Access-Aware Launch Power Optimization for RAN Fronthaul in Converged Metro-Access Optical Networks

Converged metro–access optical networks for 6G x- haul exhibit per-leaf access-loss variations among radio units (RUs), causing non-uniform received optical power at the splitter under conventional uniform launch power provisioning. This work investigates access-aware Tx-power optimization for RAN fronthaul over a realistic converged metro–access topology with multiple RUs, using an experimentally characterized 400 Gb/s DP-16QAM Phoenix DCO whitebox transceiver. Three launch- power provisioning strategies are evaluated under joint BER and 3GPP functional split 7.2 latency constraints: Uniform Launch Power (ULP), Per-leaf Adaptive (PLA), and Conservative Provisioning (CP). GSNR analysis identifies an optimum launch power of ∼+1 dBm. While ULP provides the highest GSNR, PLA achieves a uniform splitter optical power across leaves at the cost of ∼0.7 dB GSNR penalty caused by increased NLI. These results highlight the trade-off between maximizing physical-layer margin and achieving a uniform splitter power profile.