Systems and Methods of Assisted GPS

• US 20090121927A1
• Filed: 11/14/2007
• Published: 05/14/2009
• Est. Priority Date: 11/14/2007
• Status: Active Grant

• Current Assignee: Uber Technologies, Inc.
• Original Assignee: Radiofy, LLC
• Inventors: Moshfeghi, Mehran
• Granted Patent: US 8,193,978 B2
• Time in Patent Office: Days
• US Class Current: 342/357.240
• CPC Class Codes: G01S 19/072 Ionosphere corrections
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type

Abstract

Embodiments of an improved assisted global positioning system (GPS) method and system are described. Wireless access points send assistance data to GPS receivers that are integrated into cellular chipsets and other chipsets. The access points may also act as fixed location references for differential GPS (DGPS) mobile stations. Errors caused by multipath travel of the GPS signals are reduced by using fixed location reference receivers.

Claims

1. A method of position determination using global positioning system (GPS) signals, said method comprising the steps of:

receiving GPS information from a plurality of GPS satellites;

receiving a plurality of assistance data from at least one access point;

computing a combined assistance data from said plurality of assistance data; and

computing a position based on said GPS information and said combined assistance data.

2. The method of claim 1, wherein an assistance server performs said step of computing said combined assistance data, further comprising:

transmitting said combined assistance data to a mobile GPS device.

3. The method of claim 1, wherein an assistance server performs said step of computing said combined assistance data, further comprising:

transmitting said combined assistance data to a mobile GPS device, wherein said mobile GPS device performs said step of computing said position.

4. The method of claim 1, wherein a mobile GPS device performs said step of computing said combined assistance data.

5. The method of claim 1, wherein a mobile GPS device performs said step of computing said combined assistance data, further comprising:

transmitting said combined assistance data to an assistance server, wherein said assistance server performs said step of computing said position; and

transmitting said position to said mobile GPS device.

6. The method of claim 1, wherein said step of computing said combined assistance data comprises:

computing said combined assistance data from a weighted average of said plurality of assistance data.

7. The method of claim 1, wherein said at least one access point comprises a plurality of access points, wherein said step of computing said combined assistance data comprises:

computing said combined assistance data from a weighted average of said plurality of assistance data, wherein a weight assigned to each of said plurality of assistance data is determined according to a relative distance between a mobile GPS device and respectively each of said plurality of access points.

8. The method of claim 1, wherein said at least one access point comprises a plurality of access points, wherein said step of computing said combined assistance data comprises:

computing said combined assistance data from a weighted average of said plurality of assistance data, wherein a weight assigned to each of said plurality of assistance data is determined according to a reception characteristic of each of said plurality of access points.

9. The method of claim 1, further comprising:

selecting said at least one access point from a greater plurality of access points based on a received power level between a mobile GPS device and each of said greater plurality of access points.

10. The method of claim 1, further comprising:

selecting said at least one access point from a greater plurality of access points based on a received phase difference between a mobile GPS device and each of said greater plurality of access points.

11. The method of claim 1, wherein said at least one access point comprises a plurality of access points, wherein said step of computing said combined assistance data comprises:

computing said combined assistance data from a weighted average of said plurality of assistance data, wherein a weight assigned to each of said plurality of assistance data is determined according to a relative received power level between a mobile GPS device and respectively each of said plurality of access points.

12. The method of claim 1, wherein said at least one access point comprises a plurality of access points, wherein said step of computing said combined assistance data comprises:

computing said combined assistance data from a weighted average of said plurality of assistance data, wherein a weight assigned to each of said plurality of assistance data is determined according to a relative received phase difference between a mobile GPS device and respectively each of said plurality of access points.

13. The method of claim 1, wherein a mobile GPS device and said least one access point each perform said step of receiving said GPS information.

14. The method of claim 1, wherein said plurality of assistance data includes GPS assistance data and GPS differential correction data, wherein said step of computing said combined assistance data comprises:

computing said combined assistance data from said GPS assistance data and said GPS differential correction data.

15. The method of claim 1, wherein said at least one access point comprises a plurality of access points, wherein said plurality of assistance data includes a plurality of time of arrival information related to said plurality of access points, wherein said step of computing said combined assistance data comprises:

computing said combined assistance data as a triangulation of said plurality of time of arrival information.

16. The method of claim 1, wherein said at least one access point comprises a plurality of access points, wherein said plurality of assistance data includes a plurality of phase information related to said plurality of access points, wherein said step of computing said combined assistance data comprises:

computing said combined assistance data as a triangulation of said plurality of phase information.

