold. Under the proposed policy, we investigate the connection probability and secrecy probability of a randomly located user, and provide tractable expressions for the two metrics. Asymptotic analysis reveals that setting a larger access threshold increases the connection probability while decreases the secrecy probability. We further evaluate the network-wide secrecy throughput and the minimum secrecy throughput per user with both connection and secrecy probability constraints. We show that introducing a properly chosen access threshold significantly enhances the secrecy throughput performance of a HCN.

Connected through hyperedge HE-1 (induced by source paper "enhancing physical layer security of random caching in large scale multi antenna heterogeneous wireless networks"):
  with members:
    - "secure and energy efficient transmissions in cache enabled heterogeneous cellular networks performance analysis and optimization"
    - "enhancing performance of random caching in large scale wireless networks with multiple receive antennas"
    - "physical layer security in cache enabled cooperative small cell networks against randomly distributed eavesdroppers"
    - "a unified framework for the tractable analysis of multi antenna wireless networks"
    - "enhancing performance of random caching in large scale heterogeneous wireless networks with random discontinuous transmission"
    - "delivery secrecy tradeoff for cache enabled stochastic networks content placement optimization"
    - "random caching based cooperative transmission in heterogeneous wireless networks"
    - "caching at the wireless edge design aspects challenges and future directions"

Connected through hyperedge HE-2 (induced by source paper "performance of statistical and machine learning techniques for physical layer authentication"):
  with members:
    - "machine learning for intelligent authentication in 5g and beyond wireless networks"
    - "statistical and machine learning based decision techniques for physical layer authentication"
    - "learning aided physical layer authentication as an intelligent process"
    - "application of machine learning for channel based message authentication in mission critical machine type communication"
    - "analysis of channel based user authentication by key less and key based approaches"
    - "using the physical layer for wireless authentication in time variant channels"

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"
    - "a survey of physical layer security techniques for 5g wireless networks and challenges ahead"

Connected through hyperedge HE-4 (induced by source paper "multi antenna covert communications in random wireless networks"):
  with members:
    - "fundamental limits of covert communication over mimo awgn channel"
    - "covert wireless communication with a poisson field of interferers"
    - "covert communication in fading channels under channel uncertainty"
    - "covert wireless communication with artificial noise generation"
    - "safeguarding decentralized wireless networks using full duplex jamming receivers"
    - "covert communications with a full duplex receiver over wireless fading channels"
    - "on covert communication with noise uncertainty"
    - "fundamental limits of communication with low probability of detection"

Connected through hyperedge HE-5 (induced by source paper "secrecy outage analysis of non orthogonal spectrum sharing for heterogeneous cellular networks"):
  with members:
    - "security reliability tradeoff for distributed antenna systems in heterogeneous cellular networks"
    - "intelligent interference exploitation for heterogeneous cellular networks against eavesdropping"
    - "power domain non orthogonal multiple access noma in 5g systems potentials and challenges"
    - "a new look at physical layer security caching and wireless energy harvesting for heterogeneous ultra dense networks"
    - "physical layer security for spectrum sharing systems"
    - "artificial noise aided secure transmission in large scale spectrum sharing networks"
    - "location based beamforming and physical layer security in rician wiretap channels"
    - "physical layer security in millimeter wave cellular networks"

Connected through hyperedge HE-6 (induced by source paper "secrecy and covert communications against uav surveillance via multi hop networks"):
  with members:
    - "safeguarding wireless network with uavs a physical layer security perspective"
    - "coverage probability analysis of uav cellular networks in urban environments"
    - "secure routing with power optimization for ad hoc networks"
    - "securing uav communications via joint trajectory and power control"
    - "multi hop routing in covert wireless networks"
    - "robust trajectory and transmit power design for secure uav communications"
    - "securing uav communications via trajectory optimization"
    - "covert communication in fading channels under channel uncertainty"

Connected through hyperedge HE-7 (induced by source paper "enabling security and high energy efficiency in the internet of things with massive mimo hybrid precoding"):
  with members:
    - "joint optimization of computation and communication power in multi user massive mimo systems"
    - "secure massive mimo systems with limited rf chains"
    - "energy efficiency optimization of 5g radio frequency chain systems"
    - "large scale mimo relaying techniques for physical layer security af or df"
    - "jamming aided secure communication in massive mimo rician channels"
    - "on the secrecy outage capacity of physical layer security in large scale mimo relaying systems with imperfect csi"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"
    - "low complexity hybrid precoding in massive multiuser mimo systems"

Connected through hyperedge HE-8 (induced by source paper "secure users oriented downlink miso noma"):
  with members:
    - "exploiting inter user interference for secure massive non orthogonal multiple access"
    - "secure communications in noma system subcarrier assignment and power allocation"
    - "secrecy sum rate maximization in non orthogonal multiple access"
    - "relay selection for cooperative noma"
    - "on the spectral efficiency and security enhancements of noma assisted multicast unicast streaming"
    - "optimal joint power and subcarrier allocation for full duplex multicarrier non orthogonal multiple access systems"
    - "on the design of secure non orthogonal multiple access systems"
    - "energy efficient transmission design in non orthogonal multiple access"

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)