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Chapter 3
Introduction to FTTx System
The application of PON technology for providing broadband connectivity in the access network to homes, multiple-occupancy units, and small businesses commonly is called Fiber-to-the-x. This application is given the designation FTTx [14].
The next chapter consists of an extensive collection of FTTx optical transmission systems, and specifically the FTTH system by which the design and deployment of the proposed network in this project is based. Therefore, it describes general operation of such networks, standards of architecture and operating structure, as well as the current situation in the world and the services that they offer, and in the near future will be able to offer. This will provide an overview of FTTH technology and in-depth the knowledge of the particular circumstances of such networks.
3.1. FTTx networks
FTTH networks belong to the family of FTTx transmission systems within the world of telecommunications. These networks, which are considered broadband, have the ability to transport large amounts of data and information at very high bit rates up to a point close to the end user.
The FTTx family comprises a set of technologies based on transport of digital signals through optical fiber as transmission medium. Different levels of scope, depending on the degree of optical fiber closer to the end user, which arise as a result of a greater or lesser price reduction of these systems.
All FTTx networks support a logical network configuration of tree, star, bus and ring, and all with the ever present possibility of using active components depending on the location of users or end customers.
42 Depending on the degree of penetration of FTTx, these networks can be classified into the following [14]:
• FTTB, fiber-to-the-business, refers to the deployment of optical fiber from a central office switch directly into an enterprise.
• FTTC, fiber-to-the-curb, describes running optical fiber cables from central office equipment to a communication switch located within 1000 ft (about 300 m) of a home or enterprise. Coaxial cable, twisted- pair copper wires (e.g., for DSL), or some other transmission medium is used to connect the curbside equipment to customers in a building. • FTTH, fiber-to-the-home, refers to the deployment of optical fiber from
a central office switch directly into a home. The difference between FTTB and FTTH is that typically, businesses demand larger bandwidths over a greater part of the day than do home users. As a result, a network service provider can collect more revenues from FTTB networks and thus recover the installation costs sooner than for FTTH networks. • FTTN, fiber-to-the-neighborhood, refers to a PON architecture in which
optical fiber cables run to within 3000 ft (about 1 km) of homes and businesses being served by the network.
• FTTO, fiber-to-the-office, is analogous to FTTB in that an optical path is provided all the way to the premises of a business customer.
• FTTP, fiber-to-the-premises, has become the prevailing term that encompasses the various FTTx concepts. Thus FTTP architectures include FTTB and FTTH implementations. An FTTP network can use BPON, EPON, or GPON technology.
• FTTU, fiber-to-the-user, is the term used by Alcatel to describe their products for FTTB and FTTH applications.
Chapter 3 – Introduction to FTTx System
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Figure 14: Some FTTx scenarios
[http://policom.dei.polimi.it/education/comunicazioni/lezione-PON.pdf]
The use of fiber optics as medium of transmission to homes, and so, to end users, ensures network completely adapted to the needs of both current and future. The reuse of this physical infrastructure saves money over time despite strong outlay in initial phase, amortizing it in a short time.
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3.2. General architecture of an FTTH network
FTTH technology involves the introduction of fiber optic in global network, both the backbone network operator as the last mile. In relation to the last mile, it includes the fiber from the central office to each household that requires services.
The interconnection between the end subscriber and the distribution node which is going to provide the services can be done through various physical configurations, which are detailed below.
3.2.1. Point-to-point configuration
Point to point configuration, in terms of optical fiber is concerned, it is specifically a link between the central node and the end user.
Transmission point to point links are operated by companies that have access to fiber optic in outside plant and need to connect remote locations with some communications capability, which can vary from a voice or telephone link, up to high- speed data link.
As for the active part of the network is concerned, it is noteworthy that the equipment used for transmission of information in point to point links are PDH or SDH, besides WDM. These links have high capacity and are very useful in the business world. However, not all are benefits. In case of use of this configuration for home users, it would be a high cost of deployment, to which any operator, whether telecommunications or neutral, is willing to address.
In addition, it would break the pattern of global network configuration, because tree or star configuration, it would be dismantled, increasing the cost of network expansion as well as operation and maintenance.
Chapter 3 – Introduction to FTTx System
45 3.2.2. Point-to-multipoint configuration
Point to multipoint configuration, in terms of fiber optics is concerned it is in which FTTH networks are based. Typically, this configuration is called PON (Passive Optical Network).
Architecture based on PON or passive optical networks is defined as a global system devoid of active electronic elements in the last mile. As it is one of the most important points in this project, it will devote an entire chapter to explain what they are and how such networks work.
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