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: "cost effective millimeter wave communications with lens antenna array"
  Abstract: Millimeter wave (mmWave) communication is a promising technology for the fifth-generation (5G) wireless system. However, the large number of antennas used and the wide signal bandwidth in mmWave systems render the conventional multi-antenna techniques increasingly costly in terms of signal processing complexity, hardware implementation, and power consumption. In this article, we investigate cost-effective mmWave communications by first providing an overview of the main existing techniques that offer different trade-offs between performance and cost, and then focusing our discussion on a promising new technique based on the advanced lens antenna array. It is revealed that by exploiting the angle-dependent energy focusing property of lens arrays, together with the angular sparsity of the mmWave channels, mmWave lens-antenna system is able to achieve the capacity-optimal performance with very few radio-frequency (RF) chains and using the low-complexity single-carrier transmission, even for wide-band frequency-selective channels. Numerical results show that the lens-based system significantly outperforms the state-of-the-art designs for mmWave systems in both spectrum efficiency and energy efficiency.

Connected through hyperedge HE-1 (induced by source paper "spatial lobes division based low complexity hybrid precoding and diversity combining for mmwave iot systems"):
  with members:
    - "downlink precoding with mixed statistical and imperfect instantaneous csi for massive mimo systems"
    - "beam tracking for uav mounted satcom on the move with massive antenna array"
    - "pilot power allocation through user grouping in multi cell massive mimo systems"
    - "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"
    - "limited feedback hybrid precoding for multi user millimeter wave systems"
    - "turbo like beamforming based on tabu search algorithm for millimeter wave massive mimo systems"

Connected through hyperedge HE-2 (induced by source paper "optimal discrete spatial compression for beamspace massive mimo signals"):
  with members:
    - "a real time millimeter wave phased array mimo channel sounder"
    - "branch and bound precoding for multiuser mimo systems with 1 bit quantization"
    - "spatio temporal waveform design for multiuser massive mimo downlink with 1 bit receivers"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "fronthaul compression and transmit beamforming optimization for multi antenna uplink c ran"
    - "quantized precoding for massive mu mimo"
    - "hybrid beamforming for massive mimo a survey"
    - "capacity analysis of one bit quantized mimo systems with transmitter channel state information"

Connected through hyperedge HE-3 (induced by source paper "uplink channel estimation and data transmission in millimeter wave cran with lens antenna arrays"):
  with members:
    - "fronthaul limited uplink ofdma in ultra dense cran with hybrid decoding"
    - "joint millimeter wave fronthaul and ofdma resource allocation in ultra dense cran"
    - "multi user millimeter wave mimo with full dimensional lens antenna array"
    - "rf lens embedded massive mimo systems fabrication issues and codebook design"
    - "channel estimation for hybrid architecture based wideband millimeter wave systems"
    - "millimeter wave mimo with lens antenna array a new path division multiplexing paradigm"
    - "optimized uplink transmission in multi antenna c ran with spatial compression and forward"
    - "optimized backhaul compression for uplink cloud radio access network"

Connected through hyperedge HE-4 (induced by source paper "low complexity hybrid precoding and diversity combining based on spatial lobes division for millimeter wave mimo systems"):
  with members:
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "dynamic subarrays for hybrid precoding in wideband mmwave mimo systems"
    - "millimeter wave mimo with lens antenna array a new path division multiplexing paradigm"
    - "channel estimation and hybrid precoding for millimeter wave cellular systems"
    - "millimeter wave cellular wireless networks potentials and challenges"
    - "spatially sparse precoding in millimeter wave mimo systems"

Connected through hyperedge HE-5 (induced by source paper "multi user millimeter wave mimo with full dimensional lens antenna array"):
  with members:
    - "beamspace channel estimation for millimeter wave massive mimo systems with lens antenna array"
    - "rf lens embedded massive mimo systems fabrication issues and codebook design"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "low rf complexity technologies to enable millimeter wave mimo with large antenna array for 5g wireless communications"
    - "hybrid digital and analog beamforming design for large scale antenna arrays"
    - "frequency selective hybrid precoding for limited feedback millimeter wave systems"
    - "limited feedback hybrid precoding for multi user millimeter wave systems"
    - "near optimal hybrid processing for massive mimo systems via matrix decomposition"

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)