Granted Patent B1

US 9,668,233 · App. 15/208,274 · Granted May 30, 2017

Inventors: Jack Horner (Thousand Oaks, CA); Dirk I. Gates (Westlake Village, CA)

Assignee: Xirrus, Inc.

H04W64/00G01C21/20H04B17/318H04L43/0829H04W84/12

Abstract

Claims (165)

1. A method for estimating a location of a user device in a wireless communications network, comprising:

a plurality of access points defining a respective received signal strength indicator (RSSI) value for transmissions received from the user device;

each of plurality of access points receiving location information indicating locations of all of the plurality of access points;

all of the plurality of access points sending the respective RSSI values to the other access points of the plurality of access points;

one of the plurality of access points self-electing to estimate the location of the user device; and

the self-elected access point estimating a location of the user device in accordance with the formula:

e

≈

∑

i

=

1

n

⁢

(

B

i

+

RSSI

i

)

⁢

p

i

∑

i

=

1

n

⁢

(

B

i

+

RSSI

i

)

where e=(x, y, z)=estimated location of the user device;

p i =(x i , y i , z i )=location of access point i;

B i =bias value associated with access point i;

RSSI i =RSSI value (in dBm) reported by access point i for transmissions received from the user device;

n=number of access points in the plurality of access points.

2. The method of claim 1 , further comprising:

the self-elected access point setting respective bias values associated with each of the plurality of access points.

3. The method of claim 2 , wherein setting respective bias values associated with each of the plurality of access points comprises:

setting all of the bias values to a predetermined value.

4. The method of claim 2 , wherein determining respective bias values associated with each of the plurality of access points comprises:

determining a respective relative path loss between the self-elected access point and each of the other access points of the plurality of access point; and

setting the respective bias value associated with each of the other access points proportional to the respective relative path loss.

5. The method of claim 1 , wherein one of the access points self-electing further comprises:

all of the plurality of access points comparing their own RSSI value to RSSI values received from the other access points of the plurality of access points; and

the access point having the highest RSSI value self-electing to estimate the location of the user device.

6. The method of claim 1 , further comprising:

the self-elected access point sending an estimate of the location of the user device to a location server.

7. A method performed by an access point (AP) in a wireless communications network, comprising:

defining an own received signal strength indicator (RSSI) value for transmissions received from a user device;

receiving respective other AP RSSI values for transmissions received from the user devices at two or more additional access points;

receiving location information indicating an own location and respective locations of the two or more additional access points;

determining whether or not to estimate a location of the user device; and

when a determination is made to estimate the location of the user device, estimating the location of the user device in accordance with the formula:

e

≈

∑

i

=

0

n

⁢

(

B

i

+

RSSI

i

)

⁢

p

i

∑

i

=

0

n

⁢

(

B

i

+

RSSI

i

)

where e=(x, y, z)=estimated location of the user device;

p i =(x i , y i , z i )=location of access point i, where access point 0 is the access point performing the method and access points 1 to n are the additional access points;

B i =bias value associated with access point i;

RSSI i =RSSI value (in dBm) reported by access point i for transmissions received from the user device, where RSSI 0 is the own RSSI value;

n=number of additional access points.

8. The method of claim 7 , further comprising:

setting respective bias values associated with each of the additional access points.

9. The method of claim 8 , wherein setting respective bias values associated with each of the additional access points comprises:

setting all of the bias values to a predetermined value.

10. The method of claim 8 , wherein setting respective bias values associated with each of the additional access points comprises:

determining a respective relative path loss between the access point performing the method and each of the additional access points; and

setting the respective bias value associated with each of the additional access points proportional to the respective relative path loss.

11. The method of claim 7 , wherein determining whether or not to estimate a location of the user device further comprises:

comparing the own RSSI value to the other AP RSSI values; and

determining to estimate a location of the user device when the own RSSI value is greater than or equal to all of the other AP RSSI values.

12. The method of claim 7 , further comprising:

when the location of the user device has been estimated, sending the estimate of the location of the user device to a location server.

13. An access point (AP) for a wireless communications network, comprising:

a receiver to define an own received signal strength indicator (RSSI) value for transmissions received from a user device;

a network interface;

a processor coupled to the receiver and the network interface; and

a memory coupled to the processor, the memory storing instructions that, when executed by the processor, cause the access point to perform actions comprising:

receiving, via the network interface, respective other AP RSSI values for transmissions received from the user device at two or more additional access points;

receiving, via the network interface, location information indicating an own location and respective locations of the two or more additional access points;

determining whether or not to estimate a location of the user device; and

when a determination is made to estimate the location of the user device, estimating the location of the user device in accordance with the formula:

e

≈

∑

i

=

0

n

⁢

(

B

i

+

RSSI

i

)

⁢

p

i

∑

i

=

0

n

⁢

(

B

i

+

RSSI

i

)

where e=(x, y, z)=estimated location of the user device;

p i =(x i , y i , z i )=location of access point i, where access point 0 is the access point and access points 1 to n are the additional access points;

B i =bias value associated with access point i;

RSSI i =RSSI value (in dBm) reported by access point i for transmissions received from the user device, where RSSI 0 is the own RSSI value;

n=number of additional access points.

14. The method of claim 13 , the actions performed further comprising:

setting respective bias values associated with each of the additional access points.

15. The method of claim 14 , wherein setting respective bias values associated with each of the additional access points comprises:

setting all of the bias values to a predetermined value.

16. The method of claim 14 , wherein setting respective bias values associated with each of the additional access points comprises:

determining a respective relative path loss between the access point and each of the additional access points; and

setting the respective bias value associated with each of the additional access points proportional to the respective relative path loss.

17. The method of claim 13 , wherein determining whether or not to estimate a location of the user device further comprises:

comparing the own RSSI value to the other AP RSSI values; and

determining to estimate a location of the user device when the own RSSI value is higher than or equal to all of the other AP RSSI values.

18. The method of claim 13 , the actions performed further comprising:

when the location of the user device has been estimated, sending the estimate of the location of the user device to a location server.

Assignments (8)