The various offsets existed in the commodity WiFi devices greatly limit the use of ubiquitous WiFi signals for indoor applications. In this paper, we focus on the estimation and compensation of the residual carrier frequency offset (CFO) for the commodity WiFi devices. Specifically, we consider a distorted channel state information (CSI) model by taking into consideration various CSI errors such as packet detection delay (PDD) and CFO. We propose a multiscale sparse recovery algorithm to get rid of the effect of PDD and extract the carrier frequency component out of CSI. Then, we formulate the residual CFO estimation as a spectrum estimation problem and utilize the MUSIC algorithm to estimate the residual CFO. Real experiments and numerical simulations are conducted to evaluate the performance of the proposed method. The experimental results and simulation results show that the residual CFO is time-varying, and compared with existing methods, the proposed method can better estimate and compensate the residual CFO, and thus achieve better results.

中文翻译：

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商用 WiFi 的剩余载波频率偏移估计和补偿

商用 WiFi 设备中存在的各种偏移极大地限制了无处不在的 WiFi 信号在室内应用中的使用。在本文中，我们专注于商用 WiFi 设备的残余载波频率偏移 (CFO) 的估计和补偿。具体来说，我们通过考虑各种 CSI 错误（例如数据包检测延迟 (PDD) 和 CFO）来考虑失真的信道状态信息 (CSI) 模型。我们提出了一种多尺度稀疏恢复算法来摆脱PDD的影响并从CSI中提取载频分量。然后，我们将剩余 CFO 估计公式化为频谱估计问题，并利用 MUSIC 算法来估计剩余 CFO。进行了实际实验和数值模拟以评估所提出方法的性能。