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: "limited feedback based block diagonalization for the mimo broadcast channel"
  Abstract: Block diagonalization is a linear preceding technique for the multiple antenna broadcast (downlink) channel that involves transmission of multiple data streams to each receiver such that no multi-user interference is experienced at any of the receivers. This low-complexity scheme operates only a few dB away from capacity but requires very accurate channel knowledge at the transmitter. We consider a limited feedback system where each receiver knows its channel perfectly, but the transmitter is only provided with a finite number of channel feedback bits from each receiver. Using a random quantization argument, we quantify the throughput loss due to imperfect channel knowledge as a function of the feedback level. The quality of channel knowledge must improve proportional to the SNR in order to prevent interference-limitations, and we show that scaling the number of feedback bits linearly with the system SNR is sufficient to maintain a bounded rate loss. Finally, we compare our quantization strategy to an analog feedback scheme and show the superiority of quantized feedback.

Connected through hyperedge HE-1 (induced by source paper "mimo amplify and forward precoding for networked control systems"):
  with members:
    - "optimal control strategies in delayed sharing information structures"
    - "delay optimal power and subcarrier allocation for ofdma systems via stochastic approximation"
    - "pilot contamination and precoding in multi cell tdd systems"
    - "on the capacity and design of limited feedback multiuser mimo uplinks"

Connected through hyperedge HE-2 (induced by source paper "group sparse precoding for cloud ran with multiple user antennas"):
  with members:
    - "joint precoding and rrh selection for user centric green mimo c ran"
    - "energy efficiency of downlink transmission strategies for cloud radio access networks"
    - "a survey of sparse representation algorithms and applications"
    - "robust group sparse beamforming for multicast green cloud ran with imperfect csi"
    - "large scale convex optimization for ultra dense cloud ran"
    - "a comparative study of downlink mimo cellular networks with co located and distributed base station antennas"
    - "sparse beamforming and user centric clustering for downlink cloud radio access network"
    - "group sparse beamforming for green cloud ran"

Connected through hyperedge HE-3 (induced by source paper "symbol level and multicast precoding for multiuser multiantenna downlink a survey classification and challenges"):
  with members:
    - "channel estimation and performance analysis of one bit massive mimo systems"
    - "an overview on resource allocation techniques for multi user mimo systems"
    - "spatio temporal waveform design for multiuser massive mimo downlink with 1 bit receivers"
    - "joint beamforming and broadcasting in massive mimo"
    - "coordinate update algorithms for robust power loading for the mu miso downlink with outage constraints"
    - "energy efficient symbol level precoding in multiuser miso based on relaxed detection region"
    - "robust transmission in downlink multiuser miso systems a rate splitting approach"
    - "adaptive pilot clustering in heterogeneous massive mimo networks"

Connected through hyperedge HE-4 (induced by source paper "device to device cooperation in massive mimo systems with cascaded precoding"):
  with members:
    - "user cooperation in wireless powered communication networks"
    - "scaling up mimo opportunities and challenges with very large arrays"

Connected through hyperedge HE-5 (induced by source paper "uplink downlink rate balancing in cooperating cellular networks"):
  with members:
    - "a lower bound on the data rate of dirty paper coding in general noise and interference"
    - "a coordinated approach to channel estimation in large scale multiple antenna systems"
    - "fundamental limits of cooperation"
    - "large system analysis of linear precoding in correlated miso broadcast channels under limited feedback"
    - "multi user diversity vs accurate channel state information in mimo downlink channels"
    - "massive mimo how many antennas do we need"
    - "bounds on the capacity of ofdm underspread frequency selective fading channels"
    - "completely stale transmitter channel state information is still very useful"

Connected through hyperedge HE-6 (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-7 (induced by source paper "grouping based interference alignment with ia cell assignment in multi cell mimo mac under limited feedback"):
  with members:
    - "user selection in mimo interfering broadcast channels"
    - "what will 5g be"
    - "limited feedback design for interference alignment on mimo interference networks with heterogeneous path loss and spatial correlations"
    - "interference alignment with quantized grassmannian feedback in the k user constant mimo interference channel"
    - "low complexity sum rate maximization for single and multiple stream mimo af relay networks"
    - "spatial degrees of freedom of the multicell mimo multiple access channel"
    - "on feasibility of interference alignment in mimo interference networks"
    - "downlink interference alignment"

Connected through hyperedge HE-8 (induced by source paper "guaranteeing positive secrecy capacity with finite rate feedback using artificial noise"):
  with members:
    - "artificial noise revisited"
    - "capacity of a multiple antenna fading channel with a quantized precoding matrix"
    - "the secrecy capacity of the mimo wiretap channel"
    - "quantization bounds on grassmann manifolds and applications to mimo communications"

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)