An adaptive cyclic equalization procedure for digital HE modems operating in the presence of severe multipath and fading

The performance of cyclic equalization (CE) techniques for improving equalizer convergence rate is investigated for time-variant fading multipath channels. A procedure is proposed whereby a serious limitation of CE, namely, the presence of singularities in the Fourier transform of the autocovariance function of the equalizer input sequence, is effectively overcome, at the expense of a moderate increase in computation requirements. Simulation results are included to demonstrate the robustness of the CE strategy over a simulated HF channel with multipath and fading. A few fundamental limitations of the present technique are outlined and possible modifications are identified