Patent ID: 8255160

Claim:
A method, in a navigation system, of obtaining and maintaining a dynamic navigation solution for a mobile terminal of a cellular communications network which mobile terminal includes a transmission source receiver for receiving the signals from one or more unsynchronised terrestrial transmission sources of the cellular communications network, a satellite positioning receiver for receiving signals from the satellite or satellites of a satellite positioning system, and a terminal clock, the method comprising acquiring a measurement vector having a list of values, each value representing a measurement made by a receiver, and information related to the terminal's clock; computing a state vector representing the current state of the navigation system, using a previously-determined state vector, the measurement vector, and a dynamic model; and deriving a dynamic navigation solution from the state vector; wherein the elements of the state vector include at least (a) in one or more dimensions position information of the terminal; (b) representations of the biases of clocks associated with the unsynchronised terrestrial transmission sources relative to a given time; (c) the bias of the terminal clock; (d) quality indicators indicating an error associated with elements in (a) to (c); and (e) linking indicators indicating the dependency of elements in (a) to (c) on others of the elements.