Reduction of Doppler-induced ICI by interference prediction

Although wireless OFDM systems are robust against frequency-selective fading and ISI effects, their relatively long symbol lengths are vulnerable to time-selective fading and ICI (intercarrier interference) effects in mobile environments due to Doppler spread. However, commonly, a time-selective fading channel is linearly time-varying from symbol to symbol for existing wireless communication systems and vehicle speed limits. The linear property greatly reduces channel parameters. Based on this condition, we propose an ICI-reduction method. The ICI-reduction method first solves the linear channel parameters of each path, and then combines with a decision-feedback method to predict the ICI values from the estimated channel information, followed by the subtraction of the ICI components. Further, the proposed algorithm adopts an iterative ICI refinement technique to enhance the ICI prediction accuracy. The simulation results show that the new method can effectively reduce the ICI and error floor of the symbol error rate. The proposed algorithm is further simplified. The simplified version still maintains almost the same performance as before, with a much reduced complexity.