Estimation of Building Floors Based on Difference in Barometric Pressure Measured by Wireless Terminals

A data-processing system that estimates the particular building floors that are present in a particular building based on differences in barometric pressure measurements provided by wireless terminals. A wireless terminal can report one or more barometric pressure measurements at the ground floor of a building and one or more pressure measurements at one or more above- or below-ground floors, or “non-ground” floors. The data-processing system receives the pressure measurements and uses the difference in the pressure measurements to determine a change in height between the ground floor and a non-ground floor. When the system collects enough data from many wireless terminals, it is able to identify the floors that are present in a particular building and their non-ground heights. Then, when an estimate of the vertical location of a wireless terminal is provided to a location application, the system is able to provide the estimate in terms of building floor.