Research On Interference Cancellation In MIMO-OFDM System

MIMO-OFDM system combines the advantage of OFDM technology with MIMO technology. It's characteristics of high spectral-efficiency, well link-reliability and high speed conform to the development requirement of the next-generation wireless transmission network. But with the explosive growth of mobility, the characteristics of channel time variation is more obvious. Intercarrier interference (ICI) arise from lose of subcarrier orthogonality result in performance degradationIn this thesis we are concerned with inercarrier interference cancellation in MIMO-OFDM system. First of all, this thesis analyzes the reasons and the mode of inercarrier interference. Find from the simulation, in the condition of high frequency-offset, Maximum Likelihood Estimation have a good performance gain than self-cancellation. Second, we investigate the inercarrier interference arise from Doppler spread in the channel of time variation at high velocities. Based on the above ICI analysis, we propose modified algorithm combined segments equalization with successive interference cancellation. Simulation results show that the segments zero-force equalization interference cancellation algorithm is capable of reduce the the effect of the time-variant channel effectively and reduce the sensitive about the velocities. The approach can reduce the BER of system even in the condition of high Doppler shift. Finally, we mainly focus on the inercarrier interference in MIMO-OFDM system arises from Dopper spread and the effect on performance. Based on the existing time-domain linear equalization mitigation method, a modified iterative algorithm was proposed could reduce the inercarrier interference for more. The results of computer demonstrated that time-domain equalization based iterative interference mitigation algorithm could reduce the ICI effectively. The more iterative the well performance gain. In rapid time variations channel, still can have the high SIR gain.