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: "energy efficient power allocation for secure communications in large scale mimo relaying systems"
  Abstract: In this paper, we address the problem of energy-efficient power allocation for secure communications in an amplify-and-forward (AF) large-scale multiple-input multiple-output (LS-MIMO) relaying system in presence of a passive eavesdropper. The benefits of an AF LS-MIMO relay are exploited to significantly improve the secrecy performance, especially the secrecy energy efficiency (bit per Joule). We first analyze the impact of transmit power at the relay on the secrecy outage capacity, and prove that the secrecy outage capacity is a concave function of transmit power under very practical assumptions, i.e. no eavesdropper channel state information (CSI) and imperfect legitimate CSI. Then, we propose an energy-efficient power allocation scheme to maximize the secrecy energy efficiency. Finally, simulation results validate the advantage of the proposed energy-efficient scheme compared to the capacity maximization scheme.

Connected through hyperedge HE-1 (induced by source paper "mode selection in mu mimo downlink networks a physical layer security perspective"):
  with members:
    - "principles of physical layer security in multiuser wireless networks a survey"
    - "performance analysis for physical layer security in multi antenna downlink networks with limited csi feedback"
    - "energy efficient optimization for physical layer security in multi antenna downlink networks with qos guarantee"
    - "multi mode transmission for the mimo broadcast channel with imperfect channel state information"
    - "robust beamforming for security in mimo wiretap channels with imperfect csi"
    - "secure transmission with multiple antennas ii the mimome wiretap channel"
    - "the secrecy capacity region of the gaussian mimo multi receiver wiretap channel"
    - "achieving near capacity at low snr on a multiple antenna multiple user channel"

Connected through hyperedge HE-2 (induced by source paper "secrecy energy efficiency optimization for miso and siso communication networks"):
  with members:
    - "energy efficient optimization for physical layer security in multi antenna downlink networks with qos guarantee"
    - "energy efficient precoding for multiple antenna terminals"

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)