To further increase the capacity at each cell site with out increasing the number of W–CDMA carriers, a common practice is to increase the number of sector faces at the desired cell sites. A common six-sector configuration is illustratively demonstrated in Figure 6.

Figure 6. Typical Six-Sector Cell Site Configuration

Using the six-sector site configuration shown in Figure 6, the anticipated maximum number of voice users in a typical urban network is shown in Figure 7.

Figure 7. Capacity Predictions for a Typical Six-Sector Cell Site Configuration

The results presented above show that the optimal beamwidth for the configurations demonstrated in Figure 6 is 40 degrees.

As demonstrated in the previous figures, the rotational orientation of the sites and the number of sectors per site require different beamwidth antennas for optimal capacity performance. The choice of the proper antenna beamwidth is a compromise between the interference in the network by having antennas with too broad a beamwidth and the coverage holes induced by having antennas with too narrow a beamwidth. For all the capacity predictions, the overhead for the pilot was assumed to be 5 percent, and the number of sectors involved in a soft handoff was limited to three.