Robust Frequency Offset Estimation in the Presence of Time-Varying DC Offset
Robust Frequency Offset Estimation in the Presence of Time-Varying DC Offset
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DOI：
10.1587/transcom.e92.b.2577
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发表时间：
2009-08
期刊：
影响因子：
--
通讯作者：
Umut Yunus;Hai-Hsing Lin;K. Yamashita
中科院分区：
文献类型：
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作者：
Umut Yunus;Hai-Hsing Lin;K. Yamashita
在 OFDM 系统中，载波频率偏移 (CFO) 的估计/校正对于维持子载波之间的正交性至关重要。然而，CFO 估计会受到低成本直接转换接收器 (DCR) 中生成的直流偏移 (DCO) 的影响。更严重的是，实际上，由于自动增益控制，DCO 是随时间变化的。本文提出了一种存在时变 DCO 的新型 CFO 估计器。图中显示高通滤波后的残余 DCO 以线性方式变化。基于这一观察和训练序列的周期性，我们推导出独立于 DCO 的 CFO 估计器。另外，可以使用获得的CFO来估计残余DCO。通过仿真证明了所提出的估计方法的有效性。
In OFDM systems, the estimation/correction of carrier frequency offset (CFO) is crucial to maintain orthogonality among subcarriers. However, the CFO estimation suffers from DC offset (DCO) generated in low-cost direct-conversion receivers (DCRs). More seriously, in practice, DCO is time-varying due to the automatic gain control. In this paper, a novel CFO estimator in the presence of time-varying DCO is proposed. It is shown the residual DCO after high-pass filtering varies in a linear fashion. Based on this observation and the periodicity of the training sequence, we derive a CFO estimator independent of DCO. Also, the residual DCO can be estimated, using the obtained CFO. The validity of the proposed estimation method is demonstrated by simulations.