13.5 BROADBAND ACCESS TECHNOLOGIES

Broadband access systems are characterized by significantly larger channel bandwidths, enabling higher data rates and supporting multimedia services such as video, high-speed data, and interactive applications. Unlike narrowband systems, which adapted digital signals to analog voice channels, broadband systems are typically designed from the outset as fully digital end-to-end systems.

Examples include digital subscriber line (DSL) technologies, cable modem systems, fiber-to-the-premises (FTTP), and modern wireless broadband systems. These technologies combine advanced modulation, coding, and multiplexing techniques to maximize throughput over available physical media.

13.5.1 Fiber To The Home/Office (FTTH)

The broadband access technique known as fiber to the home/office (FTTH) involves using only fiber-optic cable to provide the last segment of the communications channel. The advantage of this technique is that fiber-optic cable is able to support very high data rates. For example, with the added benefits of Dense Wave Division Multiplexing (DWDM) per-fiber capacities in the multi-terabit-per-second range are achievable using dense wavelength-division multiplexing (DWDM). The major disadvantage of FTTH is the expense of laying fiber-optic cables to each customer’s premises and the individual optical-to-electrical converters required to terminate each of these cables. While fiber installation (civil works, trenching, splicing) can be expensive, the cost of optical fiber itself is often comparable to or lower than copper; the dominant cost is typically deployment rather than the medium. Additionally, if a standard modem is to be used at the customer premises, the optical signal must be converted into an electrical signal by an optical network terminal (ONT) before it can be processed by user equipment. The equipment required to perform this conversion is also much more expensive than the equipment required to terminate a standard copper cable.