Research On Fast Polarization Damage Compensation Method For Optical Fiber Communication System

With the development of technologies such as 5G,cloud computing and virtual reality,and the increasing number of users and devices accessing the Internet,the data transmission capacity has undergone earthshaking changes,resulting in an explosive increase in global data traffic,which is imperative to increase the capacity of communication networks.The pursuit of network capacity puts forward higher requirements for the transmission bandwidth and data processing capabilities of high-speed and ultra-long-distance optical fiber communication networks.Polarization multiplexing technology utilizes the two orthogonal polarization states of light to transmit independent information on each path,thereby doubling the communication capacity.However,the utilization of polarization effects also needs to consider polarization-dependent damage.The polarization-multiplexed optical signal will not only be disturbed in the fiber to cause the Rotation of State of Polarization(RSOP),but also be affected by some polarization-sensitive communication devices.Even in the presence of a lightning strike or the presence of a nearby vibration source,the polarization state of an optical signal can change extremely rapidly.Compensation of polarization state rotation damage by digital signal processing algorithm is a research hotspot.This thesis studies the key principles of polarization state rotation and Kalman filtering algorithms.The thesis mainly concerns the RSOP joint compensation scheme based on the extended Kalman filter algorithm,the RSOP and phase offset compensation scheme based on the cubature Kalman filter algorithm,and the mutation RSOP tracking scheme based on the strong tracking filter.The main contents of the thesis are as follows:(1)For the residual carrier frequency offset,carrier phase noise and RSOP impairments suffered by the signal,a RSOP joint channel compensation scheme based on constellation-oriented extended Kalman filtering is proposed,and its performance is simulated and studied.The research results show that the proposed scheme can realize the residual carrier frequency offset and phase offset compensation by using the joint impairment channel.And at the same time,it can track and compensate the rapidly changing RSOP.The proposed scheme can achieve fast timevarying RSOP tracking capability with lower SNR requirements compared to MMA.(2)Aiming at the problems of limited accuracy and high computational complexity of traditional algorithms,a polarization state rotation tracking and compensation scheme based on cubature Kalman filtering algorithm is proposed,and a 14GBaud PDM-16QAM optical communication system simulation platform is built.Simulation studies its RSOP tracking performance.Simulation results show that the proposed scheme has higher RSOP tolerance and lower SNR requirements than that of the traditional Kalman filter algorithm.And the scheme is insensitive to process noise covanance.(3)Aiming at the problem of sudden change of RSOP and filter parameter mismatch in fiber channels caused by extreme conditions such as lightning strikes and wind vibrations,a cubature Kalman filter algorithm based on strong tracking filtering is proposed,and its performance is verified by simulation.Simulation results show that the scheme is insensitive to Kalman filter parameters and initial state,and has suitable complexity.In the case of RSOP mutation and initial state mismatch,the proposed scheme has less SNR requirement,larger filter parameter value range and better bit error rate performance than that of the cubature Kalman filter algorithm.In addition,a threshold-based strong tracking cubature Kalman filter algorithm is presented to reduce the complexity.