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: "covert communication in wireless relay networks"
  Abstract: Covert communication aims to shield the very existence of wireless transmissions in order to guarantee a strong security in wireless networks. In this work, for the first time we examine the possibility and achievable performance of covert communication in one-way relay networks. Specifically, the relay opportunistically transmits its own information to the destination covertly on top of forwarding the source's message, while the source tries to detect this covert transmission to discover the illegitimate usage of the recourse (e.g., power, spectrum) allocated only for the purpose of forwarding source's information. The necessary condition that the relay can transmit covertly without being detected is identified and the source's detection limit is derived in terms of the false alarm and miss detection rates. Our analysis indicates that boosting the forwarding ability of the relay (e.g., increasing its maximum transmit power) also increases its capacity to perform the covert communication in terms of achieving a higher effective covert rate subject to some specific requirement on the source's detection performance.

Connected through hyperedge HE-1 (induced by source paper "gaussian signalling for covert communications"):
  with members:
    - "first and second order asymptotics in covert communication"
    - "covert communication over a k user multiple access channel"
    - "multipath stealth communication with jammers"
    - "covert communication achieved by a greedy relay in wireless networks"
    - "covert communication in fading channels under channel uncertainty"
    - "on covert communication with noise uncertainty"
    - "fundamental limits of communication with low probability of detection"
    - "covert communication in the presence of an uninformed jammer"

Connected through hyperedge HE-2 (induced by source paper "covert wireless communications with channel inversion power control in rayleigh fading"):
  with members:
    - "gaussian signalling for covert communications"
    - "achieving covert wireless communications using a full duplex receiver"
    - "adaptive full duplex jamming receiver for secure d2d links in random networks"
    - "covert communication achieved by a greedy relay in wireless networks"
    - "covert wireless communication with a poisson field of interferers"
    - "covert communication in fading channels under channel uncertainty"
    - "covert communications with a full duplex receiver over wireless fading channels"
    - "covert communication with finite blocklength in awgn channels"

Connected through hyperedge HE-3 (induced by source paper "covert communication achieved by a greedy relay in wireless networks"):
  with members:
    - "fundamental limits of covert communication over mimo awgn channel"
    - "covert communication in fading channels under channel uncertainty"
    - "covert communication with finite blocklength in awgn channels"
    - "on covert communication with noise uncertainty"
    - "fundamental limits of communication with low probability of detection"
    - "artificial noise aided secure transmission in large scale spectrum sharing networks"
    - "artificial noise aided secure transmission with directional modulation based on random frequency diverse arrays"
    - "covert communication in the presence of an uninformed jammer"

Connected through hyperedge HE-4 (induced by source paper "secure precise wireless transmission with random subcarrier selection based directional modulation transmit antenna array"):
  with members:
    - "symbol level and multicast precoding for multiuser multiantenna downlink a survey classification and challenges"
    - "the random frequency diverse array a new antenna structure for uncoupled direction range indication in active sensing"
    - "artificial noise aided secure transmission in wiretap channels with transmitter side correlation"
    - "location based beamforming for enhancing secrecy in rician wiretap channels"
    - "directional modulation via symbol level precoding a way to enhance security"
    - "improving physical layer security in wireless communications using diversity techniques"
    - "relay selection improves the security reliability trade off in cognitive radio systems"
    - "optimization of code rates in sisome wiretap channels"

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)