en server group and serving face is not important in CDMA, where a server group is completely defined by an antenna face, but in conventional reuse with overlaid cells, we may serve a large cell and a smaller overlaid cell with the same physical cell sector antenna. TABLE 47.1 Signal Matrix for Three Cells -101 dB -115 dB -126 dB -114 dB -100 dB -116 dB -124 dB 117 dB -99 dB 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. Propagation Models Modeling for CDMA -124dB -126dB -117dB -115dB -101dB -114dB -99dB -116dB -100dB Figure 47.8 Three cells in a row. The average path gain values shown here are just part of the signal matrix picture. We certainly want to know the log-normal standard deviations of the signal and inter- fering path distributions in the complete signal matrix picture. The next level of refinement of the signal matrix would be to consider correlation fac- tors between radio paths. The path gain from A subscribers to cell A tends to be lower when the path from A subscribers to cell B tends to be higher. Path gains of neighbor- ing cells tend to be negatively correlated because subscribers close to the neighbor tend to be further from their own serving cells. While this is statistically present, it is not terribly important in conventional reuse. It may be more important in CDMA, where neighboring cells are interfering cells. The signal matrix tells an important story. In the compact form of a numerical ma- trix, it tells the cellular engineer the source and approximate amount of interference from other cell sectors. Where these other-cell interferers are strong, the CDMA ca- pacity will be reduced for two reasons. First, there will be more interfering signal from the interfering cell's subscriber traffic. Second, there will be more soft handoffs going on when signal paths are close to equal. A soft handoff is essentially two rad