Wednesday, March 19, 2008

Article: What Is FTTP, FTTH, FTTB, And FTTD? Fiber Optic Tutorial Series Four

Submitted By: Colin Yao

The P(premises)can be business, commercial, institutional and other applications where fiber network connections are distributed to a campus, set of structures, or high density building with a centrally located network operations center.

Some other FTTx such as FTTN(fiber to the node), FTTC(fiber to the curb) still depend on copper wires for "last mile" (final connection) to the customers' premises which contrasts with FTTP.

FTTP can be further categorized into FTTH(fiber to the home), FTTB(fiber to the building), etc.

:: Network construction of FTTP

FTTP network can be divided into two major parts: optical portion and electrical portion.

1. Optical portion

Optical portion of the FTTP network is responsible for carrying optical signal to the electrical portion (electrical portion is located in the customer's telecom room).

Two fiber configurations exist for the FTTP optical portion. These are direct fiber link and shared fiber link.

Direct fiber link is the simplest form. One fiber is used for directly connecting the central office to one customer. This type of connection provides the customer the biggest bandwidth but is also the most expensive configuration.

Shared fiber link means a single fiber leaving the service providers central office is shared by many customers. Only at the final moment, the fiber is split into many individual fiber to each customer.

There are two major competing technologies for the shared fiber link configuration: active optical network (AON) and passive optical network (PON).

Active Optical Network (AON) is much more like traditional Ethernet computer networks. It needs electrically powered equipment to buffer and distribute the signal such as switches or routers. Each signal leaving the central office is routed only to the customer intended by the router or switch. On the other hand, signals from the customers are buffered by the router at the intersection avoiding colliding.

Passive Optical Network (PON) does not use any electrically powered equipment to buffer and route the signals. Instead, the light signal from central office is divided and distributed to all customers, even those who are not intended to. Once the light signal arrives at the electrical portion, where it is converted to electrical signal by the ONT(see below), the ONT decides whether to keep or discard the signal depending on its intended destination.

2. Electrical portion

Electrical portion of the FTTP network receives optical signal and converts it to traditional electrical signal which is then distributed to desktop computers via a LAN copper wire network.

This converting device is called an optical network termination(ONT). The building's phone systems, LAN and cable TV system are then connected to the ONT.

:: Other FTTx

FTTB: Fiber To The Building. This is in reference to fiber optic cable, carrying network data, connected all the way from an Internet service provider to a customer's physical building.

FTTD: Fiber To The Desk.. FTTD indicates applications where fiber optic connections are distributed from the central office to individual work stations or computers inside a structure, dwelling, or building.

FTTH: Fiber To The Home. FTTH indicates fiber network connections running from the central office to a residence, or very small multi-unit dwelling.

FTTN: Fiber to the node. FTTN is also called fiber to the neighborhood or fiber to the cabinet (FTTCab). It is a telecommunication architecture based on fiber-optic cables run to a cabinet serving a neighborhood.

FTTC: Fiber To The Curb. This is also called fibre to the kerb (FTTK). It 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.

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