BLE2LoRa: Cross-Technology Communication from Bluetooth to LoRa via Chirp Emulation
Zhijun Li, Yongrui Chen · 2020
Wireless Personal Area Network (WPAN) technologies (e.g., Bluetooth, ZigBee) have been widely used in our daily life. However, due to their short transmission distances, the delivery of urgent messages (e.g., emergency alarms) over long distance, suffers from long delay, since the messages have to be transported via multi-hop way. Recent studies show that adding low-power wide-area network (LPWAN) radios such as LoRa onto WPAN devices (e.g., Bluetooth) effectively overcomes the limitation. However, the introduce of heterogeneous communication inevitably incurs extra hardware cost, deployment inconvenience and traffic overhead from gateways. In this paper, we present BLE2LoRa, a novel Bluetooth Low Energy (BLE) to LoRaWAN cross-technology communication (CTC) approach, which leverages the frequency shifting ability of BLE device to emulate LoRa's chirp signal. Such emulation is feasible because a chirp is a signal whose frequency increases or decreases over time, while a BLE device can also construct specific signals with ladder-shaped frequencies which is similar to LoRa chirp by carefully selecting BLE payload bits. Therefore, without any hardware modification at both sender and receiver side, a LoRa device can demodulate BLE frames. Moreover, leveraging the high sensitivity of LoRa base station, a long distant CTC can be achieved. We bulid our BLE2LoRa prototype on USRP B210 (with LoRaWAN PHY) and commodity BLE chips (CC1200). Our evaluation reveals that BLE2LoRa can achieve 4.06kbps throughput from BLE to LoRa with more than 80% frame reception rate, leading to over 600 meters communication distance, which is over 20x range extension over native Bluetooth.