 by thickening pipes. The engineering of the base-station-to-MSC transport network will be addressed in de- tail in Chap. 35 and Sec. 44.1, but we can start to look at the issues and challenges here. Base-station-to-MSC transport is outside the ANSI-41 standard. In traditional telephony traffic engineering, we look at a random distribution with an average number of calls. A link might have a busy-hour average of 25 calls and a re- quirement of no more than 1 percent blocking. It is the traffic engineer's job to make sure that there are enough lines to serve that traffic distribution so that 99 percent of the calls get through. We discuss traffic engineering in Chap. 23. In this usual tele- phony traffic engineering world, there is a clear-cut notion of one telephone call, one unit of demand, and one unit of transport. Wireless voice channels are designed to conserve radio spectrum rather than to make telephone transport easier, but we can take advantage of the economy of wireless voice TABLE 13.3 European Digital Transport Protocols Signal Speed Channels 64 kbps 2.048 Mbps 34 Mbps 144 Mbps 30,720 Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com) Copyright © 2004 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use as given at the website. Telephone Transport Telephone Transport channel design in our transport networks. We can take the simple view that each base station has a certain amount of radio capacity, some number of bits per second, and that those bits have to get to and from the MSC through a transport network. 5 The low bit rate of code division multiple access (CDMA) and the Global System for Mobility (GSM) is maintained from the base station to the MSC. As a result, each base-station-to-MSC link is a data link with varying numbers of varying-bandwidth users over time. The total usage of the link is limited by the total capacity of the air interface between the base station and the user terminal. So long as this link has more 