Optimization of the equalization and the interleaving in turbo-equalization for a frequency-selective fading channel

An analysis of two crucial devices of turbo-equalization, the equalization part and the interleaving part, is developed for a frequency-selective fading channel, representative of an HF channel. First of all, we explain why the interference canceller of A. Gersho and T.L.Lim (see Bell System Technical Journal, vol.60, no.11, p.238-47, 1981) plays a key role in the convergence of turbo-equalization. Since this technique is an iterative process including the concatenation of an equalizer and a channel decoder, interleaving is also a very important task. Thanks to an analogy with coded modulation, we pinpoint the influence of the type of interleaving (bit or symbol) on the global performance.