BlueFi: Physical-layer Cross-Technology Communication from Bluetooth to WiFi

Today's wireless networks have become increasingly heterogenous, mobile and dense. To satisfy the rising demands of ubiquitous connections, billions of multi-radio gateways have to be deployed, inevitably incurring high deployment cost and extra traffic overhead. Recent advances on Cross-Technology Communication (CTC) have shown its ability to avoid these drawbacks. However, the state-of-the-art CTCs from Bluetooth to WiFi, two of the most popular wireless techniques, still suffer from low data-rate (e.g., 3.1Kbps), which severely restricts their applicability. We present BlueFi, the first physical-layer CTC (PHY-CTC) from Bluetooth Low Energy (BLE) to WiFi, which enables high throughput, bidirectional and parallel transmissions between BLE and WiFi via spectral analysis. The key observation is that commodity WiFi chipsets can operate in the spectral analysis mode, in which WiFi can recognize specific BLE signal waveforms in frequency domain at symbol-level granularity. Leveraging this feature, we manufacture desired waveforms by choosing frame payload at BLE side, and observe spectral patterns at WiFi side. To achieve bidirectional links, we design a PHY-CTC method from WiFi to BLE based on signal emulation. We implement our prototype on USRP (with 802.11g PHY) and commodity BLE devices. Extensive evaluations show that BlueFi can achieve 120Kbps per link from BLE to WiFi with more than 95% frame reception ratio, over 38x faster than state-of-the-art CTCs. Moreover, BlueFi can support 9 wireless links in parallel, leading to the total throughput over 1Mbps.