ntennas. Time division synchronized CDMA (TD-SCDMA) has made smart an- tennas an integral part of its specification, but other CDMA air interfaces might benefit from them as well. We estimate that they are able to produce a 60-degree beam, the equiv- alent of six-sector cells, but they could be more beneficial than that. The technology may develop to form narrower beams that would increase the capacity through reduced inter- ference. Another possible benefit is that each forward path has a slightly different source, and this may reduce some of the same-path multipath degradation discussed in Sec. 30.3. The downside of smart antennas is that they add complexity and cost to base station de- sign. However, radio equipment manufacturers have shown an amazing ability to come up with simple and inexpensive systems to tackle hard problems in the past. A good CDMA sector plan is one that reaches all the areas of demand with enough radio path gain and CDMA capacity to serve the traffic. A good sector plan does all this with efficient use of radio equipment. And a good sector plan orients and shapes its sec- tors to keep pilot pollution to a minimum. 33.4 Carrier Assignment In the dense-demand area of a CDMA system, there is no issue of radio spectrum man- agement. We want to use every bit of radio spectrum in every sector of every cell to squeeze the maximum revenue out of our CDMA equipment. We can think of no reason a service provider would want to back off from the best utilization of the resources equipment and bandwidth. As cells spread into the lower traffic densities, we find that coverage can dictate a maximum cell size. When cells get larger than the maximum coverage size, the CDMA capacity declines very rapidly. In low-density areas, we have a cell grid determined by local radio conditions and equipment design. And many of these cells are not serving enough demand to warrant using all the carriers on all the faces. Since we want to en- sure radio coverage and we want to enable the system to grow, we want to main