Fiber to the x (FTTX; also spelled "fibre") or fiber in the loop is a generic term for any broadband network architecture using optical fiber to provide all or part of the local loop used for last mile telecommunications. As fiber optic cables are able to carry much more data than copper cables, especially over long distances, copper telephone networks built in the 20th century are being replaced by fiber."How Fiber Optics Work". https://computer.howstuffworks.com/fiber-optic4.htm. How Stuff Works. Retrieved 2 June 2020. The carrier equipment for FTTx is often housed in a "fiber hut", point of presence or central office.
FTTX is a generalization for several configurations of fiber deployment, arranged into two groups: FTTP/FTTH/FTTB (fiber laid all the way to the premises/home/building) and FTTC/N (fiber laid to the cabinet/node, with copper wires completing the connection).
Residential areas already served by balanced pair distribution plant call for a trade-off between cost and capacity. The closer the fiber head, the higher the cost of construction and the higher the channel capacity. In places not served by metallic facilities, little cost is saved by not running fiber to the home.
Fiber to the x is the key method used to drive next-generation access (NGA), which describes a significant upgrade to the broadband available by making a step change in speed and quality of the service. This is typically thought of as asymmetrical with a download speed of plus and a fast upload speed. Ofcom have defined super-fast broadband as "broadband products that provide a maximum download speed that is greater than this threshold is commonly considered to be the maximum speed that can be supported on current generation (copper-based) networks."
A similar network called a hybrid fiber-coaxial (HFC) network is used by cable television operators but is usually not synonymous with "fiber In the loop", although similar advanced services are provided by the HFC networks. Fixed wireless and mobile wireless technologies such as Wi-Fi, WiMAX and 3GPP Long Term Evolution (LTE) are an alternative for providing Internet access.
Definitions
The telecommunications industry differentiates between several distinct FTTX configurations. The terms in most widespread use today are:
FTTE (fiber-to-the-edge) is a networking approach used in the enterprise building (hotels, convention centers, office buildings, hospitals, senior living communities, Multi-Dwelling Units, stadiums, etc.). Fiber reaches directly from the main distribution frame of a building out to the edge devices, eliminating the need for intermediate distribution frames. FTTP (fiber-to-the-premises): This term is used either as a blanket term for both FTTH and FTTB, or where the fiber network includes both homes and small businesses FTTH (fiber-to-the-home): Fiber reaches the boundary of the living space, such as a box on the outside wall of a home. Passive optical networks and point-to-point Ethernet are architectures that are capable of delivering triple-play services over FTTH networks directly from an operator's central office.Ed Gubbins, "Active Ethernet grows in PON's shadow" , NXTcomm Daily News, Penton Media, 13 May 2008. Retrieved 12 July 2013 Typically providing between 1 and FTTB (fiber-to-the-building, -business, or -basement): Fiber reaches the boundary of the building, such as the basement in a multi-dwelling unit, with the final connection to the individual living space being made via alternative means, similar to the curb or pole technologies. It can currently reach symmetrical 10 Gbit/s with G.mgfast. FTTD can mean two different things: (fiber-to-the-desktop or -desk): In an office, fiber connection is installed from the main computer room to a desk or fiber media converter near the user's desk. (fiber-to-the-door): Fiber reaches outside the flat. FTTR can mean three different things: (fiber-to-the-radio): Fiber runs to the transceivers of base stations. (fiber-to-the-router): Fiber connection is installed from the router to the ISP's fiber network. (fiber-to-the-room): Fiber connection is extended from the router to rooms in the building. FTTO (fiber-to-the-office): Fiber connection is installed from the main computer room/core switch to a special mini-switch (called FTTO Switch) located at the user's workstation or service points. This mini-switch provides Ethernet services to end user devices via standard twisted pair patch cords. The switches are decentralised and located all over the building, but managed from one central point. FTTF can mean five different things: (fiber-to-the-factory): fiber runs to factory buildings. (fiber-to-the-farm): fiber runs to agricultural farms. (fiber-to-the-feeder): a synonym of FTTN (fiber-to-the-floor): fiber reaches a junction box at a floor of a building. (fiber-to-the-frontage): This is very similar to FTTB. In a fiber to the front yard scenario, each fiber node serves a single subscriber. It can currently reach symmetrical 10 Gbit/s with G.mgfast. The fiber node may be reverse-powered by the subscriber modem. FTTM can mean four different things: (fiber-to-the-machine): In a factory, fiber runs to machines. (fiber-to-the-mast): Fiber runs to wireless masts. (fiber-to-the-mobile): Fiber runs to base stations. (fiber-to-the-multi-dwelling-unit): FTTP to apartment buildings FTTT can mean three different things: (fiber-to-the-terminal): In an office, fiber runs to desktop equipment. (fiber-to-the-tower): Fiber reaches base stations. (fiber-to-the-tent): For example, at hacker camps such as BornHack in Denmark. FTTW (fiber-to-the-wall or -workgroup): In an office, fiber runs to small switches near a group of users. FTTA can mean two different things: (fiber-to-the-amplifier): Fiber runs to street cabinets. (fiber-to-the-antenna): Fiber runs up antenna towers. FTTCS (fiber-to-the-cell-site): fiber reaches the base station site. FTTE / FTTZ (fiber-to-the-telecom-enclosure or fiber-to-the-zone): is a form of structured cabling typically used in enterprise local area networks, where fiber is used to link the main computer equipment room to an enclosure close to the desk or workstation. FTTE and FTTZ are not considered part of the FTTX group of technologies, despite the similarity in name.Robert Reid, "All multimode fiber is not created equal", Cabling Installation & Maintenance, PennWell Corporation, February 2007, retrieved 12 July 2013 FTTdp (fiber-to-the-distribution-point): This is very similar to FTTC / FTTN but is one-step closer again, moving the end of the fiber to within meters of the boundary of the customers premises in the last possible junction box, known as the "distribution point". This allows for near-gigabit speeds FTTL (fiber-to-the-loop): general term FTTN / FTTLA (fiber-to-the-node, -neighborhood, or -last-amplifier): Fiber is terminated in a street cabinet, possibly miles away from the customer premises, with the final connections being copper. FTTN is often an interim step toward full FTTH (fiber-to-the-home) and is typically used to deliver 'advanced' triple-play telecommunications services FTTC / FTTK (fiber-to-the-curb/kerb, -closet, or -cabinet): This is very similar to FTTN, but the street cabinet or pole is closer to the user's premises, typically within , within range for high-bandwidth copper technologies such as wired Ethernet or IEEE 1901 power line networking and wireless Wi-Fi technology. FTTC is occasionally ambiguously called FTTP (fiber-to-the-pole), leading to confusion with the distinct fiber-to-the-premises system. Typically providing up to FTTS can mean three different things: (fiber-to-the-screen or -seat): On an airplane, fiber reaches the IFE screens. (fiber-to-the-street): The customer is connected using copper to the fiber passing near the building, up to away. This is a compromise between FTTB and FTTC. Typically providing up to (fiber-to-the-subscriber): This is a synonym for FTTP.
To promote consistency, especially when comparing FTTH penetration rates between countries, the three FTTH Councils of Europe, North America, and Asia-Pacific agreed upon definitions for FTTH and FTTB in 2006, with an update in 2009, 2011 and another in 2015. The FTTH Councils do not have formal definitions for FTTC and FTTN.
Fiber to the premises Fiber to the premises (FTTP) is a form of fiber-optic communication delivery in which an optical fiber is run in an optical distribution network from the central office all the way to the premises occupied by the subscriber. The term "FTTP" has become ambiguous and may also refer to FTTC where the fiber terminates at a utility pole without reaching the premises.
Fiber to the premises can be categorized according to where the optical fiber ends:
FTTH (fiber-to-the-home) is a form of fiber-optic communication delivery that reaches one living or working space. The fiber extends from the central office to the subscriber's living or working space. Once at the subscriber's living or working space, the signal may be conveyed throughout the space using any means, including twisted pair, coaxial cable, Wireless, power line communication, or optical fiber. FTTB (fiber-to-the-building or -basement) is a form of fiber-optic communication delivery that necessarily applies only to those properties that contain multiple living or working spaces. The optical fiber terminates before actually reaching the subscribers living or working space itself, but does extend to the property containing that living or working space. The signal is conveyed the final distance using any non-optical means, including twisted pair, coaxial cable, wireless, or power line communication.
An apartment building may provide an example of the distinction between FTTH and FTTB. If a fiber is run to a panel inside each subscriber's apartment unit, it is FTTH. If instead, the fiber goes only as far as the apartment building's shared electrical room (either only to the ground floor or to each floor), it is FTTB.
Fiber to the curb/cabinet/node
Fiber to the curb/cabinet (FTTC) is a telecommunications system based on fiber-optic cables run to a platform that serves several customers. Each of these customers has a connection to this platform via coaxial cable or twisted pair. Here "curb" is an abstraction and can just as easily mean a pole-mounted device or communications closet or a shed. Typically any system terminating fiber within of the customer premises equipment would be described as FTTC.McCullough, Don (August 2005), "Flexibility is key to successful fiber to the premises deployments" , Lightwave 22 (8). Retrieved on 2010-01-27.
Fiber to the node or neighborhood (FTTN), sometimes identified with and sometimes distinguished from fiber to the cabinet (FTTC),da Silva, Henrique (March 2005), "Optical Access Networks" , Instituto de Telecomunicações, 9 March 2005, slide 10. Retrieved on 2007-03-25. is a telecommunication architecture based on fiber-optic cables run to a cabinet serving a neighborhood. Customers typically connect to this cabinet using traditional coaxial cable or twisted pair wiring. The area served by the cabinet is usually less than one mile in radius and can contain several hundred customers.
FTTN allows delivery of broadband services such as high-speed internet. High-speed communications protocols such as broadband cable access (typically DOCSIS) or some form of digital subscriber line (DSL) are used between the cabinet and the customers. Data rates vary according to the exact protocol used and according to how close the customer is to the cabinet.
Unlike FTTP, FTTN often uses existing coaxial or twisted-pair infrastructure to provide last mile service and is thus less costly to deploy. In the long term, however, its bandwidth potential is limited relative to implementations that bring the fiber still closer to the subscriber.