SBC: scalable smartphone barometer calibration through crowdsourcing

We have seen increasingly popularity in embedding barometer into smartphone today. A barometer measures the barometric pressure, and it can be used for a variety of applications. For example, in localization techniques, it is used to detect the altitude or altitude change of a user. Unfortunately, the smartphone barometer measurement is not accurate, and it has to calibrate appropriately before use. In this paper, we present Scalable Barometer Calibration (SBC), a scalable, transitive calibration algorithm to automatically calibrate barometer for a large number of smartphone users. SBC requires neither any infrastructure nor any human intervention, it uses smartphone barometer and accelerometer only. SBC provides high accuracy of barometer calibration and minimum energy consumption, making it more realistic for real-world deployment. Our simulation and prototype system demonstrate the performance, scalability, and robustness of SBC.