Low Complexity Successive Interference Cancellation for OFDM Systems over Time-Varying Multipath Channels

In this paper, a low complexity ordered successive interference cancellation (OSIC) equalizer based on minimum-mean squared error (MMSE) criterion is proposed for suppressing intercarrier interference (ICI) caused by time-selective channels in OFDM systems. The proposed scheme exploits a low complexity MMSE equalizer and a partial MMSE-OSIC equalizer appropriately, according to symbol selection algorithm. This algorithm chooses the number of selected symbols which should be detected by the OSIC scheme based on the required reliability (RR) of each subchannel. The RR of each subchannel means the target signal-to-interference plus noise ratio (SINR) of symbol in each subchannel. Furthermore, to reduce the computational complexity in the partial MMSE-OSIC, the average number of selected symbols is maintained under the threshold value appropriately in low SNR. It is shown in simulation results that the performance of the proposed equalizer is close to that of the existing MMSE-OSIC equalizers with high computational complexity (ges O(N²)), while achieving a significant reduction in computational complexity (O(N)).