Assigning UWB anchors for client ranging

1. A computer-implemented method comprising:

estimating, by a location server, a coarse location of a mobile device using a localization technique other than an ultra-wide band (UWB) localization technique, the localization technique involving a plurality of radio devices;

defining, by the location server, an area around the coarse location to identify a set of candidate anchors for UWB ranging for the mobile device, the set of candidate anchors being disposed within the area and comprising at least a subset of the plurality of radio devices;

modifying, by the location server, the set of candidate anchors to create a modified set of candidate anchors that includes only UWB-enabled devices;

selecting, by the location server, a primary anchor from the modified set of candidate anchors; and

sending a command to cause a UWB ranging procedure to be initiated between the primary anchor and the mobile device.

2. The computer-implemented method of claim 1 , wherein the defining comprises using a convex hull algorithm to define the area.

3. The computer-implemented method of claim 1 , wherein the modifying comprises removing from the set of candidate anchors at least one radio device within the subset of the plurality of radio devices that is not UWB-enabled.

4. The computer-implemented method of claim 1 , wherein the modifying comprises adding to the set of candidate anchors at least one UWB-enabled device that was not involved in the estimating.

5. The computer-implemented method of claim 1 , wherein the selecting comprises:

identifying a plurality of subgroups from the modified set of candidate anchors, each of the plurality of subgroups comprising a plurality of anchors from the modified set of candidate anchors, which are within a UWB range of one another; and

selecting the primary anchor from a particular one of the plurality of subgroups based on a characteristic of the particular one of the plurality of subgroups.

6. The computer-implemented method of claim 5 , wherein the selecting the primary anchor from the particular one of the plurality of subgroups comprises:

determining whether any of the plurality of subgroups includes an anchor that is set as a primary anchor for another mobile device; and

in response to determining that one of the plurality of subgroups includes a particular anchor that is set as a primary anchor for another mobile device, selecting the particular anchor as the primary anchor.

7. The computer-implemented method of claim 6 , further comprising:

calculating, for each of the plurality of subgroups, a distance to a center of the coarse location,

wherein the determining is completed in an order based on the calculating.

8. The computer-implemented method of claim 6 , further comprising:

in response to determining that none of the plurality of subgroups includes an anchor that is set as a primary anchor for another mobile device:

identifying a one of the plurality of subgroups that is farthest away from others of the plurality of subgroups; and

selecting as the primary anchor an anchor in the one of the plurality of subgroups, which anchor has a smallest neighbor count.

9. The computer-implemented method of claim 1 , wherein the estimating is performed in response to the mobile device entering a venue where the area is located.

10. An apparatus comprising:

an interface configured to enable network communications; and

one or more processors coupled to the interface and configured to perform operations including:

estimating a coarse location of a mobile device using a localization technique other than an ultra-wide band (UWB) localization technique, the localization technique involving a plurality of radio devices;

defining an area around the coarse location to identify a set of candidate anchors for UWB ranging for the mobile device, the set of candidate anchors being disposed within the area and comprising at least a subset of the plurality of radio devices;

modifying the set of candidate anchors to create a modified set of candidate anchors that includes only UWB-enabled devices;

selecting a primary anchor from the modified set of candidate anchors; and

sending a command to cause a UWB ranging procedure to be initiated between the primary anchor and the mobile device.

11. The apparatus of claim 10 , wherein the one or more processors are further configured to define the area using a convex hull algorithm.

12. The apparatus of claim 10 , wherein the one or more processors are further configured to modify the set of candidate anchors to create the modified set of candidate anchors by removing from the set of candidate anchors at least one radio device within the subset of the plurality of radio devices that is not UWB-enabled.

13. The apparatus of claim 10 , wherein the one or more processors are further configured to modify the set of candidate anchors to create the modified set of candidate anchors by adding to the set of candidate anchors at least one UWB-enabled device that was not involved in the estimating.

14. The apparatus of claim 10 , wherein the one or more processors are further configured to select the primary anchor from the modified set of candidate anchors by:

identifying a plurality of subgroups from the modified set of candidate anchors, each of the plurality of subgroups comprising a plurality of anchors from the modified set of candidate anchors, which are within a UWB range of one another; and

selecting the primary anchor from a particular one of the plurality of subgroups based on a characteristic of the particular one of the plurality of subgroups.

15. The apparatus of claim 14 , wherein the one or more processors are further configured to select the primary anchor from the particular one of the plurality of subgroups by:

determining whether any of the plurality of subgroups includes an anchor that is set as a primary anchor for another mobile device; and

in response to determining that one of the plurality of subgroups includes a particular anchor that is set as a primary anchor for another mobile device, selecting the particular anchor as the primary anchor.

16. One or more non-transitory computer readable storage media comprising instructions that, when executed by at least one processor, are configured to:

estimate a coarse location of a mobile device using a localization technique other than an ultra-wide band (UWB) localization technique, the localization technique involving a plurality of radio devices;

define an area around the coarse location to identify a set of candidate anchors for UWB ranging for the mobile device, the set of candidate anchors being disposed within the area and comprising at least a subset of the plurality of radio devices;

modify the set of candidate anchors to create a modified set of candidate anchors that includes only UWB-enabled devices;

select a primary anchor from the modified set of candidate anchors; and

send a command to cause a UWB ranging procedure to be initiated between the primary anchor and the mobile device.

17. The one or more non-transitory computer readable storage media of claim 16 , wherein the instructions further cause the processor to define the area using a convex hull algorithm.

18. The one or more non-transitory computer readable storage media of claim 16 , wherein the instructions further cause the processor to modify the set of candidate anchors to create the modified set of candidate anchors by removing from the set of candidate anchors at least one radio device within the subset of the plurality of radio devices that is not UWB-enabled.

19. The one or more non-transitory computer readable storage media of claim 16 , wherein the instructions further cause the processor to modify the set of candidate anchors to create the modified set of candidate anchors by adding to the set of candidate anchors at least one UWB-enabled device that was not involved in the estimating.

20. The one or more non-transitory computer readable storage media of claim 16 , wherein the instructions further cause the processor to select the primary anchor from the modified set of candidate anchors by:

identifying a plurality of subgroups from the modified set of candidate anchors, each of the plurality of subgroups comprising a plurality of anchors from the modified set of candidate anchors, which are within a UWB range of one another; and

selecting the primary anchor from a particular one of the plurality of subgroups based on a characteristic of the particular one of the plurality of subgroups.