Network-based vs. distributed speech recognition in adaptive multi-rate wireless systems

Tim Fingscheidt, Stefanie Aalburg, Sorel Stan, Christophe Beaugeant

Abstract: Distributed speech recognition (DSR) is motivated by the fact that codecs used in speech transmission usually reveal a degrading voice quality below some channel quality (carrier-to-interferer ratio C/I), which justifies efficient coding of features with an appropriate channel coding in the mobile terminal. The Adaptive Multi-Rate (AMR) speech codec standardized for GSM and UMTS however delivers an acceptable speech quality way down to C/I ratios of about 4 dB in the GSM full-rate speech channel.