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: "proportional fair mu mimo in 802 11 wlans"
  Abstract: We consider the proportional fair rate allocation in an 802.11 WLAN that supports multi-user MIMO (MU-MIMO) transmission by one or more stations. We characterise, for the first time, the proportional fair allocation of MU-MIMO spatial streams and station transmission opportunities. While a number of features carry over from the case without MU-MIMO, in general neither flows nor stations need to be allocated equal airtime when MU-MIMO is available.

Connected through hyperedge HE-1 (induced by source paper "wireless optimisation via convex bandits unlicensed lte wifi coexistence"):
  with members:
    - "introduction to online convex optimization"
    - "distributed user association in energy harvesting small cell networks a probabilistic bandit model"
    - "fair coexistence of scheduled and random access wireless networks unlicensed lte wifi"
    - "multi armed bandits with application to 5g small cells"
    - "kernel based methods for bandit convex optimization"
    - "an optimal algorithm for bandit convex optimization"
    - "analysis and optimization of caching and multicasting in large scale cache enabled heterogeneous wireless networks"
    - "combinatorial bandits revisited"

Connected through hyperedge HE-2 (induced by source paper "improving dl mu mimo performance in ieee 802 11ac networks through decoupled scheduling"):
  with members:
    - "mu mimo mac protocols for wireless local area networks a survey"
    - "exploiting hybrid channel information for downlink multi user mimo scheduling"
    - "on the performance of packet aggregation in ieee 802 11ac mu mimo wlans"

Connected through hyperedge HE-3 (induced by source paper "utility fair rate allocation in lte 802 11 networks"):
  with members:
    - "an overview of load balancing in hetnets old myths and open problems"
    - "rigorous and practical proportional fair allocation for multi rate wi fi"
    - "log convexity of rate region in 802 11e wlans"
    - "user network association in a wlan umts hybrid cell global individual optimality"

Connected through hyperedge HE-4 (induced by source paper "mu mimo mac protocols for wireless local area networks a survey"):
  with members:
    - "uni mumac a unified down up link mu mimo mac protocol for ieee 802 11ac wlans"
    - "leader contention based user matching for 802 11 multiuser mimo networks"
    - "massive mimo for next generation wireless systems"
    - "evolution toward 5g multi tier cellular wireless networks an interference management perspective"
    - "design and characterization of a full duplex multiantenna system for wifi networks"
    - "managing heterogeneous wsns in smart cities challenges and requirements"
    - "on the performance of packet aggregation in ieee 802 11ac mu mimo wlans"
    - "pushing the limits of full duplex design and real time implementation"

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)