FTTx it is the acronym of the English expression Fiber to the x which indicates a broadband physical layer telecommunications network architecture using optical fiber as the transmission medium to completely or partially replace the traditional metal (usually copper twisted pair) local access network used for the last mile of telecommunications.

This network infrastructure would allow the creation of the so-called Next Generation Network (NGN-NGAN) characterized by significantly higher transmission speeds for the benefit of the end user. The acronym "universal" (ending in x) was born as a generalization of the various names for possible fiber distribution configurations: FTTN, FTTC, FTTB, FTTH, FTTW, FTTR, etc. The basic term FTT is differentiated by the last letter, which becomes “x” in the most general meaning…

definition of terms

In the telecommunications field, the term is differentiated to indicate different configurations. The most common terms today are:

• FTTN – Fiber-to-the-node or even Fiber-to-the-Exchange (FTTE) (literally “fiber to the node” or “fiber to the exchange”): the fiber optic connection arrives in an external cabin several kilometers away from the customer's premises, typically up to the Line Stage of the telephone network, while the final connection remains on copper wire.
• FTTC or FTTS – Fiber-to-the-cabinet or Fiber-to-the-curb or Fiber to the Street (literally “fiber to the cabinet” or “fiber to the curb”): the connection (very similar to FTTN), arrives in an external cabin very close to the user's premises or to the next distribution cabinet, typically within 300 meters.
• FTTB – Fiber-to-the-building or Fiber-to-the-basement (literally “fiber to the building” or “fiber to the foundations”): the fiber optic connection reaches the edge of the building or terraced house, for example up to the basement or garages for one or more housing units (apartments or villas), while the final connection with the apartment remains on copper wire or with polymer fiber optic cabling and Ethernet technology.
• FTTH – Fiber-to-the-home (literally "fiber to the home"): the fiber optic connection reaches the individual dwelling unit, for example, a box on the wall of a house. It is the most expensive solution, but also the longest-term investment that guarantees maximum transmission speed to the end user in anticipation of more advanced network services.
• FTTP – Fiber-to-the-premises (literally “fiber to the premises”: a generic term used in various contexts in place of FTTH or FTTB. Fiber optic connections reach both residential homes and small business buildings (typically shops).
• FTTW or FTTR – Fiber-to-the-Wireless or Fiber-to-the-Radio (literally "fiber to the radio base station"), the fiber reaches a radio link, also called a BTS, and is received by an antenna on the building's roof; this technology is often used to bring fiber optics to places that cannot be reached by cable…

architecture

The proposed architectural models for a fiber optic access network to the user (FTTH) are:

• PTP (point to point) i.e. point-to-point architecture from the exchange to the user: it is the most expensive solution, but also the most efficient and the one that guarantees greater control by the operator, having a dedicated optical line from the control panel to the user; it is usually the option chosen by companies, public bodies, and any other structures with professional needs.
• AON (active optical network), architecture with a shared connection between all users up to an active node that selectively distributes traffic (switching) to the various end users and vice versa receives traffic from these and multiplexes them on the shared connection up to the exchange.
• PON (passive optical network), passive optical networks in which the connection point to point up to the user is carried out a few dozen meters from the building at the distributor, thanks to a splitter passive optical signal transmitting in mode broadcast towards the users, and to TDM/TDMA type multiplexing and multiple access techniques on the fibre communication channel common to all users from the concentrator point towards the exchange, using the optical band in the second and third transmission windows (1310 nm and 1550 nm) respectively for upload And download. Solutions in WDM technology with even higher capacities are also possible which assign a pair of frequencies, one for the’upload and one for the download, for each end user. It is a cheaper solution, but generally a little less performing, still capable of reaching 2.5 Gbit/s with the GPON standard; it is not well regarded by some operators as it does not guarantee direct control of the line up to the user (unbundling) this being possibly shared with other operators in the section splitter-central…

https://rertech.it/fibra-ottica/brevi-cenni-sulla-fibra-ottica/