1. A wireless device, comprising:
a wireless local area network (WLAN) positioning system, comprising:
an access point (AP) scanner configured to:
determine, prior to execution of a WLAN positioning scan, which WLAN channels are being used by APs proximate to the wireless device based on at least one of:
information retrieved from an AP database that identifies the WLAN channels:
energy levels of non-overlapping WLAN channels detected by the AP scanner;
a beacon report identifying an AP not visible to the wireless device;
geographic location of the wireless device;
execute a WLAN positioning scan for AP transmissions based on the prior determination of WLAN channels used by APs proximate to the wireless device; and
extract signal strength and AP identification information for WLAN positioning from the AP transmissions on the scanned channels.
2. The wireless device of claim 1, wherein the AP scanner is configured to discontinue scanning for APs based on identifying a number of APs sufficient to position the wireless device with a predetermined accuracy.
3. The wireless device of claim 1, further comprising a motion sensor; wherein the AP scanner is configured to scan for AP transmissions based on the motion sensor indicating that the wireless device has moved.
4. The wireless device of claim 1, wherein the AP scanner is configured to refrain from scanning for AP transmissions based on the position of the wireless device being determined to predetermined accuracy by via a non-WLAN positioning system.
5. A wireless device, comprising:
a wireless local area network (WLAN) positioning system, comprising:
an access point (AP) scanner configured to:
determine, prior to execution of a WLAN positioning scan, which WLAN channels are being used by APs proximate to the wireless device;
set a length for an interval to scan the WLAN channel;
execute a WLAN positioning scan for AP transmissions based on the prior determination of WLAN channels used by APs proximate to the wireless device;
extract signal strength and AP identification information for WLAN positioning from the AP transmissions on the scanned channels; and
adjust said scan interval length based on a number of APs identified during the interval.
6. A wireless device, comprising:
a wireless local area network (WLAN) positioning system, comprising:
an access point (AP) scanner configured to:
determine, prior to execution of a WLAN positioning scan, which WLAN channels are being used by APs proximate to the wireless device;
execute a WLAN positioning scan for AP transmissions based on the prior determination of WLAN channels used by APs proximate to the wireless device;
extract signal strength and AP identification information for WLAN positioning from the AP transmissions on the scanned channels; and
scan for an AP transmission at a time derived from a previously received beacon frame.
7. The wireless device of claim 6, wherein the time comprises a scanning interval having a length based on times of predicted beacon transmissions by a plurality of APs.
8. The wireless device of claim 7, wherein the AP scanner is configured to select the plurality of APs based on a geometry metric derived from locations of the APs.
9. The wireless device of claim 8, wherein the AP scanner is configured to base the geometry metric on at least one of:
a dilution of precision computation applied to the plurality of APs;
an area defined by a geometric contour of the plurality of APs;
mutual distance between the plurality of APs; and
angles of arrival of the plurality of APs to a predicted position of the wireless device.
10. A wireless device, comprising:
a wireless local area network (WLAN) positioning system, comprising:
an access point (AP) scanner configured to:
determine, prior to execution of a WLAN positioning scan, which WLAN channels are being used by APs proximate to the wireless device;
execute a WLAN positioning scan for AP transmissions based on the prior determination of WLAN channels used by APs proximate to the wireless device;
extract signal strength and AP identification information for WLAN positioning from the AP transmissions on the scanned channels; and
select which of an active scan and a passive scan to perform based on at least one of:
network information retrieved from an AP database;
an amount of network traffic detected by the wireless device; and
a scheduled wireless medium access by co-located wireless communication system disposed in the wireless device.
11. A wireless device, comprising:
a wireless local area network (WLAN) positioning system, comprising:
an access point (AP) scanner configured to:
determine, prior to execution of a WLAN positioning scan, which WLAN channels are being used by APs proximate to the wireless device;
execute a WLAN positioning scan for AP transmissions based on the prior determination of WLAN channels used by APs proximate to the wireless device; and
extract signal strength and AP identification information for WLAN positioning from the AP transmissions on the scanned channels;
wherein the wireless device is associated to a basic service set (BSS) and the wireless device is configured to transfer packets via the BSS, and the AP scanner is configured to scan for AP transmissions based on at least one of:
an inactive interval defined by a communication schedule of the BSS; and
an inactive period caused by a delay in transfer control protocol acknowledgement transmission by the wireless device.
