Is the Gaussian Channel Model Suitable for Converged Metro-Access Optical Networks?

We investigate the validity of the Gaussian channel model for converged metro-access optical networks, focusing on scenarios where dual-polarization coherent transmission extends across both metro and access segments. We demonstrate that, when appropriately defined, the model remains valid and is effectively characterized by amplified spontaneous emission noise from amplifiers and nonlinear interference from fiber propagation. However, in the context of single-fiber bidirectional propagation typically employed in access segments, additional impairments due to crosstalk and reflections must be considered as a distinct noise source. Furthermore, quality-of-transmission penalties arising from filtering and polarization-dependent loss can significantly impact performance and must be accounted for. To accurately capture the end-to-end system behavior, a realistic transceiver (TRX) model is essential, particularly to reflect the interplay between channel and TRX noise as a function of the received power-which may be low due to the passive nature of the access segment. Our results confirm that, with these considerations, the Gaussian channel model provides a robust and insightful framework for performance evaluation in converged optical networks.