FTTx definitions
1 Overview
The FTTx acronym is widely understood as Fibre-to-the-X, where X can denote a number of destinations. These include Home (FTTH), Premise (FTTP), Curb (FTTC), Building (FTTB), Home (FTTH), User (FTTU) and Node (FTTN). Clearly, however, there are overlaps in meaning. FTTP is similar to FTTB, and FTTC resembles FTTN.
There is also scope for confusion. While the US tends to use FTTP it could have the connotation of FTTH in Europe, yet the two terms do not necessarily mean the same. The former could include instances when the fibre-optic link does not fully extend to the home environment, whereas FTTH usually assumes it will. And the use of different terms, as the FTTH Council2 points out, can make it impossible to usefully compare FTTx studies from different research firms.
To avoid an unnecessary proliferation of acronyms – and to reduce the potential for misunderstanding – the FTTH Councils for North America, Europe and the AsiaPacific region published an agreed definition of terms in September 2006. As the focus of the FTTH Council is on promoting fibre-optic architectures that run as deep as possible into the network – that is, nearest to the subscriber – it narrows down its focus to two FTTx variants: Fibre-to-the-Home (FTTH) and Fibre-to-theBuilding (FTTB).
A summary of the two definitions is as follows:
2 Fibre-to-the-Home (FTTH)
A fibre-optic communications path that extends from the operator’s switching equipment to at least the boundary of the home living space or business office space. The definition excludes those architectures where the optical fibre terminates before reaching either the home living space or business office space and where the access path continues over a physical medium other than optical fibre.
3 Fibre-to-the-Building (FTTB)
A fibre-optic communications path that extends from the operator’s switching equipment to at least the boundary of the private property enclosing the home(s) or business(es). In this architecture, the optical fibre will terminate before reaching the home living space or business office space. The access path will then continue over another access medium – such as copper or wireless – to the subscriber.
However, these two definitions don’t cover those cases where the fibre-optic communications path terminates at a so-called ‘intermediate’ distribution point in the local access network to serve a set of homes and/or buildings. This is generally referred to as Fibre-to-the-Node (FTTN), which we will define as follows:
4 Fibre-to-the-Node (FTTN)
A fibre-optic communications path that extends from the operator’s switching equipment to a point further away from the subscriber than that defined in FTTH or FTTB. This can include the Curb or Cabinet (FTTC) or some other ‘intermediate’ point between the central office and the subscriber. The access path between the intermediate point and the subscriber is not optical fibre but another transmission medium, such as copper or wireless. For the purposes of The FTTx Mini-Guide we will restrict the scope of FTTx to FTTH, FTTB and FTTN. Only when operators or vendors make specific references to other ‘X’ variants will we refer to them.
