Shen Thomas Shun Rong, Lau Alan Pak Tao, Yu Changyuan
Photonics Research Center, Department of Electrical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong.
Opt Express. 2010 Nov 8;18(23):23608-19. doi: 10.1364/OE.18.023608.
Digital signal processing (DSP)-based coherent communications have become standard for future high-speed optical networks. Implementing DSP-based advanced algorithms for data detection requires much more detailed knowledge of the transmission link parameters, resulting in optical performance monitoring (OPM) being even more important for next generation systems. At the same time, the DSP platform also enables new strategies for OPM. In this paper, we propose the use of pilot symbols with alternating power levels and study the statistics of the received power and phase difference to simultaneously and independently monitor the carrier frequency offset between transmitter and receiver laser, laser linewidth, number of spans, fiber nonlinearity parameters as well as optical signal-to-noise ratio (OSNR) of a transmission link. Analytical predictions are verified by simulation results for systems with full chromatic dispersion (CD) compensation per span and 10% CD under-compensation per span. In addition, we show that by monitoring the changes in the statistics of the received pilot symbols during network operation, one can locate faults or OSNR degradations along a transmission link without additional monitoring equipments at intermediate nodes, which may be useful for more efficient dynamic routing and network management.
基于数字信号处理（DSP）的相干通信已成为未来高速光网络的标准。实现基于DSP的先进数据检测算法需要对传输链路参数有更详细的了解，这使得光性能监测（OPM）对下一代系统更为重要。同时，DSP平台也为OPM带来了新策略。在本文中，我们提出使用具有交替功率电平的导频符号，并研究接收功率和相位差的统计特性，以同时独立监测发射机和接收机激光器之间的载波频率偏移、激光线宽、跨段数、光纤非线性参数以及传输链路的光信噪比（OSNR）。对于每跨段具有全色度色散（CD）补偿和每跨段10% CD欠补偿的系统，通过仿真结果验证了分析预测。此外，我们表明，通过在网络运行期间监测接收到的导频符号统计特性的变化，无需在中间节点使用额外的监测设备，就可以定位传输链路中的故障或OSNR劣化，这对于更高效的动态路由和网络管理可能是有用的。
