SYSTEMS AND METHODS FOR ESTIMATING WHETHER A RECEIVER IS INSIDE OR OUTSIDE A BUILDING

• US 20160003949A1
• Filed: 06/24/2015
• Published: 01/07/2016
• Est. Priority Date: 07/01/2014
• Status: Active Grant

• Current Assignee: NextNav, LLC
• Original Assignee: NextNav, LLC
• Inventors: Venkataraman, Jagadish, Pattabiraman, Ganesh
• Granted Patent: US 10,175,364 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01S 1/08 Systems for determining direction or position line
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073
• CPC Class Codes: G01S 19/28 Satellite selection
• CPC Class Codes: G01S 19/46 the supplementary measurement being of a radio-wave signal type
• CPC Class Codes: G01S 5/015 between indoor and outdoor environments

Abstract

Systems and methods for estimating whether a receiver is indoors or outdoors. Certain approaches evaluate data associated with a network of beacons to determine whether the receiver is indoors or outdoors. Such evaluation may include any of determining whether azimuthal angles corresponding to the beacons meet an azimuthal angle condition, determining whether elevation angles corresponding to the beacons meet an elevation angle condition, determining whether signal strengths corresponding to the beacons meet a signal strength condition, and determining whether other measurements associated with the beacons meet other measurement conditions.

Claims

1. A method for estimating whether a receiver is indoors or outdoors, the method comprising:

identifying data associated with a plurality of beacons, wherein the data includes, for each of the beacons, (i) data relating to an azimuthal angle corresponding to a position of that beacon, (ii) data relating to an elevation angle corresponding to the position of that beacon, or (iii) data relating to a signal strength corresponding to a signal transmitted by that beacon; and

evaluating the identified data based on one or more predetermined conditions to estimate whether the receiver is indoors or outdoors.

2. The method of claim 1, wherein the data specifies, for each of the beacons, (i) the azimuthal angle corresponding to the position of that beacon, (ii) the elevation angle corresponding to the position of that beacon, and (iii) the signal strength corresponding to that beacon, and wherein the method further comprises:

estimating whether the receiver is indoors or outdoors based on (i) whether the azimuthal angles corresponding to the beacons meet an azimuthal angle condition, (ii) whether the elevation angles corresponding to the beacons meet an elevation angle condition, and (iii) whether the signal strengths corresponding to the beacons meet a signal strength condition,

3. The method of claim 2, wherein the azimuthal angle condition specifies that each of n azimuthal angle ranges must include a predetermined number of the azimuthal angles corresponding to the beacons, wherein the elevation angle condition specifies that each of m elevation angle ranges must include a predetermined number of the elevation angles corresponding to the beacons, and wherein the signal strength condition specifies that each of the signal strengths exceed a minimum signal strength threshold value.

4. The method of claim 2, wherein the azimuthal angle condition specifies that each of n azimuthal angle ranges must include a predetermined number of the azimuthal angles corresponding to the beacons, wherein the elevation angle condition specifies that each of m elevation angle ranges must include a predetermined number of the elevation angles corresponding to the beacons, and wherein the signal strength condition specifies that each of a plurality of median signal strengths exceed a median signal strength threshold value, where each of the plurality of median signal strengths corresponds to a different beacon from the plurality of beacons, and where each of the plurality of median signal strengths is based on two or more signal strengths measured for two or more signals that were transmitted by that different beacon during a time period.

5. The method of claim 2, wherein the azimuthal angle condition specifies that each of the azimuthal angles corresponding to the beacons must be separated from each other by at least a first amount of angular separation, wherein the elevation angle condition specifies that each of the elevation angles corresponding to the beacons must be separated from each other by at least a second amount of angular separation, and wherein the signal strength condition specifies that each of the signal strengths must exceed a minimum signal strength threshold value.

6. The method of claim 2, wherein the azimuthal angle condition specifies that each of the azimuthal angles corresponding to the beacons must be separated from each other by at least a first amount of angular separation, wherein the elevation angle condition specifies that each of the elevation angles corresponding to the beacons must be separated from each other by at least a second amount of angular separation, and wherein the signal strength condition specifies that each of a plurality of median signal strengths exceed a median signal strength threshold value, where each of the plurality of median signal strengths corresponds to a different beacon from the plurality of beacons, and where each of the plurality of median signal strengths is based on two or more signal strengths measured for two or more signals that were transmitted by that different beacon during a time period.

7. The method of claim 2, wherein the method comprises:

estimating that the receiver is indoors when each of at least n azimuthal angle ranges do not include a predetermined number of the azimuthal angles corresponding to the beacons, when each of at least m elevation angle ranges do not include a predetermined number of the elevation angles corresponding to the beacons, or when the signal strengths do not exceed a minimum signal strength threshold value; and

estimating that the receiver is outdoors when each of the n azimuthal angle ranges include the predetermined number of the azimuthal angles corresponding to the beacons, when each of the m elevation angle ranges include the predetermined number of the elevation angles corresponding to the beacons, and when the signal strengths exceed the minimum signal strength threshold value.

8. The method of claim 2, wherein the method comprises:

determining, for each of the beacons, a median signal strength based on two or more signal strengths measured for two or more signals that were transmitted by that beacon; and

estimating that the receiver is indoors when each of at least n azimuthal angle ranges do not include a predetermined number of the azimuthal angles corresponding to the beacons, when each of at least m elevation angle ranges do not include a predetermined number of the elevation angles corresponding to the beacons, or when median signal strengths corresponding to the beacons do not exceed a median signal strength threshold value; and

estimating that the receiver is outdoors when each of the n azimuthal angle ranges include the predetermined number of the azimuthal angles corresponding to the beacons, when each of the m elevation angle ranges include the predetermined number of the elevation angles corresponding to the beacons, and when the median signal strengths corresponding to the beacons exceed the median signal strength threshold value.

