Compensation of propagation delays of wireless signals

• US 8,326,319 B2
• Filed: 04/01/2009
• Issued: 12/04/2012
• Est. Priority Date: 01/23/2009
• Status: Active Grant

• Current Assignee: AT&T Mobility II LLC (AT&T, Inc.)
• Original Assignee: AT&T Mobility II LLC (AT&T, Inc.)
• Inventors: Davis, Richard W.
• Primary Examiner(s): Tran, Cong
• Application Number:
  US12/416,853
• Publication Number:
  US 20100190509A1
• Time in Patent Office: 1,343 Days
• Field of Search: 455/404.2, 455/456.1, 455/456.5, 455/456.6, 455/67.11, 455/115.1
• US Class Current: 455/456.1
• CPC Class Codes: H04W 4/02 Services making use of location information
• CPC Class Codes: H04W 56/006 using known positions of transmitter and receiver

Abstract

System(s) and method(s) for compensation of propagation delay offsets of wireless signals. Compensation is accomplished through determination of an effective wireless signal propagation delay that accounts for signal path delay and propagation delay over the air. Such determination is based at least in part on statistical analysis of accurate location estimates of reference positions throughout a coverage sector or cell, and location estimates of the reference positions generated through time-of-flight (TOF) measurements of wireless signals. Determination of propagation or signal path delay offset also is attained iteratively based at least in part on reference location estimates and TOF location estimates. High-accuracy location estimates such as those obtained through global navigation satellite systems are employed as reference location estimates. Position of probes or wireless beacons, deployed throughout a sector or cell, also are employed as reference locations. Compensation of propagation delay offset improves accuracy of conventional TOF location estimates and radio network performance.

Claims

1. A method comprising:

receiving, by a system including a processor, a first set of location estimates from a location source;

generating, by the system, a second set of location estimates through a time-of-flight assessment, wherein the first set of location estimates and the second set of location estimates correspond to a same location;

determining, by the system, a radio frequency (RF) signal propagation delay offset based at least in part on a statistical analysis of the first set of location estimates and the second set of location estimates, wherein the statistical analysis comprises a determination of a relationship between the first set of location estimates and the second set of location estimates; and

calibrating, by the system, RF signal propagation timing measurements based on the RF signal propagation delay offset.

2. The method of claim 1, wherein the receiving the first set of location estimates further comprises receiving, by the system, the first set of location estimates from a mobile device that supports reception of global navigation satellite system data.

3. The method of claim 1, wherein the receiving the first set of location estimates further comprises receiving, by the system, the first set of location estimates from a wireless beacon having a known location.

4. The method of claim 1, wherein the determining the RF signal propagation delay offset further comprises

determining, by the system, a systematic variance between the first set of location estimates and the second set of location estimates based on the statistical analysis;

and

determining, by the system, the RF signal propagation delay offset based on the systematic variance.

5. The method of claim 1, wherein the relationship is based on a function of a correlation coefficient.

6. The method of claim 1, wherein the determining the RF signal propagation delay offset further comprises refining the second set of location estimates by iteratively correcting the RF signal propagation delay offset to produce timing delay data consistent with known locations associated with the first set of location estimates.

7. The method of claim 6, wherein the iteratively correcting the RF signal propagation delay offset further comprises:

retrieving, by the system, a prior RF signal propagation delay offset;

generating, by the system, a provisional set of location estimates based on a time-of-flight assessment that utilizes the prior RF signal propagation delay offset;

comparing, by the system, the provisional set of location estimates with the known locations associated with the first set of location estimates;

updating, by the system, the RF signal propagation delay offset in response to a difference between the provisional set of location estimates and the known locations satisfying a condition with respect to a predefined threshold; and

establishing, by the system, the prior RF signal propagation delay offset as the RF signal propagation delay offset in response to the difference between the provisional set of location estimates and the known locations not satisfying the condition of the predefined threshold.

8. The method of claim 1, wherein the determining the RF signal propagation delay offset further comprises determining, by the system, the RF signal propagation delay offset for specific angles with respect to a centerline between a receiver reverse link and an emitter forward link.

9. The method of claim 1, further comprising mapping, by the system, sector identification information from the first set of location estimates to sector identification data from the second set of location estimates.

10. The method of claim 9, further comprising storing mapping data of nominal sectorization information to effective sectorization data based on the mapping.

11. A system, comprising:

a memory storing computer executable instructions; and

a processor, communicatively coupled to the memory, which facilitates execution of the computer-executable instructions to at least;

receive a first set of location estimates from a location source platform device;

generate a second set of location estimates by a time-of-flight assessment, wherein each of the first set of location estimates and the second set of location estimates correspond to a same location;

determine a wireless signal propagation delay offset based at least in part on a statistical analysis of the first set of location estimates and the second set of location estimates wherein the statistical analysis establishes a relationship between the first set of location estimates and the second set of location estimates; and

adjust a wireless signal propagation timing measurement based on the wireless signal propagation delay offset.

12. The system of claim 11, wherein the wireless signal is a radio frequency communications signal.

13. The system of claim 11, wherein the location source platform device is a mobile device that receives global navigation satellite system data.

14. The system of claim 11, wherein the location source platform device is a wireless beacon with a known location.

15. The system of claim 11, wherein the at least one processor further facilitates the execution of the computer-executable instructions to:

determine a correlation between the first set of location estimates and the second set of location estimates based on the statistical analysis; and

determine a systematic variance among the first set of location estimates and the second set of location estimates.

16. The system of claim 15, wherein the at least one processor further facilitates the execution of the computer-executable instructions to:

determine the wireless signal propagation delay offset based on the systematic variance; and

iteratively correct the wireless signal propagation delay offset until a difference between a provisional set of location estimates and known location records associated with the first set of location estimates is below a predefined level.

17. The system of claim 11, wherein the wireless signal propagation delay offset is stochastic.

18. The method of claim 11, wherein the at least one processor further facilitates the execution of the computer-executable instructions to:

map sector identification information data extracted from the first set of location estimates to sector identification information data obtained from the second set of location estimates.

19. A non-transitory computer-readable storage device comprising computer-executable instructions that, in response to execution, cause a computing device including a processor to perform operations, comprising:

receiving a first set of location estimates from a location source;

generating a second set of location estimates through a time-of-flight assessment, wherein the first set of location estimates and the second set of location estimates correspond to a same location;

determining a variance between the first set of location estimates and the second set of location estimates based on a statistical analysis;

determining a radio frequency (RF) signal propagation delay based on the variance; and

calibrating RF signal propagation timing based on the RF signal propagation delay.