Investigation of Transmission Impairment for Dynamic Base Unit Channel Allocation in DWDM Systems

The traditional approach of Fixed Base Units (FBU) in Unequally Spaced (US) Dense Wavelength Division Multiplexed (DWDM) systems outperforms Equally Spaced (ES)DWDM Systems. Currently in the scenarios of diverse bandwidth requirements for next generation optical communication systems, a novel Dynamic Base Unit (DBU) unequal channel (US) allocation strategy is designed, and the performance benefits are investigated over the traditional existing Fixed Base channel allocations. The proposed algorithm decides the total number of base units covering the optical bandwidth. After the channel allocation in the first base unit $BU_{i=0}$ the current work discusses the case of reducing the number of channels in subsequent Base Unit $(BU_{i=1,2,..})$ by a factor of 2. Moreover, the adjacent base units are allotted even and odd frequency slots. Thus, this is an optimum strategy where maximum non-uniformity is taken care of in channel allocations. This drastically reduces the nonlinear effects of Four Wave Mixing (FWM) prominent in DWDM systems using Dispersion Shifted Fibers. The proposed algorithm is evaluated in terms of the bandwidth occupancy and number of Four Wave Mixing products. Performance up to greater than 34.6% reduction in FWM is observed. Bandwidth occupancy shows 13.7%, 6.25% and 7.45% reduction than the popular Unequally Repeated US(URUS), Paired URUS and Alternately Paired RUS (PURUS) schemes respectively. The high improvement factor is observed when using DBU-US. It is concluded that Dynamic Base Unit-Unequally Spaced channel allocation is superior and is considered a suitable candidate for high speed DWDM transmission systems.