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: "managing smartphones signalling load in umts networks a practical analysis"
  Abstract: Smartphone users and application behaviors add high pressure to apply smart techniques that stabilize the network capacity and consequently improve the end-user experience. The massive increase in smartphone penetration engenders signalling load, which exceeds the network capacity in terms of signaling. The signalling load leads to network congestion, degradation in the network KPIs. The classical way to tackle the signalling is by network expansion. However, this approach is not efficient in terms of capital expenditure (CAPEX) and also in terms of efficient utilization of the network resources. More specifically, the signaling domain becomes overloaded while the data domain are underutilized. In this paper, two UMTS air-interface features; Cell-PCH (paging channel) and enhanced fast dormancy (E-FD) are analyzed to mitigate the signalling load. Practical performance analysis is conducted based on results from commercial UMTS networks. The deployment of these features offers major improvement in network KPIs and significant relief in the signaling load. It is concluded that these two features in addition to several optimization techniques, discussed in this paper, provide solution to the smartphone signaling load and efficiently utilize the available network and spectrum resources while providing users with better always-on connectivity and improved battery consumption.

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.NI(Networking and Internet Architecture)