  This paper investigates the design and analysis of minimum mean square error
(MMSE) turbo decision feedback equalization (DFE), with expectation propagation
(EP), for single carrier modulations. Classical non iterative DFE structures
have substantial advantages at high data rates, even compared to turbo linear
equalizers - interference cancellers (LE-IC), hence making turbo DFE-IC schemes
an attractive solution. In this paper, we derive an iterative DFE-IC,
capitalizing on the use of soft feedback based on expectation propagation,
along with the use of prior information for improved filtering and interference
cancellation. This DFE-IC significantly outperforms exact turbo LE-IC,
especially at high spectral efficiency, and also exhibits various advantages
and performance improvements over existing variants of DFE-IC. The proposed
scheme can also be self-iterated, as done in the recent trend on EP-based
equalizers, and it is shown to be an attractive alternative to linear
self-iterated receivers. For time-varying (TV) filter equalizers, an efficient
matrix inversion scheme is also proposed, considerably reducing the
computational complexity relative to existing methods. Using finite-length and
asymptotic analysis on a severely selective channel, the proposed DFE-IC is
shown to achieve higher rates than known alternatives, with better waterfall
thresholds and faster convergence, while keeping a similar computational
complexity.
