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: "on the error region for channel estimation based physical layer authentication over rayleigh fading"
  Abstract: For a physical layer message authentication procedure based on the comparison of channel estimates obtained from the received messages, we focus on an outer bound on the type I/II error probability region. Channel estimates are modeled as multivariate Gaussian vectors, and we assume that the attacker has only some side information on the channel estimate, which he does not know directly. We derive the attacking strategy that provides the tightest bound on the error region, given the statistics of the side information. This turns out to be a zero mean, circularly symmetric Gaussian density whose covariance matrices can be obtained by solving a constrained optimization problem. We propose an iterative algorithm for its solution: starting from the closed-form solution of a relaxed problem, we obtain, by projection, an initial feasible solution; then, by an iterative procedure, we look for the fixed-point solution of the problem. Numerical results show that for cases of interest the iterative approach converges, and perturbation analysis shows that the found solution is a local minimum.

Connected through hyperedge HE-1 (induced by source paper "learning aided physical layer authentication as an intelligent process"):
  with members:
    - "nonconvex sparse logistic regression with weakly convex regularization"
    - "reverse k nearest neighbor search over trajectories"
    - "a survey on wireless security technical challenges recent advances and future trends"
    - "rssi based distributed self localization for wireless sensor networks used in precision agriculture"
    - "security formalizations and their relationships for encryption and key agreement in information theoretic cryptography"

Connected through hyperedge HE-2 (induced by source paper "multi message authentication over noisy channel with secure channel codes"):
  with members:
    - "on the optimality of keyless authentication in a noisy model"
    - "message authentication code over a wiretap channel"
    - "achieving the secrecy capacity of wiretap channels using polar codes"
    - "cooperative secret key generation from phase estimation in narrowband fading channels"
    - "strong secrecy on the binary erasure wiretap channel using large girth ldpc codes"
    - "strong secrecy for erasure wiretap channels"
    - "applications of ldpc codes to the wiretap channel"

Connected through hyperedge HE-3 (induced by source paper "analysis of channel based user authentication by key less and key based approaches"):
  with members:
    - "artificial noise aided message authentication codes with information theoretic security"
    - "on the optimality of keyless authentication in a noisy model"
    - "principles of physical layer security in multiuser wireless networks a survey"
    - "a theoretical analysis of authentication privacy and reusability across secure biometric systems"
    - "using the physical layer for wireless authentication in time variant channels"

Connected through hyperedge HE-4 (induced by source paper "comparison between asymmetric and symmetric channel based authentication for mimo systems"):
  with members:
    - "coding in the finite blocklength regime bounds based on laplace integrals and their asymptotic approximations"

Connected through hyperedge HE-5 (induced by source paper "a physical layer authentication assisted scheme for enhancing 3gpp authentication"):
  with members:
    - "information theoretically secret key generation for fading wireless channels"
    - "using the physical layer for wireless authentication in time variant 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)