Patent attributes
A method of estimating the position of a user device is provided. The user device is initially in electronic communication with a positioning system controller through a communication network. The method comprises determining that a user device meets one or more proximity criteria with respect to an offline region where electronic communication between the user device and the positioning system controller, through the communication network, is expected to meet one or more failure criteria. Responsive thereto and in advance of the user device entering the said offline region, the positioning system controller transmitting local positioning data to the user device, the local positioning data comprising data concerning electromagnetic signal sources in the said offline region. The user device subsequently estimates its position while it is within the offline region by measuring signal data from a plurality of electromagnetic signal sources and processing the measured signal data and the local positioning data. The method may be used by, for example, a smartphone to estimate its position.
