1. III. Turbo Codes

2. Forward Recursive Equation Backward Recursive Equation
Summary MAP Algorithm
Forward Recursive Equation
Backward Recursive Equation

3. Iterative Decoding Principles
Note that

4. Iterative Decoding Principles

5. Iterative Decoding Principles

6. Iterative Decoding Principles
Define

7. Iterative Decoding Principles

8. Iterative Decoding Principles
Le12 is called the extrinsic information generated by the first decoder for the second decoder

9. Iterative Decoding Principles
For the second decoder
L1a
N-bit
De-Inter.
L1[u|y]
L2[u|y]
L2a
L12e
MAP
Decoder 1
N-bit
Interleaver
MAP
Decoder 2
L21e
y1p - - ys Lc x x Lc
N-bit
Interleaver
N-bit
De-Inter. u*
y2p

10. Performance of Iterative Decoding

11. Performance of Iterative Decoding