Iterative MAP decoding for serial concatenated convolutional codes

The paper provides detailed computational steps for implementing an iterative serial concatenated convolutional code (SCCC) decoder. These are based on maximum a posteriori probability (MAP) decoding of a single, rate 1/2, recursive, systematic convolutional code, which is reduced to easily implemented equations for forward and backward recursion. In particular, the crucial information exchange between MAP decoders is clarified. Simulation of a rate 1/3 SCCC with memory-2 codes and a coding delay of N=1000 shows a bit error rate of 10^-6 for E_b/N₀=1.5 dB, and gives a typical interleaver gain of N^-3