An adaptive multirate (AMR) codec proposed for GSM speech transmission

An adaptive multirate (AMR) speech codec pro posed for the GSM is described . By dynamically splitting the gross bit rates between source (speech) and channel coding according to the channel quality, almost wireline speech qua lity even for poor channel conditions, and higher speech quality for relati vely good conditions can be achieved, The CELP (code-excited linear predict ion) based speech codec and the RSC (recursive systematic convolutional) co de based channel codec were designed as homogenous/hierarchical as possible for a robust transmission. Novel algorithms for mode bit coding and error concealment were used. One of our design philosophy employed was that the s ource and channel codecs are jointly instead of individually optimized.