## 3 Services Layer: From Telephony to Virtual Reality
### Main Achievements, Key Services and Requirements of Each Generation
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline  & & & & & & & & \\ \hline \multicolumn{2}{c}{**Service Requirements**} & \multicolumn{2}{c}{**Service Type**} \\ \hline  & **BR/Service** & **Service Type** & **Typical BR** & **Latency** & **Reliability** & **Availability** & **eFBB** & **FFC** & **GRE** \\ \hline F1G (NB Era) & 64 kb/s & Telephony, Fax & 64 kb/s & L & - & L & & \\ \hline F2G (WB Era) & 2 Mb/s & Photos, SD Video & \textgreater{}1 Mb/s & M & - & L & & \\  & & Web Browsing & \textgreater{}1 Mb/s & M & - & M & & \\  & & Search Engines & \textgreater{}1 Mb/s & M & - & L & & \\  & & E-mail & \textgreater{}1 Mb/s & M & - & L & & \\ \hline F3G (BB Era) & 20 Mb/s & IPTV & \textgreater{}10 Mb/s & L & - & M & & \\  & & E-commerce & \textgreater{}5 Mb/s & M & - & L & & \\  & & Telecommunuting & \textgreater{}5 Mb/s & L & - & H & & \\  & & Videoconferencing & \textgreater{}10 Mb/s & L & - & L & & \\  & & E-learning & \textgreater{}5 Mb/s & M & - & L & & \\  & & E-Government & \textgreater{}10 Mb/s & M & - & L & & \\  & & Emergency & \textgreater{}10 Mb/s & L & H & L & & \\  & & Management Operations & & & & & & \\ \hline F4G (UBB Era) & 100 Mb/s & 4k HD/multiple screens & \textgreater{}50 Mb/s & L & - & L & & \\ \hline F5G (GB Era) & 1 Gb/s & UHD video streaming & \textgreater{}100 Mb/s & L & - & L & x & x \\  & & E-health & \textgreater{}200 Mb/s & L & H & H & & x \\  & & Cloud Office & \textgreater{}50 Mb/s & L & - & L & x & \\  & & Online Education & \textgreater{}500 Mb/s & L & - & M & & x \\  & & Online Entertainment & & & & & & \\  & & (Gaming, Social & \textgreater{}300 Mb/s & L & - & H & & x \\  & & Networking) & & & & & & \\  & Virtual Reality (VR) & \textgreater{}200 Mb/s & L & - & M & x & x \\  & & Augmented Reality & \textgreater{}200 Mb/s & L & - & M & x & x \\  & Smart Infrastructure & & & & & & & \\  & (Home, Factory, City) & & & & & & & \\  & Enterprise Cloudification & \textgreater{}100 Mb/s & L & - & H & & x & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Classification of services and their requirements using the F1G-F5G scheme. eFBB: Enhanced Fiber Broadband, FFC: Full Fiber Connection, GRE: Guaranteed Reliable Experience, NB: Narrowband, WB: Wideband, BB: Broadband, UBB: Ultra Broadband, GB: Gigaband. Subscriber Line (ADSL) technology, which exploited the copper spectrum more efficiently than PSTN and ISDN. _F3G: 2005-2010 (the broadband era)_  
The third generation of fixed networks introduced a broader range of broadband services targeting a variety of different users: from residential areas to businesses and from universities to government services. The requirements of each service varied, and the network provider had to tailor the network to each category in order to serve multiple heterogeneous services. For example, emergency management services require great network reliability, as their seamless and with low latency operation is mandated. Moreover, telecommuting requires high network availability due to the increased number of working hours. Further, the users of e-services categories such as e-learning, e-government and e-commerce can tolerate a medium latency. Finally, the minimum data rate required to serve F3G services is set to 5-10 Mb/s. The end users accessed these technologies using xDSL standards, where very-high-bitrate DSL (VDSL) was widely commercialized to support the F3G services, while Fiber to the Cabinet/Building (FTTC/B) increased the network connectivity. _F4G: 2010-2018 (the ultra-broadband era)_  
The fourth era of fixed networks was clearly dedicated to 4K high-definition (HD) video and the use of multiple screens. This became possible with the wide deployment of Fiber to the Home (FTTH). During this era, network development was accelerated in order to underpin 4k HD video and multiple screens, which were used in the 2012 London Olympics. The main deployed standards of the F4G era were GPON and EPON, while 10G-EPON, NG-PON2 and XG(S)-PON were standardized during this generation.