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: "secrecy wireless information and power transfer in ofdma systems"
  Abstract: In this paper, we consider simultaneous wireless information and power transfer (SWIPT) in orthogonal frequency division multiple access (OFDMA) systems with the coexistence of information receivers (IRs) and energy receivers (ERs). The IRs are served with best-effort secrecy data and the ERs harvest energy with minimum required harvested power. To enhance physical-layer security and yet satisfy energy harvesting requirements, we introduce a new frequency-domain artificial noise based approach. We study the optimal resource allocation for the weighted sum secrecy rate maximization via transmit power and subcarrier allocation. The considered problem is non-convex, while we propose an efficient algorithm for solving it based on Lagrange duality method. Simulation results illustrate the effectiveness of the proposed algorithm as compared against other heuristic schemes.

Connected through hyperedge HE-1 (induced by source paper "information and energy cooperation in ofdm relaying protocols and optimization"):
  with members:
    - "wireless information and energy transfer for two hop non regenerative mimo ofdm relay networks"
    - "secure and green swipt in distributed antenna networks with limited backhaul capacity"
    - "power allocation strategies in energy harvesting wireless cooperative networks"
    - "wireless information and power transfer with full duplex relaying"
    - "energy cooperation in energy harvesting communications"
    - "simultaneous information and power transfer for broadband wireless systems"
    - "wireless information and power transfer in multiuser ofdm systems"
    - "wireless information and power transfer energy efficiency optimization in ofdma systems"

Connected through hyperedge HE-2 (induced by source paper "joint secure beamforming for cognitive radio networks with untrusted secondary users"):
  with members:
    - "energy harvesting for physical layer security in ofdma networks"
    - "secure beamforming for mimo two way communications with an untrusted relay"
    - "spectrum leasing via cooperation for enhanced physical layer secrecy"
    - "discrete memoryless interference and broadcast channels with confidential messages secrecy rate regions"

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)