Wireless local area network (WLAN) channel radio-frequency identification (RFID) tag system and method therefor
DC
First Claim
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1. A method for determining the location of an identification tag by a wireless local area network, said method comprising:
- transmitting a signal from said identification tag on a channel of said wireless local area network, said signal bearing an identification number of said identification tag;
receiving said signal from said identification tag at multiple location units within said wireless local area network;
in response to said receiving, measuring a characteristic of said received signal at said multiple location units;
sending information corresponding to said measured characteristic from each of said corresponding multiple location units to a master unit; and
determining, within said master unit, the location of said identification tag by using location information for said multiple location units in conjunction with said sent information to determine said location of said identification tag;
sniffing said channel via a sniffer circuit to determine whether or not said channel is clear;
in response to said sniffing determining that said channel is clear, performing said transmitting at said predetermined interval; and
in response to said sniffing determining that said channel is not clear, transmitting said signal at a subsequent time when said channel is clear.
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Abstract
A wireless local area network (WLAN) radio-frequency identification (RFID) tag system provides location finding in a wireless local area network (WLAN), using a WLAN channel. Interference with the WLAN is prevented by either using a sniffer circuit to determine that no network transmission is in progress, using a modified coding sequence or preamble to cause standard WLAN receivers to ignore the RFID tag transmissions, or transmitting a message using a standard WLAN signal addressed to an address not corresponding to a unit within the WLAN. Location units (LUs) and a master unit (MU) within the WLAN receive the RFID tag transmissions and can determine the location of a tag by triangulation based on differences between the signals received at the location units from the tag. The master unit receives the signal information from the location units and computes the location of the tag. Time-difference-of-Arrival (TDOA), received signal strength indication (RSSI) or other triangulation techniques may be used.
205 Citations
27 Claims
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1. A method for determining the location of an identification tag by a wireless local area network, said method comprising:
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transmitting a signal from said identification tag on a channel of said wireless local area network, said signal bearing an identification number of said identification tag;
receiving said signal from said identification tag at multiple location units within said wireless local area network;
in response to said receiving, measuring a characteristic of said received signal at said multiple location units;
sending information corresponding to said measured characteristic from each of said corresponding multiple location units to a master unit; and
determining, within said master unit, the location of said identification tag by using location information for said multiple location units in conjunction with said sent information to determine said location of said identification tag;
sniffing said channel via a sniffer circuit to determine whether or not said channel is clear;
in response to said sniffing determining that said channel is clear, performing said transmitting at said predetermined interval; and
in response to said sniffing determining that said channel is not clear, transmitting said signal at a subsequent time when said channel is clear. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A wireless local area network (WLAN), comprising:
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a plurality of identification tags for transmitting signals on a channel of said wireless local area network and bearing an identification number corresponding to a particular identification tag;
a plurality of location units for receiving said signals transmitted by said identification tags and determining a characteristic of said received signals on a channel of said wireless local area network; and
at least one master unit for receiving information corresponding to said received characteristic from each of said location units, whereby locations of said identification tags are determined in conformity with said received characteristic, and wherein each of said identification tags comprise a sniffer circuit to determine whether or not said channel is clear, and wherein said wireless identification tags transmit said signals only when said included sniffer circuit determines that said channel is clear. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A wireless identification tag for use within a wireless local area network (WLAN), comprising:
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a storage for storing at least a identification number of said identification tag;
a transmitter coupled to said storage, for transmitting a signal from said identification tag on a channel of said wireless local area network, said signal bearing an identification number of said identification tag; and
a sniffer circuit for determining whether or not said channel is clear, and wherein said transmitter transmits said signal in response to said sniffer circuit determining that said channel is clear. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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Specification
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Litigation Data
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Current AssigneeAeroscout Limited (Stanley Black & Decker, Inc.)
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Original AssigneeAeroscout Limited (Stanley Black & Decker, Inc.)
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InventorsGranot, Yair, Tsruya, Shalom, Aljadeff, Daniel, Amsalem, Reuven
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Primary Examiner(s)Horabik, Michael
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Assistant Examiner(s)NGUYEN, NAM V
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Application NumberUS10/274,698Publication NumberTime in Patent Office1,117 DaysField of Search340/10.1, 340/10.3, 340/10.31, 340/10.4, 340/10.41, 340/10.42, 340/10.52, 340/573.1, 340/573.4, 340/539, 340/825.99, 342/357.07, 342/357.09, 342/118, 342/450US Class Current340/8.1CPC Class CodesG01S 13/765 with exchange of informatio...G01S 13/878 Combination of several spac...G01S 5/06 Position of source determin...
