PDM-CO-OFDM中采用相位传递的次符号光相位噪声抑制算法

Sub-Symbol Optical Phase Noise Suppression in PDM-CO-OFDM Adopting Phase Passing

在符号周期-光源线宽乘积较大的PDM-CO-OFDM系统中,光相位噪声引入的子载波间串扰(ICI)极大地劣化了系统的性能.采用高阶调制格式(如16QAM)的PDM-CO-OFDM系统对光相位噪声的敏感度随调制格式的升高而增加.针对上述受光相位噪声影响较大的系统,该文提出一种采用线性插值、相位传递和符号分割的光相位噪声抑制算法,即P-LI-SCPEC.推导了算法的数学模型,通过蒙特卡洛仿真研究了该算法的性能,并与已有的几种光相位噪声抑制算法进行了横向对比.仿真结果表明,该算法能有效地抑制光相位噪声,提高系统对光源线宽的容忍度,其性能优于此前提出的LI-SCPEC算法.该算法对于PDM-CO-OFDM技术在采用廉价光源的光接入网及采用高阶调制格式的主干网中的应用都具有重要的意义.

Polarization-division multiplexed coherent optical orthogonal frequency multiplexing （PDM-CO-OFDM） is an important physical layer technology for high spectrum efficiency optical network. But PDM-CO-OFDM is very sensitive to optical phase noise. In PDM-CO-OFDM system with a large symbol period-laser linewidth product, the system＇s performance is severally degraded by the optical phase noise induced inter-carrier-interference （ICI）. The PDM-CO-OFDM system employing advanced modulation format （e. g. 16QAM） beeomes. more sensitive to optical phase noise when increasing the modulation format order. To mitigate the optical phase noise in above systems, a novel algorithm, P-LI-SCPEC is proposed, which employs linear interpolation, phase passing and symbol slicing. The mathematical model of the proposed algorithm is developed. Mentor-Carol simulation has been conducted based on the model. By comparing with several other optical phase suppression algorithms including our previously proposed algorithm LI-SCPEC, the proposed algorithm achieves better performance in suppressing the optical phase noise, and thus improves the system＇s tolerance to laser linewidth. The new algorithm will promote the application of PDM-CO-OFDM both in the optical access network using low cost laser, and in the optical back-bone network with high order modulation format.