Methods and apparatuses are provided that may be implemented in a mobile device to determine two or more variations between a baseline probability distribution and two or more probability distributions for signals received from two or more sets of transmitters assigned to two or more regions of a structure. The methods and apparatuses may be further implemented to determine whether the mobile device is located in at least one of the two or more regions based, at least in part, on a comparison of the two or more determined variations.