Antenna as a Sensor: An Improved Vehicle Detection Solution via the Use of Antenna Impedance and Magnetic Signature

Smart Parking System (SPS) needs parking status information to support its reliable and efficient operation. The magnetometer-based Wireless Parking Sensors (WPS) have the advantage of low cost and convenient installation, leading to their widespread application in urban exterior parking spaces. However, the signature of magnetic signals can be interfered by neighboring vehicles. Hence, an Impedance and Magnetometer based Parking Detection (IMPD) solution is proposed in the paper, and the impedance characteristics of antenna and its auxiliary radio frequency (RF) circuit that are susceptible to vehicles composed of metal have been introduced into existing magnetometer-based parking detectors to address the inaccuracy of magnetic signatures affected by adjacent vehicle. In the solution, the value of the wireless transceiver's built-in receiving signal strength (RSS) and adjustable power amplifier units are used to achieve low-cost impedance measurement. Then, the signature of magnetic signals is fused with that of RSS patterns to achieve parking detection. Finally, the proposed solution has been evaluated in a parking space, and experiments show that the detection accuracy is up to 99.79%. Compared with the existing multi-source fusion parking detection methods, the proposed IMPD method has a higher cost-performance ratio and is suitable for large-scale application and promotion in smart parking systems.