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: "mode switching for the multi antenna broadcast channel based on delay and channel quantization"
  Abstract: Imperfect channel state information degrades the performance of multiple-input multiple-output (MIMO) communications; its effects on single-user (SU) and multiuser (MU) MIMO transmissions are quite different. In particular, MU-MIMO suffers from residual interuser interference due to imperfect channel state information while SU-MIMO only suffers from a power loss. This paper compares the throughput loss of both SU and MU-MIMO in the broadcast channel due to delay and channel quantization. Accurate closed-form approximations are derived for achievable rates for both SU and MU-MIMO. It is shown that SU-MIMO is relatively robust to delayed and quantized channel information, while MU-MIMO with zero-forcing precoding loses its spatial multiplexing gain with a fixed delay or fixed codebook size. Based on derived achievable rates, a mode switching algorithm is proposed, which switches between SU and MU-MIMO modes to improve the spectral efficiency based on average signal-to-noise ratio (SNR), normalized Doppler frequency, and the channel quantization codebook size. The operating regions for SU and MU modes with different delays and codebook sizes are determined, and they can be used to select the preferred mode. It is shown that the MU mode is active only when the normalized Doppler frequency is very small, and the codebook size is large.

Connected through hyperedge HE-1 (induced by source paper "delay performance of the multiuser miso downlink under imperfect csi and finite length coding"):
  with members:
    - "delay performance of multi antenna multicasting in wireless networks"
    - "delay performance of the multiuser miso downlink"
    - "delay performance of miso wireless communications"
    - "analysis of wireless communications with finite blocklength and imperfect channel knowledge"
    - "the dispersion of nearest neighbor decoding for additive non gaussian channels"
    - "optimal design of energy efficient multi user mimo systems is massive mimo the answer"
    - "effects of channel aging in massive mimo systems"
    - "multi user diversity vs accurate channel state information in mimo downlink channels"

Connected through hyperedge HE-2 (induced by source paper "spatial resource allocation for spectrum reuse in unlicensed lte systems"):
  with members:
    - "embedding lte u within wi fi bands for spectrum efficiency improvement"
    - "mimo broadcast channels with finite rate feedback"

Connected through hyperedge HE-3 (induced by source paper "robust group sparse beamforming for multicast green cloud ran with imperfect csi"):
  with members:
    - "large scale convex optimization for dense wireless cooperative networks"
    - "large scale convex optimization for ultra dense cloud ran"
    - "scalable coordinated beamforming for dense wireless cooperative networks"
    - "what will 5g be"
    - "group sparse beamforming for green cloud ran"
    - "joint precoding and multivariate backhaul compression for the downlink of cloud radio access networks"
    - "optimal stochastic coordinated beamforming for wireless cooperative networks with csi uncertainty"
    - "distributed robust multicell coordinated beamforming with imperfect csi an admm approach"

Connected through hyperedge HE-4 (induced by source paper "secure transmission in multi cell massive mimo systems"):
  with members:
    - "principles of physical layer security in multiuser wireless networks a survey"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "secrecy sum rates for multi user mimo regularized channel inversion precoding"
    - "energy and spectral efficiency of very large multiuser mimo systems"
    - "robust beamforming for security in mimo wiretap channels with imperfect csi"
    - "secure transmission with artificial noise over fading channels achievable rate and optimal power allocation"
    - "secure transmission with multiple antennas ii the mimome wiretap channel"
    - "the secrecy capacity region of the gaussian mimo multi receiver wiretap channel"

Connected through hyperedge HE-5 (induced by source paper "optimal stochastic coordinated beamforming for wireless cooperative networks with csi uncertainty"):
  with members:
    - "topological interference management through index coding"
    - "group sparse beamforming for green cloud ran"
    - "low complexity delay constrained beamforming for multi user mimo systems with imperfect csit"
    - "network mimo with linear zero forcing beamforming large system analysis impact of channel estimation and reduced complexity scheduling"
    - "fundamental limits of cooperation"
    - "robust monotonic optimization framework for multicell miso systems"
    - "mimo interference alignment over correlated channels with imperfect csi"
    - "completely stale transmitter channel state information is still very useful"

Connected through hyperedge HE-6 (induced by source paper "optimal feedback rate sharing strategy in zero forcing mimo broadcast channels"):
  with members:
    - "an analytical framework for heterogeneous partial feedback design in heterogeneous multicell ofdma networks"
    - "random beamforming with heterogeneous users and selective feedback individual sum rate and individual scaling laws"
    - "multi user diversity vs accurate channel state information in mimo downlink channels"
    - "stochastic control of event driven feedback in multiantenna interference channels"
    - "a scalable limited feedback design for network mimo using per cell product codebook"
    - "adaptive limited feedback for sum rate maximizing beamforming in cooperative multicell systems"
    - "limited feedback based block diagonalization for the mimo broadcast channel"
    - "antenna combining for the mimo downlink channel"

Connected through hyperedge HE-7 (induced by source paper "effects of channel aging in massive mimo systems"):
  with members:
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "massive mimo how many antennas do we need"
    - "multi user mimo with outdated csi training feedback and scheduling"
    - "pilot contamination and precoding in multi cell tdd systems"
    - "multiuser mimo achievable rates with downlink training and channel state feedback"

Connected through hyperedge HE-8 (induced by source paper "learning based adaptive transmission for limited feedback multiuser mimo ofdm"):
  with members:
    - "mimo broadcast channels with finite rate feedback"

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)