AX-CSI: Enabling CSI extraction on commercial 802.11ax Wi-Fi platforms

Abstract

Channel state information (CSI) is paramount to modern Wi-Fi communication systems, as it allows for proper equalization of frames at the receiver side and enables advanced signal processing techniques such as beamforming and MIMO. Given that the CSI can accurately mirror physical changes in the wireless channel, CSI analysis has become a valuable resource to many wireless sensing applications based on the opportunistic use of Wi-Fi signals. Since CSI can usually not be accessed by users directly, several CSI extraction tools have been published over the last few years for various Wi-Fi chipsets. In this paper, we present the first system ever capable of extracting CSI from 802.11ax consumer devices using the Broadcom 43684 Wi-Fi chipset. This platform can extract up to 160 MHz-wide CSI using 4x4 MIMO, and it is compatible with the latest HE PHY. We make our CSI extraction tool available to the research community to foster further work on this emerging topic.