Improved channel coding and estimation for adaptive multirate (AMR) speech transmission

Abstract

A variable channel coding scheme for adaptive multirate (AMR) speech transmission over mobile radio channels is proposed. Although it was developed for the GSM, the basic concept of variable channel coding can be adopted to other digital radio systems like UMTS. The AMR concept allows almost wire-line speech quality even for poor channel conditions by dynamically splitting the gross bit rate between source (speech) and channel coding according to the channel quality.