Dense wavelength division multiplexing (DWDM) is a Technology that uses multiple wavelengths to transport a vast number of separate channels. In this monograph, the combined effect of important fibre nonlinearities (stimulated Raman scattering, SRS and four wave mixing, FWM) in the presence of amplifier noise and receiver noise has been studied at different data rates. The optimization of the system parameters has been done considering SNR and BER. The investigations were repeated considering specifications of two commercially available fibres also and these results validated...