Enabling Direct Bluetooth-WiFi Communications

Abstract

Wireless communication has become an essential and ubiquitous technology in modern society. However, wireless technologies are heterogeneous where different wireless protocols were developed for various types of devices and applications. Since different wireless technologies use different waveforms, modulations, and protocol designs, direct communication between devices of different technologies is not possible. WiFi and Bluetooth are two most prominent and ubiquitous wireless technologies, but they are incompatible with each other, and thus cannot exchange information directly between them. As a result, additional hardware, such as dedicated radio chips or gateways, is required to connect devices of different technologies. This thesis investigates this long-standing incompatibility in general and explores the direct communication between WiFi and Bluetooth in particular. It presents key concepts, theories, system designs and implementations that realize direct communication between WiFi and Bluetooth devices. The novel solutions proposed in this thesis enable mismatched wireless devices compatible down to the physical-layer and waveform levels. This intercommunication opens new opportunities for information to go beyond the boundary of one wireless technology, thus enabling highly connected networks with heterogeneous communication links. Furthermore, by allowing transmitters and receivers to use different wireless technologies, heterogeneous communication links combine the strength of both technologies. For example, Internet-of-Things (IoT) networks are enabled to use simple, energy-efficient, low-cost sensor nodes with direct Internet access by leveraging existing WiFi infrastructures. This thesis presents pioneering research of Bluetooth-WiFi communication, which consists of several innovations. The first innovation, BlueFi, enables direct communication from widely-used WiFi chips to unmodified Bluetooth chips. BlueFi carefully crafts 802.11n packets on the transmitter side so that conventional Bluetooth receivers can accurately decode the waveform as legitimate Bluetooth packets. It enables practical use cases such as sending Bluetooth localization beacons with WiFi access points and streaming Bluetooth audio from WiFi cards to Bluetooth headphones. The thesis then presents FLEW that enables bidirectional communication between WiFi and FSK chips. FLEW identifies key signal processing properties and enables FSK chips to both send and receive standard WiFi packets with innovative system designs and implementations. By enabling bidirectional heterogeneous wireless links, FLEW is especially useful for IoT networks to combine the advantages of both Bluetooth (FSK) and WiFi. The third innovation is Unify, which is the first single-chip solution for bidirectional Bluetooth-WiFi communication. Unify works on widely popular FSK and BLE SoCs (System-on-a-Chip) and enables direct WiFi connectivity. Because of the high system integration of Unify, future IoT devices can be inexpensive, energy-efficient, and compact while also being capable of directly connecting to WiFi access points. To further improve the throughputs while also reducing power consumption, this thesis then proposes DREW, which enables WiFi-to-Bluetooth communication with twice the throughputs and Bluetooth-to-WiFi communication without relying on power-consuming mixers. With DREW, this thesis extends Bluetooth-WiFi communication to benefit more use cases, particularly for wearable devices and multimedia applications. The higher throughputs allow DREW to stream uncompressed, wired-equivalent stereo audio from WiFi to Bluetooth chips. Finally, this thesis applies the principle of Bluetooth-WiFi communication for other heterogeneous devices. We present BBC, which enables direct communication between Bluetooth Classic and BLE devices. BBC allows simple, energy-efficient BLE chips to communicate with Bluetooth Classic devices, such as Bluetooth headphones. Furthermore, future devices can use simpler radio hardware to support both Bluetooth Classic and BLE connections.