Cryptography Reference
In-Depth Information
Figure 7.4 - Turbo codes used in practice.
b- Each of the two elementary encoders C 1 and C 2 is characterized by
- its code memory ν
- its generator polynomials for recursivity and redundancy
- its rate
The values of ν are in practice lower than or equal to 4. The generator
polynomials are generally those that we use for classical convolutional codes
and that were the subject of much literature in the 1980s and 1990s.
c- The way in which we perform the permutation is important when the tar-
geted binary error rate is lower than around 10 5 . Above this value, per-
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