Use as given at the website. Planning Locations for Base Stations Planning for CDMA Capacity We do not recommend solving the pilot-pollution problem by reducing pilot power levels. It is the comparative radio path gains that are causing the capacity loss, not the pilot power levels being equal. If it is deemed necessary to control the size of a cell, then we can reduce its size by downtilting and lowering its antennas, as described later in Sec. 33.2. A cell layout passes the pilot-pollution test if there are very few areas with low fourth-pilot delta values. When cell coverage maps are printed using the radio propa- gation planning models described in Chap. 47, there should be few zones with four or more cells serving them. And the four-cell zones that are on the map should be areas of relatively low subscriber density. It is important to understand that the pictures we draw, and even the propagation maps, are visual aids only. As we discussed in Sec. 27.10, the lines we draw showing geometric coverage shapes are representations of complex radio propagation paths. We use these simplifications in our book because we believe that they represent radio re- ality well enough to help planners make their CDMA systems work better. However, CDMA planners should remember the complexity of signal path interaction and try to gain an intuitive feel for the radio issues in the particular wireless telephone system they are planning. Sector boundaries are also a contributor to pilot pollution. Once the cells are laid out to minimize four-cell valleys, the sectors should be oriented so that their boundaries do not cross the triple-points and valleys. Otherwise, the pilot pollution and the combina- tion of soft and softer handoffs may overwhelm the CDMA carriers in the area. 32.2 Keeping the Grid To keep pilot pollution to a minimum, the cell layout plan should avoid valleys and keep fourth-pilot delta values large. In geometric terms, the layout should avoid having ar- eas where four or more cells meet at one point. Putting cell