Sixth European Conference on Speech Communication and Technology

Budapest, Hungary
September 5-9, 1999

A Multi-Rate Speech And Channel Codec: A GSM AMR Half-Rate Candidate

S. Villette, M. Stefanovic, A. Kondoz

Centre for Communication Systems Research, University of Surrey, Guildford, Surrey, UK

The current GSM standard is a fixed rate system which has been optimised to give good performance in all channel conditions. However since the channel conditions in a terrestrial mobile communication network such as GSM vary significantly between the best and the worst case, the existing GSM speech and channel coding performance can be improved by incorporating the dynamic channel conditions into the codec design. Under the initiative of the European Telecommunications Standards Institute (ETSI) such a system has been launched. This new standard is called AMR for Adaptive Multi-Rate: the source and channel coding rates can be adapted depending on the state of the channel, thus providing optimal balance between them at any time. The University of Surrey has submitted a candidate for this competition through the Mobile VCE. This candidate was the only one amongst eleven to use a vocoder in the half-rate GSM channel instead of a CELP based coder and tests ranked it among the best. This paper presents the system submitted for the half-rate channel as well as the results of the testing.

Full Paper (PDF)   Gnu-Zipped Postscript

Bibliographic reference.  Villette, S. / Stefanovic, M. / Kondoz, A. (1999): "A multi-rate speech and channel codec: a GSM AMR half-rate candidate", In EUROSPEECH'99, 1755-1758.