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: "nonlinear precoding for phase quantized constant envelope massive mu mimo ofdm"
  Abstract: We propose a nonlinear phase-quantized constant- envelope precoding algorithm for the massive multi-user (MU) multiple-input multiple-output (MIMO) downlink. Specifically, we adapt the squared-infinity norm Douglas-Rachford splitting (SQUID) precoder to systems that use oversampling digital-to-analog converters (DACs) at the base station (BS) and orthogonal frequency-division multiplexing (OFDM) to communicate over frequency-selective channels. We demonstrate that SQUID is able to perform precoding for signals that are constrained to constant envelope, which enables the use of power-efficient analog radio-frequency circuitry at the BS. By quantizing the phase of the resulting constant-envelope signal, we obtain a finite-cardinality transmit signal that can be synthesized by low-resolution (e.g., 1-bit) DACs. We use error-rate simulations to demonstrate the superiority of SQUID over conventional linear- quantized precoders for massive MU-MIMO-OFDM systems.

Connected through hyperedge HE-1 (induced by source paper "massive mu mimo ofdm uplink with direct rf sampling and 1 bit adcs"):
  with members:
    - "timing and frequency synchronization for 1 bit massive mu mimo ofdm downlink"
    - "massive mu mimo ofdm uplink with hardware impairments modeling and analysis"
    - "one bit massive mimo precoding via a minimum symbol error probability design"
    - "directional frame timing synchronization in wideband millimeter wave systems with low resolution adcs"
    - "one bit sphere decoding for uplink massive mimo systems with one bit adcs"
    - "performance analysis for time of arrival estimation with oversampled low complexity 1 bit a d conversion"
    - "quantized precoding for multi antenna downlink channels with magiq"
    - "on out of band emissions of quantized precoding in massive mu mimo ofdm"

Connected through hyperedge HE-2 (induced by source paper "timing and frequency synchronization for 1 bit massive mu mimo ofdm downlink"):
  with members:
    - "directional frame timing synchronization in wideband millimeter wave systems with low resolution adcs"
    - "one bit precoding and constellation range design for massive mimo with qam signaling"
    - "1 bit massive mu mimo precoding in vlsi"
    - "performance analysis for time of arrival estimation with oversampled low complexity 1 bit a d conversion"
    - "quantized precoding for multi antenna downlink channels with magiq"
    - "joint cfo and channel estimation in millimeter wave systems with one bit adcs"
    - "linear precoding with low resolution dacs for massive mu mimo ofdm downlink"
    - "downlink achievable rate analysis in massive mimo systems with one bit dacs"

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"
    - "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"
    - "interference exploitation in full duplex communications trading interference power for both uplink and downlink power savings"

Connected through hyperedge HE-4 (induced by source paper "a framework for one bit and constant envelope precoding over multiuser massive miso channels"):
  with members:
    - "one bit massive mimo precoding via a minimum symbol error probability design"
    - "minimum symbol error rate based constant envelope precoding for multiuser massive miso downlink"
    - "quantized constant envelope precoding with psk and qam signaling"
    - "multiuser one bit massive mimo precoding under mpsk signaling"
    - "mse optimal 1 bit precoding for multiuser mimo via branch and bound"
    - "one bit precoding and constellation range design for massive mimo with qam signaling"
    - "accelerated gradient descent escapes saddle points faster than gradient descent"
    - "massive mimo downlink 1 bit precoding with linear programming for psk signaling"

Connected through hyperedge HE-5 (induced by source paper "multiuser one bit massive mimo precoding under mpsk signaling"):
  with members:
    - "one bit massive mimo precoding via a minimum symbol error probability design"
    - "massive mimo downlink 1 bit precoding with linear programming for psk signaling"
    - "quantized precoding for massive mu mimo"
    - "exploiting known interference as green signal power for downlink beamforming optimization"
    - "near maximum likelihood detector and channel estimator for uplink multiuser massive mimo systems with one bit adcs"
    - "quantized massive mu mimo ofdm uplink"
    - "massive mimo with 1 bit adc"
    - "scaling up mimo opportunities and challenges with very large arrays"

Connected through hyperedge HE-6 (induced by source paper "mse optimal 1 bit precoding for multiuser mimo via branch and bound"):
  with members:
    - "1 bit massive mu mimo precoding in vlsi"
    - "branch and bound precoding for multiuser mimo systems with 1 bit quantization"
    - "massive mu mimo ofdm downlink with one bit dacs and linear precoding"
    - "downlink achievable rate analysis in massive mimo systems with one bit dacs"
    - "minimum ber precoding in 1 bit massive mimo systems"
    - "an overview of signal processing techniques for millimeter wave mimo systems"
    - "five disruptive technology directions for 5g"
    - "scaling up mimo opportunities and challenges with very large arrays"

Connected through hyperedge HE-7 (induced by source paper "linear precoding with low resolution dacs for massive mu mimo ofdm downlink"):
  with members:
    - "one bit massive mimo precoding via a minimum symbol error probability design"
    - "a framework for one bit and constant envelope precoding over multiuser massive miso channels"
    - "mse optimal 1 bit precoding for multiuser mimo via branch and bound"
    - "one bit precoding and constellation range design for massive mimo with qam signaling"
    - "can hardware distortion correlation be neglected when analyzing uplink se in massive mimo"
    - "out of band radiation from antenna arrays clarified"
    - "1 bit massive mu mimo precoding in vlsi"
    - "throughput analysis of massive mimo uplink with low resolution adcs"

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)