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: "design challenges of millimeter wave communications a mac layer perspective"
  Abstract: As the spectrum is becoming more scarce due to exponential demand of formidable data quantities, the new millimiterwave (mmW) band is considered as an enabling player of 5G communications to provide multi-gigabits wireless acccess. MmW communications exhibit high attenuation and blockage, directionality due to massive beamforming, deafness, low-interference, and may need micro waves networks for coordination and fallback support. The current mmW standardizations are challenged by the overwhelming complexity given by such heterogeneous communication systems and mmW band characteristics. This demands new substantial protocol developments at all layers. In this paper, the medium access control issues for mmW communications are reviewed. It is discussed that while existing standards address some of these issues for personal and local area networks, little has been done for cellular networks. It is argued that the medium access control layer should be equipped with adaptation mechanisms that are aware of the special mmW characteristics. Recommendations for mmW medium access control design in 5G are provided. It is concluded that the design of efficient access control techniques for mmW is in its infancy and much work still has to be done.

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)