Integrity monitoring in a position location system utilizing knowledge of local topography

• US 8,160,604 B2
• Filed: 04/18/2002
• Issued: 04/17/2012
• Est. Priority Date: 04/18/2002
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gaal, Peter
• Primary Examiner(s): TORRES, MARCOS L
• Application Number:
  US10/126,035
• Publication Number:
  US 20040192330A1
• Time in Patent Office: 3,652 Days
• Field of Search: 455/411, 455/423, 455/425, 4554561-457, 342/357.06, 342/357.08, 34235712-35716, 342/450, 342/463, 370/320, 370/317
• US Class Current: 455/456.1
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type
• 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
• CPC Class Codes: G01S 2013/466 by Trilateration, i.e. two antennas or two sensors determine separately the distance to a target, whereby with the knowledge of the baseline length, i.e. the distance between the antennas or sensors, the position data of the target is determined
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G01S 5/0054 of actual mobile position, i.e. position calculation on base station
• CPC Class Codes: G01S 5/02527 Detecting or resolving anomalies in the radio frequency fingerprints of the radio-map
• CPC Class Codes: G01S 5/0268 by deriving positions from different combinations of signals or of estimated positions in a single positioning system
• CPC Class Codes: G01S 5/0273 using multipath or indirect path propagation signals in position determination
• CPC Class Codes: G01S 5/0278 involving statistical or probabilistic considerations G01S5/0252, G01S5/0294 take precedence
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A system for and method of deriving a position estimate of a receiver from a plurality of parameter measurements is provided. Each measurement is derived from a correlation function, which in turn is derived by correlating a signal received at the receiver with an identification code uniquely identifying a transmitter visible to the receiver. A plurality of position estimates are derived, each from a different subset of the plurality of measurements. Based on local topography, one of the position estimates is selected as the best estimate of the position of the receiver.

Claims

1. A method of deriving a position estimate of a receiver from a plurality of parameter measurements, each of the plurality of parameter measurements measured concurrently at the receiver and derived from a respective actual correlation function that is derived by correlating a signal received at the receiver with an identification code uniquely identifying a corresponding transmitter, comprising:

deriving a plurality of different estimates of a current position of the receiver, at least two of the plurality of different estimates of the current position of the receiver being derived with the same type of position-determination scheme, each of the different estimates derived from a subset of the plurality of parameter measurements, each of the plurality of parameter measurements measured by the receiver and each respective position estimate derived from a subset of the plurality of the parameter measurements that is different from other subsets of the plurality of parameter measurements used to derive other of the plurality of estimates of the current position of the receiver;

deriving a cost of each of the position estimates;

refining the costs based on local topography; and

selecting one of the position estimates responsive to the refined costs.

2. The method of claim 1 wherein the parameter measurements are time-of-arrival measurements.

3. The method of claim 1 wherein the identification code is a pseudo noise (PN) code.

4. The method of claim 1 wherein the derived costs are an RMS value of residual errors of measurements used in deriving the current position estimate for respective measurement subsets.

5. The method of claim 1 wherein the refining step comprises performing the following for each measurement:

estimating, based on local topography, an expected correlation function for said corresponding transmitter;

comparing the estimated expected correlation function with the actual correlation function; and

adjusting, based on the comparison, a cost for each of the position estimates derived from the respective measurement, if the divergence between the expected and actual correlation function is sufficiently great.

6. The method of claim 5 wherein said comparing comprises comparing an expected peak amplitude with an amplitude of an earliest non-sidelobe peak of the actual correlation function.

7. The method of claim 5 wherein said comparing comprises comparing an expected shape of the actual correlation function with an actual shape of the expected correlation function.

8. The method of claim 1 tangibly embodied as a series of instructions stored in a memory.

9. The method of claim 1, wherein two or more of the subsets include one or more overlapping parameter measurements.

10. The method of claim 1, wherein each signal that is used to derive the plurality of parameter measurements is received within a predetermined search window used for location estimation of the receiver at a single point in time.

11. The method of claim 1, wherein each signal that is used to derive the plurality of parameter measurements is either (i) received from a different corresponding transmitter than each other signal or (ii) based on a same transmission from a same corresponding transmitter as another signal.

