Robust Turbo Equalization Under Channel Uncertainties

We investigate robust turbo equalization over frequency selective channels in the presence of channel uncertainties. The turbo equalization framework investigated here contains a linear equalizer to combat ISI and a trellis based decoder. However, instead of completely tuning the linear equalizer parameters to the available inaccurate channel information, a minimax scheme and a competitive scheme are studied, which incorporate the uncertainty in channel information to equalizer design in order to improve robustness. Approximate implementations of these methods are also presented with reduced computational complexity. The performance improvement obtained by the proposed algorithms are demonstrated through simulations under different scenarios.