A Simplified Log-MAP Algorithm for Turbo Equalization

A simplification of the Log-MAP algorithm for turbo equalization is presented. The simplified algorithm is based on the MacLaurin series expansion of the logarithmic term in the Jacobian logarithmic function used in the Log-MAP algorithm. In terms of complexity the proposed algorithm can easily be implemented using adders and comparators as this is the case for the Max-Log-MAP algorithm. Also, simulation results show that the proposed algorithm has performance very close to the Log-MAP algorithm for turbo equalization, even in a high loss intersymbol interference (LSI) channel where there is a wide gap between the performance of the Log-MAP and the Max Log-MAP turbo equalizers