A Low Complexity ICI Cancellation Scheme with Multi-Step Windowing and Modified SIC for High-Mobility OFDM Systems

A novel low complexity scheme consists of multi-step windowing and modified SIC, is proposed for OFDM systems to reduce ICI caused by time-varying channel. Assuming that the maximum channel delay is smaller than the guard interval, a multi-step windowing module implemented by suitably shifting and summing the multiple weighted ISI-free received signal segments, is adopted to automatically alleviate ICI effect. Afterwards, a modified SIC equalizer with overlapped multi-block and parallel processing is adopted to further improve the BER performance and simultaneously reduce the iteration number for the SIC subblocks. Moreover, this work shows that the proposed windowing concentrates the ICI effect and determines the number of dominant ICI terms, and hence it helps to reduce the computation complexity in ICI reconstruction & cancellation. Computer simulation results verify that the proposed low complexity method achieves good performance with moderate iteration number for high mobility OFDM systems in the ITU Vehicular A channel.