Iterative MMSE-DFE and Error Transfer for OFDM in Doubly Selective Channels

An iterative design of minimum mean square error decision feedback equalizer (MMSE-DFE) to suppress the intercarrier interference (ICI) of orthogonal frequency division multiplexing systems in the time-variant channels is analyzed in this paper. The channel is assumed to vary in a linear fashion within a frame. The error power transfer is investigated in parallel with the equalizing process, showing the gain in iterations and aiding the MMSE decision. Iteratively, the ICI components are estimated and canceled from the receive symbol, providing an MMSE estimate of the source symbol with an increasing reliability. It is shown that based on the error power transfer analyzed in this paper, ICI components can be significantly removed via the iterative MMSE-DFE, leaving the error composed of noise and negligible residue of ICI. Simulations have verified the accuracy of the error power estimation.