Note: Within nine months of the publication of the mention of the grant of the European patent in the European PatentBulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with theImplementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has beenpaid. (Art. 99(1) European Patent Convention).

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(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mention of the grant of the patent: 27.04.2016 Bulletin 2016/17

(21) Application number: 14183999.3

(22) Date of filing: 08.09.2014

(51) Int Cl.:G06K 19/073 (2006.01) G06K 7/10 (2006.01)

G08B 21/18 (2006.01)

(54) Systems, methods, and apparatus to permit communication between passive wireless transponders

Systeme, Verfahren und Vorrichtung zur Kommunikation zwischen passiven drahtlosen Transpondern

Systèmes, procédés et appareil pour permettre une communication entre des répéteurs sans fil passifs

(84) Designated Contracting States: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30) Priority: 24.09.2013 US 201314035525

(43) Date of publication of application: 27.05.2015 Bulletin 2015/22

(73) Proprietor: Intermec IP Corp.Everett, WA 98203 (US)

(72) Inventors: • Nikitin, Pavel

Morristown, NJ New Jersey 07962-2245 (US)• Kelly, Stephen J.

Morristown, NJ New Jersey 07962-2245 (US)

(74) Representative: Houghton, Mark PhillipPatent Outsourcing Limited 1 King StreetBakewell, Derbyshire DE45 1DZ (GB)

(56) References cited: WO-A2-2007/035863 US-A1- 2007 115 125US-A1- 2012 126 945

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Description

BACKGROUND

Technical Field

[0001] The present disclosure generally relates to thefield of passive wireless transponders, more specificallyto communication between passive wireless transpond-ers in the presence of an externally applied carrier wave.

Description of the Related Art

[0002] Passive wireless transponders such as radiofrequency identification tags typically include an antenna,a control circuit or controller, and a limited quantity ofnontransitory storage. Typically, each passive wirelesstransponder includes data indicative of a unique identifierhardwired or stored in the nontransitory storage (e.g.,nonvolatile memory). Additionally, logic or machine ex-ecutable instruction sets executable by the control circuitor controller may be optionally hardwired or stored in thenontransitory storage. Passive wireless transponders re-ceive energy when illuminated or interrogated by a carrierwave within a particular frequency range. When ener-gized, passive wireless transducers may backscatterwaves which mayor may not carry data. Additionally, thepassive wireless transponders may execute one or moresets of machine executable instructions when energized.Such machine executable instructions permit passivewireless transponders to perform additional functionssuch as transmitting stored data, writing to nontransitorystorage or interacting with the ambient environment.[0003] Typically, a reader or interrogator transmits acarrier wave to energize the passive wireless transpond-ers. The reader and interrogator also typically receivesbackscatter signals from the energize passive wirelesstransponders. The reader may decode or interpret infor-mation encoded or imposed on the backscatter signals.Sometimes one or more readers or interrogators arecommunicably coupled to a host or backend processor-based system. The interrogator extracts the data carriedby the backscatter waves produced by each passivewireless device within range of the interrogator. Usingthe extracted data, the interrogator is able to performvarious functions including information lookup (e.g., de-termining the type and price of an item to which the pas-sive wireless transponder is attached) and position de-termination (e.g., indicating an approximate direction anddistance to a particular passive wireless transponder).[0004] Patent document number US2007/115125A1describes a method of tracking an item. The item is as-sociated with a tag and capable of responding to a queryfrom a tag reader and tag combination. The tag readerand tag combination are capable of identifying the itemassociated with the tag using a tag reader. In operation,a tag reader makes a request to at least one tag readerand tag combination for the identity of an item associated

with a tag. The tag reader and tag combination identifiesthe item associated with the tag and provides the identityof the item and tag to the tag reader.[0005] Patent document number WO2007/035863A2describes data carriers (such as RFID tags) which areformed into clusters of data carriers. Each cluster has atleast one bridge data carrier that can communicate witha bridge data carrier of another cluster, thereby allowingdata carriers in each cluster to communicate directly orindirectly with each other using a stochastic communica-tion protocol method. Direct tag-to-tag communicationcapability is provided between data carriers in each clus-ter and/or between clusters. The data carriers can back-scatter and modulate a carrier wave from a source, there-by using the backscattered and modulated carrier waveto convey data to each other.

