FM Backscatter: Enabling Connected Cities and Smart Fabrics

TL;DR

This paper introduces a novel backscatter communication method utilizing ambient FM radio signals, enabling everyday objects, fabrics, and billboards to transmit data to smartphones and cars with low power consumption.

Contribution

It presents the first use of ambient FM signals for backscatter communication, including a new modulation technique and practical prototypes on fabrics and posters.

Findings

Achieved data rates up to 3.2 kbps

Communication range of 5-60 feet

Power consumption as low as 11.07 μW

Abstract

This paper enables connectivity on everyday objects by transforming them into FM radio stations. To do this, we show for the first time that ambient FM radio signals can be used as a signal source for backscatter communication. Our design creates backscatter transmissions that can be decoded on any FM receiver including those in cars and smartphones. This enables us to achieve a previously infeasible capability: backscattering information to cars and smartphones in outdoor environments. Our key innovation is a modulation technique that transforms backscatter, which is a multiplication operation on RF signals, into an addition operation on the audio signals output by FM receivers. This enables us to embed both digital data as well as arbitrary audio into ambient analog FM radio signals. We build prototype hardware of our design and successfully embed audio transmissions over ambient FM signals. Further, we achieve data rates of up to 3.2 kbps and ranges of 5-60 feet, while consuming as little as 11.07{\mu}W of power. To demonstrate the potential of our design, we also fabricate our prototype on a cotton t-shirt by machine sewing patterns of a conductive thread to create a smart fabric that can transmit data to a smartphone. We also embed FM antennas into posters and billboards and show that they can communicate with FM receivers in cars and smartphones.