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: "joint spatial division and multiplexing opportunistic beamforming and user grouping"
  Abstract: Joint Spatial Division and Multiplexing (JSDM) is a recently proposed scheme to enable massive MIMO like gains and simplified system operations for Frequency Division Duplexing (FDD) systems. The key idea lies in partitioning the users into groups with approximately similar covariances, and use a two stage downlink beamforming: a pre-beamformer that depends on the channel covariances and minimizes interference across groups and a multiuser MIMO precoder for the effective channel after pre-beamforming, to counteract interference within a group. We first focus on the regime of a fixed number of antennas and large number of users, and show that opportunistic beamforming with user selection yields significant gain, and thus, channel correlation may yield a capacity improvement over the uncorrelated "isotropic" channel result of Sharif and Hassibi. We prove that in the presence of different correlations among groups, a block diagonalization approach for the design of pre-beamformers achieves the optimal sum-rate scaling. Next, we consider the regime of large number of antennas and users, where user selection does not provide significant gain. Here, we propose a simplified user grouping algorithm to cluster users into groups when the number of antennas becomes very large, in a realistic setting where users are randomly distributed and have different angles of arrival and angular spreads depending on the propagation environment. Our subsequent analysis leads to a probabilistic scheduling algorithm, where users within each group are preselected at random based on probabilities derived from the large system analysis, depending on the fairness criterion. This is advantageous since only the selected users are required to feedback their channel state information (CSIT).

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 "user association in massive mimo hetnets"):
  with members:
    - "massive mimo for next generation wireless systems"
    - "what will 5g be"
    - "massive mimo and small cells improving energy efficiency by optimal soft cell coordination"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "downlink multi antenna heterogeneous cellular network with load balancing"
    - "user association for load balancing in heterogeneous cellular networks"

Connected through hyperedge HE-3 (induced by source paper "robust pilot decontamination based on joint angle and power domain discrimination"):
  with members:
    - "pilot decontamination through pilot sequence hopping in massive mimo systems"
    - "fractional pilot reuse in massive mimo systems"
    - "dealing with interference in distributed large scale mimo systems a statistical approach"
    - "blind pilot decontamination"
    - "interference reduction in multi cell massive mimo systems i large scale fading precoding and decoding"
    - "a coordinated approach to channel estimation in large scale multiple antenna systems"
    - "large system analysis of linear precoding in correlated miso broadcast channels under limited feedback"
    - "energy and spectral efficiency of very large multiuser mimo systems"

Connected through hyperedge HE-4 (induced by source paper "directional training and fast sector based processing schemes for mmwave channels"):
  with members:
    - "a novel alternative to cloud ran for throughput densification coded pilots and fast user packet scheduling at remote radio heads"
    - "on the performance of cell free massive mimo with short term power constraints"
    - "rrh based massive mimo with on the fly pilot contamination control"
    - "compressed sensing based pilot assignment and reuse for mobile ues in mmwave cellular systems"
    - "3 d statistical channel model for millimeter wave outdoor mobile broadband communications"
    - "scalable synchronization and reciprocity calibration for distributed multiuser mimo"
    - "joint spatial division and multiplexing for mm wave channels"
    - "multiuser mimo achievable rates with downlink training and channel state feedback"

Connected through hyperedge HE-5 (induced by source paper "achievable rates of fdd massive mimo systems with spatial channel correlation"):
  with members:
    - "fundamental limits in correlated fading mimo broadcast channels benefits of transmit correlation diversity"
    - "massive mimo systems with non ideal hardware energy efficiency estimation and capacity limits"
    - "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"
    - "blind pilot decontamination"
    - "aligned image sets under channel uncertainty settling a conjecture by lapidoth shamai and wigger on the collapse of degrees of freedom under finite precision csit"
    - "trellis extended codebooks and successive phase adjustment a path from lte advanced to fdd massive mimo systems"
    - "noncoherent trellis coded quantization a practical limited feedback technique for massive mimo systems"

Connected through hyperedge HE-6 (induced by source paper "training sequence design for feedback assisted hybrid beamforming in massive mimo systems"):
  with members:
    - "pilot signal design for massive mimo systems a received signal to noise ratio based approach"
    - "pilot beam pattern design for channel estimation in massive mimo systems"
    - "distributed compressive csit estimation and feedback for fdd multi user massive mimo systems"
    - "a new approach to user scheduling in massive multi user mimo broadcast channels"
    - "downlink training techniques for fdd massive mimo systems open loop and closed loop training with memory"
    - "spatially sparse precoding in millimeter wave mimo systems"
    - "noncoherent trellis coded quantization a practical limited feedback technique for massive mimo systems"
    - "scaling up mimo opportunities and challenges with very large arrays"

Connected through hyperedge HE-7 (induced by source paper "a new approach to user scheduling in massive multi user mimo broadcast channels"):
  with members:
    - "an overview on resource allocation techniques for multi user mimo systems"
    - "on the role of transmit correlation diversity in multiuser mimo systems"
    - "two stage beamformer design for massive mimo downlink by trace quotient formulation"
    - "pilot beam pattern design for channel estimation in massive mimo systems"
    - "two tier precoding for fdd multi cell massive mimo time varying interference networks"
    - "downlink training techniques for fdd massive mimo systems open loop and closed loop training with memory"
    - "random beamforming with heterogeneous users and selective feedback individual sum rate and individual scaling laws"

Connected through hyperedge HE-8 (induced by source paper "two tier precoding for fdd multi cell massive mimo time varying interference networks"):
  with members:
    - "convergence analysis of mixed timescale cross layer stochastic optimization"
    - "convergence analysis of saddle point problems in time varying wireless systems control theoretical approach"
    - "approaching the capacity of wireless networks through distributed 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)