BRIEF SUMMARY

[0006] The present invention in its various aspects isas set out in the appended claims. Each of a plurality ofgrouped or otherwise accumulated passive wirelesstransponders can be configured to communicate with atleast one other passive wireless transponder when ex-posed to an incoming radio frequency signal such as aninterrogation carrier wave. In some instances, one ormore signal parameters (e.g., signal strength, time-of-flight) of the backscatter signals produced by each of theplurality of passive wireless transponders can be usedto deduce the physical or spatial relationship of one trans-ducer to one or more other transducers. For example,the signal parameters of the backscatter signals may beused to deduce which transducers are positioned proxi-mate a particular transponder. Additionally, through theuse of transponder-to-transponder communicationsachieved via backscatter waves, each transponder isable to provide data indicative of other transponders thatare positioned proximate the transponder providing thebackscatter signal.[0007] The ability to determine the relative physical re-lationship between passive wireless transducers opensa new realm of possibilities for use of such transpondersin commercial, security, and packaging applications. Inone example implementation, a number of frangible, pas-sive, wireless transponders may be embedded or other-wise incorporated into a substrate such as paper or pol-ymeric tape used to seal packages for shipment. In an-other example, the physical displacement of the passivewireless transponders that occurs with removal or dis-ruption of the substrate may result in an inability for thetags to communicate with one another via backscatterwaves. The frangible transponders are positioned in thesubstrate at a distance permitting neighboring trans-ponders to "communicate" when illuminated by an inter-rogator carrier wave. In at least some instances, the in-terrogator carrier wave may include one or more com-mands that are backscatter communicated by eachtransponder to a neighboring transponder. In some in-

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stances, such transmission of the command betweenneighboring transponders occurs until the originatingtransponder is reached to provide an indication of sub-strate continuity. In other instances, such transmissionof the command between neighboring transponders oc-curs until a defined endpoint is reached (i.e., from a trans-ponder positioned at the first end of the substrate to atransponder positioned at the second end of the sub-strate). Advantageously, once attached to a package orsimilar enclosure, any attempt to remove the substratefrom the package will result in the destruction of one ormore frangible transponders. Destruction of a transpond-er will interrupt the backscatter communication betweenneighboring tags, thereby providing an indication of sub-strate discontinuity that may signal tampering with thepackage has occurred.[0008] In another example, each item included in a col-lection of ordered items (e.g., library books, archiverecords) may include a passive wireless transponder.Data indicative of the identity of each transponder’sneighbor(s) is stored within a nontransitory storage cou-pled to each respective transponder. Upon receipt of aninterrogation carrier wave, each transponder can back-scatter communicate with neighboring transponders toascertain their identity. Improperly filed items, detectedwhen transponders are unable to verify the identity oftheir neighboring transponders, are advantageously lo-cated and data indicative of the improperly positioneditems communicated to a device such as an RFID inter-rogator.[0009] In yet another example, each item in a two-di-mensional matrix (e.g., shoeboxes on a store shelf) mayinclude a passive wireless transponder. Upon receipt ofan interrogation carrier wave, each transponder canbackscatter communicate with neighboring transpond-ers to ascertain their identity. The identity of each trans-ponder, along with the identities of neighboring trans-ponders detected via backscatter communication istransmitted to an external device such as an RFID inter-rogator or a backend or host processor-based system.In at least some instances, the external device can com-pile a map showing the relative location of each trans-ponder with respect to other transponders.[0010] A method to determine the relative positions ofa number of passive wireless transponders may be sum-marized as including receiving information from each ofa plurality of passive wireless transponders, the informa-tion received from each of the passive wireless trans-ponders identifying at least one neighboring passivewireless transponder that is spatially proximate the re-spective passive wireless transponder from which theinformation is received; and determining a relative posi-tion of the passive wireless transponders with respect toone another based at least in part on the information re-ceived from the passive wireless transponders.[0011] Receiving information may include receiving in-formation by an interrogator system, and may further in-clude providing an interrogation carrier wave to the plu-

