基于数字预补偿技术的超奈奎斯特波分复用型相干光通信系统的研究

With the fast growth of internet bandwidth demand and the commercialization of 100G Ethernet using polarization-division-multiplexing quadrature-phase-shift-keying, further increasing spectral efficiency (SE) to meet the bandwidth requirement is attracting a lot of research interest. Nyquist and super-Nyquist-WDM are considered as the most promising technique to realized 100Gb/s and beyond with higher spectral efficient and bandwidth utilization. In this project, we propose and investigate a digital pre-equalization scheme to accurately emphasize on the frequency loss caused by aggressive pre-filtering, which achieves a higher SE in super-Nyquist-WDM system. The reference-based pre-equalization is utilized to compensate for the serious inter-symbol interference (ISI) caused by limited channel bandwidth or aggressive pre-filtering effect provided by optical pre-filter. The research in this project will demonstrate the value of the digital pre-equalization scheme based on the reversed channel transfer function to the super-Nyquist signal. The joint digital raised-cosine (RC) pulse filter is implemented before the reference-based pre-equalization scheme to enhance the tolerance of the WDM system to crosstalk from adjacent channels. A further investigation of best solution to obtain the channel transfer function, and experiment for the super-Nyquist-WDM system will be given.

数据业务的持续增长对骨干网传输带宽提出了越来越高的需求，基于奈奎斯特(Nyquist)或超奈奎斯特波分复用技术（Super-Nyquist-WDM）被认为是提高100Gb/s或超100Gb/s WDM相干光传输系统频谱利用率和系统带宽利用效率的最佳技术。本项目以超100Gb/s super-Nyquist-WDM相干光通信系统为对象，提出和研究了数字预补偿技术对Nyquist强滤波技术损伤的消除特性。揭示系统发送端中基于参考信号频域传输函数的数字预补偿技术对super-Nyquist-WDM系统中频率损伤补偿的科学价值。同时将其与现有的其他数字预补偿技术相比较，揭示本项目所研究的基于参考信号传输函数的方案在理论上如何能够完美的消除强滤波所带来的损伤。本项目还将研究传输函数频域均衡的最佳计算方式、以及基于数字预补偿的super-Nyquist-WDM系统的实验验证这两个科学技术难点。

数据业务的持续增长对骨干网传输带宽提出了越来越高的需求，基于奈奎斯特(Nyquist)或超奈奎斯特波分复用技术（Super-Nyquist-WDM）被认为是提高100Gb/s或超100Gb/s WDM相干光传输系统频谱利用率和系统带宽利用效率的最佳解决方案。本项目以超100Gb/s super-Nyquist-WDM相干光通信系统为对象，提出并完成了对数字预补偿技术对Nyquist强滤波技术损伤的消除特性的研究。通过理论和建模的研究成果揭示了基于14Gaud BPSK参考信号(适用于112Gb/s PDM-16QAM信号)频域传输函数的数字预补偿技术对super-Nyquist-WDM信号频率损伤补偿的科学意义，实现了至少3-dB相干光(信噪比)接收机灵敏度改善。同时将项目研究的关键数字预补偿技术与传统的升余弦数字滤波器结合使用，接收机灵敏度能够再次获得0.5-dB改善。本项目同时实验研究了传输函数频域均衡的最佳计算方式、以及基于数字预补偿的super-Nyquist-WDM系统实验验证这两个科学技术问题。