Localizing tagged assets using modulated backscatter
First Claim
1. A method, comprising:
- scanning, from a reader having one or more antennas, an electromagnetic signal across a zone, the zone formed between a plurality of marker tags located in an area proximate to the reader;
affixing an asset tag to an asset; and
determining a location estimate of the asset tag based on parameters of backscatter signals, the backscatter signals received by the reader from the asset tag and the plurality of marker tags;
wherein the location estimate includes a determination of whether the asset tag is positioned within the zone formed by the plurality of marker tags;
and wherein the parameters of the backscatter signals include an angle of arrival, a range from the reader to at least one of the plurality of marker tags, and a range from the reader to the asset tag;
wherein the angle of arrival of the backscatter signals is determined based on a peak received signal strength of the backscatter signals as a function of a scan angle of the scanned electromagnetic signal; and
wherein the range from the reader to the at least one of the plurality of marker tags and the range from the reader to the asset tag are determined based on comparing shapes of vectors of received powers with vectors of expected powers.
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Accused Products
Abstract
Methods and systems for localizing an asset using the modulated backscatter from an asset tag and one or more marker tags are described. The system includes the reader, a location module and one or more marker tags. The location estimates for the asset tag are based partially on a prior knowledge of the location of each of the one or more marker tags. The location for each marker tag may be stored in a database. The location module determines a location estimate for the asset tag using the estimated parameters of the modulated backscatter signals received from one or more marker tags and from the asset tag. Using the known locations of the marker tags, a location estimate of the asset tag can be determined. The location estimate may be a relative location, an absolute location, and/or may be a zone including the marker tags. A mobile reader using the marker tags can localize asset tags throughout a large area and may, for example, take an inventory of assets throughout the large area.
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Citations
14 Claims
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1. A method, comprising:
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scanning, from a reader having one or more antennas, an electromagnetic signal across a zone, the zone formed between a plurality of marker tags located in an area proximate to the reader; affixing an asset tag to an asset; and determining a location estimate of the asset tag based on parameters of backscatter signals, the backscatter signals received by the reader from the asset tag and the plurality of marker tags; wherein the location estimate includes a determination of whether the asset tag is positioned within the zone formed by the plurality of marker tags; and wherein the parameters of the backscatter signals include an angle of arrival, a range from the reader to at least one of the plurality of marker tags, and a range from the reader to the asset tag; wherein the angle of arrival of the backscatter signals is determined based on a peak received signal strength of the backscatter signals as a function of a scan angle of the scanned electromagnetic signal; and wherein the range from the reader to the at least one of the plurality of marker tags and the range from the reader to the asset tag are determined based on comparing shapes of vectors of received powers with vectors of expected powers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method, comprising:
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(a) positioning a reader at a first stationary location; (b) scanning, by said reader, a transmit beam through a scan angle from a transmitter beamscanning system across a zone using an array of antennas, said transmit beam comprising radio frequency (RF) signals emitted from said array of antennas, said zone formed between a plurality of marker tags located in an area proximate to the reader; (c) affixing an asset tag to an asset; (d) receiving, by said reader, backscatter signals from at least one marker tag and the asset tag; (e) determining a location estimate of the asset tag based on parameters of backscatter signals, the backscatter signals received by the reader from the asset tag and the plurality of marker tags, wherein the location estimate includes a determination of whether the asset tag is positioned within the zone formed by the plurality of marker tags, and wherein the parameters of the backscatter signals include an angle of arrival, a range from the reader to at least one of the plurality of marker tags, and a range from the reader to the asset tag, wherein the angle of arrival of the backscatter signals is determined based on a peak received signal strength of the backscatter signals as a function of the scan angle, and wherein the range from the reader to the at least one of the plurality of marker tags and the range from the reader to the asset tag are determined based on comparing shapes of vectors of received powers with vectors of expected powers; and (f) moving the reader to a second stationary position and repeating steps (b)-(e) at the second stationary position. - View Dependent Claims (10, 11)
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12. A system, comprising:
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a plurality of marker tags; a reader having one or more antennas for scanning an electromagnetic signal across a zone, the zone formed between the plurality of marker tags; an asset tag affixed to an asset; and a location module configured to determine a location estimate of the asset tag, wherein the location estimate is based on parameters of backscatter signals received by the reader from the asset tag and the plurality of marker tags; wherein the location estimate includes a determination of whether the asset tag is positioned within the zone formed by the plurality of marker tags; wherein the parameters of the backscatter signals include an angle of arrival, a range from the reader to at least one of the plurality of marker tags, and a range from the reader to the asset tag; wherein the angle of arrival of the backscatter signals is determined based on a peak received signal strength of the backscatter signals as a function of a scan angle of the scanned electromagnetic signal; and wherein the range from the reader to the at least one of the plurality of marker tags and the range from the reader to the asset tag are determined based on comparing shapes of vectors of received powers with vectors of expected powers. - View Dependent Claims (13, 14)
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Specification