rality of passive wireless transponders which causes atleast some of the plurality of passive wireless devices tocommunicate with one another. Determining a relativeposition of the passive wireless transponders with re-spect to one another based at least in part on the infor-mation received from the passive wireless transpondersmay include determining the relative position of the pas-sive wireless transponders with respect to one anotherby a host processor-based system, the host processor-based system remotely located with respect to the inter-rogator system. Determining a relative position of thepassive wireless transponders with respect to one an-other based at least in part on the information receivedfrom the passive wireless transponders may include de-termining the relative position of the passive wirelesstransponders with respect to one another by the interro-gator system. Determining a relative position of the pas-sive wireless transponders with respect to one anotherbased at least in part on the information received fromthe passive wireless transponders may include\ deter-mining the relative position of the passive wireless trans-ponders with respect to one another by at least one ofthe passive wireless transponders. Providing an interro-gation carrier wave may include providing by the interro-gator system an interrogation carrier wave having a sig-nal including data modulated thereon. Providing by theinterrogator system an interrogation carrier wave havinga signal including data modulated thereon may includeproviding by the interrogator system an interrogation car-rier wave having a signal modulated thereon, the signalincluding data representative of at least one command.[0012] The plurality of wireless transponders may belocated about an enclosure and may further include de-termining based on the received information whethertampering with the enclosure has occurred; and causingan indication of tampering to be provided in response toa determination that tampering with the enclosure hasoccurred.[0013] The plurality of wireless transponders may belocated about packaging, and may further include deter-mining based on the received information whether tam-pering with the packaging has occurred; and causing anindication of tampering to be provided in response to adetermination that that tampering with the packaging hasoccurred.[0014] The plurality of wireless transponders may belocated across at least one flap of a packaging and mayfurther include determining based on the received infor-mation whether tampering with the packaging has oc-curred; and causing an indication of tampering to be pro-vided in response to a determination that that tamperingwith the packaging has occurred.[0015] The method may further include determining ifany of the passive wireless transponders are out of orderwith respect to in a defined array. Determining a relativeposition of the passive wireless transponders with re-spect to one another based at least in part on the infor-mation received from the passive wireless transponders

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may include generating a virtual map of the plurality ofpassive wireless transponders, the virtual map which rep-resents relative spatial positions of the passive wirelesstransponders with respect to one another.[0016] An interrogator system to determine the relativepositions of a plurality of passive wireless transpondersmay be summarized as including a transceiver to providean interrogation carrier wave; a processor communicablycoupled to the transceiver; and a processor-readablenontransitory storage medium including machine execut-able instructions that when executed by the processor,cause the processor to: receive information from each ofa plurality of passive wireless transponders that identifiesat least one neighboring passive wireless transponderthat is spatially proximate the respective passive wirelesstransponder from which the information is received; anddetermine a relative position of the passive wirelesstransponders with respect to one another based at leastin part on the information received from the passive wire-less transponders.[0017] The machine executable instructions that causethe processor to receive information from each of a plu-rality of passive wireless transponders may further causethe processor to: receive information from each of a plu-rality of passive wireless transponders located about anenclosure; determine based on the received informationwhether tampering with the enclosure has occurred; andresponsive to a determination that tampering with theenclosure has occurred, generate a human perceptibleoutput indicative that tampering with the enclosure hasoccurred.[0018] The machine executable instructions that causethe processor to receive information from each of a plu-rality of passive wireless transponders may further causethe processor to: receive information from each of a plu-rality of passive wireless transponders located about anpackage; determine based on the received informationwhether tampering with the package has occurred; andresponsive to a determination that tampering with thepackage has occurred, generate a human perceptibleoutput indicative that tampering with the package hasoccurred.[0019] The machine executable instructions that causethe processor to receive information from each of a plu-rality of passive wireless transponders may further causethe processor to: receive information from each of a plu-rality of passive wireless transponders located across atleast one packaging flap; determine based on the re-ceived information whether tampering with the packagehas occurred; and responsive to a determination thattampering with the package has occurred, generate ahuman perceptible output indicative that tampering withthe package has occurred.[0020] The machine executable instructions may fur-ther cause the processor to: compare information re-ceived information from each of a plurality of passivewireless transponders with stored data indicative of a de-fined array; and determine whether any of the passive

