Study On Transmission Performance Of Remodulation OFDM-WDM-PON

In recent decades, as multimedia and other broadband services emerge in access networks, the demand of bandwidth grows much higher, and the bandwidth bottleneck in access networks, which is the ‘last one mile’ of information high-speed way, has attracted more and more attention.Apparently, the traditional access networks based on electrical cables can not meet the requirements,the technology of optical fiber communication has gradually extended from the backbone and metropolitan networks to access networks, in which time-division passive optical networks are mainly used. As occurrence of high-definition television and other new applications, bandwidth requirement of access networks continue to increase, and WDM-PON appears as one of the best solution for future access networks to address the problem of bandwidth shortage. On the other hand, OFDM technology can convert high speed data signal into multiple parallel low-speed data,which can effectively reduce inter-symbol interference, and it is also a research hotpot these days.The thesis combines WDM-PON and OFDM, and focuses on the research of the system structure and transmission performance of the re-modulated OFDM-WDM-PON. The thesis first introduces the basic knowledge of optical access networks and OFDM characteristics, and then establishes the system model of OFDM-WDM-PON. Optical fiber with intensive periodic dispersion is used for dispersion management of the system, combining with different types of modulation signal format. Transmission performance of the system is studied based on the upper mentioned technologies. Finally PAPR of OFDM are studied with a combination algorithm of m sequence PTS+Walsh transform, which greatly reduces the computation complexity and improves the bandwidth utilization while guaranteeing the system BER performance,.The simulation is implanted with Optisystem and MATLAB. Optisystem is used to realize the simulation of the re-modulated OFDM-WDM-PON, MATLAB is used to simulate the Optical fiber with intensive periodic dispersion, which results are parameters inputs of the simulation of the re-modulated OFDM-WDM-PON. The simulation results show that the uplink performance of re-modulated WDM-PON with dense dispersion management is much better than that of no dispersion management. By simulation, it is found that the transmission performance with dense period dispersion in OFDM-WDM-PON has an apparent improvement, in which the bit error rate and emission light power is reduced apparently, and it can further suppress nonlinear effects. The new algorithm of m PTS+Walsh also significantly reduces the value of PAPR.