Turbocodes: from a simple idea to a telecoms standard
When in 1988, Claude Berrou had the idea of applying the feedback concept, a very useful principle in electronics, to error correction decoding he was not aware that mathematics had already decreed that this would serve no purpose. At that time it was accepted that successive locally optimised processing produced the overall best result. Today we know that optimal data exploitation via the various operations of the reception chain requires bidirectional processing. The turbo principle, a veritable paradigm, has fuelled numerous works in the international community of communication sciences and continues to be the subject of on-going research.
The first application of the turbo principle concerned error correction encoding and led to the invention of Turbocodes. By associating the feedback technique with several existing concepts, Claude Berrou, with valuable assistance from Gérard Battail, Patrick Adde and Alain Glavieux, presented France Télécom in 1990 with astonishing results which confirmed the theory developed by Claude Shannon in the mid twentieth century. A new era had just opened in the field of coding and more generally for iteratively decoded codes such as the product codes developed at Telecom Bretagne by Ramesh Pyndiah.
After the first public presentation of turbocodes in Geneva in 1993, they were rapidly adopted by the CCSDS, the consultative committee for worldwide space agencies (ESA, NASA, NASDA, …). The first European mission to use turbocodes was the SMART-1 probe which today orbits the moon. Other standardization committees rapidly integrated turbocodes in their telecommunications norms, especially in third generation mobile telephony: UMTS in Europe and CDMA2000 in the United States and Asia. Other systems using turbocodes (INMARSAT, EUTELSAT, DVB-RCS, DVB-RCT, HOMEPLUG, WIMAX, magnetic recording) have already been standardized or are in the process of doing so.
The challenge for the research group at Telecom Bretagne is to maintain its place among the world leaders in this field. This is not an easy task as the number of researchers working in turbo techniques is estimated at 3 or 4 thousand worldwide and applications of this new approach are numerous. Among these techniques, turbo-detection and turbo-equalisation were also developed at Telecom Bretagne (Catherine Douillard, Claude Berrou, Michel Jézéquel, Alain Glavieux) and are increasingly studied and adopted by industry and they represent undisputed improvements for transmission systems in difficult environments.
The determination of Telecom Bretagne to enhance its scientific activity through business partnerships has led to the creation of a joint Telecom Bretagne - Industry research centre which opened in June 2006, Pracom. This new structure will naturally concentrate its efforts on developments associated with the turbo principle.
Telecom Bretagne also participated actively in setting up the European research centre NEWCOM (Network of Excellence in Wireless Communications).
The invention of turbocodes and the extension of the turbo principle to functions other than code correction earned their inventors a number of national and international awards.
Telecom Bretagne also won the French INPI trophy for Innovation in 2002. This success was achieved thanks to the school’s policy favouring research in innovative domains, particularly in turbocodes and also its firm commitment to business creation.
1997 IEEE Stephen O. Rice Award
1998 IEEE Information Theory Society Paper Award
1998 Golden Jubilee Award for Technological Innovation
(IEEE Information Theory Society )
2003 Richard W. Hamming Medal
2005 Marconi Prize
2007 Elected to the prestigious French Academy of Sciences