Modeling and analysis of coherent metro + PON converged networks for ultra-high speed applications

To meet the ultra-high bitrate and extended-reach demands of future broadband services and 5G/6G fronthauling, today’s passive optical networks (PONs) require a significant technological jump, particularly towards coherent detection. This shift makes the development of fast and accurate models for future coherent PONs essential, especially for physical-layer network planning tools and digital twin applications. In this paper, we thus present a frequency-resolved physical-based model for performance estimation of coherent transmission over PON or ${\rm metro} + {\rm PON}$ converged networks, considering a broad range of electrical and optical impairments and two approaches for DSP-based equalization. Specifically, the model accounts for frequency- and polarization-dependent optical channels, optical and electrical noises, coherent receiver electrical bandwidth limitations, and in-phase/quadrature imbalances. Numerical validation of the proposed frequency model against extensive time-domain simulations demonstrates high accuracy across diverse impairments, with discrepancies in the estimated signal-to-noise ratio showing a standard deviation of 0.15 dB over a very wide variation range on the relevant parameters, along with significant improvements in both time and computational efficiency. We conclude the paper by presenting two examples of application of the developed model in dimensioning ultra-high bitrate future access networks.