12. The method of claim 1, wherein the type of position-determination scheme used to derive the at least two of the plurality of different estimates corresponds to (i) a Global Positioning System (GPS) scheme, (ii) an Advanced Forward Link Trilateration (AFLT) scheme or (iii) a hybrid position-determination scheme that includes a combination of the GPS and AFLT schemes.

13. The method of claim 1, wherein the respective subsets of the plurality of parameter measurements correspond to different combinations of the concurrently measured parameters that are used as inputs into the same type of position-determination scheme in order to generate the different estimates for the current position over the receiver.

14. A system for deriving a position estimate of a receiver from a plurality of parameter measurements, each of the plurality of parameter measurements measured concurrently at the receiver and derived from a respective actual correlation function that is derived by correlating a signal received at the receiver with an identification code uniquely identifying a corresponding transmitter, comprising:

first logic for deriving, from the plurality of measurements, a plurality of different estimates of a current position of the receiver, at least two of the plurality of different estimates of the current position of the receiver being derived with the same type of position-determination scheme, each different position estimate derived from a subset of the plurality of parameter measurements, each of the plurality of parameter measurements measured by the receiver and each respective position estimate derived from a subset of the plurality of parameter measurements that is different than other subsets of the plurality of parameter measurements used to derive other of the plurality of estimates of the current position of the receiver;

second logic for deriving a cost of each of the position estimates;

third logic for refining the costs based on, local topography; and

fourth logic for selecting one of the derived position estimates responsive to the refined costs.

15. The system of claim 14 wherein the parameter measurements are time-of-arrival measurements.

16. The system of claim 14 wherein the identification code is a pseudo noise (PN) code.

17. The system of claim 14 wherein the derived costs are an RMS value of residual errors of measurements used in deriving the current position estimate for respective measurement subsets.

18. The system of claim 14 wherein the third logic is configured, for each measurement from which a current position estimate is derived, to (a) estimate, based on local topography, an expected correlation function for the corresponding transmitter;

(b) compare the estimated expected correlation function with the actual correlation function; and

(c) adjust, based on the comparison, a cost for each of the position estimates derived from the respective measurement, if a divergence between the expected and actual correlation functions is sufficiently great.

19. The system of claim 18 wherein the third logic is configured to compare an expected peak amplitude of the correlation function with an amplitude of the earliest non-sidelobe peak of the actual correlation function.

20. The system of claim 18 wherein the third logic is configured to compare an expected shape of the correlation function with an actual shape of the expected correlation function.

21. A non-transitory computer-readable medium comprising instructions, which, when executed by a receiver configured to measure a plurality of parameter measurements, each of the plurality of parameter measurements measured concurrently at the receiver and derived from a respective actual correlation function that is derived by correlating a signal received at the receiver with an identification code uniquely identifying a corresponding transmitter, cause the receiver to perform operations, the instructions comprising:

program code to derive a plurality of different estimates of a current position of the receiver, at least two of the plurality of different estimates of the current position of the receiver being derived with the same type of position-determination scheme, each of the different estimates derived from a subset of the plurality of parameter measurements, each of the plurality of parameter measurements measured by the receiver and each respective position estimate derived from a subset of the plurality of the parameter measurements that is different from other subsets of the plurality of parameter measurements used to derive other of the plurality of estimates of the current position of the receiver;

program code to derive a cost of each of the position estimates;

program code to refine the costs based on local topography; and

program code to select one of the position estimates responsive to the refined costs.

22. A system for deriving a position estimate of a receiver from a plurality of parameter measurements, each of the plurality of parameter measurements measured concurrently at the receiver and derived from a respective actual correlation function that is derived by correlating a signal received at the receiver with an identification code uniquely identifying a corresponding transmitter, comprising:

means for deriving a plurality of different estimates of a current position of the receiver, at least two of the plurality of different estimates of the current position of the receiver being derived with the same type of position-determination scheme, each of the different estimates derived from a subset of the plurality of parameter measurements, each of the plurality of parameter measurements measured by the receiver and each respective position estimate derived from a subset of the plurality of the parameter measurements that is different from other subsets of the plurality of parameter measurements used to derive other of the plurality of estimates of the current position of the receiver;

means for deriving a cost of each of the position estimates;

means for refining the costs based on local topography; and

means for selecting one of the position estimates responsive to the refined costs.