her data speeds of 3G are achieved, then we will see data services in the range of 384 kbps in microcells where users are within 500 m of the base station, or perhaps farther, and 2048 kbps (2 Mbps) in picocells where users are stationary or walking slowly inside buildings or perhaps on small campuses. If these data rates are achieved, another capacity issue still needs to be addressed: How many users will be able to achieve these rates in a single cell? If usage is bursty, and therefore intermittent, it might be possible to serve many subscribers. However, if each subscriber is tuning into a different streaming video program, there may be a ca- pacity problem. User demand will be for high-quality data as well as for speed. If subscribers are playing the stock market over the Web, the costs of long delays or failed connections could be very high. Given the intrinsic tradeoff of capacity and quality on CDMA net- works, this could be a problem. Engineers may have to make decisions to limit the number of users on a cell to ensure sufficient quality of service (QoS) for current active subscribers on that cell. The interference among multiple cells also will become a more difficult issue to manage as cells become smaller. 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. Wireless Data Services Wireless Data Services 21.2 Changes at the Base Station and MSC cdma2000 migration begins with a significant overhaul of base station equipment. New channel cards are installed to support cdma2000 voice and data services. Other new equipment improves support for IP at the base station. In addition, IP support turns the backhaul link to the mobile switching center (MSC) from a traditional circuit into a packet pipe if the 2G network is not already using packet pipes. The good news is that if things go according to plan, this may be the last overhaul of base st