wireless transponders are out of order with respect to thedefined array.[0021] The machine executable instructions may fur-ther cause the processor to: generate a virtual map ofthe plurality of passive wireless transponders, the virtualmap representative of the relative spatial positions of thepassive wireless transponders with respect to each other.[0022] A method of operation of a passive wirelesstransponder may be summarized as including in re-sponse to receipt of an interrogation carrier wave, receiv-ing information from each of a number of other passivewireless transponders by the passive wireless trans-ponder; and transmitting information identifying at leastone of the other passive wireless transponders as aneighboring passive wireless transponder that is spatiallyproximate the passive wireless transponder from whichthe information is received.[0023] The method may further include categorizing atleast one of the other passive wireless transponders asa neighboring passive wireless transponder. Categoriz-ing at least one of the other passive wireless transpond-ers as a neighboring passive wireless transponder mayinclude categorizing at least one of the other passivewireless transponders as a neighboring passive wirelesstransponder based at least in part on a signal strengthof a signal received by the passive wireless transponderfrom one of the other passive wireless transponders. Cat-egorizing at least one of the other passive wireless trans-ponders as a neighboring passive wireless transpondermay include categorizing at least one of the other passivewireless transponders as a neighboring passive wirelesstransponder based at least in part on a signal strengthof a signal received by the passive wireless transponderfrom one of the other passive wireless transponders rel-ative to a signal strength of a signal received by the pas-sive wireless transponder from other ones of the otherpassive wireless transponders. Categorizing at least oneof the other passive wireless transponders as a neigh-boring passive wireless transponder may include cate-gorizing at least one of the other passive wireless trans-ponders as a neighboring passive wireless transponderbased at least in part on a time-of-flight of a signal re-ceived by the passive wireless transponder from one ofthe other passive wireless transponders. Categorizing atleast one of the other passive wireless transponders asa neighboring passive wireless transponder may includecategorizing at least one of the other passive wirelesstransponders as a neighboring passive wireless trans-ponder based at least in part on a time-of-flight of a signalreceived by the passive wireless transponder from oneof the other passive wireless transponders relative to atime-of-flight of a signal received by the passive wirelesstransponder from other ones of the other passive wirelesstransponders. Transmitting information identifying atleast one of the other passive wireless transponders asa neighboring passive wireless transponder may includebackscattering an interrogation carrier wave receivedfrom an interrogator system with the information encoded

