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: "architectures and key technical challenges for 5g systems incorporating satellites"
  Abstract: Satellite Communication systems are a promising solution to extend and complement terrestrial networks in unserved or under-served areas. This aspect is reflected by recent commercial and standardisation endeavours. In particular, 3GPP recently initiated a Study Item for New Radio-based, i.e., 5G, Non-Terrestrial Networks aimed at deploying satellite systems either as a stand-alone solution or as an integration to terrestrial networks in mobile broadband and machine-type communication scenarios. However, typical satellite channel impairments, as large path losses, delays, and Doppler shifts, pose severe challenges to the realisation of a satellite-based NR network. In this paper, based on the architecture options currently being discussed in the standardisation fora, we discuss and assess the impact of the satellite channel characteristics on the physical and Medium Access Control layers, both in terms of transmitted waveforms and procedures for enhanced Mobile BroadBand (eMBB) and NarrowBand-Internet of Things (NB-IoT) applications. The proposed analysis shows that the main technical challenges are related to the PHY/MAC procedures, in particular Random Access (RA), Timing Advance (TA), and Hybrid Automatic Repeat reQuest (HARQ) and, depending on the considered service and architecture, different solutions are proposed.

Connected through hyperedge HE-1 (induced by source paper "massive mimo transmission for leo satellite communications"):
  with members:
    - "fdd massive mimo via ul dl channel covariance extrapolation and active channel sparsification"
    - "channel acquisition for massive mimo ofdm with adjustable phase shift pilots"
    - "pilot reuse for massive mimo transmission over spatially correlated rayleigh fading channels"
    - "statistical eigenmode transmission over jointly correlated mimo channels"

Connected through hyperedge HE-2 (induced by source paper "leo small satellite constellations for 5g and beyond 5g communications"):
  with members:
    - "integration of satellites in 5g through leo constellations"
    - "optical communication in space challenges and mitigation techniques"
    - "survey of inter satellite communication for small satellite systems physical layer to network layer view"

Connected through hyperedge HE-3 (induced by source paper "on the impact of satellite communications over mobile networks an experimental analysis"):
  with members:
    - "beam tracking for uav mounted satcom on the move with massive antenna array"
    - "lte based satellite communications in leo mega constellations"
    - "big data caching for networking moving from cloud to edge"

Connected through hyperedge HE-4 (induced by source paper "5g new radio evolution meets satellite communications opportunities challenges and solutions"):
  with members:
    - "precoding in multigateway multibeam satellite systems"

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)