## 2 Broadband System
### Fixed-Line Broadband System
#### 2.1.4 Fiber Technologies  
A notable solution for enhancing the system performance is fiber-based technology. It entails the deployment of optical fiber straight from the CO to each provider's equipment that is located on the customer's premises (Customer premises equipment (CPE)). The resulting network loops are known as FTTH loops [18]. An FTTH network can be implemented based on architectural solutions such as Passive Optical Network (PON), point-to-point (PtP) fiber, and hybrid PONs architectures. As discussed in Section 7, PON is the most widely employed solution, and it enables multiple homes to coexist on shared passive fiber infrastructure. Consequently, all subscribers share the exchange costs, and the cost per subscriber metric is significantly reduced. Apart from the fact that the passive nature of the PON solution helps in reducing network complexity, it also aids in improving the system's reliability. Similarly, the PtP network, also known as All-Optical Ethernet Network, offers a dedicated line connection from the operator to each subscriber's home or apartment. This presents a significant benefit over the PON networks. Higher bandwidth with enhanced traffic security can be easily delivered to the subscriber. Moreover, due to its close similarity to the Local Area Network (LAN), the PtP network can effectively leverage the existing LAN equipment and components in order to reduce the network cost. Nevertheless, in PtP networks, powered or active nodes are required for management purposes. This may result in expenditure increase and reduction in the system reliability [16; 18]. Another FTTH network architecture is the hybrid PON system in which PtP and PON architectures are combined [18]. \begin{table}
\begin{tabular}{l l l} \hline \hline  & \multicolumn{2}{c}{**Codec Technology**} \\ \cline{2-3}
**Video Format** & **HEVC a (Mbps)** & **VVC b (Mbps)** \\ \hline
720p HD (1280 \(\times\) 720) & 2 & 1.3 \\
1080p HD (1920 \(\times\) 1080) & 4 & 2.6 \\
4k UHD (3840 \(\times\) 2160) & 12 & 7.8 \\ \hline \hline \end{tabular}  
* Current. b Future. HEVC: High-efficiency video coding; VVC; Versatile video coding.  
\end{table} 
Table 3: Data rate requirements for HD and UHD video considering various codec technologies [141]. Note that FTTH network deployment may be a very costly investment. Consequently, for a cost-effective realization of the network requirements, service providers with copper wire network and DSL technology are exploiting hybrid optical fiber and/or the existing network [7]. Moreover, some of the existing optical broadband network architectures are significantly addressing the network performance bottleneck through progressive service delivery in close proximity to the customers. Furthermore, the generic term for describing some variants of fiber-based broadband network architecture is FTTx. A typical FTTx architecture is shown in Figure 4. Note that optical fiber can be employed for all or part of the last-mile network local loop. Therefore, the employed FTTx type, like fiber to the node (FTTN), fiber to the building (FTTB), fiber to the cabinet (FTTC), fiber to the premise (FTTP), and FTTH, is majorly determined by the termination of optical fiber and the copper line with respect to the CO and the CPE [7; 143; 144]. In addition, with reference to the PON system that will be presented in Section 7, FTTx networks can be effectively supported by the architecture. This depends on the ONU deployments as well as the demarcation point between the optical fiber and copper cable termination. For instance, with the implementation of FTTC, ONUs deployment can be effected beside the telegraph pole junction boxes. Based on this arrangement, some twisted-pair cables can be employed to connect the individual customer to the ONUs. Note that FTTC network is not only a cost-effective technology, but also a practical solution for supporting narrowband services. Nevertheless, it is not an ideal solution in a scenario where narrowband and broadband services are to be merged [143; 144].