Systematic design of single carrier overlap frequency domain equalization

This paper proposes a systematic design method of overlap frequency domain equalization (FDE) for single carrier (SC) transmission without a guard interval (GI). Based on the analysis of signal-to-interference-plus-noise ratio (SINR) of the equalizer output for each symbol, the authors adaptively determine the block of the overlap FDE, where the block is defined as a set of symbols at the equalizer output with sufficiently low error rate, for a certain fixed sliding window size, which corresponds to a fast Fourier transform (FFT) window size. The proposed method takes advantage of the fact that the utility part of the equalized signal is localized around the center of the FFT window. In addition, the authors also propose to adjust the block size in order to control the computational complexity of the equalization per processed sample associating with the average bit error rate (BER) of the system. Simulation results show that the proposed scheme can achieve comparable BER performance to the conventional SC-FDE scheme with sufficient GI insertion for both the coded and uncoded cases with various modulation levels, while requiring lower computational complexity compared to the SC overlap FDE transmission with the fixed block.