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: "spectral and energy efficiency of multi pair massive mimo relay network with hybrid processing"
  Abstract: We consider a multi-pair massive multiple-input multiple-output (MIMO) relay network, where the relay is equipped with a large number, N, of antennas, but driven by a far smaller number, L, of radio frequency (RF) chains. We assume that K pairs of users are scheduled for simultaneous transmission, where K satisfies 2K = L. A hybrid signal processing scheme is presented for both uplink and downlink transmissions of the network. Analytical expressions of both spectral and energy efficiency are derived with respect to the RF chain number under imperfect channel estimation. It is revealed that, under the condition N > 4L^2/pi, the transmit power of each user and the relay can be respectively scaled down by 1=sqrt(N) and 2K=sqrt(N) if pilot power scales with signal power, or they can be respectively scaled down by 1=N and 2K=N if the pilot power is kept fixed, while maintaining an asymptotically unchanged spectral efficiency (SE). While regarding energy efficiency (EE) of the network, the optimal EE is shown to be achieved when Pr = 2KPs, where Pr and Ps respectively refer to the transmit power of the relay and each source terminal. We show that the network EE is a quasi-concave function with respect to the number of RF-chains which, therefore, admits a unique globally optimal choice of the RF-chain number. Numerical simulations are conducted to verify our observations.

Connected through hyperedge HE-1 (induced by source paper "secure massive mimo communication with low resolution dacs"):
  with members:
    - "optimal multiuser loading in quantized massive mimo under spatially correlated channels"
    - "mimo channel information feedback using deep recurrent network"
    - "quantized constant envelope precoding with psk and qam signaling"
    - "on performance of quantized transceiver in multiuser massive mimo downlinks"
    - "power efficient and secure wpcns with hardware impairments and non linear eh circuit"
    - "a tractable framework for performance analysis of dense multi antenna networks"
    - "analysis of one bit quantized precoding for the multiuser massive mimo downlink"
    - "analysis and design of secure massive mimo systems in the presence of hardware impairments"

Connected through hyperedge HE-2 (induced by source paper "hybrid transceiver optimization for multi hop communications"):
  with members:
    - "hybrid beamforming for millimeter wave systems using the mmse criterion"
    - "majorization minimization aided hybrid transceivers for mimo interference channels"
    - "hybrid precoding architecture for massive multiuser mimo with dissipation sub connected or fully connected structures"
    - "hybrid beamforming with selection for multiuser massive mimo systems"
    - "spectral efficiency optimization for millimeter wave multiuser mimo systems"
    - "multi user precoding and channel estimation for hybrid millimeter wave systems"
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "on weighted mse model for mimo transceiver optimization"

Connected through hyperedge HE-3 (induced by source paper "non uniform quantization codebook based hybrid precoding to reduce feedback overhead in millimeter wave mimo systems"):
  with members:
    - "downlink precoding with mixed statistical and imperfect instantaneous csi for massive mimo systems"
    - "channel feedback based on aod adaptive subspace codebook in fdd massive mimo systems"
    - "pilot power allocation through user grouping in multi cell massive mimo systems"
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "structured compressive sensing based spatio temporal joint channel estimation for fdd massive mimo"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "dynamic subarrays for hybrid precoding in wideband mmwave mimo systems"
    - "mixed adc massive mimo detectors performance analysis and design optimization"

Connected through hyperedge HE-4 (induced by source paper "a framework on hybrid mimo transceiver design based on matrix monotonic optimization"):
  with members:
    - "hybrid beamforming via the kronecker decomposition for the millimeter wave massive mimo systems"
    - "a new view of multi user hybrid massive mimo non orthogonal angle division multiple access"
    - "hybrid analog digital beamforming for massive mimo systems"
    - "hybrid analog and digital beamforming for mmwave ofdm large scale antenna arrays"
    - "codebook based hybrid precoding for millimeter wave multiuser systems"
    - "a novel hybrid beamforming algorithm with unified analog beamforming by subspace construction based on partial csi for massive mimo ofdm systems"
    - "hybrid beamforming for large antenna arrays with phase shifter selection"
    - "hybrid digital and analog beamforming design for large scale antenna arrays"

Connected through hyperedge HE-5 (induced by source paper "rethinking uplink hybrid processing when is pure analog processing suggested"):
  with members:
    - "massive mimo relaying with hybrid processing"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"
    - "spatially sparse precoding in millimeter wave mimo systems"
    - "low complexity hybrid precoding in massive multiuser mimo systems"
    - "scaling up mimo opportunities and challenges with very large arrays"

Connected through hyperedge HE-6 (induced by source paper "hybrid precoding architecture for massive multiuser mimo with dissipation sub connected or fully connected structures"):
  with members:
    - "on performance of quantized transceiver in multiuser massive mimo downlinks"
    - "multiuser millimeter wave beamforming strategies with quantized and statistical csit"
    - "two dimensional aod and aoa acquisition for wideband millimeter wave systems with dual polarized mimo"
    - "hybrid analog digital precoding revisited under realistic rf modeling"
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "linear precoding of data and artificial noise in secure massive mimo systems"
    - "on the number of rf chains and phase shifters and scheduling design with hybrid analog digital beamforming"

Connected through hyperedge HE-7 (induced by source paper "performance analysis of multi cell millimeter wave massive mimo networks with low precision adcs"):
  with members:
    - "on low resolution adcs in practical 5g millimeter wave massive mimo systems"
    - "a hardware efficient analog network structure for hybrid precoding in millimeter wave systems"
    - "a comparison of hybrid beamforming and digital beamforming with low resolution adcs for multiple users and imperfect csi"
    - "secure massive mimo systems with limited rf chains"
    - "on performance of quantized transceiver in multiuser massive mimo downlinks"
    - "throughput analysis of massive mimo uplink with low resolution adcs"
    - "base station selection for massive mimo networks with two stage precoding"
    - "frequency synchronization for uplink massive mimo systems"

Connected through hyperedge HE-8 (induced by source paper "hybrid processing design for multipair massive mimo relaying with channel spatial correlation"):
  with members:
    - "secure massive mimo systems with limited rf chains"
    - "framework of channel estimation for hybrid analog and digital processing enabled massive mimo communications"
    - "massive mimo with imperfect channel covariance information"
    - "hybrid digital and analog beamforming design for large scale antenna arrays"
    - "channel covariance estimation in massive mimo frequency division duplex systems"
    - "hybrid beamforming for massive mimo a survey"
    - "hybrid mimo architectures for millimeter wave communications phase shifters or switches"
    - "massive mimo relaying with hybrid processing"

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)