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in the backscattered signal.[0024] A passive wireless transponder may be sum-marized as including an antenna; a controller communi-cably coupled to the antenna; and a nontransitory storagemedia communicably coupled to the controller includingmachine executable instructions that cause the controllerto: receive information from each of a number of otherpassive wireless transponders responsive to the receiptof an interrogation carrier wave by the antenna; andtransmit information that identifies at least one of the oth-er passive wireless transponders as a spatially proxi-mate, neighboring, passive wireless transponder.[0025] The machine-executable instructions that maycause the controller to transmit information that identifiesat least one of the other passive wireless transpondersas a spatially proximate, neighboring, passive wirelesstransponder may further cause the controller to: identifyat least one of the other passive wireless transpondersas a spatially proximate, neighboring, passive wirelesstransponder based on a received signal strength repre-sentative of a signal received from each of the other pas-sive wireless transponders; and transmit information thatidentifies at least one of the other passive wireless trans-ponders as a spatially proximate, neighboring, passivewireless transponder.[0026] The machine-executable instructions that maycause the controller to transmit information that identifiesat least one of the other passive wireless transpondersas a spatially proximate, neighboring, passive wirelesstransponder may further cause the controller to: comparea signal strength representative of a signal received fromone of the other passive wireless transponders with sig-nal strengths of signals received from other ones of theother passive wireless transponders; identify at least oneof the other passive wireless transponders as a spatiallyproximate, neighboring, passive wireless transponderbased on the compared signal strengths; and transmitinformation that identifies at least one of the other passivewireless transponders as a spatially proximate, neigh-boring, passive wireless transponder.[0027] The machine-executable instructions that maycause the controller to transmit information that identifiesat least one of the other passive wireless transpondersas a spatially proximate, neighboring, passive wirelesstransponder may further cause the controller to: identifyat least one of the other passive wireless transpondersas a spatially proximate, neighboring, passive wirelesstransponder based on a time-of-flight parameter of a sig-nal received from each of the other passive wirelesstransponders; and transmit information that identifies atleast one of the other passive wireless transponders asa spatially proximate, neighboring, passive wirelesstransponder.[0028] The machine-executable instructions that maycause the controller to transmit information that identifiesat least one of the other passive wireless transpondersas a spatially proximate, neighboring, passive wirelesstransponder may further cause the controller to: compare

a time-of-flight parameter of a signal received from oneof the other passive wireless transponders with time-of-flight parameters of signals received from other ones ofthe other passive wireless transponders; identify at leastone of the other passive wireless transponders as a spa-tially proximate, neighboring, passive wireless trans-ponder based on the compared times-of-flight; and trans-mit information that identifies at least one of the otherpassive wireless transponders as a spatially proximate,neighboring, passive wireless transponder.[0029] A method of operation may be summarized asincluding providing an interrogation carrier wave to theplurality of passive wireless transponders, the interroga-tion carrier wave which causes the passive wirelesstransponders to transmit to a neighboring passive wire-less transponder in a defined order; receiving informationfrom at least one of the plurality of passive wireless trans-ponders, the information received from the at least oneof the plurality of passive wireless transponders indica-tive of whether each of the passive wireless transpondershave successfully transmitted to a respective neighbor-ing passive wireless transponder in the defined order;and determining based on the received informationwhether each of the passive wireless transponders havesuccessfully transmitted to a respective neighboring pas-sive wireless transponder in the defined order. Providingan interrogation carrier wave to the plurality of passivewireless transponders may include providing an interro-gation carrier wave which causes the passive wirelesstransponders to successively pass a command along adefined sequence of the passive wireless transponders.Providing an interrogation carrier wave to the plurality ofpassive wireless transponders may include providing aninterrogation carrier wave which causes the passive wire-less transponders to successively pass a commandalong a defined sequence of the passive wireless trans-ponders in a closed loop starting from and ending with afirst one of the passive wireless transponders. Providingan interrogation carrier wave to the plurality of passivewireless transponders may include providing an interro-gation carrier wave which causes the passive wirelesstransponders to successively pass a command along adefined sequence of the passive wireless transpondersin a first direction from a first one to a last one of thepassive wireless transponders in the defined sequence.Providing an interrogation carrier wave to the plurality ofpassive wireless transponders may include providing aninterrogation carrier wave signal which causes the pas-sive wireless transponders to successively pass a com-mand along a defined sequence of the passive wirelesstransponders in a first direction from a first one to a lastone of the passive wireless transponders in a first definedsequence and then in a second direction from the lastone to the first one of the passive wireless transpondersin a second defined sequence. Providing an interrogationcarrier wave to the plurality of passive wireless trans-ponders may includes providing an interrogation carrierwave which causes the passive wireless transponders

