Mostly, motion signals are inaccurate, especially if the mobile device is not a proprietary device, and one has to reckon that the bearer wears the mobile device somewhere else than where it is supposed to be worn in order to coincide with the laboratory conditions. However, the information conveyed by the motion signals is sufficient in order to discriminate and detect between different typical wearing/carrying conditions, and accordingly position tracking based on such motion signals may be rendered far more efficiently by, first of all, using the motion signals gained from the one or more motion sensors so as to attribute them to one of a plurality of analysis parameter sets so as to obtain a selected analysis parameter set and, second, analyzing the motion signals using the selected analysis parameter set so as to obtain a signal indicating a locomotion of the bearer.