论文标题
在802.11ac商品wifi的相位偏移量
On Phase Offsets of 802.11ac Commodity WiFi
论文作者
论文摘要
我们分析了现代IEEE 802.11ac芯片的RF链之间的相位偏移。我们在每个OFDM子载波级别上研究了2.4和5GHz频段。结果表明，接收天线之间的相位偏移归因于随机相位旋转半时不变，最多四个可能的值。而且，它是频率依赖性的。我们提出了一种简单的算法，该算法使我们能够在无需校准的情况下即时纠正相位偏移量。作为概念验证，我们使用音乐算法实现了到达角度（AOA）。为了达到更高的精度，我们缝合了2.4GHz频段中可用的13个重叠的20MHz通道，以有效地具有一个80MHz通道。结果表明，尽管只使用了两个接收天线，但AOA的精度非常好。
We analyze the phase offsets between RF chains of modern IEEE 802.11ac chips. We investigate both the 2.4 and 5GHz bands on a per OFDM subcarrier level. Results reveal that the phase offset between receive antennas is due to random phase rotations semi-time-invariant with up to four possible values. Moreover, it is frequency-dependent. We propose a simple algorithm, which allows us to correct the phase offset on the fly without any calibration. As proof-of-concept, we implemented Angle of Arrival (AoA) using MUSIC algorithm. To achieve higher accuracy we stitched the thirteen overlapping 20MHz channels available in 2.4GHz band together to effectively have a single 80MHz channel. Results show very good AoA precision although only two receive antennas were used.
