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: "transmit energy focusing for doa estimation in mimo radar with colocated antennas"
  Abstract: In this paper, we propose a transmit beamspace energy focusing technique for multiple-input multiple-output (MIMO) radar with application to direction finding for multiple targets. The general angular directions of the targets are assumed to be located within a certain spatial sector. We focus the energy of multiple (two or more) transmitted orthogonal waveforms within that spatial sector using transmit beamformers which are designed to improve the signal-to-noise ratio (SNR) gain at each receive antenna. The subspace decomposition-based techniques such as MUSIC can then be used for direction finding for multiple targets. Moreover, the transmit beamformers can be designed so that matched-filtering the received data to the waveforms yields multiple (two or more) data sets with rotational invariance property that allows applying search-free direction finding techniques such as ESPRIT or parallel factor analysis (PARAFAC). Unlike previously reported MIMO radar ESPRIT/PARAFAC-based direction finding techniques, our method achieves the rotational invariance property in a different manner combined also with the transmit energy focusing. As a result, it achieves better estimation performance at lower computational cost. The corresponding Cramer-Rao bound is derived and its dependence on the number of waveforms used is discussed. Simulation results also show the superiority of the proposed technique over the existing techniques.

Connected through hyperedge HE-1 (induced by source paper "machine learning based high resolution doa measurement and robust dm for hybrid analog digital massive mimo transceiver"):
  with members:
    - "robust secure transmission of using main lobe integration based leakage beamforming in directional modulation mu mimo systems"
    - "secure swipt for directional modulation aided af relaying networks"
    - "broadband doa estimation using convolutional neural networks trained with noise signals"
    - "hybrid analog and digital beamforming for mmwave ofdm large scale antenna arrays"
    - "alternating minimization algorithms for hybrid precoding in millimeter wave mimo systems"
    - "an overview of signal processing techniques for millimeter wave mimo systems"

Connected through hyperedge HE-2 (induced by source paper "transmit array interpolation for doa estimation via tensor decomposition in 2 d mimo radar"):
  with members:
    - "transmit radiation pattern invariance in mimo radar with application to doa estimation"
    - "efficient transmit beamspace design for search free based doa estimation in mimo radar"
    - "phased mimo radar a tradeoff between phased array and mimo radars"

Connected through hyperedge HE-3 (induced by source paper "broadbeam for massive mimo systems"):
  with members:
    - "massive mimo 10 myths and one grand question"
    - "transmit radiation pattern invariance in mimo radar with application to doa estimation"
    - "a generalized spatial correlation model for 3d mimo channels based on the fourier coefficients of power spectrums"
    - "massive mimo for next generation wireless systems"
    - "preliminary results on 3d channel modeling from theory to standardization"
    - "five disruptive technology directions for 5g"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "constant envelope multi user precoding for frequency selective massive mimo systems"

Connected through hyperedge HE-4 (induced by source paper "an algebraic approach to a class of rank constrained semi definite programs with applications"):
  with members:
    - "discrete signal processing on graphs frequency analysis"
    - "the emerging field of signal processing on graphs extending high dimensional data analysis to networks and other irregular domains"
    - "discrete signal processing on graphs"
    - "the algebraic combinatorial approach for low rank matrix completion"
    - "phase retrieval via matrix completion"
    - "interference alignment as a rank constrained rank minimization"
    - "phased mimo radar a tradeoff between phased array and mimo radars"

Connected through hyperedge HE-5 (induced by source paper "joint robust transmit receive adaptive beamforming for mimo radar using probability constrained optimization"):
  with members:
    - "phased mimo radar a tradeoff between phased array and mimo radars"

Connected through hyperedge HE-6 (induced by source paper "ambiguity function of the transmit beamspace based mimo radar"):
  with members:
    - "spatial compressive sensing for mimo radar"
    - "efficient transmit beamspace design for search free based doa estimation in mimo radar"
    - "moving target parameters estimation in noncoherent mimo radar systems"
    - "optimal joint target detection and parameter estimation by mimo radar"
    - "mimo radar using compressive sampling"
    - "phased mimo radar a tradeoff between phased array and mimo radars"
    - "diversity integration tradeoffs in mimo detection"

Connected through hyperedge HE-7 (induced by source paper "transmit radiation pattern invariance in mimo radar with application to doa estimation"):
  with members:
    - "efficient transmit beamspace design for search free based doa estimation in mimo radar"
    - "phased mimo radar a tradeoff between phased array and mimo radars"

Connected through hyperedge HE-8 (induced by source paper "colocated mimo radar waveform design for transmit beampattern formation"):
  with members:
    - "efficient transmit beamspace design for search free based doa estimation in mimo radar"

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)