mmComb: High-speed mmWave Commodity WiFi Backscatter

High-speed connectivity is key to enabling a range of novel IoT applications. Millimeter-wave (mmWave) backscatter has emerged as a possible solution to create high-speed, low-power IoT networks. However, state-of-the-art mmWave backscatter systems are costly due to the need for dedicated mmWave reader devices. This paper presents mmComb, a mmWave backscatter system that is built to operate on commodity mmWave WiFi. mmComb is developed with the aim that mmWave backscatter tags can be directly integrated into 802.11ad/ay mmWave WiFi networks. mmComb makes two key contributions. First, We propose a technique to communicate with backscatter tags using existing beamforming protocol frames from mmWave WiFi devices, without any protocol modification. Second, we develop a self-interference suppression solution that intelligently uses receive beamforming to extract weak mmWave backscatter signal even in indoor multipath-rich channels. We implement our solution with a tag prototype and 60 GHz commodity WiFi devices. Our results show that mmComb can achieve a maximum data rate of 55 Mbps just by leveraging 802.11ad/ay control frames while consuming 87.3 µW with BER lower than 10 -3 up to 5.5 m range.