Statistical Route Feasibility in Metro-Access Optical Networks for Next-Generation RAN X-Haul

This paper investigates the statistical feasibility of routes in converged metro-access optical networks for next-generation RAN x-haul. Two network topologies are considered: N1 with longer metro spans and N2 with shorter, denser connectivity. Route feasibility is evaluated via Bit Error Rate (BER) profiling under two thresholds (10−3 and 10−2), using two commercially available coherent transceivers: Cassini DCO (DP-QPSK, DP-8QAM, DP-16QAM) and Phoenix DCO (DP-QPSK, DP-16QAM). A Python-based physical-layer simulator models attenuation, ASE, and NLI to derive GSNR and end-to-end SNR per route; BER is then computed via modulation-dependent closed forms. Results show that DP-QPSK provides near-universal feasibility in both networks, while higher-order formats, especially DP-16QAM, are strongly topology and threshold dependent. N2 enables significantly broader applicability of high-order modulation than N1, and Cassini’s intermediate DP-8QAM offers a robust capacity–reliability trade-off absent in Phoenix. These findings highlight the importance of network-aware planning and transceiver flexibility to ensure route viability for RAN transport over converged optical infrastructures.