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Quasi-light Storage for Optical Data Packets
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Low-complexity LDPC decoding algorithms for ultra-high-order modulated signals.

Hongjun Zhu, Meiyu Fu, Chen Hou

    Optics Express
    |December 13, 2023
    PubMed
    Summary
    This summary is machine-generated.

    This study introduces a low-complexity decoding algorithm for ultra-high-order modulation, significantly reducing table lookups for faster optical communications. The new method enhances performance for 1024-QAM signals with minimal data rate sacrifice.

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    Area of Science:

    • Optical Communications
    • Information Theory
    • Signal Processing

    Background:

    • Achieving data rates over 1 Tbps requires low-complexity decoding and ultra-high-order modulation.
    • Information bottleneck algorithms show promise for LDPC decoding, comparable to existing methods.
    • Limited research exists on applying information bottleneck decoding to ultra-high-order modulation formats.

    Purpose of the Study:

    • To develop a low-complexity LDPC decoding technique for ultra-high-order modulated signals.
    • To address the computational complexity of table lookups in optical communication systems.
    • To enable efficient decoding for advanced modulation schemes like 1024-QAM.

    Main Methods:

    • Developed an information bottleneck framework using multivariate covariates for 1024-QAM signals.
    • Utilized a bidirectional recursive network and quantized information symmetry for table reuse.
    • Reduced table lookup operations from quadratic to linear complexity relative to node degree.

    Main Results:

    • The proposed algorithm effectively decodes ultra-high-order modulated signals, demonstrated in a coherent optical system with 1024-QAM.
    • Achieved a reduction in table lookup operations from square to linear magnitude.
    • Resulted in a performance sacrifice of only 0.2–0.3 dB.

    Conclusions:

    • The novel LDPC decoding technique significantly reduces decoding time in optical communications.
    • The method offers a practical solution for high-speed optical systems employing advanced modulation.
    • The approach successfully combines higher-order modulation with LDPC codes efficiently.