Apparatus and method for tracking the position of an intermittently operable Wi-Fi tag
A server has a processor and a memory connected to the processor. The memory stores instructions executed by the processor to collect scan lists from client devices, where each scan list specifies a Wi-Fi access point identifier collected by a client device and geographic coordinates of the client device when the Wi-Fi access point identifier was collected. A cluster of geographic coordinates around a designated Wi-Fi access point is formed. A centroid within the cluster is identified. The location of the centroid is ascribed the geographic position of the designated Wi-Fi access point. The geographic position of the designated Wi-Fi access point is added to a Wi-Fi access point location database. A Wi-Fi tag scan list is processed to form a tag path listing known geographic locations of Wi-Fi access points observed by the Wi-Fi tag. The tag path is supplied in response to a request.
1. A server, comprising:
a processor; and
a memory connected to the processor, the memory storing instructions executed by the processor to:
collect scan lists from client devices, wherein each scan list specifies a Wi-Fi access point identifier collected by a client device and geographic coordinates of the client device when the Wi-Fi access point identifier was collected,
form a cluster of geographic coordinates around a designated Wi-Fi access point,
identify a centroid within the cluster,
ascribe the location of the centroid as the geographic position of the designated Wi-Fi access point,
add the geographic position of the designated Wi-Fi access point to a Wi-Fi access point location database,
process a Wi-Fi tag scan list from a Wi-Fi tag to form a tag path listing known geographic locations of Wi-Fi access points observed by the Wi-Fi tag, wherein the Wi-Fi tag scan list includes a plurality of identifiers of Wi-Fi access points observed during periodic wake states of the Wi-Fi tag attached to an item in commerce, and
supply the tag path in response to a request, wherein the tag path characterizes the movement of the item in commerce.
2. The server of claim 1 further comprising instructions executed by the processor to rank the scan lists.
3. The server of claim 2 wherein the instructions executed by the processor to rank the scan lists is based upon a mobile device value, a signal value and a measure of geographic accuracy.
4. The server of claim 3 wherein the mobile device value is a function of whether global positioning data is enabled on the mobile device.
5. The server of claim 3 wherein the signal value is a measure of signal strength from the designated Wi-Fi access point.
6. The server of claim 3 wherein the measure of geographic accuracy is derived from geographic accuracy information from the mobile device and a measure of the age of the geographic information.
7. The server of claim 1 in combination with the Wi-Fi tag, comprising:
a Wi-Fi interface,
a second processor connected to the Wi-Fi interface,
a second memory connected to the second processor, the second memory storing instructions executed by the processor to:
(a) periodically determine whether to place the Wi-Fi tag in a wake state,
(b) collect from the Wi-Fi interface a scan list during the wake state, wherein the scan list includes identifiers of Wi-Fi access points observed during the wake state of the Wi-Fi tag attached to an item in commerce,
(c) store the scan list,
(d) enter a sleep mode; and
(e) repeat operations (a)-(d) to collect data to characterize the movement of the item in commerce.
8. The Wi-Fi tag of claim 7 further comprising instructions executed by the second processor to utilize the Wi-Fi interface to connect to a free Wi-Fi access point.
9. The Wi-Fi tag of claim 8 further comprising instructions executed by the second processor to upload session details to the server.
10. The Wi-Fi tag of claim 9 further comprising instructions executed by the second processor to upload the scan list to the server.
11. The Wi-Fi tag of claim 10 further comprising instructions executed by the second processor to wait for an acknowledgement from the server.
12. The Wi-Fi tag of claim 11 further comprising instructions executed by the second processor to take an action specified by the server.