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: "green cognitive relaying opportunistically switching between data transmission and energy harvesting"
  Abstract: Energy efficiency has become an encouragement, and more than this, a requisite for the design of next-generation wireless communications standards. In current work, a dual-hop cognitive (secondary) relaying system is considered, incorporating multiple amplify-and-forward relays, a rather cost-effective solution. First, the secondary relays sense the wireless channel, scanning for a primary network activity, and then convey their reports to a secondary base station (SBS). Afterwards, the SBS, based on these reports and its own estimation, decides cooperatively the presence of primary transmission or not. In the former scenario, all the secondary nodes start to harvest energy from the transmission of primary node(s). In the latter scenario, the system initiates secondary communication via a best relay selection policy. Performance evaluation of this system is thoroughly investigated, by assuming realistic channel conditions, i.e., non-identical link-distances, Rayleigh fading, and outdated channel estimation. The detection and outage probabilities as well as the average harvested energy are derived as new closed-form expressions. In addition, an energy efficiency optimization problem is analytically formulated and solved, while a necessary condition in terms of power consumption minimization for each secondary node is presented. From a green communications standpoint, it turns out that energy harvesting greatly enhances the resources of secondary nodes, especially when primary activity is densely present.

Connected through hyperedge HE-1 (induced by source paper "opportunistic ambient backscatter communication in rf powered cognitive radio networks"):
  with members:
    - "pixelated vlc backscattering for self charging indoor iot devices"
    - "wirelessly powered backscatter communications waveform design and snr energy tradeoff"
    - "ambient backscatter communications a contemporary survey"
    - "energy efficient resource allocation for wireless powered communication networks"
    - "wireless networks with rf energy harvesting a contemporary survey"

Connected through hyperedge HE-2 (induced by source paper "a new interweave cognitive radio scheme for out band energy harvesting systems"):
  with members:
    - "distributed wireless power transfer with energy feedback"
    - "a tractable product channel model for line of sight scenarios"
    - "the kappa mu shadowed fading model with integer fading parameters"
    - "massive machine type communications in 5g physical and mac layer solutions"
    - "on the efficiency of far field wireless power transfer"
    - "on green energy powered cognitive radio networks"
    - "spatial throughput of mobile ad hoc networks powered by energy harvesting"
    - "throughput maximization in wireless powered communication networks"

Connected through hyperedge HE-3 (induced by source paper "optimal power allocation and active interference mitigation for spatial multiplexed mimo cognitive systems"):
  with members:
    - "optimal power control in cognitive mimo systems with limited feedback"
    - "massive mimo for next generation wireless systems"
    - "on peak versus average interference power constraints for protecting primary users in cognitive radio networks"
    - "femtocell networks a survey"

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)