Interleaver design for turbo codes by distance spectrum shaping

Interleavers play a critical role in the performance of turbo codes. They can be best designed given the structure of the code. In this paper a new methodology for systematically designing the interleaver for a parallel-concatenated convolutional code (PCCC) is presented that exploits the structure of the code. Some novel approaches that result from this methodology are introduced. This methodology can be a basis for constructing algorithms to design very good interleavers for turbo-like codes. This algorithm tries to maximize the minimum distance of the code. The performance of the interleavers designed with this methodology is compared with previous methods and its superiority is illustrated by simulation results.