BLE-horn: A smartphone-based bluetooth low energy vehicle-to-pedestrian safety system

Vehicles to Pedestrians (V2P) communication always plays a critical role in Intelligent Transportation System (ITS). Recent researches show that Wi-Fi module in smartphones could be used to improve the traffic safety by broadcasting pedestrian position data. However, these Wi-Fi-based schemes could not achieve two-way communication with low latency, which would seriously affect the user experience. To address this issue, we propose an Android application called BLE-Horn, using Bluetooth Low Energy (BLE) to realize the bidirectional many-to-many communications. What's more, BLE also has advantages like lower battery consumption, low latency, low cost and it is also widely supported by smartphones. We redefine a Compressed GPS Information Packet (CGIP) in Bluetooth advertising packets and use a collision warning algorithm to detect the potential collision. In the real road test, we show that BLE-Horn can support at least 5 devices to communicate simultaneously between each other. The measured communication latency is as low as 56ms. With BLE-Horn running for an hour in the background, the battery level drops off only by 8.2 percents.