Iterative Frequency Domain Equalization for OFDM Over Doubly Selective Channels

In this paper, we present an iterative frequency domain equalization method for orthogonal frequency division multiplexing (OFDM) over doubly selective channels. We approximate the channel by the oversampling basis expansion model (OBEM) because it can increase the model accuracy for the systems with high mobility However, the OBEM will create more serious inter-carrier interference (ICI) than the nonoversampling BEM. We propose a new iterative method to suppress the ICI effects in the frequency domain. The channel frequency response matrix (CFRM) is divided into two parts: a main band matrix as target CFRM and an out-of-band matrix as interference CFRM. At each iteration, the interference signals caused by interference CFRM are cancelled from the received signal and the target CFRM deduces the equalizer to obtain the signal estimate. Simulation results show that our proposed method outperforms the linear MMSE equalizer and has lower complexity.