Quality of Transmission Estimation for Planning of Disaggregated Optical Networks

Modern optical networks depend upon advanced software-defined networking (SDN) technologies, which in turn rely on a network abstraction to infer the quality of transmission (QoT). In general, the QoT estimation is based upon the generalized signal-to-noise ratio (GSNR), which takes into account the ASE noise, cross-phase modulation (XPM) and self-phase modulation (SPM) components of the nonlinear interference (NLI). Uniquely, the SPM accumulates coherently, causing the total amount of SNR degradation to depend upon the physical lightpath (LP) history, preventing a fully disaggregated GSNR degradation evaluation. As the current signal symbol rate are increasing, the SPM will provide a progressively more significant contribution to the SNR degradation. We propose a method to evaluate the equivalent SPM component of the NLI that is generated in each fiber span within an optical line system (OLS), independent of the history or configuration of the optical network.