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 optimality of linear precoding for secrecy in the mimo broadcast channel"
  Abstract: We study the optimality of linear precoding for the two-receiver multiple-input multiple-output (MIMO) Gaussian broadcast channel (BC) with confidential messages. Secret dirty-paper coding (SDPC) is optimal under an input covariance constraint, but there is no computable secrecy capacity expression for the general MIMO case under an average power constraint. In principle, for this case, the secrecy capacity region could be found through an exhaustive search over the set of all possible matrix power constraints. Clearly, this search, coupled with the complexity of dirty-paper encoding and decoding, motivates the consideration of low complexity linear precoding as an alternative. We prove that for a two-user MIMO Gaussian BC under an input covariance constraint, linear precoding is optimal and achieves the same secrecy rate region as S-DPC if the input covariance constraint satisfies a specific condition, and we characterize the corresponding optimal linear precoders. We then use this result to derive a closed-form sub-optimal algorithm based on linear precoding for an average power constraint. Numerical results indicate that the secrecy rate region achieved by this algorithm is close to that obtained by the optimal S-DPC approach with a search over all suitable input covariance matrices.

Connected through hyperedge HE-1 (induced by source paper "physical layer security in downlink multi antenna cellular networks"):
  with members:
    - "principles of physical layer security in multiuser wireless networks a survey"
    - "secrecy rates in the broadcast channel with confidential messages and external eavesdroppers"
    - "downlink mimo hetnets modeling ordering results and performance analysis"
    - "linear precoding for broadcast channels with confidential messages under transmit side channel correlation"
    - "new results on multiple input multiple output broadcast channels with confidential messages"
    - "large system analysis of linear precoding in miso broadcast channels with confidential messages"
    - "physical layer security in cellular networks a stochastic geometry approach"
    - "secrecy sum rates for multi user mimo regularized channel inversion precoding"

Connected through hyperedge HE-2 (induced by source paper "secrecy rates in the broadcast channel with confidential messages and external eavesdroppers"):
  with members:
    - "principles of physical layer security in multiuser wireless networks a survey"
    - "linear precoding for broadcast channels with confidential messages under transmit side channel correlation"
    - "new results on multiple input multiple output broadcast channels with confidential messages"
    - "large system analysis of linear precoding in miso broadcast channels with confidential messages"
    - "secrecy sum rates for multi user mimo regularized channel inversion precoding"
    - "large system analysis of linear precoding in correlated miso broadcast channels under limited feedback"
    - "secrecy degrees of freedom of mimo broadcast channels with delayed csit"
    - "the secrecy graph and some of its properties"

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)