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: "user scheduling for heterogeneous multiuser mimo systems a subspace viewpoint"
  Abstract: In downlink multiuser multiple-input multiple-output (MU-MIMO) systems, users are practically heterogeneous in nature. However, most of the existing user scheduling algorithms are designed with an implicit assumption that the users are homogeneous. In this paper, we revisit the problem by exploring the characteristics of heterogeneous users from a subspace point of view. With an objective of minimizing interference non-orthogonality among users, three new angular-based user scheduling criteria that can be applied in various user scheduling algorithms are proposed. While the first criterion is heuristically determined by identifying the incapability of largest principal angle to characterize the subspace correlation and hence the interference non-orthogonality between users, the second and third ones are derived by using, respectively, the sum rate capacity bounds with block diagonalization and the change in capacity by adding a new user into an existing user subset. Aiming at capturing fairness among heterogeneous users while maintaining multiuser diversity gain, two new hybrid user scheduling algorithms are also proposed whose computational complexities are only linearly proportional to the number of users. We show by simulations that the effectiveness of our proposed user scheduling criteria and algorithms with respect to those commonly used in homogeneous environment.

Connected through hyperedge HE-1 (induced by source paper "on the throughput of large but finite mimo networks using schedulers"):
  with members:
    - "tomlinson harashima precoding for multiuser mimo systems with quantized csi feedback and user scheduling"
    - "network mimo with linear zero forcing beamforming large system analysis impact of channel estimation and reduced complexity scheduling"
    - "multi user mimo scheduling in the fourth generation cellular uplink"
    - "multi cell mimo downlink with cell cooperation and fair scheduling a large system limit analysis"
    - "sum rates rate allocation and user scheduling for multi user mimo vector perturbation precoding"
    - "maximum sum rate of mimo multiuser scheduling with linear receivers"

Connected through hyperedge HE-2 (induced by source paper "an overview on resource allocation techniques for multi user mimo systems"):
  with members:
    - "low complexity downlink user selection for massive mimo systems"
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "user association in 5g networks a survey and an outlook"
    - "cell free massive mimo versus small cells"
    - "mu mimo mac protocols for wireless local area networks a survey"
    - "on the number of rf chains and phase shifters and scheduling design with hybrid analog digital beamforming"
    - "hybrid digital and analog beamforming design for large scale antenna arrays"

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)