12. A wireless device, comprising:
a wireless local area network (WLAN) positioning system, comprising:
an access point (AP) scanner configured to:
determine, prior to execution of a WLAN positioning scan, which WLAN channels are being used by APs proximate to the wireless device; execute a WLAN positioning scan for AP transmissions based on the prior determination of WLAN channels used by APs proximate to the wireless device;
extract signal strength and AP identification information for WLAN positioning from the AP transmissions on the scanned channels;
determine, prior to execution of a WLAN positioning scan, an order for scanning WLAN channels, the order determined to minimize scanning time applied to identify a predetermined number of APs; and
execute the WLAN positioning scan based on the determined order.
13. A method, comprising:
scanning, by a wireless device, a wireless network channel for a transmission from an access point (AP);
identifying, by the wireless device, an AP based on a transmission detected by the scanning;
computing, by the wireless device, a position uncertainty value for the wireless device based on the identified AP;
comparing, by the wireless device, the position uncertainty value to a predetermined uncertainty threshold;
terminating scanning based on the uncertainty threshold exceeding the position uncertainty value; and
determining which of an active scan and a passive scan to perform based on at least one of wireless medium use scheduled for a coexisting wireless transceiver in the wireless device, and a level of traffic on the WLAN.
14. A method, comprising:
scanning, by a wireless device, a wireless network channel for a transmission from an access point (AP);
identifying, by the wireless device, an AP based on a transmission detected by the scanning;
computing, by the wireless device, a position uncertainty value for the wireless device based on the identified AP;
comparing, by the wireless device, the position uncertainty value to a predetermined uncertainty threshold; and
terminating scanning based on the uncertainty threshold exceeding the position uncertainty value; and
changing the WLAN channel used in the scanning based on the uncertainty threshold not exceeding the position uncertainty value and one of:
all APs on the previously scanned WLAN channel being identified; and
a predetermined percentage of the APs on the previously scanned WLAN being identified.
15. A method, comprising:
scanning, by a wireless device, a wireless network channel for a transmission from an access point (AP);
identifying, by the wireless device, an AP based on a transmission detected by the scanning;
computing, by the wireless device, a position uncertainty value for the wireless device based on the identified AP;
comparing, by the wireless device, the position uncertainty value to a predetermined uncertainty threshold;
terminating scanning based on the uncertainty threshold exceeding the position uncertainty value;
setting a time interval to scan the WLAN channel; and
extending the time interval based on the uncertainty threshold not exceeding the position uncertainty value and all APs on the WLAN channel not being identified.
16. A method, comprising:
scanning, by a wireless device, a wireless network channel for a transmission from an access point (AP);
identifying, by the wireless device, an AP based on a transmission detected by the scanning;
computing, by the wireless device, a position uncertainty value for the wireless device based on the identified AP;
comparing, by the wireless device, the position uncertainty value to a predetermined uncertainty threshold;
terminating scanning based on the uncertainty threshold exceeding the position uncertainty value; and
changing the network radio frequency modulation mode based on the uncertainty threshold not exceeding the position uncertainty value and all APs on the WLAN using the previous network radio frequency modulation mode being identified.
17. A method, comprising:
scanning, by a wireless device, a wireless network channel for a transmission from an access point (AP);
identifying, by the wireless device, an AP based on a transmission detected by the scanning;
computing, by the wireless device, a position uncertainty value for the wireless device based on the identified AP;
comparing, by the wireless device, the position uncertainty value to a predetermined uncertainty threshold; and
terminating scanning based on the uncertainty threshold exceeding the position uncertainty value; and
accessing an AP database and retrieving from the database a value indicating a number of APs proximate to the wireless device.
18. A method, comprising:
scanning, by a wireless device, a wireless network channel for a transmission from an access point (AP);
identifying, by the wireless device, an AP based on a transmission detected by the scanning;
computing, by the wireless device, a position uncertainty value for the wireless device based on the identified AP;
comparing, by the wireless device, the position uncertainty value to a predetermined uncertainty threshold;
terminating scanning based on the uncertainty threshold exceeding the position uncertainty value; and
adjusting a scan time interval during the scanning based on a percentage of APs on a channel identified prior to the adjusting.
19. A method, comprising:
executing, by a wireless device, a passive scan and identifying a set of all visible access points (APs) based on the passive scan;
selecting a sub-set of the set of all visible APs based on predicted beacon frame transmission times for the APs of the subset, comprising:
identifying all combinations of APs of the set; wherein each AP of each combination is at least a predetermined distance from each other AP of the combination;
computing a dilution of precision value for each combination; and
discarding each combination having a dilution of precision value greater than a predetermined value;
scanning for APs during a time interval defined based on the predicted beacon frame transmission times for the APs of the subset.
