Zero-knowledge real-time indoor tracking via outdoor wireless directional antennas

WiFi localization and tracking of indoor moving objects is an important problem in many contexts of ubiquitous buildings, first responder environments, and others. Previous approaches in WiFi-based indoor localization and tracking either assume prior knowledge of indoor environment or assume many data samples from location-fixed WiFi sources (i.e. anchor points). However, such assumptions are not always true, especially in emergency scenarios. This paper explores the possibility of real-time indoor localization and tracking without any knowledge of indoor environment and with real-time data samples from only few anchor points outside the building. By using a small set of synchronized directional antennas as outdoor anchor points to actively scan in various directions, a moving device inside the building can be localized and tracked from the received signal in real-time manner. The paper proposes an angle-of-arrival estimator for accurate localization and adaptive per-antenna angular scheduling for real-time indoor tracking. The validation results from real experiment and simulation yield effectiveness and accuracy of the proposed schemes.