Channel equalization for DMT with insufficient cyclic prefix

In discrete multi-tone (DMT) systems a cyclic prefix is added to the front of each modulated symbol-frame in order to partition the whole channel into many narrow independent sub-channels. When the length of the cyclic prefix is shorter than the channel length, inter-carrier interference (ICI) and inter-symbol interference (ISI) will occur in the output signal. This paper presents a decision feedback equalizer (DFE) on a symbol level to deal with this problem. The DFE first removes the ISI. It then recovers the distortion caused by ICI. The advantage of this equalizer is that the cyclic prefix for the equalizer can be discarded thus leads to no bandwidth loss. Several simulation examples are presented to show the significant improvement of the equalized signal over the unequalized one.