基于QC-LDPC的水下激光通信编码技术

Underwater Laser Communication Coding Technology Based on QC-LDPC

针对水下蓝绿激光远距离可靠通信的需求,文中提出了PPM与QC-LDPC相结合的调制编码通信方法。通过对不同码长、码率与PPM调制阶数的组合方案进行仿真,找出在不同SNR条件下的最优QC-LDPC编码与PPM调制的组合方案。文中介绍了经典PPM信号的原理与QC-LDPC码的基本结构,并通过MATLAB软件模拟实现PPM信号的产生,构建了QC-LDPC的校验矩阵,对不同码字仿真得到不同组合方案的BER性能曲线。仿真结果表明,经过QC-LDPC编码后的性能得到改善。不同码长和码率的QC-LDPC码在不同信噪比SNR条件下的误码率性能差异较大。在相同SNR条件下对于同一码字,PPM调制阶数越高,误码率越低。同一码长不同码率的码字在相同调制阶数条件下,BER性能曲线差异较大。

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.