Telecommunications companies typically use fiber optic cables for long distance runs, because of their resistance to attenuation and electromagnetic interference. However, the so-called last mile - the connection from the nearest switch to the end user’s premises - has traditionally been a copper-based medium. Copper cables are relatively inexpensive to install and maintain and have long provided adequate performance and bandwidth within a certain range. However, some of the larger communications companies have launched high-speed broadband services that run fiber optic cables through some or all of the last mile.
Generic names for these services are various, depending on where the fiber optic cable terminates, but they all follow the format FTTx, where x is the terminus of the fiber optic cable. Fiber-to the-node (FTTN) and Fiber-to-the-curb (FTTC) refer to services that run fiber to within a few kilometers or less than a kilometer from the subscriber’s location, respectively. Fiber-to-the-premises (FTTP), sometimes called Fiber-to-the-home (FTTH), runs the fiber optic cable all the way to a demarcation point on the outside wall or in the basement of the sub- scriber’s building. Fiber-to-the-desk (FTTD) refers to a fiber optic run all the way to a terminal or media converter inside the subscriber’s premises.
The performance of these services depends on the proximity of the fiber optic run to the user’s premises. Running the fiber optic cable all the way to the building means that the high - speed services can connect directly to a home or office network running a Gigabit Ethernet or 802.11 wireless LAN. If the fiber terminus is more than 100 meters away, then some sort of interim medium is needed, such as VDSL.
Fiber optic cable is much more difficult and expensive to install than any of the standard types of copper cable. Deploying fiber in the last mile is an expensive proposition, and one of the methods providers use to control leased line price is the passive optical network. A passive optical network (PON) is an arrangement in which data from an optical line ter- minal (OLT) at the provider’s central office runs through a single fiber optic cable to a series s of optical splitters near the subscribers’ premises. The splitters duplicate all of the incoming signals and send them out through separate fiber runs to optical network terminals (ONTs) at the individual users’ locations.
A PON is a lower-cost alternative to an active optical network (AON), because it uses unpowered splitters to duplicate the incoming signals, rather than a complex router that separates the data stream into the packets intended for each subscriber. Commercial implementations of this technology typically bundle voice, video, and data services into a single package, providing a complete media solution for the subscriber. Internet access is generally available in several tiers, with varying prices. Theoretical speeds can reach as high as 150 Mbps downstream and 25 Mbps upstream.