Demonstration of Bi-Directional Point-to-Multipoint Coherent PON Using Digital Subcarrier Multiplexing for Broadband Access and Wireless Fronthaul

The integration of fiber and wireless communications presents a promising avenue to enhance communication networks, supporting the evolution of 5G-A/6G technologies, which includes upgrades to traditional access networks and mobile X-haul. We propose a point-to-multipoint (PtMP) coherent passive optical network (PON) architecture based on digital subcarrier multiplexing (DSCM) supporting fiber-wireless convergence scenarios as a promising solution for fixed and mobile access networks. The characteristics and potential applications of coherent PON, DSCM, and analog fiber-wireless transmission technologies are analyzed in the context of access networks. To evaluate our proposed scheme, we demonstrated a rate-flexible PtMP coherent PON architecture with downlink and uplink using DSCM to support fixed broadband access and W-band millimeter wave (mm-Wave) wireless access simultaneously. The architecture implements four 25G subcarriers for downstream and up to four 25G (fiber-wired) /12.5G (mm-Wave wireless) subcarriers for upstream, respectively. The results show that over 40 dB/42 dB power budget at SD-FEC threshold in fixed broadband access downstream/upstream transmission can be achieved, and over 34 dB/47 dB power budget in mm-Wave wireless access downstream/upstream (50G) transmission can be achieved, respectively. This scheme offers a favorable balance between system complexity and cost-effectiveness for next-generation optical networks and wireless access in the 5G-A/6G era.