An Improved SIC based Turbo Equalizer

--This paper investigates a new soft interference canceller (SIC) based turbo equalizer. The SIC is configured as a decision feedback (DF) equalizer that uses two linear transversal filters. Both the filters update their taps as per the least mean square (LMS) algorithm. This receiver is different from the receivers discussed in literature in the sense that it uses the soft outputs of both the equalizer and the decoder in order to provide an improved estimate of the post cursors. It also uses the variance of the soft data bit estimates in its computation of the log-likelihood ratios (LLR). Probability distribution function for the soft data bit estimate is derived. This SIC based turbo equalizer is shown to result in a faster convergence and improved error floor at the decoder output. This study is carried out for a two typical highly frequency selective channels in order to establish the better performance of the proposed receiver. Key-Words: SIC, LLR, SCS, LMS, Soft Output