Researchers in China Developed a Prototype Wi-Fi and Bluetooth Traffic Detection System to Test the Feasibility of RSSI Error Correction Algorithms.
Shanghai, China
Multimodal Traffic Speed Monitoring: A Real-Time System Based on Passive Wi-Fi and Bluetooth Sensing Technology
Summary Information
Wi-Fi and Bluetooth passive sensing technology could be used as an effective method for obtaining traffic speed data, even though some challenges do exist greatly affecting the accuracy of the estimated traffic speeds. This study developed a real-time algorithm for estimating and correcting traffic speeds in areas covered by these sensors, utilizing signal strength indicators. Furthermore, a novel clustering algorithm was created to identify the traffic modes of device owners. The performance of the algorithms was evaluated using data from four sensors at Tongji University, Shanghai, including Wi-Fi and Bluetooth MAC addresses, and ground truth data from video recordings on June 2 and 3, 2019, between 4 PM and 6 PM. The study analyzed 106,926 data points and 26,596 unique MAC addresses. Additionally, traffic mode data for 408 MAC trips were collected with the help of ten volunteers, who navigated between sensors using various modes of transport.
- Properly address any potential errors in Wi-Fi and Bluetooth detection in estimating traffic speeds. This study used Received Signal Strength Indicator (RSSI) to apply a correction to the estimated speeds to make up for the inherent errors in capturing the exact locations of flow entities with Wi-Fi and Bluetooth detection technology.
- Identify the traffic modes of valid MAC trips based on the characteristics of each trip. In this study, a semi-supervised clustering algorithm was effectively used to categorize the traffic mode of each MAC trip, detected through passive Wi-Fi and Bluetooth sensing, enhancing the system's ability to monitor and analyze varying traffic patterns accurately.
- Keep the Wi-Fi and Bluetooth antenna extended to the outside of the roadside cabinet with waterproof protection. This was important since the metal shell of cabinets generated interference for Wi-Fi and Bluetooth signal communications as a result of signal shielding.
- Explore the feasibility of utilizing the cell phone signal of 5G and 6G for traffic speed monitoring. This kind of improvement would better capture the street-level movements by phone communication data as the communication range of 5G and 6G is much shorter than 3G/4G communication.
