Turbo detection of turbo coded symbols over time varying frequency selective Rayleigh fading channel

This work deals with the transmission of turbo coded symbols in a frequency selective time varying channel. To reduce the channel effect, we use the turbo equalizer proposed in Laot et al. (2001). The equalizer consists of an intersymbol interference canceller and a MAP-BCJR decoder. Unlike Laot, where data information is convolutionally coded, in this paper, we use a turbo encoder. Thus, we have to redefine the channel reliability factor used by the MAP-BCJR decoding algorithm. We propose a new metric that takes into account the statistics of the signal at the equalizer output. Simulations show that the redefined channel reliability improves BER performance and the proposed equalizer is better than the classical DFE equalizer.