Equalization scheme for OFDM systems in long delay spread channels

A decision feedback equalizer (DFE) type of equalization scheme is proposed to mitigate the effect of delay spread for orthogonal frequency division multiplexing (OFDM) systems. The performance degradation is severe in case that the delay spread of wireless channels is longer than a cyclic prefix (CP) due to the effect of inter-symbol interference (ISI) and inter-carrier interference (ICI). The effect of ICI and ISI is analytically described in matrix equations which includes signal-to-noise ratio (SNR) degradation for a given channel condition. The proposed scheme improves the performance using decision feedback mechanism without increasing the length of CP, which preserves the system efficiency for the OFDM.