## 3 Services Layer: From Telephony to Virtual Reality
### Main Achievements, Key Services and Requirements of Each Generation
The requirements for 4k HD video include a data rate of at least 50 Mb/s, while latency and availability became tolerable. _F5G: 2018-2025 (the gigaband era)_  
The fifth generation of fixed networks unleashes a new era of services while skyrocketing the overall user's QoE. This era is characterized by Gb/s data rates, full fiber connectivity and very low latency in order to seamlessly support a whole new set of services. The network providers are challenged to transform their infrastructure in order to provide at least 1 Gb/s data rate, full fiber coverage as well as less than 1 ms latency. The network and service providers that will invest in this transformation will directly profit from the continuously increasing digital economy, which is expected to rise up to USD 23 - trillion by 2025 [3]. Each F5G service has its own merits, however, some predictions on their dynamics have been drawn in [3] and are summarized here. Cloud VR (Virtual Reality) aims for a high user experience exploiting a 360\({}^{\circ}\) view starting from movies and games. The use of VR headsets is expected to grow with an annual rate of 66.7%, attaining an approximate number of about 440 million users by 2025. Smart homes include a wide range of \"intelligent\" devices exploiting high data rate connections, Internet of Things (IoT), cloud computing and Artificial Intelligence (AI) integrated with HD video in order to offer the ultimate experience to the residential user. The smart home industry is expected to grow by 129% in a five-year period, achieving an overall market value of USD 154 billion. Online gaming is a well-established market with more than 2 billion players with an annual growth rate of 9.3% from 2017-2021 and with an overall market value of USD 151.9 billion. VR is expected to significantly boost this type of service. Cloud desktops or virtual PCs expect to transfer the working office environment everywhere. The growth rate within the period 2016-2022 is expected to reach 39.4%. Safe city belongs to the smart city family and includes video surveillance, aiming to secure both public and private property. The overall market size is expected to reach USD 24.1 billion by the end of 2022. Enterprise cloudification will accelerate the migration of core services, such as daily office, enterprise resource planning, customer relationship management, etc., to the cloud. It is forecast that 85% of enterprises will be on the cloud by the end of 2025, and the annual growth will exceed 30% by 2022. Importantly, online education has accelerated during the COVID-19 pandemic, and it is an attractive solution for students as it allows them to learn anything from anywhere. The online education market worldwide is expected to grow between 2017 and 2026 with a compound annual growth rate of 9.5%, attaining a total of USD 398.15 billion. E-health aims to remotely monitor patients and perform diagnosis, treatment and consultation. A critical requirement that has to be met is reliability in order to accurately diagnose any potentially unpleasant condition instantly. The global market value of e-health is expected to exceed USD 66 billion by 2022, with an annual growth rate in of 22% China. Smart manufacturing incorporates the interconnection and integration of all devices onto a single platform for monitoring and configuration. The \"digital twin\" is expected to play a major role here by digitally replicating the whole production line. The most important requirements are reliability and very low latency in order to fully comply with safety regulations. The market size and growth rate predictions for several F5G services, according to [3], are summarized in Table 2.