Physical layer performance of multi-band optical line systems using raman amplification

Network operators are aiming to overcome the envisioned data traffic crunch by relying on already installed fiber cables. Multiband optical line systems (LSs) will thus be the solution, starting from the extension to C+L band transmission. Such a bandwidth extension also speeds up network disaggregation to avoid an increase in costs. Thus, LS controllers need quality-of-transmission estimator (QoT-E) modules capable of quickly estimating the merit of lightpaths, and so analytical models for the transmission layer are mandatory. We review the generalized Gaussian noise (GGN) model for wideband prediction of nonlinear interference generation and validate its accuracy by comparing C+L simulative results to model predictions. Results are obtained for the case of amplification using a hybrid Raman and erbium-doped fiber amplifier, and display excellent conservative accuracy. We also present an experimental validation performed on commercial equipment that confirms how the GGN model is the most feasible solution for QoT-E modules in multiband LS controllers, enabling a frequency-resolved minimization of system margins.