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to successively pass information along a defined se-quence of the passive wireless transponders. Providingan interrogation carrier wave to the plurality of passivewireless transponders may include providing an interro-gation carrier wave which causes the passive wirelesstransponders to successively pass information along adefined sequence of the passive wireless transpondersin a closed loop starting from and ending with a first oneof the passive transponders. Providing an interrogationcarrier wave to the plurality of passive wireless trans-ponders may include providing an interrogation carrierwave which causes the passive wireless transpondersto successively pass information along a defined se-quence of the passive wireless transponders in a firstdirection from a first one to a last one of the passive wire-less transponders in the defined sequence. Providing aninterrogation carrier wave to the plurality of passive wire-less transponders may include providing an interrogationcarrier wave which causes the passive wireless trans-ponders to successively pass information along a definedsequence of the passive wireless transponders in a firstdirection from a first one to a last one of the passive wire-less transponders in a first defined sequence and thenin a second direction from the last one to the first one ofthe passive wireless transponders in a second definedsequence. The interrogation carrier wave may causesthe passive wireless transponders to each retrieve froma memory of the passive wireless transponder a uniqueidentifier for at least one respective neighboring passivewireless transponder.[0030] The plurality of wireless transponders may belocated about an enclosure and may further include de-termining based on the received information whethertampering with the enclosure has occurred; and causingan indication of tampering to be provided in response toa determination that tampering with the enclosure hasoccurred.[0031] The plurality of wireless transponders may belocated about packaging and may further include deter-mining based on the received information whether tam-pering with the packaging has occurred; and causing anindication of tampering to be provided in response to adetermination that tampering with the packaging has oc-curred.[0032] The plurality of wireless transponders may belocated across at least one flap of a packaging and mayfurther include determining based on the received infor-mation whether tampering with the packaging has oc-curred; and causing an indication of tampering to be pro-vided in response to a determination that tampering withthe packaging has occurred.[0033] An interrogator system to determine the relativepositions of a plurality of passive wireless transpondersmay be summarized as including a transceiver to providean interrogation carrier wave; a processor communicablycoupled to the transceiver; and a processor-readablenontransitory storage medium including machine execut-able instructions that when executed by the processor,

cause the processor to: transmit an interrogation carrierwave to each of a plurality of passive wireless transpond-ers that causes each of the plurality of wireless trans-ponders to transmit a backscatter signal to a neighboringpassive wireless transponder in a defined order; receiveinformation from at least one of the plurality of passivewireless transponders, the information received from theat least one of the plurality of passive wireless transpond-ers indicative of whether each of the passive wirelesstransponders have successfully transmitted to a respec-tive neighboring passive wireless transponder in the de-fined order; and determine based on the received infor-mation whether each of the passive wireless transpond-ers have successfully transmitted to a respective neigh-boring passive wireless transponder in the defined order.[0034] The machine-executable instructions that maycause the processor to transmit an interrogation carrierwave to each of a plurality of passive wireless transpond-ers may further cause the processor to: transmit an in-terrogation carrier wave to each of a plurality of passivewireless transponders that causes each of the pluralityof wireless transponders to successively transmit a com-mand using a backscatter signal to a defined sequenceof passive wireless transponders.[0035] The machine-executable instructions that maycause the processor to transmit an interrogation carrierwave to each of a plurality of passive wireless transpond-ers may further cause the processor to: transmit an in-terrogation carrier wave to each of a plurality of passivewireless transponders that causes each of the pluralityof wireless transponders to successively transmit a com-mand using a backscatter signal to a defined sequenceof passive wireless transponders in a closed loop, start-ing and ending with a first one of the passive wirelesstransponders.[0036] The machine-executable instructions that maycause the processor to transmit an interrogation carrierwave to each of a plurality of passive wireless transpond-ers may further cause the processor to: transmit an in-terrogation carrier wave to each of a plurality of passivewireless transponders that causes each of the pluralityof wireless transponders to successively transmit a com-mand using a backscatter signal to a defined sequenceof passive wireless transponders in a first direction froma first one to a last one of the passive wireless transpond-ers in a defined sequence.[0037] The machine-executable instructions that maycause the processor to transmit an interrogation carrierwave to each of a plurality of passive wireless transpond-ers may further cause the processor to: transmit an in-terrogation carrier wave to each of a plurality of passivewireless transponders that causes each of the pluralityof wireless transponders to successively transmit a com-mand using a backscatter signal to a defined sequenceof passive wireless transponders in a first direction froma first one to a last one of the passive wireless transpond-ers in a first defined sequence and then in a second di-rection from the last one to the first one of the passive

