Electronic Dispersion Compensation In High Speed Optical Communication System With New Modulation Formats

With the data transmission rate of single channel in optical communication system increases, dispersion effect is becoming the main factor affecting the transmission rate and bandwidth. To reduce transmission impairments and increase the system capacity and transmission rates, a variety of new technologies and new methods are springing up, in which, various new modulation techniques and electronic dispersion compensation technique are two key ones, and the combination of them can be more effective.The two technologies and the interaction between them are studied. Two structures of equalizers are studied and compared, which are FFE and DFE normally used in engineering. Computer simulation results verify that DFE is more powerful compared with FFE.Influences caused by different parameters in LMS algorithm are also studied and the method of adjusting various parameters in actual application is summarized. Moreover, a new improved LMS algorithm is proposed to solve the limitation of poor convergence. The proposed LMS algorithm has good convergence and track performance since present error signal is used to evaluate next recursive step size.A comprehensive assessment for different intensity and phase modulations is proposed. Results show that 66% duty cycle RZ signal, namely the CSRZ pattern, has the best performance in the intensity modulations. In the phase modulations, the most outstanding modulation method is DPSK. DQPSK modulation is also a very promising choice if the noise disturbance could be resolved.Finally, the performance of electronic dispersion compensation equator is evaluated when using various new modulation methods. Results show that modulations whose carrier wave is restrained do not have obvious effects.