On design of interleavers with practical size for turbo codes

We propose a new method to design an interleaver with practical size for turbo codes. In order to construct an optimal interleaver, we first set up the following design rules: (i) to suppress the interleaver correlation; (ii) to break up self-terminating weight-2 input sequences; and (iii) to avoid edge effects. We then synthesize a new type of interleaver structure, starting with the conventional block interleaver and applying simple transformation steps. The resulting interleaver can create turbo codes with relatively small block size that yield better performance than previously known interleavers. Advantages of the new interleaver are demonstrated by conducting comprehensive comparisons based on both theoretical analyses and computer simulations