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: "comparative study of qos parameters of sip protocol in 802 11a and 802 11b network"
  Abstract: Present day, the internet telephony growth is much faster than previous. Now we are familiar with digitized packet of voice stream. So, we have required VOIP communication. SIP is one type of VOIP protocol. This one has a SIP proxy. There have one of the important communication environment Wireless LAN (WLAN). WLAN have different radio link standard. Here I am comparing SIP protocol in two radio link standard 802.11a and 802.11b environment. The first one have maximum transmission rate of 54Mbps and second one have maximum transmission rate of 11Mbps. In this paper I want to show the results in a comparative plot. These comparisons include server /client throughput, packet drops, end to end delay etc.

Connected through hyperedge HE-1 (induced by source paper "an open source p2p encrypted voip application"):
  with members:
    - "proposed video encryption algorithm v s other existing algorithms a comparative study"
    - "new security and control protocol for voip based on steganography and digital watermarking"
    - "an analysis of the skype peer to peer internet telephony protocol"

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)