Benefits of Selective Hollow-Core Fiber Deployment for 6G X-Haul in Converged Metro-Access Networks

Hollow-core fiber (HCF) has recently emerged as a promising candidate for supporting X-haul transport with stringent latency and capacity requirements, owing to its reduced propagation delay and negligible nonlinear effects compared to standard single-mode fiber (SSMF). Despite these advantages, the implications of HCF deployment for future 6G X-haul transport under realistic fronthaul and midhaul constraints remain largely unexplored. In this work, we investigate the impact of HCF deployment on 6G X-haul over converged metro-access optical networks under joint bit error rate (BER) and latency requirements, considering functional split 7.2 as defined by 3GPP. Using an experimentally characterized digital subcarrier multiplexing (DSCM) coherent transceiver (TRx) model, we perform a routelevel feasibility analysis comparing SSMF with both complete and partial replacement of metro fiber spans by HCF. While HCF provides an inherent propagation-delay advantage of up to 30% over SSMF, topology-wide evaluation shows that this translates into an average end-to-end latency reduction of approximately 9% for complete HCF deployment, together with up to 32.8% higher route feasibility compared to SSMF in the considered scenario. While complete replacement of metro spans with HCF yields the highest performance gains, selective deployment over latency and impairment critical metro segments achieves a substantial portion of these benefits with significantly reduced fiber substitution. This demonstrates that hybrid HCF deployment provides a cost-efficient and scalable design option for meeting stringent 6G X-haul transport requirements in converged metroaccess networks.