Groupwise successive ICI cancellation for OFDM systems in time-varying channels

Orthogonal frequency division multiplexing (OFDM) is known as a promising technique for data transmission over broadband wireless communication channels. However, bit error rate (BER) performance of OFDM deteriorates significantly in time-varying channels due to presence of inter-channel interference (ICI). Previous works proposed time or frequency domain equalizers to reduce the effect of ICI. In this paper, we consider a combination of equalization and interference cancellation techniques to obtain better BER performance of OFDM in time-varying channels. Particularly, we propose a combined scheme of frequency domain minimum mean square error (MMSE) equalization and successive interference cancellation. A groupwise processing algorithm, which detects a group of subchannels in one iteration, is proposed to reduce the processing delay due to iterative successive cancellation. With the same third order of complexity, the proposed scheme provides large BER improvement over the conventional MMSE equalizer.