FLEW: Fully emulated WiFi

Abstract

WiFi is the de facto standard for providing wireless access to the Internet using the 2.4GHz ISM band. Tens of billions of WiFi devices were shipped worldwide and WiFi Access Points (APs) are ubiquitous in public, enterprise and personal environments. We have also witnessed the fast growth of IoT (Internet of Things) devices. With more stringent board-space and power requirements, many IoT devices use more power-efficient, lower-cost and smaller wireless chips, such as Bluetooth or proprietary wireless chips. Due to the mismatch of different wireless technologies, these devices access the Internet indirectly via far less ubiquitous IoT gateways. Bluetooth and most proprietary wireless chips are based on FSK (Frequency-Shift Keying) modulation since FSK can be implemented with extremely simple and low-power FM (Frequency Modulation) circuits. In this paper, we present FLEW (Fully Emulated WiFi), which uses a single FSK chip to fully emulate both transmission and reception of WiFi signals. Using FLEW, FSK-equipped IoT or mobile/wearable devices can directly communicate with unmodified WiFi APs, just like any WiFi device. FLEW combines the best of both technologies: extremely simple and low-power hardware and ubiquitous Internet access. We evaluate FLEW extensively with chips from all major chip makers. At 20 meters, FLEW can sustain 708kbps uplink and 857kbps downlink at the transport layer.