20. A method, comprising:
executing, by a wireless device, a passive scan and identifying a set of all visible access points (APs) based on the passive scan;
selecting a sub-set of the set of all visible APs based on predicted beacon frame transmission times for the APs of the subset;
scanning for APs during a time interval defined based on the predicted beacon frame transmission times for the APs of the subset; and
extending the time interval based on not receiving a beacon from transmission from each AP of the sub-set.
21. A method, comprising:
executing, by a wireless device, a passive scan and identifying a set of all visible access points (APs) based on the passive scan;
selecting a sub-set of the set of all visible APs based on predicted beacon frame transmission times for the APs of the subset;
scanning for APs during a time interval defined based on the predicted beacon frame transmission times for the APs of the subset; and
executing a scan for all visible APs responsive to either of not receiving a beacon from transmission from each AP of the sub-set and receiving a beacon from an AP having a signal strength value greater than a predetermined value not in the sub-set.
22. A method, comprising:
executing, by a wireless device, a passive scan and identifying a set of all visible access points (APs) based on the passive scan;
selecting a sub-set of the set of all visible APs based on predicted beacon frame transmission times for the APs of the subset, comprising choosing APs transmitting on the same WLAN channel;
scanning for APs during a time interval defined based on the predicted beacon frame transmission times for the APs of the subset.
23. A method, comprising:
executing, by a wireless device, a passive scan and identifying a set of all visible access points (APs) based on the passive scan;
selecting a sub-set of the set of all visible APs based on predicted beacon frame transmission times for the APs of the subset;
scanning for APs during a time interval defined based on the predicted beacon frame transmission times for the APs of the subset;
determining, based on APs identified by the scanning, whether the wireless device has moved since the passive scan was executed.
24. The method of claim 21, wherein the selecting comprises excluding from the sub-set APs having a received signal strength lower than a predetermined value.
25. The method of claim 21, wherein the selecting comprises excluding from the sub-set APs positioned less than a predetermined distance from the wireless device.
26. The method of claim 23, wherein the selecting comprises excluding from the sub-set APs having a received signal strength lower than a predetermined value.
27. The method of claim 23, wherein the selecting comprises excluding from the sub-set APs positioned less than a predetermined distance from the wireless device.
28. The method of claim 20, wherein the selecting comprises excluding from the sub-set APs having a received signal strength lower than a predetermined value.
29. The method of claim 20, wherein the selecting comprises excluding from the sub-set APs positioned less than a predetermined distance from the wireless device.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An electrode sheet having a layered structure in which a first insulating layer, a first electrode layer, an inter-electrode insulating layer, a second electrode layer, and a second insulating layer are stacked and attracting a substrate on the first insulating layer, the first electrode layer having a plurality of openings in a specific planar area, and the second electrode layer having opening equivalent portions provided at positions at which the openings in the first electrode layer are projected onto the second electrode layer in a depth direction of the electrode sheet and having almost the same area as the projected openings, and connection portions that connect the opening equivalent portions.
2. The electrode sheet according to claim 1, wherein the first electrode layer has the openings disposed in a grid pattern, and the second electrode layer is formed in a grid pattern using the opening equivalent portions and the connection portions.
3. The electrode sheet according to claim 1, wherein, when a shortest distance between the adjacent openings in the first electrode layer is referred to as X, and the length of a line segment defined by the feet of perpendiculars when projecting the centers of gravity of the adjacent openings onto an imaginary straight line parallel to a straight line along which the adjacent openings are provided at the shortest distance X is referred to as L, the first electrode layer satisfies LX\u22671.5 and L\u22662.5 mm.
4. The electrode sheet according to claim 1, wherein the openings in the first electrode layer are circular holes, and the second electrode layer has circular opening equivalent portions.
5. The electrode sheet according to claim 1, wherein a capacitance C1 between the first electrode layer and the second electrode layer when the electrode sheet attracts the substrate and a capacitance C2 between the first electrode layer and the second electrode layer when the electrode sheet does not attract the substrate satisfy (C1\u2212C2)C1\u22670.03.
6. An electrostatic chuck comprising a metal base and the electrode sheet according to claim 1 that is bonded to the metal base.
7. The electrostatic chuck according to claim 6, wherein the electrode sheet is bonded to the metal base through a flexible silicone rubber layer having a thickness of 500 to 1000 \u03bcm.