SIR-BASED POWER CONTROL IN THIRD GENERATION CDMA SYSTEMS

Abstract In this paper, we investigate the problem of fast power control based on signal-to-interference ratio (SIR) on the reverse link of a CDMA system in slow multipath fading environments. We concentrate our study on the issue of SIR estimation, which is crucial for a good power control performance. We propose a novel and simple method for SIR estimation using an auxiliary spreading sequence. The performance of closed loop power control (CLPC) using our new SIR estimate is evaluated in terms of bit error rate (BER) versus E b /I o (ratio of bit energy-to-interference power spectral density) and compared to the performance with another standard SIR estimation scheme. The complexity of our SIR estimation is N times lower than that of the standard technique, where N is the processing gain, because our technique operates after despreading while the standard technique partly operates at the chip level. However, simulation results show that BER performance of CLPC using our new SIR estimate is comparable to that when the standard SIR estimate is used.