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 cellular networks a stochastic geometry approach"
  Abstract: This paper studies the information-theoretic secrecy performance in large-scale cellular networks based on a stochastic geometry framework. The locations of both base stations and mobile users are modeled as independent two-dimensional Poisson point processes. We consider two important features of cellular networks, namely, information exchange between base stations and cell association, to characterize their impact on the achievable secrecy rate of an arbitrary downlink transmission with a certain portion of the mobile users acting as potential eavesdroppers. In particular, tractable results are presented under diverse assumptions on the availability of eavesdroppers' location information at the serving base station, which captures the benefit from the exchange of the location information between base stations.

Connected through hyperedge HE-1 (induced by source paper "secure communication in dynamic wireless ad hoc networks"):
  with members:
    - "k connectivity in random key graphs with unreliable links"
    - "tradeoff between delay and physical layer security in wireless networks"
    - "directional cell search delay analysis for cellular networks with static users"
    - "toward a tractable delay analysis in ultra dense networks"
    - "connectivity in secure wireless sensor networks under transmission constraints"
    - "on topological properties of wireless sensor networks under the q composite key predistribution scheme with on off channels"
    - "on the throughput cost of physical layer security in decentralized wireless networks"
    - "information propagation speed in mobile and delay tolerant networks"

Connected through hyperedge HE-2 (induced by source paper "tradeoff between delay and physical layer security in wireless networks"):
  with members:
    - "when mmwave communications meet network densification a scalable interference coordination perspective"
    - "secure transmission with large numbers of antennas and finite alphabet inputs"
    - "5g software defined vehicular networks"
    - "toward a tractable delay analysis in ultra dense networks"
    - "heterogeneous cellular networks with spatio temporal traffic delay analysis and scheduling"
    - "secure massive mimo transmission with an active eavesdropper"
    - "5g ultra dense cellular networks"
    - "performance laws of large heterogeneous cellular networks"

Connected through hyperedge HE-3 (induced by source paper "physical layer security in heterogeneous networks with jammer selection and full duplex users"):
  with members:
    - "exploiting full duplex receivers for achieving secret communications in multiuser miso networks"
    - "power allocation for secure swipt systems with wireless powered cooperative jamming"
    - "hybrid duplex switching in heterogeneous networks"
    - "opportunistic jamming for enhancing security stochastic geometry modeling and analysis"
    - "physical layer security in millimeter wave cellular networks"
    - "a survey on wireless security technical challenges recent advances and future trends"
    - "physical layer security in heterogeneous cellular networks"
    - "secure communication in uplink transmissions user selection and multiuser secrecy gain"

Connected through hyperedge HE-4 (induced by source paper "artificial interference aided physical layer security in cache enabled heterogeneous networks"):
  with members:
    - "the three primary colors of mobile systems"
    - "cache enabled physical layer security for video streaming in wireless networks with limited backhaul"
    - "physical layer security in three tier wireless sensor networks a stochastic geometry approach"
    - "analysis on cache enabled wireless heterogeneous networks"
    - "fundamental limits of caching with secure delivery"
    - "enhancing secrecy with multi antenna transmission in wireless ad hoc networks"
    - "a tractable approach to coverage and rate in cellular networks"

Connected through hyperedge HE-5 (induced by source paper "physical layer security in heterogeneous cellular networks"):
  with members:
    - "optimal power allocation for artificial noise under imperfect csi against spatially random eavesdroppers"
    - "secrecy transmit beamforming for heterogeneous networks"
    - "physical layer security in downlink multi antenna cellular networks"
    - "principles of physical layer security in multiuser wireless networks a survey"
    - "throughput and energy efficiency analysis of small cell networks with multi antenna base stations"
    - "enhancing secrecy with multi antenna transmission in wireless ad hoc networks"
    - "on the design of artificial noise aided secure multi antenna transmission in slow fading channels"
    - "heterogeneous cellular networks with flexible cell association a comprehensive downlink sinr analysis"

Connected through hyperedge HE-6 (induced by source paper "impact of artificial noise on cellular networks a stochastic geometry approach"):
  with members:
    - "optimal power allocation for artificial noise under imperfect csi against spatially random eavesdroppers"
    - "d2d enhanced heterogeneous cellular networks with dynamic tdd"
    - "what will 5g be"
    - "physical layer security in downlink multi antenna cellular networks"
    - "throughput and energy efficiency analysis of small cell networks with multi antenna base stations"
    - "enhancing secrecy with multi antenna transmission in wireless ad hoc networks"
    - "coordinated beamforming for multiuser miso interference channel under rate outage constraints"
    - "on the design of artificial noise aided secure multi antenna transmission in slow fading channels"

Connected through hyperedge HE-7 (induced by source paper "artificial noise aided secure transmission in large scale spectrum sharing networks"):
  with members:
    - "physical layer security in three tier wireless sensor networks a stochastic geometry approach"
    - "secrecy outage and diversity analysis of cognitive radio systems"
    - "physical layer security in downlink multi antenna cellular networks"
    - "principles of physical layer security in multiuser wireless networks a survey"
    - "enhancing secrecy with multi antenna transmission in wireless ad hoc networks"
    - "physical layer security with multiuser scheduling in cognitive radio networks"
    - "on the throughput cost of physical layer security in decentralized wireless networks"
    - "secure transmission with artificial noise over fading channels achievable rate and optimal power allocation"

Connected through hyperedge HE-8 (induced by source paper "physical layer security in three tier wireless sensor networks a stochastic geometry approach"):
  with members:
    - "safeguarding massive mimo aided hetnets using physical layer security"
    - "physical layer security in downlink multi antenna cellular networks"
    - "enhancing secrecy with multi antenna transmission in wireless ad hoc networks"
    - "optimal relay selection for physical layer security in cooperative wireless networks"
    - "modeling and analysis of k tier downlink heterogeneous cellular networks"
    - "random deployment of data collectors for serving randomly located sensors"
    - "on the throughput cost of physical layer security in decentralized wireless networks"
    - "diversity multiplexing tradeoff for the multiple antenna wire tap channel"

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)