17. The method of claim 1, wherein said step or computing said position comprises:

computing said position by executing a weighted least squares process on said GPS information and said combined assistance data.

18. The method of claim 1, wherein said step of computing said position comprises:

computing said position by executing an extended Kalman filter process on said GPS information and said combined assistance data.

19. The method of claim 1, wherein said step of computing said position comprises:

computing said position based on said GPS information and said combined assistance data using a first set of weights in an indoor location and a second set of weights in an outdoor location.

20. The method of claim 1, wherein said step of computing said position comprises:

computing said position based on said GPS information having a first weight and said combined assistance data having a second weight.

21. The method of claim 1, wherein said GPS information includes a final position, velocity and time solution, wherein said step of computing said position comprises:

computing said position based on said final position, velocity and time solution having a first weight and said combined assistance data having a second weight.

22. The method of claim 1, wherein said GPS information includes raw GPS measurements, wherein said step of computing said position comprises:

computing said position based on said raw GPS measurements having a first weight and said combined assistance data having a second weight.

23. The method of claim 1, wherein said GPS information includes in-phase and quadrature symbols, wherein said step of computing said position comprises:

computing said position based on said in-phase and quadrature symbols having a first weight and said combined assistance data having a second weight.

24. The method of claim 1, wherein said combined assistance data includes a final position, velocity and time solution, wherein said step of computing said position comprises:

computing said position based on said final position, velocity and time solution having a first weight and said GPS information having a second weight.

25. The method of claim 1, wherein said combined assistance data includes raw navigation measurements, wherein said step of computing said position comprises:

computing said position based on said raw navigation measurements having a first weight and said GPS information having a second weight.

26. The method of claim 1, wherein said combined assistance data includes in-phase and quadrature symbols, wherein said step of computing said position comprises:

computing said position based on said in-phase and quadrature symbols having a first weight and said GPS information having a second weight.

27. An apparatus for performing position determination using global positioning system (GPS) signals, said apparatus comprising:

a GPS receiver that receives GPS information from a plurality of GPS satellites;

a wireless communication module, coupled to said GPS receiver, that receives a plurality of assistance data from a plurality of access points; and

a processor, coupled to said wireless communication module and said GPS receiver, that computes a combined assistance data from said plurality of assistance data.

28. The apparatus of claim 27, wherein said processor further computes a position based on said GPS information and said combined assistance data.

29. The apparatus of claim 27, wherein said wireless communication module transmits said combined assistance data and said GPS information to an assistance server that computes a position based on said GPS information and said combined assistance data, and wherein said wireless communication module receives said position from said assistance server.

30. An apparatus for performing position determination using global positioning system (GPS) signals, said apparatus comprising:

a GPS receiver that receives GPS information from a plurality of GPS satellites;

a wireless communication module, coupled to said GPS receiver, that receives wireless information from at least one access point; and

a combined navigation processor, coupled to said GPS receiver and said wireless communication module, that determines a position of said apparatus based on said GPS information and said wireless information.

31. The apparatus of claim 30, wherein said combined navigation processor determines said position based on said GPS information having a first weight and said wireless information having a second weight.

32. The apparatus of claim 30, wherein said combined navigation processor determines said position by executing a weighted least squares process on said GPS information and said wireless information.

33. The apparatus of claim 30, wherein said combined navigation processor determines said position by executing an extended Kalman filter process on said GPS information and said wireless information.

34. The apparatus of claim 30, wherein said wireless information includes differential correction data and assistance data, further comprising:

a wireless differential correction data decoder, coupled to said combined navigation processor, that decodes said differential correction data; and

a wireless assistance data decoder, coupled to said combined navigation processor, that decodes said assistance data,

wherein said combined navigation processor determines said position based on said GPS information, said differential correction data, and said assistance data.

35. The apparatus of claim 30, further comprising:

a wireless navigation engine that receives said wireless information and that generates a final position, velocity and time solution,

wherein said combined navigation processor determines said position based on said GPS information having a first weight and said final position, velocity and time solution having a second weight.

36. The apparatus of claim 30, further comprising:

a wireless measurement engine that receives said wireless information and that generates raw navigation measurements,

wherein said combined navigation processor determines said position based on said GPS information having a first weight and said raw navigation measurements having a second weight.

37. The apparatus of claim 30, further comprising:

a wireless core receiver that receives said wireless information and that generates in-phase and quadrature symbols,

wherein said combined navigation processor determines said position based on said GPS information having a first weight and said in-phase and quadrature symbols having a second weight.

