Patent attributes
A system obtains from each of a plurality of mobile devices a batch of data for a site. A batch includes data enabling a determination of a reference position, sensor data of motion sensors and sets of results of measurements performed by the mobile device on radio signals at different locations, each set including at least one indication of a received signal strength of radio signals and an associated identifier of at least one radio transmitter transmitting the radio signals. In at least two iterations, the system processes each batch to determine for each mobile device a (refined) sequence of fingerprints associating a respective position, which is based on the at least one reference position, the sensor data (and estimated characteristics of radio transmitters), with each set of results of measurements; and estimates characteristics of the radio transmitters based on the (refined) sequences of fingerprints.
