Improved interleaver design for turbo coded intersymbol interference channels

We consider an improved S-random interleaver design for the serial concatenation of a high rate punctured convolutional code and a precoded intersymbol interference (ISI) channel separated by an interleaver. We first identify the error patterns that dominate the performance in the floor region. We then modify the S-random interleaver design such that the dominant weight-2 error patterns are eliminated. Simulation results indicate that a performance improvement of about 0.4 dB at a probability of error of about 10^-6 is possible. More investigation, however, is still required in order to understand the effect of the new design on the distance spectrum corresponding to higher weight patterns.