Lecture notes on turbo codes.

d kdelayline (L 1 )InterleavingX kY kC 1(2, 1, 2) resursivesystematicconvolutional codeY 1kY 2kC 2(2, 1, 2) resursivesystematicconvolutional codeWe can now decode the information sequence or move to the second decoderwhich will decode for the same information sequence but in the interleaved form.Now we’ll make use of the L e (i) generated by the first encoder.This can be given as a priori (L e (i) as L I2 (i) -after interleaving) information to thesecond decoder.So effectively we can interleave L sys (i) and L e (i) and feed it to the second decoder.p ap (i t =-1) and p ap (i t =1) can be used associated with γ, in the calculation of α,β forthe second decoder .Thus the output of the second decoder will be of the formL app (i) = L sys2 (i) + L I2 (i) + L e2 (i)- 10 -