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: "statistical beamforming on the grassmann manifold for the two user broadcast channel"
  Abstract: A Rayleigh fading spatially correlated broadcast setting with M = 2 antennas at the transmitter and two users (each with a single antenna) is considered. It is assumed that the users have perfect channel information about their links, whereas the transmitter has only statistical information of each user's link (covariance matrix of the vector channel). A low-complexity linear beamforming strategy that allocates equal power and one spatial eigenmode to each user is employed at the transmitter. Beamforming vectors on the Grassmann manifold that depend only on statistical information are to be designed at the transmitter to maximize the ergodic sum-rate delivered to the two users. Toward this goal, the beamforming vectors are first fixed and a closed-form expression is obtained for the ergodic sum-rate in terms of the covariance matrices of the links. This expression is nonconvex in the beamforming vectors ensuring that the classical Lagrange multiplier technique is not applicable. Despite this difficulty, the optimal solution to this problem is shown to be the same as the solution to the maximization of an appropriately defined average signal-to-interference and noise ratio metric for each user. This solution is the dominant generalized eigenvector of a pair of positive-definite matrices where the first matrix is the covariance matrix of the forward link and the second is an appropriately designed “effective” interference covariance matrix. In this sense, our work is a generalization of optimal signalling along the dominant eigenmode of the transmit covariance matrix in the single-user case. Finally, the ergodic sum-rate for the general broadcast setting with M antennas at the transmitter and M-users (each with a single antenna) is obtained in terms of the covariance matrices of the links and the beamforming vectors.

Connected through hyperedge HE-1 (induced by source paper "statistical beamforming for fdd downlink massive mimo via spatial information extraction and beam selection"):
  with members:
    - "semi blind channel and signal estimation for uplink massive mimo with channel sparsity"
    - "multi band covariance interpolation with applications in massive mimo"
    - "structured turbo compressed sensing for downlink massive mimo ofdm channel estimation"
    - "fdd massive mimo via ul dl channel covariance extrapolation and active channel sparsification"
    - "channel estimation for tdd fdd massive mimo systems with channel covariance computing"
    - "dictionary learning based sparse channel representation and estimation for fdd massive mimo systems"
    - "pilot reuse for massive mimo transmission over spatially correlated rayleigh fading channels"
    - "massive mimo for next generation wireless systems"

Connected through hyperedge HE-2 (induced by source paper "sum throughput maximization in multi tag backscattering to multiantenna reader"):
  with members:
    - "optimal channel estimation for reciprocity based backscattering with a full duplex mimo reader"
    - "cooperative ambient backscatter communications for green internet of things"
    - "fractional programming for communication systems part i power control and beamforming"
    - "retrodirective large antenna energy beamforming in backscatter multi user networks"
    - "transmit precoding and receive power splitting for harvested power maximization in mimo swipt systems"
    - "max min sinr in large scale single cell mu mimo asymptotic analysis and low complexity transceivers"
    - "inference from randomized transmissions by many backscatter sensors"
    - "throughput optimization for massive mimo systems powered by wireless energy transfer"

Connected through hyperedge HE-3 (induced by source paper "downlink precoding with mixed statistical and imperfect instantaneous csi for massive mimo systems"):
  with members:
    - "massive mimo with imperfect channel covariance information"
    - "a rate splitting strategy for massive mimo with imperfect csit"
    - "massive mimo ten myths and one critical question"
    - "two stage subspace constrained precoding in massive mimo cellular systems"
    - "power scaling of uplink massive mimo systems with arbitrary rank channel means"
    - "dealing with interference in distributed large scale mimo systems a statistical approach"
    - "pilot beam pattern design for channel estimation in massive mimo systems"
    - "two tier precoding for fdd multi cell massive mimo time varying interference networks"

Connected through hyperedge HE-4 (induced by source paper "channel reconstruction based hybrid precoding for millimeter wave multi user mimo systems"):
  with members:
    - "millimeter wave mimo prototype measurements and experimental results"
    - "common codebook millimeter wave beam design designing beams for both sounding and communication with uniform planar arrays"
    - "directional beamforming for millimeter wave mimo systems"
    - "investigation of prediction accuracy sensitivity and parameter stability of large scale propagation path loss models for 5g wireless communications"
    - "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"
    - "beamforming tradeoffs for initial ue discovery in millimeter wave mimo systems"
    - "limited feedback hybrid precoding for multi user millimeter wave systems"

Connected through hyperedge HE-5 (induced by source paper "throughput region of spatially correlated interference packet networks"):
  with members:
    - "linear degrees of freedom of mimo broadcast channels with reconfigurable antennas in the absence of csit"
    - "optimal sum dof of the k user miso bc with current and delayed feedback"
    - "optimal dof of the k user broadcast channel with delayed and imperfect current csit"
    - "when does spatial correlation add value to delayed channel state information"
    - "two user erasure interference channels with local delayed csit"
    - "transmit beamforming for miso broadcast channels with statistical and delayed csit"
    - "informational bottlenecks in two unicast wireless networks with delayed csit"
    - "secure degrees of freedom region of the two user miso broadcast channel with alternating csit"

Connected through hyperedge HE-6 (induced by source paper "multiuser millimeter wave beamforming strategies with quantized and statistical csit"):
  with members:
    - "sum rate maximization for linearly precoded downlink multiuser miso systems with partial csit a rate splitting approach"
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "achievable dof regions of mimo networks with imperfect csit"
    - "miso networks with imperfect csit a topological rate splitting approach"
    - "enhancing the estimation of mm wave large array channels by exploiting spatio temporal correlation and sparse scattering"
    - "hierarchical codebook design for beamforming training in millimeter wave communication"
    - "robust transmission in downlink multiuser miso systems a rate splitting approach"
    - "a rate splitting strategy for max min fair multigroup multicasting"

Connected through hyperedge HE-7 (induced by source paper "thresholds optimization for one bit feedback multi user scheduling"):
  with members:
    - "multiuser switched diversity scheduling schemes"

Connected through hyperedge HE-8 (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"

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)