Wireless communication network with distributed device location determination

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

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

all of the three or more access points sending the respective RSSI values to the other access points of the three or more access points;

all of the three or more access points comparing its own RSSI value associated with the user device to RSSI values associated with the user device received from the other access points of the three or more access points;

an access point having an own RSSI value associated with the user device higher than RSSI values associated with the user device received from the other access points determining it is responsible for estimating the location of the user device;

access points having own RSSI values associated with the user device less than at least one RSSI value associated with the user device received from the other access points determining they are not responsible for estimating the location of the user device; and

the responsible access point estimating a location of the user device based, at least in part, on the RSSI values associated with the user device.

2. The method of claim 1 , further comprising:

all of the three or more access points receiving location information indicating locations of all of the three or more access points; and

the responsible access point estimating the location of the user device based, at least in part, on the RSSI values associated with the user device and the location information.

3. The method of claim 2 , further comprising:

the responsible access point estimating the location of the user device in accordance with the formula:

d

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1

n

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(

w

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p

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i

=

1

n

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where

d=(x, y, z)=location of the user device;

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

wi=weight determined from the RSSI value reported by access point i;

n=number of access points.

4. The method of claim 3 , further comprising:

the responsible access point determining, for each access point i of the three or more access points, the respective weight wi by adding a respective bias value to the RSSI value associated with the user device reported by access point i.

5. The method of claim 4 , further comprising:

the responsible access point setting, for each access point i of the three or more access points, the respective bias value to a predetermined value.

6. The method of claim 4 , further comprising:

the responsible access point setting, for each access point i of the three or more access points, the respective bias value by:

determining a respective relative path loss between the responsible access point and each of the other access points of the three or more access points; and

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

7. The method of claim 1 , further comprising:

the responsible access point sending an estimate of the location of the user device to a location server.

8. A method performed by every access point (AP) of a group of three or more access points that receive transmissions from a user device in a wireless communications network, comprising:

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

transmitting the own RSSI value associated with the user device to the other access points of the group of access points;

receiving, from the other access points of the group of access points, respective other AP RSSI values for transmissions received from the user device at the other access points;

comparing the own RSSI value associated with the user device to the other AP RSSI values associated with the user device;

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

when a determination is made to estimate the location of the user device, estimating the location of the user device based, at least in part, on the own RSSI value associated with the user device and the other AP RSSI values associated with the user device.

9. The method of claim 8 , further comprising:

receiving location information indicating an own location and respective locations of all other access points of the group of access points; and

when a determination is made to estimate the location of the user device, estimating the location of the user device based, at least in part, on the own RSSI value associated with the user device, the other AP RSSI values associated with the user device and the location information.

10. The method of claim 9 , further comprising:

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:

d

=

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i

=

1

n

⁢

(

w

i

)

⁢

p

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∑

i

=

1

n

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(

w

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where

d=(x, y, z)=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 other access points in the group of access points;

wi=weight determined from the RSSI value reported by access point i;

n=number of access points.

11. The method of claim 10 , further comprising:

determining, for each access point i, the respective weight wi by adding a respective bias value to the RSSI value associated with the user device reported by access point i.

12. The method of claim 11 , further comprising:

setting, for each access point i, the respective bias value to a predetermined value.

13. The method of claim 11 , further comprising:

setting, for each access point i, the respective bias value by:

determining a respective relative path loss between a self-elected 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.

14. The method of claim 8 , 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.

15. An access point (AP) for a wireless communications network including three or more access points, 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:

transmitting, via the network interface, the own RSSI value associated with the user device to all other access points of the three or more access points;

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

comparing the own RSSI value associated with the user device to the other AP RSSI values associated with the user device;

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

when a determination is made to estimate the location of the user device, estimating the location of the user device based, at least in part, on the own RSSI value associated with the user device and the other AP RSSI values associated with the user device.

16. The access point of claim 15 , the actions performed further comprising:

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

when a determination is made to estimate the location of the user device, estimating the location of the user device based, at least in part, on the own RSSI value associated with the user device, the other AP RSSI values associated with the user device and the location information.

17. The access point of claim 16 , the actions performed further comprising: 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:

d

=

∑

i

=

1

n

⁢

(

w

i

)

⁢

p

i

∑

i

=

1

n

⁢

(

w

i

)

where

d=(x, y, z)=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 other access points in the group of access points;

wi=weight determined from the RSSI value reported by access point i;

n=number of access points.

18. The access point of claim 17 , the actions performed further comprising:

determining, for each access point i, the respective weight wi by adding a respective bias value to the RSSI value associated with the user device reported by access point i.

19. The access point of claim 18 , the actions performed further comprising:

setting, for each access point i, the respective bias value to a predetermined value.

20. The access point of claim 18 , the actions performed further comprising:

setting, for each access point i, the respective bias value by:

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

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

21. The access point of claim 15 , 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.