What is Fiber to the curb?

Fiber to the curb allows delivery of broadband services such as high speed internet. Usually existing wire is used with communications protocols such as broadband cable access (typically DOCSIS) or some form of DSL connecting the curb/cabinet and the customers. In these protocols, the data rates vary according to the exact protocol used and according to how close the customer is to the cabinet.

Where it is feasible to run new cable, both fiber and copper Ethernet are capable of connecting the "curb" with a full 100 megabit or 1000 megabit connection. Even using relatively cheap outdoor category5 copper over several hundred meters, all Ethernet protocols including Power over Ethernet are supported. Most fixed wireless technologies rely on PoE including Motorola Canopy which has low-power radios capable of running on a 12VDC power supply fed over > 100 meters of cable.

Powerline networking deployments also rely on FTTC: Using the IEEE P1901 protocol (or its predecessor HomePlug AV) existing electric service cables move up to a gigabit of data per second from the curb/pole/cabinet into every AC electrical outlet in the home - coverage equivalent to a robust Wi-Fi implementation, with the added advantage of a single cable for power and data.

FTTC is subtly distinct from FTTN or FTTP (all are versions of Fiber in the Loop). The main difference is the placement of the cabinet. FTTC will be placed near the "curb" which differs from FTTN which is placed far from the customer and FTTP which is placed right at the serving location.

Unlike the competing fiber to the premises (FTTP) technology, fiber to the curb can use the existing coaxial, twisted pair or AC power line infrastructure to provide last mile service. The G.hn and IEEE P1905 efforts were attempts to unify these existing cables under one management protocol.

By avoiding new cable and its cost and liabilities, fiber to the curb costs less to deploy. However, it also has historically had lower bandwidth potential than fiber to the premises. In practice, the relative advantage of fiber depends on the bandwidth available for backhaul, usage-based billing restrictions that prevent full use of last mile capabilities, and customer premises equipment and maintenance restrictions, and the cost of running fiber which can vary widely with geography and building type.

In the United States of America and Canada, the largest deployment of FTTC was carried out by BellSouth Telecommunications. With the acquisition of BellSouth by AT&T, deployment of FTTC will end. Future deployments will be based on either FTTN or FTTP. Existing FTTC plant may be removed and replaced with FTTP. Verizon, meanwhile, announced in March 2010 they were winding down Verizon FiOS expansion, concentrating on completing their network in areas that already had FiOS franchises but were not deploying to new areas, suggesting that FTTH was uneconomic beyond these areas.

Verizon also announced (at CES 2010) its entry into the smart home and power utility data management arenas, indicating it was considering using P1901-based FTTC or some other existing-wire approach to reach into homes, and access additional revenues from the secure AES-128 bandwidth required for advanced metering infrastructure. However, the largest gigabit deployment in the US, in Chattanooga, TN, despite being conducted by a power utility , was FTTH not FTTC, and reached every single subscriber in a 600 square mile area. Pricing, US$350 for 1000 megabits, reflected this generally high cost of deployment.

Historically, both telephone and cable companies avoided hybrid networks using several different transports from their point of presence into customer premises. The increased competitive cost pressure, availability of three different existing wire solutions, smart grid deployment requirements (as in Chattanooga), and better hybrid networking tools (with major vendors like Alcatel-Lucent and Qualcomm Atheros, and Wi-Fi solutions for edge networks, IEEE 1905 and IEEE 802.21 protocol efforts and SNMP improvements) all make FTTC deployments more likely in areas uneconomic to serve with FTTP/FTTH. In effect FTTC serves as a halfway measure between fixed wireless and fiber to homes, with special advantages for smart appliances and electric vehicles that rely on PLC use already.