phony infrastructure. This means that service providers are setting up wire- less telephone systems, often as primary telephone service for subscribers, where there is no backbone transport network. This means that each MSC is probably going to be located near the geographic center of its base stations to keep its backhaul costs down. In such a case, we have to minimize inter-MSC transport cost. With only a few MSCs, it is reasonable to enumerate all the possible networks of inter-MSC transport and 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. Adding Transport Increasing Capacity select the least-expensive option. Even a huge wireless telephone system with 5 MSCs has only 10 pairs of MSCs to connect. As the wireless system grows and the MSCs grow, the inter-MSC transport must grow along with it. We should be prepared for the inter-MSC transport to grow pro- portionally faster than the growth of the rest of the system. 44.3 Adding MSC-to-PSTN Capacity Voice traffic in cellular systems has been growing steadily for two decades. During the last decade of the twentieth century, cellular telephony doubled every 2 years, a 40 per- cent per year increase in subscriber traffic. While the rate of growth may be declining, we expect voice traffic to continue to grow. 2 This means that we expect to see a contin- ued increase in the amount of transport required between the MSC and the PSTN. One of the two reasons for third-generation (3G) CDMA is to provide a large increase in wireless capacity at a low cost. As 3G CDMA brings lower cost cellular service to the world market, we may see strong growth in voice traffic. This means that the MSC-to- PSTN links will have to increase to meet the growing demand. The other reason for 3G CDMA is the introduction of wireless data and other ad- vanced services. It may be that the growth opportunity is not in voice