Antenna Diversity Reception

Code Division Multiple Access (CDMA) system is a promising access technology for the next generation wireless network. An important aspect of CDMA is that it requires tight power control to reduce multiple access interference among CDMA users. Closed loop power control has been implemented in CDMA to mitigate the effect of fading channel [1]. However in practice, signal fluctuation due to multipath fading can not be mitigated completely because power control algorithm is not perfect, particularly when the channel goes into deep fades. Fig. 1 shows the controlled signal-to-interference ratio (SIR) when the target level is set at 10 dB. We can see that power control error (deviation from the target SIR) is larger when fading is deeper because power control fails to track deep fades.