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 robustness of massive mimo systems against passive eavesdropping under antenna selection"
  Abstract: In massive MIMO wiretap settings, the base station can significantly suppress eavesdroppers by narrow beamforming toward legitimate terminals. Numerical investigations show that by this approach, secrecy is obtained at no significant cost. We call this property of massive MIMO systems `secrecy for free' and show that it not only holds when all the transmit antennas at the base station are employed, but also when only a single antenna is set active. Using linear precoding, the information leakage to the eavesdroppers can be sufficiently diminished, when the total number of available transmit antennas at the base station grows large, even when only a fixed number of them are selected. This result indicates that passive eavesdropping has no significant impact on massive MIMO systems, regardless of the number of active transmit antennas.

Connected through hyperedge HE-1 (induced by source paper "robustness of low complexity massive mimo architectures against passive eavesdropping"):
  with members:
    - "papr limited precoding in massive mimo systems with reflect and transmit array antennas"
    - "glse precoders for massive mimo systems analysis and applications"
    - "stepwise transmit antenna selection in downlink massive multiuser mimo"
    - "scalable and energy efficient millimeter massive mimo architectures reflect array and transmit array antennas"
    - "optimal transmit antenna selection for massive mimo wiretap channels"
    - "asymptotics of nonlinear lse precoders with applications to transmit antenna selection"
    - "asymptotics of transmit antenna selection impact of multiple receive antennas"
    - "hybrid analog digital precoding revisited under realistic rf modeling"

Connected through hyperedge HE-2 (induced by source paper "secure regularized zero forcing for multiuser mimome channels"):
  with members:
    - "glse precoders for massive mimo systems analysis and applications"
    - "nonlinear precoders for massive mimo systems with general constraints"
    - "asymptotics of nonlinear lse precoders with applications to transmit antenna selection"
    - "physical layer security for massive mimo an overview on passive eavesdropping and active attacks"
    - "applications of large random matrices in communications engineering"
    - "linear precoding for broadcast channels with confidential messages under transmit side channel correlation"
    - "large system analysis of linear precoding in miso broadcast channels with confidential messages"
    - "secrecy sum rates for multi user mimo regularized channel inversion precoding"

Connected through hyperedge HE-3 (induced by source paper "joint user selection and precoding in multiuser mimo systems via group lasso"):
  with members:
    - "secure regularized zero forcing for multiuser mimome channels"
    - "precoding via approximate message passing with instantaneous signal constraints"
    - "glse precoders for massive mimo systems analysis and applications"
    - "theoretical bounds on map estimation in distributed sensing networks"
    - "nonlinear precoders for massive mimo systems with general constraints"
    - "asymptotics of nonlinear lse precoders with applications to transmit antenna selection"
    - "generalized approximate message passing for estimation with random linear mixing"
    - "consistency of the group lasso and multiple kernel learning"

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)