A novel frequency domain equalization method for single-carrier wireless transmissions over doubly-selective fading channels

A novel iterative frequency domain equalization method is proposed for single-carrier (SC) based wireless systems operating over a time- and frequency-selective (or doubly-selective) channel. We adopt the basis expansion channel model (BEM) to approximate the doubly-selective channel with a set of Fourier exponentials. Using BEM, time-varying multipath interference is translated into inter-carrier-like interference in the frequency domain. We design a low-complexity iterative method which relies on a sliding-window-based MMSE widely-linear filter with inter-carrier interference cancellation, and iterated time-domain soft-decisions. Simulations are shown to justify the validity of our approach and the results indicate that this approach outperforms the high-complexity linear block MMSE equalizer and other iterative approaches of similar complexity.