On the interleaver depth in concatenated coding schemes

The performance of concatenated codes, with an inner (possibly punctured) convolutional code, is analyzed. In particular, the required interleaver depth is considered. Given the statistics of burst lengths at the inner decoder output, tight upper bounds to the word error probability at the output of the outer decoder are derived. A priori also very long error events, too rare to be simulated, must be considered. Their probability can be upper bounded by the union bound. It is shown that the union bound alone can provide a preliminary, fast evaluation of the required interleaver depth. Then the analysis can be refined combining simulation and union bound. Numerical results are presented for some concatenated codes that are being considered in the European Project on Satellite EHF Communications for Mobile Multimedia Services (SECOMS) in the ACTS Program.