On filter-based turbo equalization with serially concatenated trellis coded modulation

A recursive trellis coded modulation (TCM) precoder is combined with a linear minimum mean squared error (LMMSE) turbo equalizer. The system is optimized by using inner and outer codes with maximum slope of the active burst distance, and also by maximizing the minimum distance between inner and outer code extrinsic transfer functions. A great improvement is obtained in the frame error rate (FER) compared to the LMMSE turbo equalizer. Optimum precoders are selected from the set of 2-state bit geometrically uniform (BGU) encoders for the 8-PSK signal set.