ng to gain CDMA capacity by in- stalling more sectors. 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 Cells to a CDMA System Increasing Capacity 42.6 Picocells for Specific Local Areas The concentration of traffic can be so extreme that even a microcell is too large. We think of a single office building with a lot of traffic, enough to justify one or more CDMA carriers. While such a load seems like an unusually large building when we think of voice calls, third-generation (3G) data services may generate this kind of demand in many office buildings in a large city. Picocells are designed to serve traffic concentrated in a single building. The ranges are limited to 10 or 20 m mostly by placing the picocell inside the walls of the building. Since a picocell is already isolated from the rest of the wireless telephone system by being in- side a building, issues of other-cell interference and pilot pollution should be attenuated because the radio signal is attenuated by the walls of the building being served. Picocells offer close-range service, so we can use the very high data rates of 3G that were designed for short distances and high radio path gains. The cdma2000 1x EV-DO offers a data service of 2.45 Mbps in only 1.25 MHz of radio spectrum using more com- plex constellations than the normal CDMA air interface. This technology is available in the forward direction only when the radio path is very short and very clean. Having a picocell right in the building gives us the opportunity to create such a clean link and offer these high data rates to subscribers. The high-rate data service offered by picocells may be part of the main wireless tele- phone system, but it also may be offered on a private data network. The picocell could be an Internet Protocol (IP) node by itself, as we described in Sec. 35.4. A private com- munity of data subsc