tailieunhanh - Mạng và viễn thông P17

Fibre in the Loop (FITL) and Other Access Networks Theadvent ofopticalfibrecommunicationhascoincidedwithaworldwidetrendtowards deregulation public of telecommunication network services. This caused has rapid heavy investment in optical fibre networks, including access networks for the connection of customers. | Networks and Telecommunications Design and Operation Second Edition. Martin P. Clark Copyright 1991 1997 John Wiley Sons Ltd ISBNs 0-471-97346-7 Hardback 0-470-84158-3 Electronic __17 Fibre in the Loop FITL and Other Access Networks The advent of optical fibre communication has coincided with a worldwide trend towards deregulation of public telecommunication network services. This has caused rapid heavy investment in optical fibre networks including access networks for the connection of customers. This in turn has brought not only focus onto the development of new modulation and multiplexing technologies for use in conjunction with optical fibres themselves but also the development of new techniques to enable the better usage of existing copper and coaxial cable access network lineplant as encumbent operators attempt to make the best of the installed lineplant. In this chapter we review some of the most important of these new technologies. FIBRE ACCESS NETWORKS A number of new terms have appeared to describe different initiatives developing solutions for the deployment of fibre cables in business and residential customer access networks. These can all be classified as various forms of fibre in the loop FITL . Subcategories of FITL are fibre to the building FTTB providing direct fibre connection of business customers office buildings of campus sites fibre to the home FTTH providing video on demand VoD cable television and telephone services to residential premises and fibre to the curb FTTC whereby the fibre extends only as far as the streetside cabinet from which existing copper or coaxial lineplant can be used to connect customer premises. Figure illustrates these various concepts. FIBRE TO THE BUILDING FTTB The main driver for FTTB fibre to the building has been the boom in demand from business telecommunications users for line capacity. It is nowadays usually most economic for network oeprators to lay .