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: "improving physical layer security in wireless communications using diversity techniques"
  Abstract: Due to the broadcast nature of radio propagation, wireless transmission can be readily overheard by unauthorized users for interception purposes and is thus highly vulnerable to eavesdropping attacks. To this end, physical-layer security is emerging as a promising paradigm to protect the wireless communications against eavesdropping attacks by exploiting the physical characteristics of wireless channels. This article is focused on the investigation of diversity techniques to improve physical-layer security differently from the conventional artificial noise generation and beamforming techniques, which typically consume additional power for generating artificial noise and exhibit high implementation complexity for beamformer design. We present several diversity approaches to improve wireless physical-layer security, including multiple-input multiple-output (MIMO), multiuser diversity, and cooperative diversity. To illustrate the security improvement through diversity, we propose a case study of exploiting cooperative relays to assist the signal transmission from source to destination while defending against eavesdropping attacks. We evaluate the security performance of cooperative relay transmission in Rayleigh fading environments in terms of secrecy capacity and intercept probability. It is shown that as the number of relays increases, both the secrecy capacity and intercept probability of cooperative relay transmission improve significantly, implying there is an advantage in exploiting cooperative diversity to improve physical-layer security against eavesdropping attacks.

Connected through hyperedge HE-1 (induced by source paper "jamming assisted eavesdropping over parallel fading channels"):
  with members:
    - "multi antenna wireless legitimate surveillance systems design and performance analysis"
    - "proactive eavesdropping via jamming over harq based communications"
    - "surveillance and intervention of infrastructure free mobile communications a new wireless security paradigm"
    - "wireless information surveillance via proactive eavesdropping with spoofing relay"
    - "a survey on wireless security technical challenges recent advances and future trends"
    - "proactive eavesdropping via cognitive jamming in fading channels"
    - "proactive eavesdropping via jamming for rate maximization over rayleigh fading channels"
    - "physical layer security for massive mimo an overview on passive eavesdropping and active attacks"

Connected through hyperedge HE-2 (induced by source paper "secrecy outage for wireless sensor networks"):
  with members:
    - "intercept behavior analysis of industrial wireless sensor networks in the presence of eavesdropping attack"
    - "optimal relay selection for physical layer security in cooperative wireless networks"
    - "rethinking the secrecy outage formulation a secure transmission design perspective"

Connected through hyperedge HE-3 (induced by source paper "on secure mixed rf fso systems with tas and imperfect csi"):
  with members:
    - "cognitive mimo rf fso cooperative relay communication with mobile nodes and imperfect channel state information"
    - "opportunistic scheduling in underlay cognitive radio based mimo rf fso networks"
    - "optimal resource allocation for power efficient mc noma with imperfect channel state information"

Connected through hyperedge HE-4 (induced by source paper "vehicle communication using secrecy capacity"):
  with members:
    - "vehicular communications for 5g cooperative small cell networks"

Connected through hyperedge HE-5 (induced by source paper "multi antenna wireless legitimate surveillance systems design and performance analysis"):
  with members:
    - "secure massive mimo systems with limited rf chains"
    - "analysis and design of secure massive mimo systems in the presence of hardware impairments"
    - "on secrecy performance of antenna selection aided mimo systems against eavesdropping"
    - "linear precoding of data and artificial noise in secure massive mimo systems"
    - "throughput analysis and optimization of wireless powered multiple antenna full duplex relay systems"
    - "wireless information surveillance via proactive eavesdropping with spoofing relay"
    - "a survey on wireless security technical challenges recent advances and future trends"
    - "proactive eavesdropping via cognitive jamming in fading channels"

Connected through hyperedge HE-6 (induced by source paper "boundaries can enhance physical layer security at high data rates"):
  with members:
    - "temporal correlation of interference and outage in mobile networks over one dimensional finite regions"
    - "physical layer security in wireless ad hoc networks under a hybrid full half duplex receiver deployment strategy"
    - "stochastic geometry based comparison of secrecy enhancement techniques in d2d networks"
    - "temporal correlation of interference in bounded mobile ad hoc networks with blockage"
    - "physical layer security in heterogeneous cellular networks"
    - "physical layer security in three tier wireless sensor networks a stochastic geometry approach"
    - "analyzing the impact of access point density on the performance of finite area networks"
    - "more is less connectivity in fractal regions"

Connected through hyperedge HE-7 (induced by source paper "intelligent interference exploitation for heterogeneous cellular networks against eavesdropping"):
  with members:
    - "robust and secure resource allocation for full duplex miso multicarrier noma systems"
    - "physical layer security in wireless ad hoc networks under a hybrid full half duplex receiver deployment strategy"
    - "safeguarding decentralized wireless networks using full duplex jamming receivers"
    - "power constrained secrecy rate maximization for joint relay and jammer selection assisted wireless networks"
    - "relay selection for wireless communications against eavesdropping a security reliability trade off perspective"
    - "physical layer security for spectrum sharing systems"
    - "on secrecy performance of antenna selection aided mimo systems against eavesdropping"
    - "analytical modeling of interference aware power control for the uplink of heterogeneous cellular networks"

Connected through hyperedge HE-8 (induced by source paper "applications of economic and pricing models for wireless network security a survey"):
  with members:
    - "charging and discharging of plug in electric vehicles pevs in vehicle to grid v2g systems a cyber insurance based model"
    - "data collection and wireless communication in internet of things iot using economic analysis and pricing models a survey"
    - "a multitier wireless spectrum sharing system leveraging secure spectrum auctions"
    - "decomposition by partial linearization parallel optimization of multi agent systems"
    - "principles of physical layer security in multiuser wireless networks a survey"
    - "incentives for privacy tradeoff in community sensing"
    - "ps trust provably secure solution for truthful double spectrum auctions"
    - "truthful mechanisms for secure communication in wireless cooperative system"

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)