38. The apparatus of claim 30, further comprising:

a GPS navigation engine that receives said GPS information and that generates a final position, velocity and time solution;

wherein said combined navigation processor determines said position based on said wireless information having a first weight and said final position, velocity and time solution having a second weight.

39. The apparatus of claim 30, further comprising:

a GPS measurement engine that receives said GPS information and that generates raw GPS measurements,

wherein said combined navigation processor determines said position based on said wireless information having a first weight and said raw GPS measurements having a second weight.

40. The apparatus of claim 30, further comprising:

a GPS core receiver that receives said GPS information and that generates in-phase and quadrature symbols,

wherein said combined navigation processor determines said position based on said wireless information having a first weight and said in-phase and quadrature symbols having a second weight.

41. The apparatus of claim 30, wherein said at least one access point comprises a plurality of access points, wherein said wireless information includes a plurality of time of arrival information related to said plurality of access points, and wherein said combined navigation processor determines said position based on said GPS information having a first weight and said plurality of time of arrival information having a plurality of second weights.

42. The apparatus of claim 30, wherein said at least one access point comprises a plurality of access points, wherein said wireless information includes a plurality of phase information related to said plurality of access points, and wherein said combined navigation processor determines said position based on said GPS information having a first weight and said plurality of phase information having a plurality of second weights.

43. The apparatus of claim 30, wherein said at least one access point comprises a plurality of access points, said apparatus further comprising:

a radio frequency identification (RFID) tag, wherein said plurality of access points determine a triangulated position of said RFID tag using time of arrival information, wherein said wireless information includes said triangulated position, and wherein said combined navigation processor determines said position based on said triangulated position having a first weight and said GPS information having a second weight.

44. The apparatus of claim 30, wherein said at least one access point comprises a plurality of access points, said apparatus further comprising:

a radio frequency identification (RFID) tag, wherein said plurality of access points determine a triangulated position of said RFID tag using phase information, wherein said wireless information includes said triangulated position, and wherein said combined navigation processor determines said position based on said triangulated position having a first weight and said GPS information having a second weight.

45. The apparatus of claim 30, wherein said wireless communication module comprises a first wireless communication module and said wireless information comprises first wireless information, further comprising;

a second wireless communication module, coupled to said GPS receiver, that receives second wireless information from said at least one access point,

wherein said combined navigation processor determines said position based on said first wireless information having a first weight, said second wireless information having a second weight, and said GPS information having a third weight.

46. An apparatus including an assistance server for performing position determination using global positioning system (GPS) signals, said assistance server comprising:

a communication module that receives a plurality of assistance data generated by at least one access point; and

a processor, coupled to said wireless communication module, that computes a combined assistance data from said plurality of assistance data based on a relationship between a mobile GPS device and said at least one access point.

47. The apparatus of claim 46, wherein said communication module further communicates said combined assistance data to said mobile GPS device.

48. The apparatus of claim 46, wherein said communication module further receives GPS information from said mobile GPS device, and wherein said processor further computes a position of said mobile GPS device using said GPS information and said combined assistance data.

49. The apparatus of claim 46, wherein said processor computes said combined assistance data from a weighted average of said plurality of assistance data.

50. The apparatus of claim 46, wherein said plurality of assistance data includes GPS assistance data and GPS differential correction data, and wherein said processor computes said combined assistance data from said GPS assistance data and said GPS differential correction data.

51. The apparatus of claim 46, wherein said at least one access point comprises a plurality of access points, wherein said plurality or assistance data includes a plurality of time of arrival information related to said plurality of access points, and wherein said processor computes said combined assistance data as a triangulation of said plurality of time of arrival information.

52. The apparatus of claim 46, wherein said at least one access point comprises a plurality of access points, wherein said plurality of assistance data includes a plurality of phase information related to said plurality of access points, and wherein said processor computes said combined assistance data, as a triangulation of said plurality of phase information.

53. An apparatus including an access point for communicating with a wireless device, said access point comprising:

a global positioning system (GPS) receiver that receives GPS information from a plurality of GPS satellites;

a GPS assistance manager that generates assistance data based on said GPS information;

a GPS differential correction manager that generates differential correction data based on said GPS information; and

a wireless transmitter and receiver that communicates wireless information with a mobile station, wherein said wireless information includes said assistance data and said differential correction data.

54. The apparatus of claim 53, wherein said access point further comprises:

a combined navigation processor that receives said wireless information and mobile device GPS information from said mobile station, and that determines a position of said mobile station based on said mobile device GPS information having a first weight and said wireless information having a second weight.