Patent ID: 7639179

Claim:
A method of supplying position assistance information to a receiver of a satellite positioning system, contained within a mobile terminal having a timing reference, said mobile terminal being connected to a cellular communications network and also able to communicate via a bi-directional link with one or more remote devices capable of calculating position information, the method comprising the steps of: (a) at a first location, where satellite signals are available, obtaining satellite position information of the mobile terminal from the satellite positioning system, storing said satellite position information within said terminal, measuring first time offsets, of the signals received by the terminal from a first plurality of transmitters of said cellular communications network, relative to each other or to the timing reference; (b) sending said first time offset measurements to a remote device, calculating a first terminal cellular position information in the remote device using said time offset measurements, and storing said first terminal cellular position information; (c) assigning a first time-tag to the first time offset measurements and storing said first time-tag; (d) at a second location, where signals from the satellite positioning system are not adequately available, measuring second time offsets, of the signals received by the terminal from the first or a second plurality of the transmitters of said cellular communications network, relative to each other or to the timing reference; (e) sending said second time offset measurements to, and calculating a second terminal cellular position information in, the or another remote device using said second time offset measurements; (f) assigning a second time-tag to the second time offset measurements and storing said second time-tag; (g) retrieving the first terminal cellular position information and the first time-tag and calculating a cellular average motion vector from the first and second terminal cellular position information and the first and second time-tags, and sending the cellular average motion vector to the mobile terminal; (h) calculating in the terminal a position difference vector using said cellular average motion vector and the first and second time-tags, and adding said cellular position difference vector to the satellite position information stored within the mobile terminal and obtaining therefrom position assistance information of the mobile terminal at the second location; (i) providing said position assistance information to the satellite receiver within the mobile terminal to aid the acquisition of satellite signals by the satellite receiver.