tailieunhanh - Wireless địa phương vòng - lý thuyết và ứng dụng P5

Wireless Local Loop (WLL) systems offer quick deployment, high data rates and dynamic capacity. These should be compelling reasons for WLL System to supplant wired systems. WLL systems are having only limited success in displacing wired systems because wired systems provide proven reliability at lower cost. Will this always be true? This chapter addresses that one technology path designers can follow to reduce WLL system cost, especially for the more numerous low data rate and voice user. A discussion of cost and other market needs is helpful to understand the technical challenges that must be addressed to have WLL systems. | Wireless Local Loops Theory and Applications Peter Stavroulakis Copyright 2001 John Wiley Sons Ltd ISBNs 0-471-49846-7 Hardback 0-470-84187-7 Electronic 5 Low Sequency W-CDMA Codes Lead to More Economic WLL and Infostation Terminals James G. Evans and B. R. Badrinath Introduction Wireless Local Loop WLL systems offer quick deployment high data rates and dynamic capacity. These should be compelling reasons for WLL System to supplant wired systems. WLL systems are having only limited success in displacing wired systems because wired systems provide proven reliability at lower cost. Will this always be true This chapter addresses that one technology path designers can follow to reduce WLL system cost especially for the more numerous low data rate and voice user. A discussion of cost and other market needs is helpful to understand the technical challenges that must be addressed to have WLL systems compete more successfully with wired alternatives. WLL Market Challenges In developed nations there is a large demand for additional connectivity because of the need for Internet access a growth of small businesses in the home and the demands of children for their own phone. Examining the United States as a market there are approximately seven million businesses and 110 million homes 1 . Of the businesses over 80 have less than 20 employees. Thus there is a large small office the applicability of WLL to large businesses is unclear. There certainly is an opportunity for in-building wireless systems home office SOHO and residential market with increasing communication needs. This is a cost sensitive market with voice being the primary communication need and data needs rapidly growing. These needs are primarily served today by the Local Exchange Carriers LECs . The current method to add capacity is a second line or local loop LL . The average embedded cost of the LEC local loop is 600. An emerging alternative is to install Asymmetric digital Subscriber line ADSL .