# A Vision of 6 th Generation of Fixed Networks (F6G): Challenges and Proposed Directions
## 2 Services and Requirements for F6G
### Upcoming Categories of Services and Their Requirements  
As shown in Figure 1, network evolution is service driven, and network operators and service providers continuously try to introduce \"fresh\" services to users in order to capitalize their investments on their network upgrades/transformations. Consequently, the service needs are always increasing with time. As in this paper we focus mainly on F6G, we tabulate a list with the most representative categories and services for the F6G ecosystem (Table 1). We classify the services into six categories based on three key requirements, which are bit-rate, fiber density, and latency. Three categories require only one of these requirements to be met in order to operate without disruptions and are named Enhanced Fiber BroadBand (eFBB), Full Fiber Connection (FFC), and Guaranteed Reliable Experience (GRE) [7]. The main key requirement for each category is a high bit rate, high densification, and low latency, respectively. Further, three more categories require a combination of the aforementioned three key requirements and are named Full Fiber BroadBand Connection (FFBC), requiring both high fiber density and high bit rate; Guaranteed Reliable Fiber Broadband (GRFB), requiring both low latency and high bit rate, and; Guaranteed Reliable Full Fiber Experience (GRFFE), requiring both high fiber density and low latency. It is worth mentioning, that some services may require _all the three key requirements to be met concurrently_, as they need to collect bandwidth-consuming signals and data (e.g., video) from various network points in order to process them in real time and inform the respective element in order to make a decision. Indicative services for this category are ultra-smart ports, airports, railways, and autonomous truck and taxi-fleets. Our vision of the F6G ecosystem incorporating the six service categories is pictorially described in Figure 2.  
The categorization scheme for the 6G services presented in Figure 2 is equivalent to the scheme proposed in [9], which focuses mainly on the categories supported by the wireless part of the network. In the current work, the proposed scheme includes 6G services underpinned by the fixed part of the network. Both schemes complement each other in order to offer all service categories to the users at any point on the globe and regardless of the technology the users exploit to access the network. The equivalent categories of services accessed using the wireless part of the network are designated in Figure 2 in parentheses in red. Another classification that can be made regarding F6G services is based on the domain of operation. The first domain includes 14.0 services, such as digital twins, automated operations in a harsh environment, collaborative robots (cobots), Augmented Reality (AR), and AI synergy with cloud computing, which aims to improve the quality of decisions on the production line. These services require high bandwidth, low latency, high reliability, and medium fiber density in order to operate efficiently. The second category includes entertainment/communication services, such as holograms, immersive extended reality, and internet of senses. There is a dissimilarity regarding the requirements of these services (e.g., holographic communications and extended reality require a high bit rate and low latency while the internet of senses shows more relaxed needs on latency and bit rate). The third category includes ultra-smart transportation and can be introduced in various typesof mediums, such as ports, airports, city roads, highways, and railways. Safety is one of the most important requirements here, but reliability, sufficient availability, high bandwidth, and low latency are also a must. The fourth category includes e-health services, such as Telesurgery, AR field medical support, and remote areas diagnosis/consultations, which mandate low latency and very high reliability.