A Passenger Flow Monitoring Method in Hongqiao Hub Area Based on Gridded Wi-Fi Sniffing

Among various methods of monitoring passenger flow, Wi-Fi sniffer monitoring method has the advantages of simple hardware layout and intermediate monitoring range. However, the single Wi-Fi sniffer monitoring capabilities will be reduced due to the size of different application environment, such as the Shanghai Hongqiao hub, in most locations only one single Wi-Fi sniffer can't cover the target area. In order to make the monitoring results closer to the real traffic, this paper proposes a method to grid the Wi-Fi sniffer monitoring area. Firstly, through field test and data acquisition in Hongqiao hub, the RSSI optimal estimates of the probe request frame for different propagation distances are fitted and modeled by classical logarithmic model; Secondly, meshing the target area according to the actual size, and using fitting model to calculate the dynamic threshold of the grid to constraint the Wi-Fi sniffer monitoring range into the grid; Finally, by large data analysis method to merge the small passenger flow data in the grid can show the overall passenger flow in the target area. Compared with the actual count results, the simulation result of the method has accuracy up to 90%. The overall passenger flow obtained can be used as the real-time basic data of the target area passenger flow for the traffic safety management, which provides a practical technical means for large-scale passenger flow monitoring.