Indication of Pedestrian's Travel Direction Through Bluetooth Low Energy Signals Perceived by a Single Observer Device

This paper presents a study to understand the directional sensitivity of a Bluetooth Low Energy (BLE) monitoring device (Observer) and whether, using a single such Observer, the characteristics of its antenna can be used to identify the direction of a pedestrian's movement. To comprehend the directional characteristics of the antenna of the Observer employed for this study, the device is subjected to BLE signals emitted from a BLE beacon (Broadcaster) in an anechoic chamber. The results of this study confirmed that in the clean, noiseless environment of the chamber, the antenna we employed is clearly more receptive to signals emerging from certain directions. To confirm the validity of these results in an outdoor noisy environment, we performed another experiment where BLE Received Signal Strength (RSS) values were recorded from a Broadcaster held by a stationary volunteer pedestrian at different chosen points on a linear walkway. The results suggest that the directional sensitivity of the Observer's antenna holds true in outdoor settings. Finally, to determine the likelihood of inferring a pedestrian's travel direction, we deployed an Observer on a linear walkway where a volunteer pedestrian was recorded each time they passed over a series of chosen location markers. Overall, the results suggest that an assertion of travel direction through this method is indicative rather than conclusive and while the directional sensitivity of the Observer can be observed in controlled environments such as an anechoic chamber, it may not be as pronounced or reliable in outdoor settings. The findings highlight the importance of considering environmental factors when analysing BLE signals to infer pedestrian direction.