Body Shadowing in an Indoor Positioning System Based on UWB

The Indoor Positioning System (IPS) based on Ultra-Wideband (UWB) discussed in this article uses signals from fixed devices or nodes to determine the position of an object or person carrying a mobile node in an indoor environment. However, when the system is estimating the position of a person, the mobile node may encounter a Non Line of Sight (NLOS) condition due to body shadowing, where the human body itself obstructs the signal. This condition affects the system’s accuracy and precision. The article demonstrates that the impact of body shadowing can be mitigated by implementing estimation tools such as the Extended Kalman Filter (EKF). The study presents results from localizing and tracking a person following a route in three classrooms at the University of Cauca, Popayan, Colombia. It concludes that´ body shadowing can cause a mean position error of up to 2 meters. However, this error significantly decreases when the EKF is applied, resulting in a mean position error of 30 cm, which represents a loss of accuracy of approximately 20 cm compared to results without body shadowing.