2. Turbocodes

2.1 Convoluted turbocodes

Encoding: the first turbocode system proposed is illustrated in figure 3 . It is built around two convolutional encoders. The input information frame is first encoded by the first encoder. The frame is then permuted and directed to the input of the second encoder. The final frame transmitted on the transmission channel is then made up of the initial data frame and the two redundancy frames formed by each of the two decoders. The permutation, which is fixed, ensures greater spatial diversity. The overall code thus obtained has a minimum distance, and therefore a correction power, generally superior to that of the elementary convolutional codes used in...