Improved error correction for Stanag 4539 appendix H proposal: HF XL

A new appendix [1] for STANAG 4539 [2] is currently under review by the NATO BLOS CaT experts. This proposal introduces a wideband non-contiguous waveform that offers more reliability thanks to the introduction of frequency diversity and also is able to reach throughputs in excess of 150kb/s. This waveform, called “HF XL” proposes to use Turbo codes instead of traditional convolutional codes as forward error correction (FEC) coding scheme. This paper explains the rationale behind that choice and presents simulation results proving the interest of Turbo codes over wideband HF channels.