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 massive mimo"
  Abstract: We consider a single-cell downlink massive MIMO communication in the presence of an adversary capable of jamming and eavesdropping simultaneously. We show that massive MIMO communication is naturally resilient to no training-phase jamming attack in which the adversary jams only the data communication and eavesdrops both the data communication and the training. Specifically, we show that the secure degrees of freedom (DoF) attained in the presence of such an attack is identical to the maximum DoF attained under no attack. Further, we evaluate the number of antennas that base station (BS) requires in order to establish information theoretic security without even a need for Wyner encoding. Next, we show that things are completely different once the adversary starts jamming the training phase. Specifically, we consider an attack, called training-phase jamming in which the adversary jams and eavesdrops both the training and the data communication. We show that under such an attack, the maximum secure DoF is equal to zero. Furthermore, the maximum achievable rates of users vanish even in the asymptotic regime in the number of BS antennas. To counter this attack, we develop a defense strategy in which we use a secret key to encrypt the pilot sequence assignments to hide them from the adversary, rather than encrypt the data. We show that, if the cardinality of the set of pilot signals are scaled appropriately, hiding the pilot signal assignments from the adversary enables the users to achieve secure DoF, identical to the maximum achievable DoF under no attack. Finally, we discuss how computational cryptography is a legitimate candidate to hide the pilot signal assignments. Indeed, while information theoretic security is not achieved with cryptography, the computational power necessary for the adversary to achieve a non-zero mutual information leakage rate goes to infinity.

Connected through hyperedge HE-1 (induced by source paper "vulnerabilities of massive mimo systems to pilot contamination attacks"):
  with members:
    - "optimal transmit antenna selection for massive mimo wiretap channels"
    - "massive mimo has unlimited capacity"
    - "exploiting full duplex receivers for achieving secret communications in multiuser miso networks"
    - "frequency synchronization for uplink massive mimo systems"
    - "linear precoding of data and artificial noise in secure massive mimo systems"
    - "massive mimo ten myths and one critical question"
    - "individual secrecy for broadcast channels with receiver side information"
    - "5g cellular key enabling technologies and research challenges"

Connected through hyperedge HE-2 (induced by source paper "a survey of physical layer security techniques for 5g wireless networks and challenges ahead"):
  with members:
    - "secure massive mimo systems with limited rf chains"
    - "secure transmission with large numbers of antennas and finite alphabet inputs"
    - "probabilistically robust swipt for secrecy misome systems"
    - "exploiting full duplex receivers for achieving secret communications in multiuser miso networks"
    - "full duplex bidirectional secure communications under perfect and distributionally ambiguous eavesdropper s csi"
    - "safeguarding decentralized wireless networks using full duplex jamming receivers"
    - "physical layer security aware routing and performance tradeoffs in ad hoc networks"
    - "hybrid procoder and combiner design for secure transmission in mmwave mimo systems"

Connected through hyperedge HE-3 (induced by source paper "pilot spoofing attack by multiple eavesdroppers"):
  with members:
    - "admm based fast algorithm for multi group multicast beamforming in large scale wireless systems"
    - "impact of artificial noise on cellular networks a stochastic geometry approach"
    - "an algorithm for global maximization of secrecy rates in gaussian mimo wiretap channels"
    - "secure massive mimo transmission with an active eavesdropper"
    - "secret key agreement with large antenna arrays under the pilot contamination attack"
    - "securing massive mimo at the physical layer"
    - "secure communication over parallel relay channel"
    - "robust secure transmission in miso channels based on worst case optimization"

Connected through hyperedge HE-4 (induced by source paper "secure massive mimo transmission with an active eavesdropper"):
  with members:
    - "channel acquisition for massive mimo ofdm with adjustable phase shift pilots"
    - "linear precoding of data and artificial noise in secure massive mimo systems"
    - "physical layer security in heterogeneous cellular networks"
    - "an overview of transmission theory and techniques of large scale antenna systems for 5g wireless communications"
    - "joint csit acquisition based on low rank matrix completion for fdd massive mimo systems"
    - "large scale mimo relaying techniques for physical layer security af or df"
    - "multi antenna relay aided wireless physical layer security"
    - "jamming aided secure communication in massive mimo rician 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)