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: "secure communication through wireless powered friendly jamming jointly online optimization over geography energy and time"
  Abstract: Exploring the interference-emitting friendly jammers to protect the sensitive communications in the presence of eavesdroppers has increasingly being investigated in literature. In parallel, scavenging energy from abient radio signals for energy-constrained devices, namely wireless energy harvesting (WEH), has also drawn significant attention. Without relying on external energy supply, the wireless-powered friendly jammer by WEH from legitimate wireless devices is an effective approach to prolong their lifetime and gain the flexibility in deployments. This paper studies the online optimization of the placement and WEH of a set of friendly jammers in a geographic location with the energy-efficiency (EE) consideration. We adopt a simple “time switching” protocol where power transfer and jammerassisted secure communications occur in different time blocks when WEH requests are launched. Our scheme has the following important advantages: 1) The proposed online jammers placement and interfering power allocation to attack eavesdroppers is the first distributed and scalable solutions within any specified geographic region; 2) We model the WEH for jammers as a JAM-NET lifetime maximization problem, where online scheduling algorithms with heterogeneous energy demands of each jammer (from energy sources) are designed; 3) Under our model, the problem of placing a minimum number of jammers with distancebased power assignments is NP-hard, and near optimal PTAS approximation algorithms are provided; 4) When durations of the eavesdropping and legitimate communicating are available and the scenario is extended to the multi-channels setting, our results are strengthened to see further improved EE and reduced number of jammers. Simulations back up our theory.

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.CR(Cryptography and Security)