d 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. Increasing Capacity of a Base Station Increasing Capacity There are two different directions, forward and reverse, with two different radio en- vironments. The forward direction has shared radio paths that aggravate multipath losses and has to use multiple transmissions for soft handoff. The reverse direction has a much smaller power amplifier available and has to use more rapid power control to get the same balance. While we can speculate as to which direction will saturate first, as we did in Sec. 30.7, it is best to keep a close watch on both the forward and reverse CDMA carriers. In the forward direction, we are looking for a base station amplifier frequently reach- ing one-third or one-half power. The rate of reaching significant power levels now will be the rate of blocking when the system grows. The warning power threshold should be set higher for larger cells that are mostly for coverage, around half power. The warn- ing threshold should be set lower for smaller cells that are mostly interference-limited, 20 to 30 percent of full power. When the amplifier reaches these warning levels for more than 5 percent of the busy hour, we are looking at a base station that will soon need relief as the system grows. In the reverse direction, we are looking for total received CDMA signal power fre- quently exceeding the receiver noise floor. The rate of matching the noise floor now will be the rate of blocking when the system grows. The warning threshold for CDMA sig- nal power should be set lower for larger-coverage cells, around one-third of the noise power. The warning threshold should be set higher for smaller cells, around two-thirds of the noise power. When the received CDMA signal reaches these warning levels for more than 5 percent of the busy hour, we are looking at a base station that will need rel