A Better Understanding of the Performance of Rate-1/2 Binary Turbo Codes   that Use Odd-Even Interleavers
  The effects of the odd-even constraint - as an interleaver design criterion - on the performance of rate-1/2 binary turbo codes are revisited. According to the current understanding, its adoption is favored because it makes the information bits be uniformly protected, each one by its own parity bit. In this paper, we provide instances that contradict this point of view suggesting for a different explanation of the constraint's behavior, in terms of distance spectrum. 
Konstantinos S. Arkoudogiannis, Christos E. Dimakis, and Konstantinos   V. Koutsouvelis
cs.IT math.IT