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: "d2d communications underlaying wireless powered communication networks"
  Abstract: In this paper, we investigate the resource allocation problem for D2D communications underlaying wireless powered communication networks, where multiple D2D pairs harvest energy from a power station equipped with multiple antennas and then transmit information signals simultaneously over the same spectrum resource. The aim is to maximize the sum throughput via joint time scheduling and power control, while satisfying the energy causality constraints. The formulated non-convex problem is first transformed into a nonlinear fractional programming problem with a tactful reformulation. Then, by leveraging D.C. (difference of two convex functions) programming, a suboptimal solution to the non-convex problem is obtained by iteratively solving a sequence of convex problems. Simulation results demonstrate that the proposed scheme works well in different scenarios and can significantly improve the system throughput compared with the-state-of-the-art schemes.

Connected through hyperedge HE-1 (induced by source paper "analysis of d2d communication with rf energy harvesting and interference management"):
  with members:
    - "energy harvesting wireless communications a review of recent advances"
    - "d2d enhanced heterogeneous cellular networks with dynamic tdd"
    - "wireless networks with rf energy harvesting a contemporary survey"
    - "cognitive and energy harvesting based d2d communication in cellular networks stochastic geometry modeling and analysis"
    - "spatial throughput of mobile ad hoc networks powered by energy harvesting"
    - "five disruptive technology directions for 5g"
    - "opportunistic wireless energy harvesting in cognitive radio networks"
    - "power control for d2d underlaid cellular networks modeling algorithms and analysis"

Connected through hyperedge HE-2 (induced by source paper "secrecy energy efficiency optimization for artificial noise aided physical layer security in ofdm based cognitive radio networks"):
  with members:
    - "power constrained secrecy rate maximization for joint relay and jammer selection assisted wireless networks"
    - "cognitive network cooperation for green cellular networks"
    - "security of rechargeable energy harvesting transmitters in wireless networks"
    - "linear precoding of data and artificial noise in secure massive mimo systems"
    - "artificial noise aided secure transmission in wiretap channels with transmitter side correlation"
    - "a survey on wireless security technical challenges recent advances and future trends"
    - "principles of physical layer security in multiuser wireless networks a survey"
    - "cooperative jamming for secure communications in mimo relay networks"

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)