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A low complexity ZF Equalization for OFDM Systems over Time-varying Channels  

Park, Ji-Hyun (School of Electrical & Electronic Engineering at Yonsei University)
Hwang, Seung-Hoon (School of Electronic Engineering at Dongguk)
Whang, Keum-Chan (School of Electrical & Electronic Engineering at Yonsei University)
Publication Information
Journal of the Institute of Electronics Engineers of Korea TC / v.45, no.4, 2008 , pp. 1-8 More about this Journal
Abstract
In orthogonal frequency division multiplexing (OFDM) system the time selectivity of wireless channel introduces intercarrier interference (ICI), which degrades system performance in proportion to Doppler frequency. To mitigate the ICI effect, we can generally employ a classical zero-forcing (ZF) equalizer. However, the ZF scheme requires an inverse of a large matrix, which results in prohibitively high computational complexity. In this paper, we propose a low complexity ZF equalization scheme for suppressing the ICI caused by highly time-varying channels in OFDM systems. From the fact that the ICI on a subcarrier is mainly caused by several neighboring subcarriers, the proposed scheme exploits a numerical approximation for matrix inversion based on Neumann's Series (truncated second order). To further improve performance, the partial ICI cancellation technique is also used with reduced complexity. Complexity analysis and simulation results show that the proposed scheme provides the advantage of reducing computational complexity significantly, while achieving almost the same performance as that of the classical ZF a roach.
Keywords
OFDM; equalization; intercarrier interference;
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