Effect of mobile power control saturation in DS-CDMA

In the IS-95 DS-CDMA system, reverse link fast power control is one of the most important system requirements. By controlling each mobile´s transmit power, the near-far effect is minimized which in turn maximizes the system capacity. The fast power control is especially effective at slow speeds, since it can follow the deep fades. This benefit is true, provided that the mobile power amplifier has adequate headroom. But, what happens when a mobile, close to the cell boundary, is operating at its maximum power (200 mW for portables) and it has no headroom to turn up its power? This paper addresses the problem of mobile power control saturation using a combination of analytical tools, modem simulator and system simulator for both the 9.6 kbps and the 14.4 kbps systems. It is shown that although power control may not be effective at slow speeds when mobile power saturation occurs, the degradation due to this saturation effect is mostly mitigated by soft-handoff