tailieunhanh - Mạng và viễn thông P38

Network Economy Measures People who plan telecommunications networks are always searching for equipment economy a network for a given information carrying capacity; or, measures: reducing cost the of conversely, increasing the information throughput of a fixed network resource. To achieve their aims, can they either maximize electrical the bandwidth available from a given physical transmission path,or (if it is the other kindof economy they want)they can reduce the amount of electrical bandwidth required to carry individual messages or 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 38 Network Economy Measures People who plan telecommunications networks are always searching for equipment economy measures reducing the cost of a network for a given information carrying capacity or conversely increasing the information throughput of a fixed network resource. To achieve their aims they can either maximize the electrical bandwidth available from a given physical transmission path or if it is the other kind of economy they want they can reduce the amount of electrical bandwidth required to carry individual messages or connections. This chapter describes a few of the practical economy measures open to them. COST MINIMIZATION Reducing the cost of equipment required for a given information throughput is important for public and private network operators alike both will be keen to to reduce the quantity and the cost of lineplant and switch gear. If a given resource say a transmission link is already laid on then there is not much to be gained by applying economy measures which have the sole effect of making some of the available capacity redundant. In such circumstances it may be advantageous to squeeze extra capacity from the line especially if it is nearing its limit. This can be valuable for one of three reasons first it enables expenditure on more capacity to be delayed second it may be the only practicable means or third the cost of duplication may be prohibitive. The first reason might postpone the need for a private network operator to lease more capacity from the PTO public telecommunication operator . The second case might arise because of a need to make more telephone channels available from a limited radio bandwidth. The third might reflect a lack of resources to finance the prohibitive cost of a transatlantic undersea cable. Earlier chapters in this book have .