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: "effect of receive spatial diversity on the degrees of freedom region in multi cell random beamforming"
  Abstract: The random beamforming (RBF) scheme, together with multi-user diversity based user scheduling, is able to achieve interference-free downlink transmission with only partial channel state information (CSI) at the transmitter. The impact of receive spatial diversity on RBF, however, is not fully characterized even under a single-cell setup. In this paper, we study a multi-cell multiple-input multiple-output (MIMO) broadcast system with RBF applied at each base station and either the minimum-meansquare-error (MMSE), matched filter (MF), or antenna selection (AS) based spatial receiver applied at each mobile terminal. We investigate the effect of different spatial diversity receivers on the achievable sum-rate of the multi-cell RBF system subject to both the intra- and inter-cell interferences. We focus on the high signal-to-noise ratio (SNR) regime and for a tractable analysis assume that the number of users in each cell scales in a certain order with the per-cell SNR. Under this setup, we characterize the degrees of freedom (DoF) region for the multi-cell RBF system, which constitutes all the achievable sum-rate DoF tuples of all the cells. Our results reveal significant sum-rate DoF gains with the MMSE-based spatial receiver as compared to the case without spatial diversity or with suboptimal spatial receivers (MF or AS). This observation is in sharp contrast to the existing result that spatial diversity only yields marginal sum-rate gains based on the conventional asymptotic analysis in the regime of large number of users but with fixed SNR per cell.

Connected through hyperedge HE-1 (induced by source paper "opportunistic downlink interference alignment for multi cell mimo networks"):
  with members:
    - "codebook based opportunistic interference alignment"
    - "opportunistic downlink interference alignment"
    - "on the achievable dof and user scaling law of opportunistic interference alignment in 3 transmitter mimo interference channels"
    - "parallel opportunistic routing in wireless networks"
    - "opportunistic interference alignment for mimo interfering multiple access channels"
    - "multiuser diversity in interfering broadcast channels achievable degrees of freedom and user scaling law"
    - "multi cell random beamforming achievable rate and degrees of freedom region"
    - "can one achieve multiuser diversity in uplink multi cell networks"

Connected through hyperedge HE-2 (induced by source paper "cell coverage extension with orthogonal random precoding for massive mimo systems"):
  with members:
    - "performance analysis of massive mimo for cell boundary users"
    - "spatially common sparsity based adaptive channel estimation and feedback for fdd massive mimo"
    - "distributed compressive csit estimation and feedback for fdd multi user massive mimo systems"
    - "downlink training techniques for fdd massive mimo systems open loop and closed loop training with memory"
    - "trellis extended codebooks and successive phase adjustment a path from lte advanced to fdd massive mimo systems"
    - "asymptotic coverage probability and rate in massive mimo networks"
    - "multi cell random beamforming achievable rate and degrees of freedom region"
    - "energy and spectral efficiency of very large multiuser mimo systems"

Connected through hyperedge HE-3 (induced by source paper "opportunistic downlink interference alignment"):
  with members:
    - "on the achievable dof and user scaling law of opportunistic interference alignment in 3 transmitter mimo interference channels"
    - "parallel opportunistic routing in wireless networks"
    - "opportunistic interference alignment for mimo interfering multiple access channels"
    - "multiuser diversity in interfering broadcast channels achievable degrees of freedom and user scaling law"
    - "multi cell random beamforming achievable rate and degrees of freedom region"
    - "can one achieve multiuser diversity in uplink multi cell networks"
    - "opportunistic interference mitigation achieves optimal degrees of freedom in wireless multi cell uplink networks"
    - "downlink interference alignment"

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)