Combined AMR Mode Adaptation and Fast Power Control for GSM Phase 2+

The conventional power control of Global System for Mobile communications (GSM) with a control interval of 480 ms is often too slow to react to fast channel variations encountered at even moderate vehicular speeds. As a result, the delivered voice quality can be degraded or unnecessarily high transmission power can be used. In the second case, the excess interference caused due to unnecessarily high transmission power can reduce the network capacity. Although the Adaptive Multi-Rate (AMR) speech codec has been proposed for GSM phase 2+, its application has been considered independently of power control. In this paper, an algorithm is proposed that jointly controls the AMR rate and transmitter power. Computer simulation results are presented that show that the proposed scheme can reduce transmission power by at least 2.5 dB as compared with its counterpart.