6. Priority-Based Dispersion-Reduced Wavelength Assignment Scheme

Dispersion in optical fiber degrades the quality of signal in optical networks. Although the use of dispersion compensating fiber (DCF) reduces the effects of dispersion, it requires additional cost, and has more propagation loss compared to step-index fiber (SIF). This chapter introduces a priority based dispersion-reduced wavelength assignment (PDRWA) scheme to reduce overall dispersion in optical networks. The introduced PDRWA scheme assigns longer lightpath requests to the wavelengths having lesser dispersion and the wavelengths having higher dispersion are assigned to the lightpaths with shorter distance. If the lightpath requests are assigned to the wavelengths using such constraint on dispersion, the overall dispersion in the network is reduced to a great extent, which leads to better performance of the network in terms of overall signal quality (Q-factor) without increasing network setup cost. The performance analysis of the introduced PDRWA scheme using SIF is conducted with different channel speeds, such as 10, 40 and 100 Gbps, in terms of total dispersion and compared the same with the use of DCF. Simulation results indicates that the Q-factor, considering PMD effect, using the introduced PDRWA scheme with SIF is higher than that of using the introduced PDRWA scheme with DCF due to the higher PMD coefficient.