Iterative Decoding Trajectories of Parallel Concatenated Codes

Mutual information transfer charac-teristics for soft in/soft out decoders are proposed as a tool to better understand the convergence behavior of iterative decoding schemes. The exchange of extrin-sic information is visualized as a decoding trajectory in the Extrinsic Information Transfer Chart. This al-lows the prediction of turbo cliff position and bit er-ror rate after an arbitrary number of iterations. The influence of code memory, generator polynomials as well as different constituent codes on the convergence behavior is studied for parallel concatenated codes. I