Abstract
Unique word based single carrier (UW-SC) systems have been proposed as an alternative to orthogonal frequency division multiplexing (OFDM) systems. UW-SC not only avoids the peak-to-average power ratio problem that plagues OFDM but also supplies the known information of unique words for additional purposes. Although UW-SC is very robust to frequency selective fading in a multipath environment, it is sensitive to the time selective in wireless channel that corrupts the orthogonality of the channel matrix in the frequency domain. In this thesis, we first derive a low-complexity time-domain block minimum mean-squared error (MMSE) solution as a feedforward filter for UW-SC systems in the presence of inter-symbol interference (ISI) caused by doubly selective channel. For residual ISI reduction, we also present a decision feedback filter after the feedforward filter to form a new decision feedback equalizer adapted by unique word. Simulation results and complexity comparisons are given to show that the proposed method has considerably satisfactory performance and lower complexity than linear MMSE and iterative MMSE.