Electronic Science and Technology ›› 2022, Vol. 35 ›› Issue (2): 14-19.doi: 10.16180/j.cnki.issn1007-7820.2022.02.003

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Underwater Laser Communication Coding Technology Based on QC-LDPC

GUAN Jingkai1,CAI Wenyu1,ZHU Zhangfeng2,TANG Guodong1   

  1. 1. School of Electronic Information,Hangzhou Dianzi University,Hangzhou 310018,China
    2. State Grid Ningbo Beilun District Power Supply Company,Ningbo 315000,China
  • Received:2020-10-15 Online:2022-02-15 Published:2022-02-24
  • Supported by:
    Zhejiang Public Welfare Technology Research Project(LGF20F010005);Special Funds for Fundamental Scientific Research Business Fees of Zhejiang Provincial Universities(GK209907299001-001)


In response to the need for long-distance and reliable communication with underwater blue-green lasers, a modulation and coding communication method combining PPM and QC-LDPC is proposed in this study. By simulating combinations of different code lengths, code rates, and PPM modulation orders, the optimal combination of QC-LDPC coding and PPM modulation under different SNR conditions is found. The principle of the classic PPM signal and the basic structure of the QC-LDPC code are introduced, and the generation of the PPM signal is realized through MATLAB software simulation.The check matrix of QC-LDPC is constructed, and the BER performance curves of different combinations schemes obtained are by simulating different code words. The simulation results show that the performance of QC-LDPC encoding is improved, and QC-LDPC codes with different code lengths and code rates have large differences in BER performance under different SNR conditions. For the same codes under the same SNR conditions, the higher the PPM modulation order, the lower the bit error rate. The BER performance curves of codes with the same code length and different code rates are quite different under the same modulation order.

Key words: quasi-cyclic LDPC code, pulse position modulation, cyclic matrix, base matrix, shift matrix, channel coding, signal to noise ratio, bit error rate

CLC Number: 

  • TN401