Research On Ultra-High-Speed Long Haul Transmission System Based On OOFDM

Optical orthogonal frequency division multiplexing(OOFDM) is a new optical transmission technology,and it's also a new type of optical communication technology which focuses on the advantages of the digital signal processing and optical communication technology,not only it can resist chromatic dispersion,polarization mode dispersion and other nonlinear effects in optical fiber link, but also it can improve spectrum efficiency greatly.Using OOFDM technology we can realize ultra-high-speed transmission without dispersion compensation, the requirements of the optical amplifiers can be reduced as well.As a result, the transmission capacity can be increased greatly.Therefore,OOFDM technology is extensively used in high-speed long haul transmission systems.In this thesis, the transmission system based on OOFDM technology was studied,mainly including systems theory model,different modulation schemes,system performance,time synchronization and high-speed long haul simulation.Specific contents as follows:Firstly,we analyzed the model of OOFDM transmission system and the principle of the coherent optical communication system.Combined the two technologies'advantages,we proposed the 10Gbps experimental model based on CO-OFDM technology.Secondly,according to the experimental model,we studied the timing synchronization algorithms,and solved the synchronization problem of the system.At first, we introduced the principle the synchronization and the impacts due to,then the timing synchronization algorithm based on Zadoff-Chu sequence was theoretical analyzed and simulated.Without considering optical dispersion compensation, the system's transmission performance in different modulation methods were studied, meanwhile we analyzed of the relationships of the system transmission distance,optical signal to noise ratio (OSNR) and bit error rate(BER).According to the simulation results,we obtained that 4QAM was the optimal modulation method in the 100Gbps long haul transmission system under the current experiment conditions.Thirdly, the 100Gbps long haul transmission system based on CO-OFDM technology was simulated and studied on the optisystem simulation platform.PDM and XC-OFDM technology were introduced, and the 100Gbps CO-OFDM long haul transmission system based on OBM and PDM was raised,the simulation results were given as well.The relationship between system BER and launch power was studied.The OSNR-BER curves of back to back transmission and 1000km transmission were compared.Using random data filling validated the reliability the simulation,the system performances of the single channel and WDM with random filling and uniform filling were studied.