Research On Nonlinear Online Monitoring Of Fiber Link Based On FPGA

In modern society,the application of the users to the high communication efficiency and quality of broadband video,multimedia services,cloud computing,big data and other emerging data business needs to grow.Optical communication network has become the preferred technology of communication applications because of its enormous bandwidth and transparency.However,it is sensitive to the dispersion and nonlinear damage in the fiber link,and it is urgently needed to accurately monitor and compensate the influence of dispersion and nonlinearity in the channel.Therefore,this dissertation focuses on the principle of dispersion and nonlinearity in high-speed optical fiber communication system,and proposes a flexible and effective on-line monitoring scheme of link light performance,and the system carries out the simulation experiment.Firstly,the mechanism of nonlinear effect in fiber channel and its effect on fiber channel are expounded in detail.According to the nonlinear on-line monitoring mechanism based on Pilot and the ENPC compensation Scheme,this paper proposes an on-line optical performance monitoring system based on FPGA,and builds the simulation platform and verifies the feasibility of hardware platform based on ISE software.Simulation results show that the scheme can realize the data transmission and monitoring process of fiber link,and transmit the digital intermediate frequency signal generated by FPGA,then the transfer of the DAC into the fiber optic link,then pass the filter,photoelectric detector and ADC transfer back to FPGA to make the data of phase deviation calculation and compensation.Finally,this paper concretely studies the high-speed transmission protocol JESD204B,and builds the data transmission structure between the receiver and the transmitter of the FPGA and ADC/DAC based on the JESD204B criterion,which is divided into four levels:the application layer,the scrambling layer,the transmission layer and the link are designed,and the transport layer adds two-bit control characters to the 8-bit data group at the end of the transmitting data.The scrambling layer adopts the mode of synchronous scrambling,which will enter the adjacent data of the scrambling layer module.The results of the next periodic data are repeated or disturbed;the link layer mainly completes the sending Data group synchronization,the sending channel initializes the synchronization sequence,the receiving end sends the response signal completes the initialization process.The 8B/10B codec part is based on the module to encode the polarity deviation value,which ensure the effective clock conversion and the frequency of data conversion.The simulation results show that it based on ENPC of the phase deviation of the monitoring results.When the effective transmission distance reaches 800km,the BER is less than 10^-2.