UWB Measurements for Spatial Variability and Ranging: Parked Car in Underground Garage

The randomness in ultrawideband channel for small positional variations around a car, parked in an underground garage, is reported. Keeping the receiver fixed at the conventional rooftop antenna location, the transmitter location is changed to study the variations against distance, angle, and height. The path loss is found to be monotonically increasing with distance, but varies randomly with angle and height and thereby renders signal-strength-based ranging inaccurate for such scenarios. On the other hand, the first peak can reliably provide distance estimate irrespective of transmitter angle or height. The number of clusters in the delay profile reduces with distance, but the shape of the profile remains fairly consistent across angle. The Saleh-Valenzuela parameter values also vary with distance and height, but their average values are close to the IEEE 802.15.3 standard.