1. A method for determining a location of a mobile device, comprising: analyzing call data records of the mobile device to determine a first cell where the mobile device resided and time which the mobile device spent in moving from the first cell to a second cell; determining probability densities that the mobile device was located at respective locations within the first cell, based on a moving speed of the mobile device and the time; and determining possible locations of the mobile device within the first cell, according to the probability densities.