Quality control for AMR speech channels in GSM networks

In the competitive environment of cellular radio networks, the speech quality experienced by the end user is of vital importance for the network operator. Therefore, the operator needs reliable measures for monitoring and controlling the speech quality. For GSM mobile radio networks employing the adaptive multi-rate (AMR) speech codec, a new instrumental and non-intrusive speech quality metric is proposed. ´Non-intrusive´ means that the metric is based only on received transmission parameters, such as the frame erasure rate, and needs neither the original nor the transmitted speech samples. However, for the validation of a new metric, standardized intrusive speech quality measures like PESQ, link-level simulations and field measurements are used. Furthermore, for an improved control of speech quality, a novel AMR mode switching procedure is introduced which outperforms the recommended method of the GSM standard.