A new Turbo equalizer with linear complexity

In this paper a new soft input - soft output (SISO) equalizer of linear complexity is developed. The algorithm can be used in the so-called Turbo equalization scheme as a low cost solution in place of the Maximum A-Posteriori (MAP) equalization algorithm which has a prohibitive complexity for most real world applications. The proposed equalizer consists of two parts, namely, a Soft Interference Canceller (SIC) and a pre-processing part which is a new Variable-Threshold Decision Feedback Equalizer (VTDFE). The role of the second part is to increase the amount of a-priori information supplied to the SIC. Simulation results have shown that the proposed turbo equalizer exhibits a superior performance as compared to the turbo equalization scheme based on the conventional SIC as well as other linear complexity SISO equalizers.