Nonlinear Effect And Compensation Of High Speed Optical WDM System

With the emergence of the Internet and emerging industries,the communication network has gradually entered the era of traffic explosion.The demand for network bandwidth of various Internet applications,such as big data,cloud computing,online education,webcast,is growing rapidly.In the aspect of data transmission,there is a higher demand for transmission rate,transmission distance and transmission bandwidth.Under the condition of high-speed transmission,it will inevitably be affected by more serious nonlinear effects.How to more efficiently complete the compensation of transmission damage is particularly important.Wavelength division multiplexing(WDM)is one of the most widely used transmission systems,which can improve the channel capacity and bandwidth,and also meet the data transmission requirements of the new generation of optical communication.This thesis focuses on the estimation model of nonlinear effect in coherent optical WDM system,the digital reverse transmission algorithm for nonlinear compensation and the probability shaping technology which can improve the channel capacity and spectral efficiency.A simplified nonlinear effect estimation model,an improved adaptive digital reverse transmission algorithm and a fusion scheme of probability shaping and reverse transmission algorithm are proposed.The main contents and innovations of this thesis are as follows(1)The concept and theoretical model of coherent optical WDM system are studied.The nonlinear effect in coherent optical WDM system is mainly studied.A simplified noise estimation model of coherent optical WDM system is proposed.The innovation of the scheme is that the computational complexity of nonlinear noise is greatly simplified.The noise estimation effect in conventional optical WDM system and elastic optical WDM system is simulated,The results show that the simplified noise model not only simplifies the complexity,but also estimates the system noise well.(2)The digital reverse transmission algorithm for nonlinear damage compensation is studied,and an adaptive digital reverse transmission search scheme based on dichotomy is proposed.The innovation of the scheme is that the optimal nonlinear parameters can be calculated by dichotomy search when the transmission link parameters are unknown,and the computational complexity of compensation is greatly reduced.The simulation results show that the proposed algorithm can compensate the transmission damage when the transmission link parameters are unknown.Compared with the traditional method,the proposed algorithm has good compensation effect and greatly reduces the computational complexity.(3)The basic principle of probability shaping is studied,and a joint compensation scheme based on probability shaping and digital reverse transmission algorithm is proposed.The innovation of the scheme is that through the fusion compensation of the two,it can not only improve the transmission channel capacity,but also have good compensation effect.The transmission performance and influence factors of the joint compensation scheme are studied by simulation.The results show that the compensation scheme can achieve good transmission performance close to the mutual information limit of transmission under the condition of selecting appropriate parameters.