Improving the Performance of 4-State Turbo Codes with the Correction Impulse Method and Data Puncturing

Abstract

Turbo codes offer excellent error-rate performance and have been included in a wide variety of systems and standards. However, these gains are limited as the signal-to-noise ratio (SNR) increases by "flares" in their error-rate curves. These flares may disqualify Turbo codes from applications that require very low error rates. Recently, an effective method for reducing these error flares that is applicable to any Turbo or Turbo-like code has been proposed. This paper shows that this technique is of tremendous value even when applied to relatively weak 4-state, single-binary Turbo codes, particularly when used in conjunction with data puncturing and well-designed interleavers.

Convergence performance and EXIT analysis of 4-state partially-systematic Turbo codes

“…Fully-constrained or mod interleavers [13], [14] are those where all data symbol indices are forced to correspond to the same data puncture mask offset in both codes. That is, for a data puncture mask length of m, all symbols at offset k in the mask, 0≤ k ≤ m-1, go to positions that are also at offset k. In effect, the data symbols are divided into m sets and permuted within these sets.…”