【作者】 高雨良；

【导师】 伍剑；

【作者基本信息】 北京邮电大学 ， 电磁场与微波技术， 2011， 硕士

【摘要】 随着光通信对更大带宽、更长传输距离和更高接收灵敏度的不断追求,数字相干光通信技术应运而生。数字相干光通信技术不仅可以提高接收灵敏度,同时能够得到全部的光场信息,从而使其拥有传统强度调制／直接检测(IM/DD)系统无法比拟的优势。数字相干光通信技术的迅速发展,得益于新型码型调制技术和数字信号处理器(DSP)的高速发展。新型码型调制技术通过灵活的信息加载方式提高了相干光通信系统的频谱利用率,而随着数字信号处理器的运算速度的提高,数字化的相干光通信系统已经成为了下一代光网络的有力竞争者之一。论文研究相干接收机内的数字补偿算法,重点研究载波频率差估计算法和载波相位恢复算法。首先通过VPItransmisionMakerTM软件或者Matlab软件仿真受到噪声影响的信号,再利用Matlab软件实现离线的信号处理,部分算法还做了相应的实验验证。借助以上仿真平台和算法,实现了没有色散补偿光纤、无需锁相环的偏振分集接收。同时,提出采用加权的前馈相位恢复算法,其可以提高灵敏度代价0.2dB；以及基于QPSK分类和最大似然检测的前馈相位恢复算法,其复杂度为同类算法的一半以下。所提出的新型载波恢复算法可以有效提高系统性能或降低系统复杂度,为方便今后实时高速相干光通信系统的实现。最后研究分析系统性能,论文所搭建的仿真平台及数字信号处理算法可以完成误码率小于10-3的PDM-QPSK以及PDM-16QAM相干传输,其结果能够真实反应实验现象,为以后数字相干光通信的高速实时实现提供研究基础和理论指导。更多还原

【Abstract】 In the field of optical communications, with constant pursuit for larger bandwidth, longer transmission distance and higher receiver sensitivity, coherent optical communications technology came into being. Coherent detection can not only improve the receiver sensitivity but also acquire all the light field information can be obtained, thus giving coherent optical communications unparallel advantages over traditional Intensity Modulation/Direct Detection (IM/DD) system. Thanks to high-speed development in advanced modulation format and digital signal processor (DSP), digital coherent optical communication technology is developing rapidly. Advanced modulation formats provide flexible methods of information encoding in coherent optical communication system and improve the spectrum efficiency. On the other hand, with the improved digital signal processor computation speed, digital coherent optical communication systems has become a promised candidate for next-generation optical networks.Thesis investigated the digital compensation algorithms in coherent communication receivers with the focus on carrier frequency offset estimation and carrier phase estimation. Firstly we investigate various noise and distortion effects in the transmission via a systematic simulation using VPItransmissionMakerTM and Matlab. Then, the received signal is off-line processed and the performance is analyzed. Also, some of the algorithms have been tested experimentally. By using the simulation platform and digital compensation algorithms mentioned above, we have achieved polarization diversity detection system with no dispersion compensation fiber and phase-lock-loop. Meanwhile, we proposed a carrier phase recovery algorithm with weighting coefficients, which can improve the sensitivity penalty by 0.2dB; a feedforward carrier phase recovery algorithm based on QPSK partitioning and maximum likelihood detection, the complexity is less than half of reported algorithms in other literatures, The proposed new carrier recovery algorithm either improves system performance or reduces computation complexity, which will relief hardware burden in future high-speed real-time coherent optical communication systems. Finally, system performance is analyzed. The paper sets up a simulation platform incorporated with digital signal processing algorithms and achieved PDM-QPSK and PDM-16QAM coherent transmission system with bit error rate lower than 10-3, the results agrees with experimental outcomes and will provide back ground and theoretical guidance for future high-speed digital coherent optical communication systems.更多还原