Just about done with my fundamental problem...

Few regular readers of this would care, but it relates to some of the properties of turbo codes, which, as it turns out, are substantially less mysterious than I used to think.

The properties and design of turbo codes hinge on the design of a good pseudo-random number generator.

Luckily, I have read (albeit, long ago) Donald Knuth.

American Scientist has included [The Art of Computer Programming] among the best twelve physical-science monographs of the twentieth century,[2] and within the computer science community it is regarded as the first and still the best comprehensive treatment of its subject. Covers of the third edition of Volume 1 quote Bill Gates as saying, "If you think you're a really good programmer […] read (Knuth's) Art of Computer Programming […] You should definitely send me a resume if you can read the whole thing." (According to folklore, Steve Jobs made this claim.)

Once you know how to generate good pseudo-random numbers, evidently the world is your oyster or other preferred shellfish.