Abstract:

We develop a model for the multiple-input multiple-output orthogonal frequency division multiplexing(MIMO-OFDM) system over time varying frequency selective fading channels. Using this model, we analyze the impacts of the channel on time variation characteristics within a transmission block which destroy the orthogonality of subcarrier and cause serious intercarrier interference(ICI). To circumvent this problem, we propose a frequency-domain iterative ICI cancellation algorithm. By separating the channel transfer function matrix into data and the ICI part, data are initially obtained by the zero-forcing algorithm, the interference between adjacent subcarriers, created by ICI matrix, is then subtracted from received symbols and finally the parallel interference cancellation detection using the data matrix is performed to suppress the multistream interference from different antennas. By restricting the interference to eighteen neighboring subcarriers, under the condition that the performance loss is neglectable compared with the original method, computational complexity can be drastically reduced. Simulation results show that the proposed method can effectively mitigate the effect of ICI at different doppler shifts and approach the ICI-free performance at a low signal-to-noise ratio.

Key words: multiple-input multiple-output(MIMO), orthogonal frequency division multiplexing(OFDM), intercarrier interference(ICI), time varying channels, Doppler