Variable step-size algorithm for modified decision feedback equalizer turbo code DS/CDMA system based on SOVA decoding

In this paper a variable step-size algorithm for modified decision feedback adaptive equalizer (VS-MDFE) for turbo coded direct-sequence code division multiple access (DS/CDMA) communication system is presented. The modified decision feedback equalizer (MDFE) structure is based on the decision feedback equalizer (DFE) structure. The proposed adaptive equalizer is using a performance of the system to control the adaptation process of the MDFE. By this technique, the performances of the proposed adaptive equalizer cooperate with the attractive soft output Viterbi algorithm (SOVA) of turbo decoder for the DS/CDMA system provides a good statistical in non-stationary channel condition scenario. The simulation results confirm that the performance of the proposed system in terms of bit error rate has been improved over the conventional MDFE equalizer and the variable step-size algorithm for the conventional DFE.