Method and system for determining relative positions of networked mobile communication devices

• US 7,031,725 B2
• Filed: 08/11/2003
• Issued: 04/18/2006
• Est. Priority Date: 08/13/2002
• Status: Active Grant

• Current Assignee: DRS Signal Solutions, Inc. (Leonardo S.p.A.)
• Original Assignee: DRS Communications Co. LLC (Leonardo S.p.A.)
• Inventors: Rorabaugh, C. Britton
• Primary Examiner(s): Tran, CongVan
• Application Number:
  US10/641,588
• Publication Number:
  US 20040033808A1
• Time in Patent Office: 981 Days
• Field of Search: 455/456.1, 455/456.2, 455/456.3, 455/404.2, 455/407, 455/427, 455/517, 455/67.11, 455/67.1, 342/147, 342/357.06, 342/357.07, 342/357.08, 342/357.09
• US Class Current: 455/456.1
• CPC Class Codes: G01S 11/02 using radio waves G01S19/00 takes precedence
• CPC Class Codes: G01S 5/0289 of multiple transceivers, e.g. in ad hoc networks
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

Relative positions of a plurality of mobiles communication devices, which form a wirelessly networked group of mobiles, are determined at each of the mobiles of the group without the need for external positioning information obtained from a location remote from the actual locations of the mobiles of the group. The relative positions are determined at the mobiles of the group based on mobile-to-mobile range measurements, distance and direction of movement measurements and altitude measurements made at the respective mobiles.

Claims

1. A method for determining relative positions in three dimensions of at least four mobile communications devices of a wirelessly networked group, the method comprising:

providing each of the mobiles of the group with a transceiver for wirelessly communicating with the transceivers of the other respective mobiles of the group;

measuring ranges between each of the mobiles of the group and each of the other mobiles of the group respectively, wherein the measuring is based on propagation time data obtained from wireless communications between the respective mobiles of the group; and

constructing, based on the ranges, first and second virtual constellations representative of estimated actual locations of each of the mobiles of the group, wherein the first constellation is a mirror image of the second constellation.

2. The method of claim 1 further comprising:

measuring, at each of the mobiles of the group, altitude of the mobile with respect to a common altitude calibration point; and

horizontally orienting the first and second constellations based on the altitudes.

3. The method of claim 2 further comprising:

measuring distance and direction of movement at each of the mobiles of the group; and

orienting the horizontally oriented first and second constellations with respect to azimuth based on the distance and direction of movement of the respective mobiles of the group.

4. The method of claim 3 further comprising:

following the horizontal and azimuth orienting of the first and second constellations, selecting one of the first and second constellations as a true image of the relative positions of the mobiles of the group based on consistency of the directions of the measured movements of the mobiles of the group.

5. The method of claim 1 further comprising:

wirelessly communicating the range measured between a first of the mobiles and a second of the mobiles to the first mobile or the second mobile.

6. The method of claim 2 further comprising:

at predetermined intervals, wirelessly communicating with a time stamp the altitude measurement at each of the mobiles to each of the other mobiles of the group.

7. The method of claim 3 further comprising:

at predetermined intervals, categorizing the measured distance and direction of movement for each of the mobiles as not moving, regular forward walking or running and motion other than forward walking or running and wirelessly communicating with a time stamp the movement categorizations from each of the mobiles in the group to each of the other mobiles in the group.

8. The method of claim 7 further comprising:

at predetermined intervals, for each of the mobiles having the movement categorized as forward walking or running, wirelessly communicating with a time stamp the measured direction and distance of the movement to the other mobiles in the group.

9. The method of claim 1, wherein the measuring of the ranges further comprises transmitting at least one of ultrawideband signals, acoustical ranging signals and optical ranging signals.

10. The method of claim 1, wherein the measuring of the ranges further comprises correlating pseudorandom sequences modulated on a radio frequency carrier signal.

11. The method of claim 3, wherein the transceivers of the respective mobiles transmit on a wireless communication signal measured movement, ranges and altitude for the mobiles to each of the other mobiles of the group.

12. The method of claim 3, wherein the measuring of the movement further comprises generating time stamped data representative of detected motion and compass bearing.

13. The method of claim 2, wherein the horizontal orienting of the virtual constellations further comprises optimizing fit between measured altitudes of the respective mobiles and altitudes corresponding to the horizontally oriented virtual constellations.

14. The method of claim 13, wherein the optimizing the fit includes performing at least one of a linear least square estimation, a non-linear least square estimation, a minimum mean squared error estimation, a method of moments estimation, a maximum likelihood estimation and a minimum variance estimation.

15. The method of claim 7 further comprising:

orienting the virtual constellations with respect to North for optimizing fit between measured intervals of regular walking or running motion at at least one of the mobiles and corresponding virtual movements attributable to the one mobile based on changes in the estimated three-dimensional geometric shape of the virtual constellation.

