BlueFi

Abstract

Bluetooth and WiFi are the two dominant technologies enabling the communication of mobile and IoT devices. Built with specific design goals and principles, they are vastly different, each using its own hardware and software. Thus, they are not interoperable and require different hardware. One may, therefore, ask a simple, yet seemingly impossible question: “Can we transmit Bluetooth packets on commercial off-the-shelf (COTS) WiFi hardware?” We answer this question positively by designing, implementing and demonstrating a novel system called BlueFi. It can readily run on existing, widely-deployed WiFi devices without modifying NIC firmware/hardware. BlueFi works by reversing the signal processing of WiFi hardware and finds special 802.11n packets that are decodable by unmodified Bluetooth devices. With BlueFi, every 802.11n device can be used simultaneously as a Bluetooth device, which instantly increases the coverage of Bluetooth, thanks to the omnipresence of WiFi devices. BlueFi is particularly useful for WiFi-only devices or environments. We implement and evaluate BlueFi on devices with widely-adopted WiFi chips. We also construct two prevalent end-to-end apps — Bluetooth beacon and audio — to showcase the practical use of BlueFi. The former allows ordinary APs to send location beacons; the latter enables WiFi chips to stream Bluetooth audio in real time.