Super-Broadband Optical Access Networks in 6G: Vision, Architecture, and Key Technologies

The sixth generation (6G) mobile networks are envisioned to provide ubiquitous super-band-width access services in the future. Academia and industry are making efforts to explore 6G technologies, especially enabling technologies of 6G radio access networks (RANs). Meanwhile, as the cornerstone of communication networks, optical fiber networks will continue playing a vital role in the 6G era. Next-generation OANs (NG-OANs), which are regarded as the main force of ultra-gigabit access, can provide users with stable super-broadband services, and are expected to support various super-bandwidth applications, including 3D holographic communication, 8K video streaming services, and so on. 6G RANs and NG-OANs are optional solutions to provide super-broadband access services, and their suitable scenarios to serve are different due to their pros and cons. It is envisioned that 6G RANs and NG-OANs will coexist and develop together in the 6G era. Toward this end, we provide in this article a detailed analysis of the architecture, enabling technologies, applications, and challenges of NG-OANs, and perform some comparisons between 6G RANs and NG-OANs on several critical metrics. After that, we propose a vision for the integrated fiber-wireless access networks supporting super-broadband services, and speculate on some potential challenges ahead.