高阶矢量调制格式信号光纤传输损伤及其数字相干接收研究

High-order vector modulation format is one of the development orientations of high-speed optical fiber communication systems and is crucial to ultra-high-speed transmission. Although this format of modulation benefits the transmission system in terms of spectral efficiency, the system is more likely to be aggravated by various factors. Currently, the digital coherent reception fails to meet requirements of future optical fiber transmission systems of Tbit/s, considering the effectiveness and real-time processing of various algorithms. This program will focus on the characteristics and mechanics of transmission impairments of high-order vector modulation signal, like frequency offset, phase noise, chromatic dispersion, nonlinear effects, etc., and on new approaches to extract these features. Furthermore, we plan to propose digital coherent reception algorithms with higher accuracy and lower complexity, attempting to achieve breakthroughs in the following aspects, Mechanisms and Algorithms of Frequency Offset Compensation with Low Complexity, Mechanisms and Algorithms of Phase Noise Estimation with High Tolerance, Research on Blind Dispersion Equalization Algorithms with Low Complexity, and Research of Mechanisms and Algorithms of Nonlinearity Effects Compensation against Various Transmission Impairments. In addition, experimental and simulation platforms are supposed to be set up to verify the principles of high-speed digital coherent reception. Thus, by running this program, we could lay solid foundations for the applications of the next generation of optical fiber transmission system of Tbit/s, thereby enhancing our research capacity in and influence on this filed internationally.

采用高阶矢量调制格式是高速光纤通信系统的发展方向之一，对实现超高信息传输有着重要的意义。高阶矢量调制格式在带来超高频谱效率的好处的同时也更容易受到各种传输损伤的影响。当前的数字相干接收技术在算法的复杂性、鲁棒性和实时性方面还不能满足未来的Tbit/s光纤传输系统的需要。本项目将深入研究高阶矢量调制信号频率偏移、相位噪声、色散、非线性效应等传输损伤的表现特征和统计特性，探索提取这些特征的新方法和新机理，进而提出精度更高、复杂度更低的数字相干接收算法。在"低复杂度频率偏移补偿机理与算法"、"大容限相位噪声估计机理与算法"、"低复杂度色散盲均衡算法的研究"以及"多种传输损伤效应下的非线性效应补偿机理及算法研究"方面取得突破，并搭建高速数字相干接收原理验证平台（实验与仿真），为下一代Tbit/s级的光纤传输系统的实用化提供有力支撑，提升我国在该领域的研究水平和国际影响力。

课题根据高阶矢量调制信号频率偏移、相位噪声、非线性效应等传输损伤的表现特征和统计特性，基于机器学习的概念，首次提出了使用多元支持向量机（SVM）作为非参方法来消除相干光通信系统中的非线性相位噪声（NLPN），降低了计算的复杂性。并基于SVM方法，优化了幅度相位联合调制（APSK）格式，指出了（88-APSK）调制格式有较高的非线性容限的，给出了基于SVM的检测方法。同时，深入分析了传统的分步傅立叶算法（SSFM），指出了传统SSFM中的梯形近似是造成其计算误差和多次迭代运算的原因，并提出了改进的I-SSFM算法，可降低计算复杂度50%。本课题针对光OFDM技术所面临的非线性损伤问题，重点开展了恒包络OFDM的研究，通过恒包络OFDM与MSK调制格式的结合，既兼顾了频谱效率又降低了系统的非线性效应，还提出一种新的调制格式tri-h CPFSK-OFDM去提升MSK-OFDM的频谱效率。课题执行期间，课题组发表SCI收录论文29篇，EI收录论文5篇，申请国家发明专利3项，培养硕士研究生8名，博士研究生3名。.课题圆满完成了预定研究任务。