Bolt interleavers for turbo codes

A procedure is described to produce efficient turbo-code interleavers. It is well suited to the selection of interleavers that produce a large minimum distance for the resulting turbo codes. A feature of these interleavers is that the final state of the two elementary encoders is simultaneously zero. Examples are given and the corresponding codes are simulated. They seem to be among the best ones for rate 1/3 turbo codes.