1. A method comprising: obtaining power information indicating a detected power of respective signals received in a mobile device from multiple transmitters; determining a plurality of sample positions, each sample position being a possible location of the mobile device; determining, using at least the obtained power information, known locations of the transmitters, and the sample positions, a probability model, the probability model including respective probability values of the sample positions, each probability value indicating a probability that the mobile device is located at a corresponding sample position, the probability value of each sample position being determined based at least in part on: a function measuring contributions of power of a signal from a first transmitter and power of a signal from a second transmitter to signals measurable at the sample location, the detected power of respective signals from the first transmitter and the second transmitter, and the respective known locations of the first transmitter and the second transmitter; and identifying, from the plurality of sample positions, an estimated position of the mobile device based at least in part on the determined probability values.