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FTTH (Fiber to the Home)

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The majority of the Internet and the carrier networks are constructed with optical fiber cable, which provides gigabit-level speeds within the core. In contrast, the "local loop" and the "last mile" are still largely copper cable in the form of the twisted-pair telephone line and coaxial cable (CATV). DSL and cable modems have boosted access rates for home and small business users, but promoters of fiber to the home have a bigger goal. They want to deliver voice (up to six lines), data, and television services over a single cable. Extending fiber all the way to the home is now getting more attention because of reduced equipment costs and a bigger demand for service.

Note that fiber to the home is similar to HFC (hybrid fiber/coaxial) networks, which are built with a combination of fiber and copper cabling. A similar hybrid system extends fiber cable to carrier remote terminals and then takes advantage of DSL services over the copper wire into homes.

A typical FTTH fiber installation consists of multiple splitters. A trunk cable extends from the central office to a remote terminal, where it is split into 8 separate cables that extend to clusters of homes. Near the homes, the cable is split again to service 4 homes. This allows a single trunk from the central office to service 32 homes. The first split can be up to 30,000 feet from the central office. The cable can then extend another 3,000 feet from this splitter. Note that some systems support many hundreds or thousands of users.

Inside the home, the cable terminates at an ONT (optical network termination) box that typically contains an Ethernet 10/100Base-TX network interface. This services an Ethernet network within the home. The ONT performs an optical-to-electrical conversion on the signal arriving from the central office. Multiple services may be extracted from the signal, including voice telephone signals, high-speed data, and television signals.

One method of transporting signals over the cable is ATM PON (Asynchronous Transfer Mode passive optical network), which is an ITU specification, ATM PON is a "passive" optical system that does not require power or active electronic components between the service provider and customer. It consists only of the optical fiber, splitters, splice points, and connectors. A single fiber services multiple customers, as compared to older systems that required a separate fiber to each customer. PONs can be used over great distances and are ideal for rural areas. See "PON (Passive Optical Network)."

While ATM PON is promoted by the telecommunication carriers, Ethernet PON is being promoted by new network providers that intend to build competitive broadband service networks in metropolitan areas. Another alternative is SONET PON.

Copyright (c) 2001 Tom Sheldon and Big Sur Multimedia.
All rights reserved under Pan American and International copyright conventions.