Position computation in a positioning system using synchronization time bias

• US 7,991,414 B2
• Filed: 02/02/2009
• Issued: 08/02/2011
• Est. Priority Date: 09/05/2002
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Riley, Wyatt Thomas, Marshall, Grant Alexander
• Primary Examiner(s): Nguyen; Tu X
• Application Number:
  US12/364,399
• Publication Number:
  US 20090195448A1
• Time in Patent Office: 911 Days
• Field of Search: 455/456.1, 455/502, 455/524, 455/552.1, 455/427, 455/12.1, 455/16, 342/464
• US Class Current: 455/502
• CPC Class Codes: G01S 19/20 Integrity monitoring, fault detection or fault isolation of space segment
• CPC Class Codes: G01S 19/48 by combining or switching between position solutions derived from the satellite radio beacon positioning system and position solutions derived from a further system

Abstract

In general, this disclosure is directed to techniques for computing a positioning solution for a mobile unit based on signals received from the satellite navigation system and the wireless communication system. The techniques allow for, and resolve, a synchronization bias that constrains a system time for the satellite navigation system and a system time for the wireless communication system relative to each other. The mobile unit may utilize the defined constraint to compute a position solution in environments where additional independent measurements would otherwise be required. The mobile unit may incorporate Receiver Autonomous Integrity Monitoring (RAIM) functionality to validate the position and time solutions derived from each of received signals. According to the techniques described herein, the mobile unit may be able to utilize the defined synchronization bias to apply RAIM or similar techniques in environments where such techniques would otherwise be indeterminate.

Claims

1. A method of determining position, the method comprising:

receiving signals from a satellite navigation system;

receiving signals from a wireless communication system; and

obtaining a synchronization bias constraint that defines a limit of a difference between a system time of the wireless communication system and a system time of the satellite navigation system; and

determining a position solution for a mobile unit in an asynchronous environment as a function of the received signals, the synchronization bias constraint, and a number of independent measurements based on a position location technique for a synchronous environment, wherein the number of independent measurements is fewer than a minimum number of measurements for a position location technique in the asynchronous environment.

2. The method of claim 1, wherein receiving signals from the satellite navigation system comprises receiving signals from a Global Positioning System.

3. The method of claim 1, wherein receiving signals from the satellite navigation system comprises receiving signals from a Wide Area Augmentation System.

4. The method of claim 1, wherein receiving signals from the satellite navigation system comprises receiving signals from a Global Navigation Satellite System.

5. The method of claim 1, wherein receiving signals from the wireless communication system comprises receiving signals from a Code Division Multiple Access (CDMA) base station.

6. The method of claim 1, wherein receiving signals from the wireless communication system comprises receiving signals from a time division multiple access base station.

7. The method of claim 1, wherein obtaining the synchronization bias constraint comprises retrieving the synchronization bias constraint from a memory within the mobile unit.

8. The method of claim 1, wherein obtaining the synchronization bias constraint comprises receiving the synchronization bias constraint from a component of the wireless communication system.

9. The method of claim 1, wherein obtaining the synchronization bias constraint comprises receiving the synchronization bias constraint defining a bias constraint for the entire wireless communication system.

10. The method of claim 1, wherein obtaining the synchronization bias constraint comprises receiving the synchronization bias constraint defining a bias constraint for a region in which the mobile unit is located.

11. The method of claim 1, wherein obtaining the synchronization bias constraint comprises receiving the synchronization bias constraint specific to the mobile unit.

12. The method of claim 1, wherein obtaining the synchronization bias constraint comprises receiving the synchronization bias constraint associated with an identifier of the mobile unit.

13. The method of claim 1, wherein determining the position solution for the mobile unit comprises determining the position solution based on a hybrid position location technique.

15. The method of claim 1, further comprising:

resolving system times of the satellite navigation system and the wireless communication system;

computing a synchronization bias based on the system times; and

transmitting the synchronization bias to a component of the wireless communication system.

16. The method of claim 1, further comprising:

receiving an additional independent measurement from one of the satellite navigation system or wireless communication system; and

applying Receiver Autonomous Integrity Monitoring (RAIM) to detect the presence of one or more erroneous measurements.

17. The method of claim 1, further comprising receiving altitude-aiding data from the wireless communication system, and wherein determining the position solution for the mobile unit is based on the altitude-aiding data.

14. The method of clan 1, wherein determining the position solution for the mobile unit comprises determining the position solution based on Advanced Forward Link Trilateration.

