tailieunhanh - Mạng và viễn thông P16

Cordless Telephony and Radio in the Local Loop (RILL) The rapid deregulation of telephone network services taking place during the 1990s has brought a large number of new public network operators to the market, each of which has an interest in optimizing the cost of customer connection to network. Much interest, in particular, has been his channelled into radio technologies(so-called‘radio-in-the-localloop’ or ‘wireless localloop’, WLL), as these are seen as aquickandeconomic way to create newaccess infrastructure, bypassing the dependence on the established monopoly operators for ‘last-mile’ connections | 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 16 Cordless Telephony and Radio in the Local Loop RILL The rapid deregulation of telephone network services taking place during the 1990s has brought a large number of new public network operators to the market each of which has an interest in optimizing the cost of customer connection to his network. Much interest in particular has been channelled into radio technologies so-called radio-in-the-local loop or wireless local loop WLL as these are seen as a quick and economic way to create new access infrastructure bypassing the dependence on the established monopoly operators for last-mile connections. In this chapter we discuss some of the most important technologies in this sector. We also discuss cordless telephone technology as a means for providing limited mobility access to fixed networks. THE DRIVE FOR RADIO IN THE LOCAL LOOP It was historically the case that a monopoly existed on both the public telephone service and the construction and operation of telecommunications transmission networks. The state-owned monopoly carrier had the sole right to lay cables in the street or construct radio transmission links. Although competition in public telephone network services may have been introduced in many countries there has not necessarily been a relaxation of the transmission network monopoly. In consequence the new telephone carriers network operators may be dependent on their strongest competitors for the supply of all transmission links. Thankfully for the new operators if a little slowly the national transmission monopolies are also being removed. Unfortunately however this does not immediately remove the dependence of the new operators on the exmonopoly carrier because the large base of established lineplant and investment is difficult for the new carriers to duplicate quickly. .