ath better climbs higher on the curve and gains little on the horizontal axis, which is CDMA capacity. When a cell layout has areas of poor radio coverage, we can use more powerful base station amplifiers and higher-gain antennas to reach those areas. It may make sense to have a thin-wedge sector, using a narrow-beam antenna with high gain. We lean toward antenna gain rather than amplifier power as a solution because the user ter- minal is limited in its transmit power. While the busy areas in CDMA are forward- direction-limited, the reverse direction is often the radio range limiter of CDMA. Higher-gain antennas extend the range in both forward and reverse directions, but higher transmitter power helps only the forward direction. When more power and more antenna gain are not sufficient, we can consider adding microcells for coverage. The obvious cases are commuter tunnels and geographic val- leys, where the serving radio signal has a hard time reaching. A more subtle use for microcell is a busy four-way zone with four weak radio paths that is hard to avoid macrocell planning. A microcell placed in such an area can ensure coverage, perhaps for significantly lower cost than a full-fledged macrocell. When the weak radio area is far from telephone transport, we can use a repeater and connect it to an existing macrocell. But we tend to prefer the microcell solution to re- peaters because microcells serve their own subscribers and do not use capacity from nearby macrocells. However, sometimes the lack of available transport facilities makes the repeater a more attractive solution. Finally, we can add cells in the coverage rough spots. We recommend treating these as growth cells and placing them on the cell grid as growth cells using the four-to-one cell-splitting scheme described in Sec. 32.3. The most tempting place for a new cell on 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 T