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: "constant envelope precoding for mimo systems"
  Abstract: Constant envelope (CE) precoding is an appealing transmission technique, which enables highly efficient power amplification, and is realizable with a single radio frequency (RF) chain at the multi-antenna transmitter. In this paper, we study the transceiver design for a point-to-point multiple-input multiple-output (MIMO) system with CE precoding. Both single-stream transmission (i.e., beamforming) and multi-stream transmission (i.e., spatial multiplexing) are considered. For single-stream transmission, we optimize the receive beamforming vector to minimize the symbol error rate (SER) for any given channel realization and desired constellation at the combiner output. By reformulating the problem as an equivalent quadratically constrained quadratic program (QCQP), we propose an efficient semi-definite relaxation (SDR) based algorithm to find an approximate solution. Next, for multi-stream transmission, we propose a new scheme based on antenna grouping at the transmitter and minimum mean squared error (MMSE) or zero-forcing (ZF) based beamforming at the receiver. The transmit antenna grouping and receive beamforming vectors are then jointly designed to minimize the maximum SER over all data streams. Finally, the error-rate performance of single- versus multi-stream transmission is compared via simulations under different setups.

Connected through hyperedge HE-1 (induced by source paper "capacity characterization for intelligent reflecting surface aided mimo communication"):
  with members:
    - "miso wireless communication systems via intelligent reflecting surfaces"
    - "secure wireless communication via intelligent reflecting surface"
    - "cascaded channel estimation for large intelligent metasurface assisted massive mimo"
    - "resource allocation for secure irs assisted multiuser miso systems"
    - "intelligent reflecting surface meets ofdm protocol design and rate maximization"
    - "enabling secure wireless communications via intelligent reflecting surfaces"
    - "intelligent reflecting surface assisted non orthogonal multiple access"
    - "weighted sum power maximization for intelligent reflecting surface aided swipt"

Connected through hyperedge HE-2 (induced by source paper "intelligent reflecting surface meets ofdm protocol design and rate maximization"):
  with members:
    - "capacity characterization for intelligent reflecting surface aided mimo communication"
    - "towards smart and reconfigurable environment intelligent reflecting surface aided wireless network"
    - "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"
    - "beamforming optimization for intelligent reflecting surface with discrete phase shifts"
    - "reconfigurable intelligent surfaces for energy efficiency in wireless communication"
    - "large intelligent surface assisted wireless communication exploiting statistical csi"
    - "on the feasibility of wireless energy transfer using massive antenna arrays"
    - "what will 5g be"

Connected through hyperedge HE-3 (induced by source paper "quantized constant envelope precoding with psk and qam signaling"):
  with members:
    - "1 bit massive mu mimo precoding in vlsi"
    - "branch and bound precoding for multiuser mimo systems with 1 bit quantization"
    - "quantized precoding for multi antenna downlink channels with magiq"
    - "nonlinear precoding for phase quantized constant envelope massive mu mimo ofdm"
    - "linear precoding with low resolution dacs for massive mu mimo ofdm downlink"
    - "psk precoding in multi user miso systems"
    - "massive mimo downlink 1 bit precoding with linear programming for psk signaling"
    - "an efficient manifold algorithm for constructive interference based constant envelope precoding"

Connected through hyperedge HE-4 (induced by source paper "intelligent reflecting surface enhanced wireless network via joint active and passive beamforming"):
  with members:
    - "beamforming optimization for wireless network aided by intelligent reflecting surface with discrete phase shifts"
    - "weighted sum power maximization for intelligent reflecting surface aided swipt"
    - "intelligent reflecting surface assisted secrecy communication via joint beamforming and jamming"
    - "towards smart and reconfigurable environment intelligent reflecting surface aided wireless network"
    - "achievable rate maximization by passive intelligent mirrors"
    - "beyond massive mimo the potential of data transmission with large intelligent surfaces"
    - "beamforming optimization for intelligent reflecting surface with discrete phase shifts"
    - "intelligent reflecting surface enhanced wireless network joint active and passive beamforming design"

Connected through hyperedge HE-5 (induced by source paper "minimum symbol error rate based constant envelope precoding for multiuser massive miso downlink"):
  with members:
    - "one bit massive mimo precoding via a minimum symbol error probability design"
    - "an efficient manifold algorithm for constructive interference based constant envelope precoding"
    - "scaling up mimo opportunities and challenges with very large arrays"
    - "per antenna constant envelope precoding for large multi user mimo systems"

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)