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: "opportunistic secrecy with a strict delay constraint"
  Abstract: We investigate the delay limited secrecy capacity of the flat fading channel under two different assumptions on the available transmitter channel state information (CSI). The first scenario assumes perfect prior knowledge of both the main and eavesdropper channel gains. Here, upper and lower bounds on the delay limited secrecy capacity are derived, and shown to be tight in the high signal-to-noise ratio (SNR) regime. In the second scenario, only the main channel CSI is assumed to be available at the transmitter where, remarkably, we establish the achievability of a non-zero delay-limited secure rate, for a wide class of channel distributions, with a high probability. In the two cases, our achievability arguments are based on a novel two-stage key-sharing approach that overcomes the secrecy outage phenomenon observed in earlier works.

Connected through hyperedge HE-1 (induced by source paper "on the security analysis of a cooperative incremental relaying protocol in the presence of an active eavesdropper"):
  with members:
    - "power allocation and cooperative diversity in two way non regenerative cognitive radio networks"
    - "security versus reliability analysis of opportunistic relaying"
    - "intercept probability analysis of cooperative wireless networks with best relay selection in the presence of eavesdropping attack"
    - "on the design of artificial noise aided secure multi antenna transmission in slow fading channels"
    - "three receiver broadcast channels with side information"
    - "a secure communication game with a relay helping the eavesdropper"
    - "joint relay and jammer selection for secure two way relay networks"
    - "buffers improve the performance of relay selection"

Connected through hyperedge HE-2 (induced by source paper "secure transmission of delay sensitive data over wireless fading channels"):
  with members:
    - "secure communications in the presence of a buffer aided wireless powered relay with self energy recycling"
    - "a survey on wireless security technical challenges recent advances and future trends"
    - "joint power control in wiretap interference channels"
    - "cross layer scheduling for ofdma based cognitive radio systems with delay and security constraints"
    - "energy efficient optimization for physical layer security in multi antenna downlink networks with qos guarantee"
    - "secure wireless communication and optimal power control under statistical queueing constraints"
    - "secure communication in the low snr regime"
    - "analysis of energy efficiency in fading channels under qos constraints"

Connected through hyperedge HE-3 (induced by source paper "secrecy wireless information and power transfer in fading wiretap channel"):
  with members:
    - "secrecy wireless information and power transfer with miso beamforming"
    - "multiuser miso beamforming for simultaneous wireless information and power transfer"
    - "spatially selective artificial noise aided transmit optimization for miso multi eves secrecy rate maximization"
    - "wireless information transfer with opportunistic energy harvesting"
    - "wireless information and power transfer architecture design and rate energy tradeoff"
    - "mimo broadcasting for simultaneous wireless information and power transfer"
    - "secure transmission with artificial noise over fading channels achievable rate and optimal power allocation"

Connected through hyperedge HE-4 (induced by source paper "enhancing secrecy rates in a wiretap channel"):
  with members:
    - "previous messages provide the key to achieve shannon capacity in a wiretap channel"
    - "secrecy via sources and channels"
    - "strong secrecy from channel resolvability"
    - "the wiretap channel with feedback encryption over the channel"

Connected through hyperedge HE-5 (induced by source paper "achieving shannon capacity in a fading wiretap channel"):
  with members:
    - "previous messages provide the key to achieve shannon capacity in a wiretap channel"

Connected through hyperedge HE-6 (induced by source paper "practical provably secure multi node communication"):
  with members:
    - "keys through arq theory and practice"
    - "arq security in wi fi and rfid networks"
    - "arq secrecy from theory to practice"
    - "on the secrecy capacity of fading channels"

Connected through hyperedge HE-7 (induced by source paper "secrecy outage capacity of fading channels"):
  with members:
    - "keys through arq theory and practice"

Connected through hyperedge HE-8 (induced by source paper "diversity multiplexing tradeoff for the multiple antenna wire tap channel"):
  with members:
    - "interference alignment for secrecy"
    - "mimo wiretap channels with arbitrarily varying eavesdropper channel states"
    - "secure transmission with multiple antennas ii the mimome wiretap channel"
    - "secured communication over frequency selective fading channels a practical vandermonde precoding"
    - "towards the secrecy capacity of the gaussian mimo wire tap channel the 2 2 1 channel"
    - "on the compound mimo broadcast channels with confidential messages"
    - "on the delay limited secrecy capacity of fading channels"
    - "discrete memoryless interference and broadcast channels with confidential messages secrecy rate regions"

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)