A Low-Complexity Double EP-Based DFE for Turbo Equalization

In this paper, a new double expectation propagation-based decision feedback equalizer (DEP-DFE) for server inter-symbol interference (ISI) channels employing turbo equalization is proposed. The EP algorithm is used at the equalizer output and the channel decoder output. The proposed DEP-DFE offers a new approach to alleviate error propagation. Additionally, its computational complexity is nearly half of the EP-based minimum mean square error (MMSE)-based linear equalizer (EP-MMSE-LE) proposed by Santos et al. The bit error ratio performance of the proposed equalizer is verified through simulation in the well-known severely frequency selective Proakis-C channel for different scenarios. Simulation results demonstrate that the proposed DEP-DFE can achieve similar or better performance than the EP-MMSE-LE. Moreover, it has significant improvement over the double expectation propagation-based MMSE-LE (DEP-MMSE-LE).