RSSI based passive detection of persons for waiting lines using Bluetooth Low Energy.

Knowledge about the presence of persons in a waiting line can help estimating the waiting time or guiding the decision about opening a second line. However, existing presence detection systems for waiting lines are either mounted at fixed positions, take a long time to deploy, need a power connection or require users to carry devices. Past research on the analysis of the Received Signal Strength Indicator (RSSI) of a radio transmission indicates that it can be used to detect the presence of persons. Here, the accuracy of the detection is directly linked to the quality of the radio link. Radio links based on Bluetooth Low Energy (BLE) offer a stable connection, but implement a mandatory frequency hopping scheme, with the information about the current channel typically not accessible. In this work we extend the concept of passive presence detection to work on BLE radio links. We adapt two RSSI based presence detection techniques and evaluate their performance in experiments. The experimental results indicate that it is possible to achieve a 92% accuracy using BLE when compared to the ground truth.