nnas is complete when the cell layout covers the service area with high radio sig- nal path gain and controls intercell interference. 33.3 Sector Plans Each CDMA sector is a separate server with its own CDMA carriers serving their own wireless subscribers. More sectors means more subscribers and more revenue for the service provider. The capacity increase of adding sectors is not linear because sectors on the same cell interfere with each other. The amount of sector-to-sector interference depends on the radiation patterns of the antenna faces. All the antenna faces of a cell are at the same place, give or take 2 m, so techniques such as downtilting that protect one cell from an- other are not going to protect one sector from another on the same cell. A three-sector cell can get about 2.5 times the traffic of a single omnidirectional antenna. A six-sector cell is limited to about 4 times the omnidirectional traffic. The second and third sector we add to an omnidirectional cell add nearly their full capacity. 4 The loss due to intersector interference is about 15 percent of the total ca- pacity. Given the high fixed cost of installing a base station, having at least three sec- tors on a cell seems like an obviously good decision. Adding more sectors still adds capacity, but with decreasing economy of scale. The fourth, fifth, and sixth sectors on a cell add about half as much capacity as the first three sectors, from 2.5 to 4 times a single omnidirectional cell. This is so because more sectors generate more interference and antenna radiation patterns do not have sharp edges. A 60-degree sector has proportionally more of its area in sector border zones. We are under no obligation to stick to three or six sectors as we did in FDMA and TDMA systems. Nor are we required to have equal-angle wedges for all the sectors of cell. The sector plan for each cell can be a separate design problem depending on the individual requirements of that cell and its subscriber community. There are adminis- trative advantages in a system 