Evaluating Metro-Access Optical Networks as-a-Service for Flexible RAN X-haul

This article examines the feasibility of employing converged core-metro-access optical networks to support Radio Access Network (RAN) fronthaul and mid-haul transport under realistic performance constraints. The analysis focuses on the profile of the bit error rate (BER) and the latency evaluation in the context of 5G functional splits. We used a commercially available Nokia ICE-X 400G multi-carrier coherent transceiver, leveraging its digital subcarrier multiplexing (DSCM) capability: Supporting DP-16QAM modulation at 4 GHz channel spacing and 64 GBaud symbol rate per subcarrier. The study is carried out on a representative metro-access topology, where all Radio Unit (RU)- Distributed Unit (DU) - Central Unit (CU) paths are evaluated against BER thresholds and latency bounds for front-haul and mid-haul segments, respectively. The results reveal critical trade-offs between optical reach, modulation format robustness, and latency compliance and demonstrate how mid-haul link distances and routing diversity significantly impact overall transport feasibility for disaggregated RAN deployments. This work emphasizes the potential of transparent optical metro-access infrastructures to serve as an efficient and scalable transport layer for 5G and beyond.