18. A method of determining position, the method comprising:

determining a first number of independent positioning measurement based on signals from a satellite navigation system;

determining a second number of independent positioning measurements based on signals from a wireless communication system;

determining a synchronization bias constraint that constrains a system time of the wireless communication system in relation to a system time of the satellite navigation system;

identifying presence of redundant measurements based on a minimum number of measurements for a position location technique in a synchronous environment and the synchronization bias constraint;

applying Receiver Autonomous Integrity Monitoring (RAIM) to detect the presence of one or more erroneous measurements based on redundant measurements;

isolating erroneous measurements; and

determining a position solution for a mobile unit based on a hybrid position location technique in an asynchronous environment, and as a function of the independent positioning measurements, the synchronization bias constraint, a number of independent measurements at least equal to a minimum number of measurements for a position location technique in a synchronous environment, and excluding the isolated erroneous measurements, wherein the minimum number of independent measurements in the synchronous environment is fewer than a minimum number of measurements for a position location technique in the asynchronous environment.

19. An apparatus for determining position, the apparatus comprising:

a Satellite Positioning System (SPS) receiver configured to receive signals from a satellite positioning system;

a wireless communication system receiver configured to receive signals from a wireless communication system and further configured to receive a synchronization bias constraint that defines a limit of a difference between a system time of the wireless communication system and a system time of the satellite positioning system; and

a processor configured to determine a position solution for a mobile unit in an asynchronous environment as a function of the received signals, the synchronization bias constraint, and a number of independent measurements based on a position location technique for a synchronous environment, wherein the number of independent measurements is fewer than a minimum number of measurements for a position location technique in the asynchronous environment.

20. The apparatus of claim 19, wherein the synchronization bias constraint defines a bias constraint for the entire wireless communication system.

21. The apparatus of claim 19, wherein the synchronization bias constraint defines a bias constraint for a region in which the mobile unit is located.

22. The apparatus of claim 19, wherein the synchronization bias constraint is associated with an identifier of the mobile unit.

23. The apparatus of claim 19, wherein the processor determines presence of redundant measurements based on a minimum number of measurements for a position location technique in a synchronous environment and the synchronization bias constraint and applies Receiver Autonomous Integrity Monitoring (RAIM) to detect the presence of one or more erroneous measurements based on redundant measurements.

24. The apparatus of claim 19, wherein the processor determines system time of the SPS and system time of the wireless communication system, calculates a system bias, and communicates the system bias to a component in the wireless communication system.

25. The apparatus of claim 19, wherein the satellite positioning system comprises a Global Positioning System (GPS), and the wireless communication system comprises a Code Division Multiple Access (CDMA) wireless communication system.

26. The apparatus of claim 19, wherein the processor computes a latitude, a longitude and an altitude for the mobile unit.

27. An apparatus for determining position, the apparatus comprising:

means for receiving signals from a satellite navigation system;

means for receiving signals from a wireless communication system;

means for obtaining a synchronization bias constraint that defines a limit of a difference between a system time of the wireless communication system and a system time of the satellite navigation system; and

means for determining a position solution for a mobile unit in an asynchronous environment as a function of the received signals, the synchronization bias constraint, and a number of independent measurements based on a position location technique for a synchronous environment, wherein the number of independent measurements is fewer than a minimum number of measurements for a position location technique in the asynchronous environment.

28. The apparatus of claim 27, further comprising:

means for resolving system times of the satellite navigation system and the wireless communication system;

means for computing a synchronization bias based on the system times; and

means for transmitting the synchronization bias to a component of the wireless communication system.

29. The apparatus of claim 27, wherein at least one of the means for receiving signals from the satellite navigation system or means for receiving signals from the wireless communication system receives an additional independent measurement, and wherein the apparatus further comprises means for applying Receiver Autonomous Integrity Monitoring (RAIM) to detect the presence of one or more erroneous measurements.

30. The apparatus of claim 27, further comprising means for receiving altitude-aiding data from the wireless communication system, and wherein the means for determining the position solution determines the position solution for the mobile unit based on the altitude-aiding data.

31. A non-transitory, computer-readable medium encoded with one or more instructions, when executed by a computer, determining position, the instructions comprising:

instructions for receiving signals from a satellite navigation system;

instructions for receiving signals from a wireless communication system;

instructions for obtaining a synchronization bias constraint that defines a limit of a difference between a system time of the wireless communication system and a system time of the satellite navigation system; and

instructions for determining a position solution for a mobile unit in an asynchronous environment as a function of the received signals, the synchronization bias constraint, and a number of independent measurements based on a position location technique for a synchronous environment, wherein the number of independent measurements is fewer than a minimum number of measurements for a position location technique in the asynchronous environment.