se looks like a normal three-sector cell. All the cells do not have to use the same sector plan either. A CDMA system can mix three- and six-sector cells and even five- and nine-sector cells. Whatever configuration best uses the CDMA air interface to serve the demand is what we should put into the system. There may be an administrative hassle in having 50 different sector plans in a system of 500 cells, but this has to be weighed against the foolish consistency of insist- ing that all the cells look the same. An alternative to adding more sectors with narrower fixed-beam antennas is to change a base station to adaptive phased arrays (smart antennas). Time division syn- chronized CDMA (TD-SCDMA) requires smart antennas as part of the specification, but other CDMA systems might use them as well. They may be more expensive and complicated than fixed-beam antennas today in 2002, but this is the kind of technology that comes down in price as it becomes more widespread. Base stations with smart antennas can be the equivalent of six-sector cells. The ver- sions being used in TD-SCDMA generate a 60-degree beam width. With larger and more complex antenna arrays, we might be able to get radio path isolation equivalent to 40 degrees or even 20 degrees, the equivalent of 10 or 20 sectors per cell. We add antenna faces or smart antennas for capacity when adding the equipment to an existing base station is more cost-effective than adding more base stations to the wireless system. We want to make sure that new sector boundaries do not create a ca- pacity problem in pilot pollution that mitigates the capacity advantage of having more CDMA sectors in one cell. 41.5 Installing Repeaters Repeaters are often thought of as a stop-gap coverage measure, a quick fix for areas with low radio signal path gain to their base stations. In a growing CDMA system, re- peaters can fix poor-coverage red areas, as described in Sec. 40.2, but they also can sup- port yellow areas and improve the capacity of their base stations. Repeaters are radio r