Dual-Rate Automatic Gain Controller for WCDMA Mobile Receiver

Abstract

High fluctuation of signal level potentially degrades the signal reception quality of receivers in a mobile communication system. An Automatic Gain Controller (AGC) acts to trace such unpredictable received signal variation in a timely manner so that the signal relatively remains at a desired level. In such condition, an ordinary AGC with single-rate accumulator does not improve the system performance; even worsen it at high noise power. This paper proposes a dual-rate AGC, where there are two different rates of sample accumulation, as a solution to improve the signal reception performance in such conditions. Results show that the dual-rate AGC significantly improves both the BER performance and the power level stability at the receiver. The AGC architecture is investigated through simulations in 3GPP WCDMA system.