Prefiltered Turbo Equalization With SINR Mismatch

In this paper, we consider the use of a channel shortening prefilter in conjunction with a turbo equalizer, in order to allow its use with arbitrarily long channel impulse responses. We show that the residual intersymbol interference (ISI), caused by imperfect channel shortening, results in considerable performance loss. However, by intentionally introducing a particular signal-to-interference plus noise ratio (SINR) mismatch, some of the penalty incurred can be overcome. We also show that the coloring of the noise through the prefllter results in a significant performance loss, which is insensitive to SINR mismatch and cannot be improved by choosing an appropriate SINR mismatch.