Technology convergence is reshaping the 6G access network architecture, but are our infrastructures ready to cope? [Invited]

The goal of 6G is to further advance the quality of experience in human–human communications while it transforms the I4.0 landscape by integrating a diverse set of technologies, services, and applications. To achieve this goal, there are rapid convergence steps between wireline and wireless technologies toward a unified transportation platform, something that prompts architectural modifications. Intelligence is now distributed closer to end-users, with far-edge nodes becoming essential. However, these nodes must balance performance and affordability for operators. Moreover, the converged wireline and wireless technologies must consider the scarcity of fiber in the last mile. In this work, we contribute to the debate of parallel, decoupled fiber infrastructures versus a single passive PtMP connectivity scheme under the framework of fiber scarcity and for residential users with multi-Gb/s line rates, while small cells exploit mmWave technology with ${\gt}{100}\;{\rm MHz}$ RF bandwidth. Our analysis is based on the information supplied by operators regarding the practical constraints and limitations arising from real-life deployments, and it is based on realistic geospatial data. We conclude that fiber utilization becomes prohibitively high under both alternatives when low-cost, gray interfaces are employed, and the deployments become viable in terms of fiber utilization only when colored interfaces and WDM are introduced. Furthermore, this work contributes to the discussion on the efficacy of next-generation PON technology in accommodating varied capacity requirements without increasing fiber use. The recently announced 25G and 50G TDM PONs are struggling to satisfy connectivity demands within the current fiber deployment frameworks when small cells utilizing high-layer splits (F1) and residential users are served by multi-Gb/s line rates. Beyond this point, when small cells employing low-layer splits are deployed alongside multi-Gb/s line-rate residential users, a shared scheme utilizing PtMP trees and technologies supporting a total capacity of 400G seems to be the next barrier to reach to prevent the depletion of fiber infrastructures. At the end, we report our findings based on the benchmark of alternative 400G solutions against their resource utilization.