On the Feasibility of Millimeter-wave Backscatter using Commodity 802.11ad 60 GHz Radios

Backscattering RFIDs have emerged as a versatile platform for low-power wireless networking and sensing in the era of Internet-of-Things (IoT). At the same time, millimeter-wave (mmWave) wireless has gained substantial attraction with high-speed WLAN and 5G cellular networks. Although the majority of RFID backscatter research focuses on lower frequencies, mmWave backscatter provides unique opportunities due to its directionality and wide bandwidth. Existing mmWave backscatter systems rely on expensive, custom-designed, dedicated readers which limit their widespread use. In this work, we present an empirical characterization of the first-of-its-kind mmWave backscatter system using 60 GHz commercial off-the-shelf (COTS) 802.11ad radios. Our presented system only relies on Channel State Information (CSI) and requires no modification to hardware or protocol. Through experimentation, we demonstrate that mmWave backscatter can be detected at a distance of up to 6m at different angles and locations. We also present how the backscatter can be leveraged in estimating the blockages in a WLAN which can reduce the beamsearching overhead. Our work opens a new direction of research where mmWave backscatter can be used to realize an integrated mmWave networking, sensing, and applications.