16. The method of claim 7 further comprising:

estimating an angular rotation for orienting the virtual constellations by performing at least one of a linear least squares estimation, a non-linear least squares estimation, a minimum mean squared error estimation, a method of moments estimation, a maximum likelihood estimation and a minimum variance estimation.

17. The method of claim 3 further comprising:

periodically repeating the measuring of the range, movement and altitude at each of the mobiles and then repeating the constructing of the first and second constellations, followed by the horizontal orienting of the first and second constellations, then followed by the orienting of the horizontally oriented first and second constellations as to azimuth and then the selecting of the true image from the horizontally and azimuthly oriented first and second constellations.

18. The method of claim 3 further comprising:

transmitting the relative positions of the mobiles of the group to a location remote from the location of the mobiles of the group.

19. The method of claim 1, wherein one of the mobiles in the group is in a fixed location.

20. The method of claim 19, wherein the one mobile has global positioning system capability.

21. The method of claim 19, wherein the fixed location is substantially at a nexus of communication propagation paths of the other mobiles in the group.

22. A mobile communications device for determining relative positions of a group of at least four wirelessly networked mobile communications devices comprising:

a ranging transceiver module and a data transceiver module for wirelessly communicating with a ranging transceiver module and a data transceiver module contained in each of the other respective mobiles of the group, wherein the ranging transceiver module measures ranges to each of the other mobiles of the group, wherein the measuring is based on propagation time data obtained from wireless communications with each of the other respective mobiles of the group; and

a position processing module for constructing, based on the measured ranges and mobile-to-mobile ranges generated at each of the other mobiles of the group and received at the data transceiver module, first and second virtual constellations representative of estimated actual locations of each of the mobiles of the group, wherein the first constellation is a mirror image of the second constellation.

23. The device of claim 22 further comprising:

a movement assessment module for measuring altitude of the mobile with respect to a common altitude calibration point, and wherein the position processing module horizontally orients the first and second constellations based on the measured altitude and altitudes measured at each of the other mobiles of the group and received at the data transceiver module.

24. The device of claim 23, wherein the movement assessment module measures distance and direction of movement, and wherein the position processing module orients the horizontally oriented first and second constellations with respect to azimuth based on (i) the measured distance and direction of movement and (ii) distance and direction movement measured at each of the other mobiles of the group and received at the data transceiver module.

25. The device of claim 24, wherein the position processing module, following the horizontal and azimuth orienting of the first and second constellations, selects one of the first and second constellations as a true image of the relative positions of the mobiles of the group based on consistency of the directions of the measured movements of the mobiles of the group.

26. The device of claim 22, wherein the data transceiver module wirelessly communicates the measured range with respect to a first of the mobiles of the group to at least one of the other mobiles in the group.

27. The device of claim 23, wherein the data transceiver module, at predetermined intervals, wirelessly communicates with a time stamp the altitude measurement to each of the other mobiles of the group.

28. The device of claim 24, wherein the movement assessment module, at predetermined intervals, categorizes the measured distance and direction of movement as not moving, regular forward walking or running and motion other than forward walking or running and wherein the data transceiver module wirelessly communicates with a time stamp the movement categorizations to each of the other mobiles in the group.

29. The device of claim 28, wherein the data transceiver module, at predetermined intervals, wirelessly communicates with a time stamp the measured direction and distance of the movement categorized as forward walking or running to each of the other mobiles in the group.

30. The device of claim 22, wherein the ranging transceiver module transmits at least one of ultrawideband signals acoustical ranging signals and optical ranging signals for measuring the range.

31. The device of claim 22, wherein the ranging transceiver module transmits pseudorandom sequences modulated on a radio frequency carrier signal for measuring the range.

32. The device of claim 24, wherein the data transceiver module transmits on a wireless communication signal measured movement, ranges and altitude for the mobiles to each of the other mobiles of the group.

33. The device of claim 24, wherein the movement assessment module generates time stamped data representative of detected motion and compass bearing.

34. The device of claim 23, wherein the position processing module as part of horizontal orientation of the virtual constellations optimizes fit between measured altitudes of the respective mobiles and altitudes corresponding to the horizontally oriented virtual constellations.

35. The device of claim 34, wherein the optimizing the fit includes performing at least one of a linear least square estimation, a non-linear least square estimation, a minimum mean squared error estimation, a method of moments estimation, a maximum likelihood estimation and a minimum variance estimation.

36. The device of claim 28, wherein the position processing module orients the virtual constellations with respect to North for optimizing fit between measured intervals of regular walking or running motion at at least of one of the mobiles and corresponding virtual movements attributable to the one mobile based on changes in the estimated three-dimensional geometric shape of the virtual constellation.

37. The device of claim 28, wherein the orienting of the virtual constellations is achieved by performing at least one of a linear least square estimation, a non-linear least square estimation, a minimum mean squared error estimation, a method of moments estimation, a maximum likelihood estimation and a minimum variance estimation.