Global positioning system signal acquisition assistance

• US 20050285783A1
• Filed: 11/03/2004
• Published: 12/29/2005
• Est. Priority Date: 06/29/2004
• Status: Active Grant

• Current Assignee: TeleCommunication Systems Inc (Comtech Telecommunications Corporation)
• Original Assignee: Andrew Corporation (CommScope Holding Company, Inc.)
• Inventors: Harper, Neil
• Granted Patent: US 7,209,077 B2
• Time in Patent Office: Days
• US Class Current: 342/357.69
• CPC Class Codes: G01S 19/06 employing an initial estimate of the location of the receiver as aiding data or in generating aiding data
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence

Abstract

There is disclosed a method of determining a code phase search window for use by a satellite positioning system receiver associated with a mobile terminal of a communications network when acquiring a signal from a satellite of a satellite positioning system.

Claims

1. A method of determining a code phase search window for use by a satellite positioning system receiver associated with a mobile terminal of wireless communications network when acquiring a signal from a satellite of a satellite positioning system, including:

determining an approximate position of the satellite positioning system receiver having an non-circular position uncertainty region associated therewith;

determining a minimum range to the satellite for a mobile terminal within the position uncertainty region;

determining a maximum range to the satellite for a mobile terminal within the position uncertainty region;

determining a code phase search window for use by the satellite positioning system receiver that includes a code phase interval encompassing code phase values corresponding to the minimum and maximum ranges to the satellite.

2. The method of claim 1 further including;

deriving at least one of the approximate position of the satellite positioning system receiver, and the non-circular position uncertainty region associated therewith from radio communications parameter data associated with the mobile terminal.

3. The method of claim 1 wherein the method further includes, determining a point within the non-circular position uncertainty region that is closest to the satellite.

4. The method of claim 1 wherein the method further includes, determining a point within the non-circular position uncertainty region that is farthest from the satellite.

5. The method of claim 1 further including determining a midpoint for the uncertainty region which lies equidistant from the point within the non-circular position uncertainty region that is closest to the satellite and the point within the non-circular position uncertainty region that is farthest from the satellite.

6. The method of claim 5 wherein determining a midpoint for the code phase search window by determining the code phase of a point having a range to the satellite that is halfway between the minimum range to the satellite and the maximum range for a mobile terminal within the uncertainty region.

7. The method of claim 1 in which the position uncertainty region is a three dimensional region.

8. The method of claim 1 in which the position uncertainty region is defined by a two dimensional position uncertainty region and a vertical position uncertainty.

9. The method of claim 1 wherein the uncertainty region is determined on the basis of at least a transmission pattern of a transmitter of the communications network with which the mobile terminal is in communication.

10. The method of claim 1 wherein the non-circular uncertainty region assigned to the approximate position is selected from a list including:

an elliptical region, an ellipsoid, a polygonal region, an arc band.

11. The method of claim 8 wherein the vertical uncertainty is assigned on the basis of the topology of the two dimensional uncertainty region.

12. The method of claim 1 further comprising transmitting the code phase search window to the satellite positioning system receiver.

13. A method, in a satellite positioning system receiver associated with a mobile terminal of a wireless communications network, of determining a code phase offset between a locally generated encoded signal and an encoded signal received from a satellite of the satellite positioning system, the method comprising:

comparing the phase of the locally generated encoded signal to the received signal for a plurality of the code phase offsets in a code phase search window until a phase match is identified, wherein the code phase search window is determined on the basis of an approximate position of the satellite positioning system receiver and an associated a non-circular position uncertainty region and is representative of a range of possible code phase offsets for a terminal located in said non-circular position uncertainty region.

14. The method of claim 13 wherein the code phase search window is determined by;

determining a minimum range to the satellite for a mobile terminal within the position uncertainty region;

determining a maximum range to the satellite for a mobile terminal within the position uncertainty region;

determining a code phase search window for use by the satellite positioning system receiver that includes a code phase interval encompassing code phase values corresponding to the minimum and maximum ranges to the satellite.

15. The method of claim 13 further including, deriving at least one of the approximate position of the satellite positioning system receiver, and the non-circular position uncertainty region associated therewith from radio communications parameter data associated with the mobile terminal.

16. The method of claim 13 in which a midpoint for the code phase search window is determined by determining the code phase of a point having a range to the satellite that is halfway between a point within uncertainty region having a minimum range to the satellite and a point within uncertainty region having a maximum range to the satellite.

17. The method of claim 13 in which the position uncertainty region is a three dimensional region.

18. The method of claim 13 in which the position uncertainty region is defined by a two dimensional position uncertainty region and a vertical position uncertainty.

19. The method of claim 13 wherein the uncertainty region is determined on the basis of at least a transmission pattern of a transmitter of the communications network with which the mobile terminal is in communication.

20. The method of claim 13 wherein the non-circular uncertainty region assigned to the approximate position is selected from a list including:

an elliptical region, an ellipsoid, a polygonal region, an arc band.

21. The method of claim 18 wherein the vertical uncertainty is assigned on the basis of the topology of the two-dimensional uncertainty region.

22. The method of claim 13 wherein the code phase search window is transmitted to the satellite positioning system receiver by the radio communications network.

23. A method of assisting a satellite positioning system receiver associated with a mobile terminal operating in a wireless communications network to determine a code phase offset between an encoded signal generated in the receiver and an encoded signal received from a satellite of the satellite positioning system, the method including:

determining, on the basis of an approximate position of the mobile terminal and an associated a non-circular uncertainty region, a code phase search window; and

communicating the determined code phase search window to the receiver.

