AFOROS: A Low-Cost Wi-Fi-Based Monitoring System for Estimating Occupancy of Public Spaces

Estimating the number of people present in a given venue in real-time is extremely useful from a security, management, and resource optimization perspective. This article presents the architecture of a system based on the use of Wi-Fi sensor devices that allows estimating, almost in real-time, the number of people attending an event that is taking place in a venue. The estimate is based on the analysis of the probe request messages periodically transmitted by smartphones to determine the existence of Wi-Fi access points in the vicinity. The method considers the MAC address randomization mechanisms introduced in recent years in smartphones, which prevents the estimation of the number of devices by simply counting different MAC addresses. To solve this difficulty, our Wi-Fi sensors analyze other fields present in the header of the IEEE 802.11 frames, the information elements, to extract a unique fingerprint from each smartphone. The designed system was tested in a set of real scenarios, obtaining an estimate of attendance at different public events with an accuracy close to 95%.

Automated summary

This article introduces a system architecture using Wi-Fi sensor devices to estimate the number of people present in a venue in real-time. By analyzing probe request messages from smartphones, the system can estimate the number of attendees almost in real-time. To address the challenge of MAC address randomization in smartphones, Wi-Fi sensors analyze other fields in IEEE 802.11 frames to extract a unique fingerprint from each smartphone. The system was tested in real scenarios and achieved an accuracy of around 95% in estimating attendance at different public events.