er the first higher carriers. The first carrier's service area is the entire system. Each higher carrier should have a convex service area, as we described in Sec. 32.3 for growth cells. This means that there may be a few transition cells using a carrier to make its coverage region rounder and to reduce pilot pollution for that carrier. Each carrier must be engineered to reduce pilot pollution. The result is a system with nested carrier coverage, as shown in Fig. 33.2. The fringe areas are served by one-carrier F1 cells, and we move through F2, F3, and F4 cells. When we get to the densest area Figure 33.2 Carrier count of a network of cells with five CDMA carriers. 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. Base Station Planning Planning for CDMA Capacity served by F5 cells, we start to see cell splitting to serve greater demand. Each carrier service area is convex, no holes and no dimpled U shapes on the boundary. The small- grid area also is convex. This grid as shown has very little pilot pollution. The two carriers used in F2 cells and the three carriers used in F3 cells are adjacent in frequency. While the concern of adjacent carrier interference is real, filters are eas- ier to design and manage for adjacent carriers than for carriers with spectrum space in between. We stack the carriers SO that all the F1 cells use the same carrier. It might seem rea- sonable to stagger the carriers, to use different carriers in different cells, SO that each cell has fewer cocarrier cells, fewer cells interfering, and less cell-to-cell interference system wide. Staggering carriers is almost certainly a bad thing to do. The effect of staggering carriers is to make the individual cells for each carrier larger and to create coverage prob- lems in addition to neighbor-cell interference problems. Also, staggered carriers would only support hard handof