Comparison of distance measurement methods for turbo codes

Abstract — Reliable distance measurement methods for turbo codes are a key element in the design of interleavers with high minimum distances, which are essential for lowering the flare effect at low error rates. The usefulness of such methods depends strongly on their computational complexity, especially for long interleavers with high minimum distances. This paper improves the reliability of the double-impulse iterative decoding method and compares it with Garello’s true minimum distance method, the error-impulse method and the all-zero iterative decoding method. The comparison is based on the interleavers specified in the Digital Video Broadcasting with Return Channel via Satellite (DVB-RCS) standard, random interleavers and dithered relative prime (DRP) interleavers. A new interleaver for an MPEG packet of size 1504 information bits is designed for the DVB-RCS standard. The new interleaver provides an improvement of at least 0.4 dB at low error rates. I