A Low Complexity ICI Cancellation Method for High Mobility OFDM Systems

Abstract

Orthogonal frequency division multiplexing (OFDM) can significantly reduce a receiver complexity using one-tap frequency domain equalizer in a frequency-selective fading channel. However, the channel variation due to high mobility gives a time-selectivity in one OFDM symbol. As a result, each OFDM subcarrier experiences inter-carrier interference (ICI) that makes the equalization process very complicate. We propose a low complexity ICI cancellation method that takes advantage of the ICI power distribution. Instead of computing the inversion of the whole channel frequency response (CFR) matrix, we split the matrix into several small sub-matrices that contain significant channel information and perform a linear minimum mean squared error (LMMSE) equalization. We also propose an efficient successive interference cancellation (SIC) method that can effectively utilize a time diversity resulting from the mobility. Simulation results show that the performance improvements is remarkable even though the sub-matrix size is much smaller than that of the whole CFR matrix while taking high computational efficiency.