9. The method of claim 2, wherein the method comprises:

estimating that the receiver is indoors when a predetermined number of the azimuthal angles corresponding to the beacons are not separated from each other by at least a first amount of angular separation, when a predetermined number of the elevation angles corresponding to the beacons are not separated from each other by at least a second amount of angular separation, or when the signal strengths do not exceed a minimum signal strength threshold value; and

estimating that the receiver is outdoors when each of the azimuthal angles corresponding to the beacons are separated from each other by at least the first amount of angular separation, when each of the elevation angles corresponding to the beacons are separated from each other by at least the second amount of angular separation, and when the signal strengths exceed the minimum signal strength threshold value.

10. The method of claim 2, wherein the method comprises:

determining, for each of the beacons, a median signal strength based on two or more signal strengths measured for two or more signals that were transmitted by that beacon; and

estimating that the receiver is outdoors when each of the azimuthal angles corresponding to the beacons are separated from each other by at least a first amount of angular separation, when each of the elevation angles corresponding to the beacons are separated from each other by at least a second amount of angular separation, and when median signal strengths corresponding to the beacons exceed a median signal strength threshold value; and

estimating that the receiver is indoors when a predetermined number of the azimuthal angles corresponding to the beacons are not separated from each other by at least the first amount of angular separation, when a predetermined number of the elevation angles corresponding to the beacons are not separated from each other by at least a second amount of angular separation, or when median signal strengths corresponding to the beacons do not exceed the median signal strength threshold value.

11. The method of claim 1, wherein the data specifies, for each of the beacons, an azimuthal angle corresponding to the position of that beacon, and wherein the method comprises:

estimating whether the receiver is indoors or outdoors based on whether the azimuthal angles corresponding to the beacons meet an azimuthal angle condition, wherein;

the azimuthal angle condition specifies that each of the azimuthal angles corresponding to the beacons must be separated from each other by at least a first amount of angular separation, the number of beacons is 6 to 12, and the first amount of angular separation is between 30 and 60 degrees, or

the azimuthal angle condition specifies that each of n azimuthal angle ranges must include a predetermined number of the azimuthal angles corresponding to the beacons, n equals 6 to 12, the predetermined number is 1 or more, and each of the n azimuthal ranges do not overlap by more than 10 degrees.

12. The method of claim 11, wherein the method comprises:

estimating that the receiver is indoors when the azimuthal angles corresponding to the beacons are not separated from each other by at least a first amount of angular separation; and

estimating that the receiver is outdoors when each of the azimuthal angles corresponding to the beacons are separated from each other by at least a first amount of angular separation.

13. The method of claim 11, wherein the method comprises:

estimating that the receiver is indoors when each of at least n azimuthal angle ranges do not include a predetermined number of the azimuthal angles corresponding to the beacons; and

estimating that the receiver is outdoors when each of n azimuthal angle ranges include a predetermined number of the azimuthal angles corresponding to the beacons.

14. The method of claim 1, wherein the data specifies, for each of the beacons, an elevation angle corresponding to the position of that beacon, and wherein the method comprises:

estimating whether the receiver is indoors or outdoors based on whether the elevation angles corresponding to the beacons meet an elevation angle condition, and wherein;

the elevation angle condition specifies that each of the elevation angles corresponding to the beacons must be separated from each other by at least a second amount of angular separation, and the second amount of angular separation is 15 degrees of angular separation, or

the elevation angle condition specifies that each of m elevation angle ranges must include a predetermined number of the elevation angles corresponding to the beacons, and each of the m elevation ranges do not overlap by more than 5 degrees.

15. The method of claim 14, wherein the method comprises:

estimating that the receiver is indoors when the elevation angles corresponding to the beacons are not separated from each other by at least a second amount of angular separation; and

estimating that the receiver is outdoors when each of the elevation angles corresponding to the beacons are separated from each other by at least a second amount of angular separation

16. The method of claim 14, wherein the method comprises:

estimating that the receiver is indoors when each of at least m elevation angle ranges do not include a predetermined number of the elevation angles corresponding to the beacons; and

estimating that the receiver is outdoors when each of m elevation angle ranges include a predetermined number of the elevation angles corresponding to the beacons.

17. The method of claim 1, wherein the data specifies, for each of the beacons, the signal strength corresponding to that beacon, and wherein the method comprises:

estimating whether the receiver is indoors or outdoors based on whether the signal strengths corresponding to the beacons meet a signal strength condition, wherein;

the signal strength condition specifies that each of the signal strengths must exceed a minimum signal strength threshold value, or

the signal strength condition specifies that each of a plurality of median signal strengths exceed a median signal strength threshold value, where each of the plurality of median signal strengths corresponds to a different beacon from the plurality of beacons, and where each of the plurality of median signal strengths is based on two or more signal strengths measured for two or more signals that were transmitted by that different beacon during a time period.

18. The method of claim 17, wherein the method comprises:

estimating that the receiver is indoors when each of the signal strengths do not exceed a minimum signal strength threshold value; and

estimating that the receiver is outdoors when each of the signal strengths exceed a minimum signal strength threshold value.

19. The method of claim 17, wherein the method comprises:

determining, for each of the beacons, a median value of two or more signal strengths corresponding to that beacon;

estimating that the receiver is indoors when each of the median values does not exceed a median signal strength threshold value; and

estimating that the receiver is outdoors when each of the median values exceeds a median signal strength threshold value.

20. The method of claim 1, wherein the method comprises:

using a pressure measurement from a pressure sensor that is co-located with the receiver to estimate whether the receiver is indoors or outdoors.