Forward Error Correction Applied To Polarization Mode Dispersion Compensation System

Optical fibre communications have been expected to be a high-speed and high-capacity communication, which has a lot of advantages such as low loss, high spectra capacity, small size, low weight. In the early period, due to the development of optical fibre and relevant optoelectronic equipments and devices, system performance was so good that forward error correction technique was not even needed to be used in, communication system, and the relatively faster optical information rate made that error correction did not match the codec with the transmission system. Until the light transmission rate gone up to the Gb/s, and the transmission distance without repeaters had been extended by the applying of optical amplification, some factors such as polarization mode dispersion, were found to be bottleneck in the further improvement of system performance, while these factors in the short-range, low-rate system was not obvious,. So the research of FEC applied in optical communication system started. LDPC code is near the Shannon limit performance of "good" code and the decoding complexity is relatively low. The polarization mode dispersion compensation and polarization mode dispersion mitigation (FEC) in combination has some theoretical and practical value.◆Brief introduction of the production mechanism of polarization mode dispersion, the representation of state of polarization (SOP) and the related concept of feedback control algorithm for polarization mode dispersion.◆Introduction of some basic concepts and the definition of low-density parity-check (LDPC) codes (which currently has the best theoretical performance), the method for constructing and the H matrix, and some commonly used decoding method, such as……(SPA) and bit reversal algorithms (bii-flipping).◆LDPC codes are compared with the Gaussian channel is transmitted in optical fibre transmission error correction performance of the simulator, numerical simulation and the specific discussion, concluded that the LDPC codes for optical fiber transmission to reduce the error rate and improve the tolerance of PMD Played a good role. Obtained simulation result of 5-6dB BER improvement for lOGb/s OOK transmission by using both PMDC and LDPC.◆The error correction performance of LDPC codes in the Gaussian channel and the optical fiber transmission system with PMD simulator have been simulated and compared. It has been proofed that he LDPC codes for optical fiber transmission could reduce the error rate and improve the tolerance of PMD. And the simulation result of 4-7dB BER improvement for 10Gb/s OOK transmission by using both PMDC and LDPC has been obtained.Establishment of LDPC and LDPC FEC scheme interwoven cascade of polarization mode dispersion compensation system, a collection of numerical simulation model to analyze the results of polarization mode dispersion compensation and mitigation devices to a certain effect and improve the BER and the tolerance of PMD Degrees. Established cascade LDPC and RS FEC programs intertwined with enhanced polarization mode dispersion compensation system, to analyze the results showed that the compensation of polarization mode dispersion played a certain effect and improve the bit error rate, and increased the polarization mode dispersion tolerance. Obtained simulation result of at least 6dB BER improvement for 40Gb/s OOK transmission by using PMDC and eFEC.