To accomplish the sad duty of paying homage to Alain Glavieux, I have referred to his biography as much as my own memories. Two points of this biography struck me, although I had hardly paid attention to them until now. I first noted that Alain Glavieux, born in 1949, is the exact contemporary of information theory, since it was based on the articles of Shannon in 1948 and 1949. I also noted that his first research at the Ecole Nationale Sup rieure de T l communications de Bretagne (ENST Brittany) related to underwater acoustic communications.

To work on these communications, first of all, meant to be interested in concrete local problems linked to the maritime vocation of the town of Brest. It also meant daring to face extreme difficulties because the marine environment is one of the worst transmission channels there is. Carrying out effective underwater communications can be conceived only by associating multiple functions (coding, modulation, equalizing, synchronizing) that do not only have to be optimized separately, but must be conceived together. This experience, along with the need for general solutions, which are the only effective ones in overcoming such difficulties, has prepared him, I believe, for the masterpiece of the invention of turbocodes, born from his very fruitful collaboration with Claude Berrou. Better still, no one could understand better than him that iterative decoding, the principal innovation introduced apart from the actual structure of the turbocodes, implies a more general principle of exchange of information between elements with different functions but...