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: "performance of orthogonal beamforming for sdma with limited feedback"
  Abstract: On the multi-antenna broadcast channel, the spatial degrees of freedom support simultaneous transmission to multiple users. The optimal multiuser transmission, known as dirty paper coding, is not directly realizable. Moreover, close-to-optimal solutions such as Tomlinson-Harashima precoding are sensitive to CSI inaccuracy. This paper considers a more practical design called per user unitary and rate control (PU2RC), which has been proposed for emerging cellular standards. PU2RC supports multiuser simultaneous transmission, enables limited feedback, and is capable of exploiting multiuser diversity. Its key feature is an orthogonal beamforming (or precoding) constraint, where each user selects a beamformer (or precoder) from a codebook of multiple orthonormal bases. In this paper, the asymptotic throughput scaling laws for PU2RC with a large user pool are derived for different regimes of the signal-to-noise ratio (SNR). In the multiuser-interference-limited regime, the throughput of PU2RC is shown to scale logarithmically with the number of users. In the normal SNR and noise-limited regimes, the throughput is found to scale double logarithmically with the number of users and also linearly with the number of antennas at the base station. In addition, numerical results show that PU2RC achieves higher throughput and is more robust against CSI quantization errors than the popular alternative of zero-forcing beamforming if the number of users is sufficiently large.

Connected through hyperedge HE-1 (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"

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"
    - "effect of receive spatial diversity on the degrees of freedom region in multi cell random beamforming"
    - "asymptotic coverage probability and rate in massive mimo networks"
    - "multi cell random beamforming achievable rate and degrees of freedom region"

Connected through hyperedge HE-3 (induced by source paper "recent advances in cloud radio access networks system architectures key techniques and open issues"):
  with members:
    - "fronthaul compression and precoding design for c rans over ergodic fading channels"
    - "optimal fronthaul quantization for cloud radio positioning"
    - "inter tier interference suppression in heterogeneous cloud radio access networks"
    - "contract based interference coordination in heterogeneous cloud radio access networks"
    - "are heterogeneous cloud based radio access networks cost effective"
    - "energy efficient resource assignment and power allocation in heterogeneous cloud radio access networks"
    - "cooperative interference mitigation and handover management for heterogeneous cloud small cell networks"
    - "fronthaul constrained cloud radio access networks insights and challenges"

Connected through hyperedge HE-4 (induced by source paper "rf lens embedded massive mimo systems fabrication issues and codebook design"):
  with members:
    - "performance analysis of massive mimo for cell boundary users"
    - "compressed channel feedback for correlated massive mimo systems"
    - "millimeter wave mimo with lens antenna array a new path division multiplexing paradigm"
    - "achievable rates of fdd massive mimo systems with spatial channel correlation"
    - "what will 5g be"
    - "downlink training techniques for fdd massive mimo systems open loop and closed loop training with memory"
    - "noncoherent trellis coded quantization a practical limited feedback technique for massive mimo systems"
    - "five disruptive technology directions for 5g"

Connected through hyperedge HE-5 (induced by source paper "antenna grouping based feedback compression for fdd based massive mimo systems"):
  with members:
    - "pilot beam pattern design for channel estimation in massive mimo systems"
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"
    - "statistical estimation of block sparse time varying signals from multiple measurement vectors"
    - "bounds on eigenvalues of a spatial correlation matrix"
    - "kronecker product correlation model and limited feedback codebook design in a 3d channel model"
    - "downlink training techniques for fdd massive mimo systems open loop and closed loop training with memory"
    - "noncoherent trellis coded quantization a practical limited feedback technique for massive mimo systems"
    - "effects of channel aging in massive mimo systems"

Connected through hyperedge HE-6 (induced by source paper "unified performance analysis of orthogonal transmit beamforming methods with user selection"):
  with members:
    - "performance analysis of optimum zero forcing beamforming with greedy user selection"

Connected through hyperedge HE-7 (induced by source paper "multi user diversity vs accurate channel state information in mimo downlink channels"):
  with members:
    - "capacity of a multiple antenna fading channel with a quantized precoding matrix"
    - "antenna combining for the mimo downlink channel"
    - "space division multiple access with a sum feedback rate constraint"
    - "multiuser mimo achievable rates with downlink training and channel state feedback"
    - "mimo broadcast channels with finite rate feedback"
    - "on the capacity of fading mimo broadcast channels with imperfect transmitter side information"
    - "on the user selection for mimo broadcast channels"

Connected through hyperedge HE-8 (induced by source paper "random beamforming over quasi static and fading channels a deterministic equivalent approach"):
  with members:
    - "large system analysis of linear precoding in correlated miso broadcast channels under limited feedback"
    - "free deterministic equivalents rectangular random matrix models and operator valued free probability theory"
    - "asymptotic moments for interference mitigation in correlated fading channels"
    - "a deterministic equivalent for the analysis of correlated mimo multiple access channels"
    - "eigenvalue distributions of sums and products of large random matrices via incremental matrix expansions"

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)