BackFi

TLDR

BackFi is a novel system that enables high‑throughput, long‑range communication between low‑power backscatter devices and WiFi access points by using ambient WiFi signals as excitation. BackFi designs devices and WiFi APs so that the AP can decode backscatter signals modulated onto ambient WiFi transmissions while simultaneously transmitting to regular clients. Prototype experiments show BackFi achieves up to 5 Mbps at 1 m and 1 Mbps at 5 m, outperforming prior WiFi backscatter by 1–3 orders of magnitude while consuming negligible power per bit.

Abstract

We present BackFi, a novel communication system that enables high throughput, long range communication between very low power backscatter devices and WiFi APs using ambient WiFi transmissions as the excitation signal. Specifically, we show that it is possible to design devices and WiFi APs such that the WiFi AP in the process of transmitting data to normal WiFi clients can decode backscatter signals which the devices generate by modulating information on to the ambient WiFi transmission. We show via prototypes and experiments that it is possible to achieve communication rates of up to 5 Mbps at a range of 1 m and 1 Mbps at a range of 5 meters. Such performance is an order to three orders of magnitude better than the best known prior WiFi backscatter system [27,25]. BackFi design is energy efficient, as it relies on backscattering alone and needs insignificant power, hence the energy consumed per bit is small.