24. The method of claim 23 wherein the code phase search window is determined by;

determining a minimum range to the satellite for a mobile terminal within the position uncertainty region;

determining a maximum range to the satellite for a mobile terminal within the position uncertainty region;

determining a code phase search window for use by the satellite positioning system receiver that includes a code phase interval encompassing code phase values corresponding to the minimum and maximums ranges to the satellite.

25. The method of claim 23 her including, deriving at least one of the approximate position of the satellite positioning system receiver, and the non-circular position uncertainty region associated therewith from radio communications parameter data associated with the mobile terminal.

26. The method of claim 23 in which a midpoint for the code phase search window is determined by determining the code phase of a point having a range to the satellite that is halfway between a point within uncertainty region having a minimum range to the satellite and a point within uncertainty region having a maximum range to the satellite.

27. The method of claim 23 in which the position uncertainty region is a three dimensional region.

28. The method of claim 23 in which the position uncertainty region is defined by a two dimensional position uncertainty region and a vertical position uncertainty.

29. The method of claim 23 wherein the uncertainty region is determined on the basis of at least a transmission pattern of a transmitter of the communications network with which the mobile terminal is in communication.

30. The method of claim 23 wherein the non-circular uncertainty region assigned to the approximate position is selected from a list including:

an elliptical region, an ellipsoid, a polygonal region, an arc band.

31. The method of claim 28 wherein the vertical uncertainty is assigned on the basis of the topology of the two-dimensional uncertainty region.

32. The method of claim 23 wherein data representative of the determined code phase search window is transmitted via the cellular telecommunications network for use by the satellite positioning system receiver.

33. The method of claim 23 wherein the code phase search window is determined by a network element of the cellular telecommunications network.

34. The method of claim 33 wherein at least one of the non-circular uncertainty region are determined for the mobile terminal by a second network element.

35. A network element of a communications network configured to determine a code phase search window for use by a satellite positioning system receiver associated with a mobile terminal operating within the communications network, wherein the network element is configured to determine a code phase search window on the basis of:

an approximate position assigned to the satellite positioning system receiver having a non-circular position uncertainty region associated wherewith.

36. The network element of claim 35 wherein the network element is a mobile location centre of a cellular telecommunications network.

37. The network element of claim 35 which is further includes transmission means configured to communicate data representative of the code phase search window to the satellite positioning system receiver via the communications network.

42. A communication network including a network element as claimed in claim 35.

43. A communication network as claimed in claim 42 wherein the network is one of the following types of network:

Global System for Mobile (GSM) network, code-division multiple access (CDMA) network, Universal Mobile Telecommunications Service (UMTS) network.

38. A network element of a communications network including;

a processor configured to determine a code phase search window for use by a satellite positioning system receiver associated with a mobile terminal operating within the communications network, the processor being configured to determine a code phase search window on the basis of;

an approximate position assigned to the satellite positioning system receiver;

a non-circular position uncertainty region associated with the approximate position; and

transmission means configured to transmit data representative of the code phase search window to the mobile terminal via the communications network.

39. The network element of claim 38 including reception means configured to receive data from the communication network from which the approximate position assigned to the satellite positioning system receiver and a non-circular position uncertainty region can be derived.

40. The network element of claim 38 further including memory means configured to store thereon a database structure including vertical position uncertainty data useable by the processor to determine a code phase search window for a mobile terminal.

41. The network element of claim 38 wherein the network element is a mobile location centre of a cellular telecommunications network.

44. A communication network including a network element as claimed in claim 38.

45. A communication network as claimed in claim 44 wherein the network is one of the following types of network;

Global System for Mobile (GSM) network, code-division multiple access (CDMA) network, Universal Mobile Telecommunications Service (UMTS) network.

46. A method of determining a code phase search window for use by a satellite positioning system receiver associated with a mobile terminal of wireless communications network when acquiring a signal from a satellite of a satellite positioning system, wherein the code phase search window is determined based on an approximate position of the satellite positioning system receiver and an associated non-circular uncertainty region surrounding the approximate position.

47. The method of claim 46 further including, deriving at least one of the approximate position of the satellite positioning system receiver, and the non-circular position uncertainty region associated therewith from radio communications parameter data associated with the mobile terminal.

48. The method of claim 46 wherein a midpoint for the code phase search window is determined by determining the code phase of a point having a range to the satellite that is halfway between the minimum range to the satellite and the maximum range for a mobile terminal within the uncertainty region.

49. The method of claim 46 in which the position uncertainty region is a three dimensional region.

50. The method of claim 46 in which the position uncertainty region is defined by a two dimensional position uncertainty region and a vertical position uncertainty.

51. The method of claim 46 wherein the uncertainty region is determined on the basis of at least a transmission pattern of a transmitter of the communications network with which the mobile terminal is in communication.

52. The method of claim 46 wherein the non-circular uncertainty region assigned to the approximate position is selected from a list including:

an elliptical region, an ellipsoid, a polygonal region, an arc band.

53. The method of claim 50 wherein the vertical uncertainty is assigned on the basis of the topology of the two-dimensional uncertainty region.

54. The method of claim 46 further comprising transmitting the code phase search window to the satellite positioning system receiver.

55. The method of claim 46 further comprising

receiving data representative of at least one of, the approximate position of the satellite positioning system receiver, and the non-circular uncertainty region associated therewith.