Smart Parking System Based on an Ultrasonic Sensor and Bluetooth Low Energy in the Internet of Things

Technology related to the Internet of Things (IoT) has contributed greatly to smart living environments. The smart parking system is one of the main services based on IoT applications. To identify parked vehicles, previous parking systems used special identification devices where Radio-Frequency Identification (RFID) tags were carried by the users and high-quality cameras could recognize the vehicle license numbers. However, the previous methods were inefficient in terms of cost and they were not user-friendly. Thus, to address these problems, we propose a smart parking system based on ultrasonic sensors and the received signal strength indicator (RSSI) in Bluetooth communication. The proposed system determines the available spaces by using sensor motes located in the parking spaces. In addition, it recognizes the location of a parked vehicle based on Bluetooth low energy (BLE) communication between the user’s smartphone and the sensor motes. Furthermore, to improve the location awareness for users, we transform the RSSI strength into a distance range by applying the triangulation method. Based on IoT technology, the smart parking system can guide users to locations for their vehicles. We implemented the sensor motes for the ultrasonic sensor as well as the BLE modules in order to evaluate the proposed smart parking system. The sensor motes were deployed in parking spaces and we confirmed that the ultrasonic sensors successfully detected the available parking spaces, and they guided cars to the parking spaces divided into cell units.