A Better Understanding of the Performance of Rate-1/2 Binary Turbo Codes that Use Odd-Even Interleavers

TL;DR

This paper reevaluates how the odd-even interleaver constraint affects rate-1/2 binary turbo codes, challenging existing beliefs and proposing a new explanation based on the distance spectrum for its performance impact.

Contribution

It offers a new perspective on the odd-even constraint's role, emphasizing the importance of the distance spectrum over uniform bit protection.

Findings

Contradicts the belief that odd-even interleavers ensure uniform bit protection.

Highlights the significance of the distance spectrum in performance analysis.

Provides examples showing the odd-even constraint's effects are more complex than previously thought.

Abstract

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.