# A Vision of 6 th Generation of Fixed Networks (F6G): Challenges and Proposed Directions
###### Abstract  
Humankind has entered a new era wherein a main characteristic is the convergence of various technologies providing services and exerting a major impact upon all aspects of human activity, be it social interactions with the natural environment. Fixed networks are about to play a major role in this convergence, since they form, along with mobile networks, the backbone that provides access to a broad gamut of services, accessible from any point of the globe. It is for this reason that we introduce a forward-looking approach for fixed networks, particularly focused on Fixed 6 th Generation (F6G) networks. First, we adopt a novel classification scheme for the main F6G services, comprising six categories. This classification is based on the key service requirements, namely latency, capacity, and connectivity. F6G networks differ from those of previous generations (F1G-F5G) in that they concurrently support multiple key requirements. We then propose concrete steps towards transforming the main elements of fixed networks, such as optical transceivers, optical switches, etc., such that they satisfy the new F6G service requirements. Our study categorizes the main networking paradigm of optical switching into two categories, namely ultra-fast and ultra-high capacity switching, tailored to different service categories. With regard to the transceiver physical layer, we propose (a) the use of all-optical processing to mitigate performance barriers of analog-to-digital and digital-to-analog converters (ADC/DAC) and (b) the exploitation of optical multi-band transmission, space division-multiplexing, and the adoption of more efficient modulation formats. f 10 2023 4 2  
and eventually the fusion, of those technologies that define our technosphere into a single technological continuum [2; 3; 4]. Social interactions are about to deepen through a broad gamut of novel services to be offered to end-users by service/network providers and will be emerging in the context of the 6 th Generation of Fixed networks (F6G). The work of [5] presented the evolution of services as well as the various network layers over the first five fixed-network generations (F1G-F5G), based on a layered approach to enable deeper understanding of the key drivers underlying the evolution. More specifically, ref. [5] examined and reviewed the key technological advances, standards, enablers, and limitations in fixed telecommunication networks over the past 50 years. The starting point of [5] was 1970 and the ending point is 2020, examining the impact of the third Industrial Revolution on the various layers of the telecommunications ecosystem. In the current work, we are examining the impact of the fourth Industrial Revolution on the various layers of the telecommunications ecosystem particularly focusing on F6G services and their requirements, following a dialectical procedure and observing that the limitations of F5G are becoming the novelties of F6G. The main aim of the work of [5] and the current visionary work is to shed light particularly on the fixed part of the network, as the wireless part of the network and its generations have been extensively investigated in the literature. For telecommunications, fixed constitutes one pillar and wireless the other; for this reason, from the end users' perspectives, they are of equal importance, as they can exploit one or the other pillar to access the network and enjoy the offered services. Both fixed and wireless parts of the network have specific Key Performance Indicators (KPIs) and requirements, which need to be satisfied in order to ensure seamless operation of the 6G/F6G demanding services during the entire service life-cycle; the most important can be found in [6]. In this work, our methodology for presenting our vision is as follows. First, we explore the strict requirements demanded of the service/network providers, such as high bit-rate, low latency, dense connectivity, and more (Section 2).