Azimuth based localization for mobile phones

Based on measured acceleration and compass data of smart phones a concept for GPS-free localization and traveling route estimation is presented. The built-in compass is used to measure the relative direction changes of the traveling user. The resulting azimuth trajectories are then successively matched to a vectorized street map. In order to relate the measured trajectory to the street map data, it has to be scaled correctly by the current user velocity. To estimate the current velocity, pattern matching is applied to the acceleration sensor data to detect the current means of transportation (MOT). By associating typical velocities with each MOT, a set of possible scaled azimuth trajectories can be found.