Technology for Tracking the Movement of Subscribers Within the Territory of a Critical Infrastructure Enterprise

The article discusses the pressing issue of ensuring reliable positioning of subscribers at critical infrastructure facilities in conditions of possible spoofing or jamming of GPS signals. An innovative method for tracking subscriber movement using Bluetooth Low Energy (BLE) beacon technology is proposed as an effective alternative to satellite positioning. The developed system is based on a network of strategically placed BLE beacons that transmit pre-set GPS coordinates via data in advertising packets at an optimal interval of 100 ms, which ensures a balance between accuracy and energy consumption. For the practical implementation of the experiment, publicly available hardware based on ESP32 microcontrollers with built-in OLED displays was used, demonstrating the accessibility and cost-effectiveness of the solution. Specialized software was developed for transmitters (beacons) and receivers (subscribers) with the implementation of a set of positioning algorithms, including gradient descent triangulation methods, adaptive Kalman filters, and the weighted least squares (WLS) method. The system also includes a web interface for displaying results in real time and an API for integrating existing security systems. Experimental studies were conducted in real conditions in a 110 m² room with a high density of beacons (one per 15 m²) and the presence of about 20 active BLE devices to simulate a typical office environment. Detailed calibration of the system was performed with a standard signal attenuation of minus 83 dBm based on more than 3,000 measurements. The results showed that for stationary objects, the system provides satisfactory positioning accuracy of 1–2 meters without the use of additional digital filters, while for moving subscribers, the use of Kalman and WLS filters is necessary, which increases the computational load on the microcontroller by 30–35%, but significantly improves tracking quality. The system successfully demonstrates the possibility of creating autonomous high-precision positioning in the absence of or unreliability of satellite signals using available technologies and standard components.