Iterative Block Fractionally Spaced Nonlinear Equalization for Wideband Channels

For a transmission over frequency-selective channels, we propose a fractionally spaced (FS) iterative block decision feedback equalizer (FS-IBDFE) receiver that combines the advantages of FS equalization, nonlinear processing, and frequency-domain (FD) implementation. The contributions of the letter are as follows: 1) the extension of existing FD iterative equalization schemes considering an FS processing; 2) the design of the FD equalizer coefficients minimizing the mean square error at the detection point; and 3) a simple equalizer design procedure where equalization coefficients are computed in closed form, without matrix inversions. As an example, the performance of the proposed scheme is assessed in a Rayleigh fading channel, and it is seen that the FS-IBDFE significantly outperforms the FS linear equalizer, the non-FS IBDFE, and the noise prediction FS FD equalizer.