The calibration of phase offsets between RF chains on commodity WiFi chips has been an key obstacle for many WiFi-based applications. In this paper, we conduct extensive experiments to explore the characteristics of the phase offsets. The real experimental results reveal that the phase offsets are actually deterministic. We explain such a phenomena via the circuit design of WiFi chips. We also show that the phase offsets are even the same among different chips. With extensive experiments, we obtain and report the measured phase offset values for the commodity Intel 5300 and Atheros AR9380 WiFi chips. With the observation illustrated in this paper, the calibration of the phase offsets can be simplified greatly.

中文翻译：

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校准商品WiFi的相位偏移

商品WiFi芯片上RF链之间的相位偏移校准一直是许多基于WiFi的应用的主要障碍。在本文中，我们进行了广泛的实验以探索相位偏移的特性。实际的实验结果表明，相位偏移实际上是确定性的。我们通过WiFi芯片的电路设计来解释这种现象。我们还表明，不同芯片之间的相位偏移甚至相同。通过广泛的实验，我们获得并报告了商用英特尔5300和Atheros AR9380 WiFi芯片的测量相位偏移值。通过本文所示的观察，可以大大简化相位偏移的校准。