Ambient Backscatter with a Single Commodity AP

Ambient backscatter is one of the most promising wireless communication techniques that can accommodate the ever-growing scale of IoT devices and connections. The state-of-the-art ambient backscatter systems, however, have to employ two commodity receivers for tag-data demodulation, resulting in additional software and hardware overhead. Using off-the-shelf ambient WiFi signals and a single AP to achieve backscatter communication has seldom been studied before. In this paper, we introduce Twoferscatter, an innovative ambient backscatter system that uses a single commodity AP to decode tag data alone. We propose a nomination-verification decoding strategy to achieve tag-data decoding with the backscatter data. We also develope a block-level modulation method that extends our system to massive MIMO excitation. Our experiments demonstrate that Twoferscatter can successfully demodulate tag data with a single AP. It can deliver up to 5.62 kbps tag-data goodput and work at tag-Rx distances of up to 12
$m$
using an unmodified NIC receiver. We believe Twoferscatter has a bright future in passive IoT applications since it is the first ambient backscatter that uses ambient WiFi as excitation and requires only a single AP for demodulation.