Research Into Intercarrier Interference Cancellation For OFDM System In High Mobile Environment

Orthogonal frequency-division multiplexing (OFDM) is widely adopted inbroadband wireless signal transmission due to its high data transfer rate, high spectralefficiency and the ability of anti-multipath. The current communication standardwhich will evolve to4G (eg, WiMAX802.16m, and3Gpp proposed LTE) are requiredto provide broadband communication services, when the terminals are moving at thespeed over350Km/h. In this scenario, the assumption of quasi-static channel is nolonger present. The time-varying channel will destroy the orthogonality betweensub-carriers resulting in inter-carrier interference (ICI) and affect the performance of thecommunication system. Therefore, the research into the ICI cancellation for OFDM inhigh mobile environment has important significance.Firstly, the paper introduces the development of the ICI cancellation, the influenceof the time-varying channel in high mobile environment and the mechanism of ICI inOFDM. Secondly, the paper concludes the current methods of ICI cancellation. For theproblem that the MMSE-SD has the high complexity, the paper adopts the methodwhich calculates the inverse matrix recursively instead of directly. As a result, themethod reduces the computational complexity greatly, while it has the sameperformance as the original method. Finally, the paper researches on the low complexityMMSE frequency domain equalization method. The Q-tap MMSE frequency domainequalization ignores the residual ICI to reduce the calculation complexity, which resultsin performance degradation. For the problem, the paper proposes a Q-tap MMSEfrequency domain equalization based on whitening residual ICI and noise. It whitens theresidual ICI and noise in the received signal together, and then detects the receivedsignal with the Q-tap MMSE frequency domain equalizer. The simulation results showthat the proposed method performs better than the traditional with no more complexity...