Application of turbo codes to HF data transmission

Since their introduction by Berrou et al. (see Proc. IEEE Int. Conf. Commun., p.1740-5, 1993), turbo codes have generated considerable interest within the coding community as they offer near-Shannon limit performance at very low values of signal-to-noise ratio (SNR). As yet, there is little application of these codes in practical systems and the vast majority of results thus far have been from simulations. The paper discusses turbo codes with particular reference to their application in HF systems and offers possible solutions for future implementation. Turbo decoding is performed using a combination of three basic principles: recursive systematic convolutional, non-systematic convolutional or block codes, combined with interleaving and iterative stage decoding.