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wireless transponders in a second defined sequence.[0038] The machine executable instructions that maycause the processor to receive information from each ofa plurality of passive wireless transponders further causethe processor to: receive information from each of a plu-rality of passive wireless transponders located about anenclosure; determine based on the received informationwhether tampering with the enclosure has occurred; andresponsive to a determination that tampering with theenclosure has occurred, generate a human perceptibleoutput indicative that tampering with the enclosure hasoccurred.[0039] The machine executable instructions that maycause the processor to receive information from each ofa plurality of passive wireless transponders further causethe processor to: receive information from each of a plu-rality of passive wireless transponders located across atleast one packaging flap; determine based on the re-ceived information whether tampering with the packagehas occurred; and responsive to a determination thattampering with the package has occurred, generate ahuman perceptible output indicative that tampering withthe package has occurred.[0040] A method of operation of a first passive wirelesstransponder may be summarized as including receivingan interrogation carrier wave by the first passive wirelesstransponder; in response to receipt of the interrogationcarrier wave, transmitting a first signal by the first passivewireless transponder to at least one neighboring passivewireless transponder; and receiving a second signal fromat least one neighboring passive wireless transponderby the first passive wireless transponder, the receivedsecond signal indicative of whether each of a plurality ofpassive wireless transponders, which includes at leastthe first and at least the neighboring passive wirelesstransponders, have successfully transmitted to one an-other in a defined order.[0041] The method may further include determiningwhether each of the passive wireless transponders havesuccessfully transmitted to a respective neighboring pas-sive wireless transponder in the defined order based onthe received second signal.[0042] The method may further include determining byat least one circuit of the first passive wireless transpond-er whether each of the passive wireless transpondershave successfully transmitted to a respective neighbor-ing passive wireless transponder in the defined orderbased at least in part on the received second signal.[0043] The method may further include transmitting in-formation to an interrogation system by the first passivewireless transponder, the information indicative of wheth-er each of the plurality of passive wireless transpondershave successfully transmitted to one another in a definedorder. Transmitting a first signal by the first passive wire-less transponder may include transmitting a first signalwhich includes at least one unique identifier that uniquelyidentifies a respective neighboring passive wirelesstransponder. Transmitting a first signal by the first pas-

sive wireless transponder may include transmitting a firstsignal which omits any unique identifiers that uniquelyidentify any neighboring passive wireless transponders.Transmitting a first signal by the first passive wirelesstransponder may include transmitting a first signal whichincludes a unique identifier that uniquely identifies thefirst passive wireless transponder.[0044] A passive wireless transponder may be sum-marized as including an antenna; a controller communi-cably coupled to the antenna; and a nontransitory storagemedia communicably coupled to the controller includingmachine executable instructions that cause the controllerto: transmit a first signal to at least one neighboring pas-sive wireless transponder responsive to receipt of an in-terrogation carrier wave by the antenna; and receive asecond signal from at least one neighboring passive wire-less transponder, the received second signal indicativeof whether each of a plurality of passive wireless trans-ponders have successfully transmitted a defined signalto one another in a defined order.[0045] The machine-executable instructions may fur-ther cause the controller to: determine whether each ofthe passive wireless transponders have successfullytransmitted to a respective neighboring passive wirelesstransponder in the defined order based on the receivedsecond signal.[0046] The machine-executable instructions may fur-ther cause the controller to: transmit a signal to an inter-rogation system, the signal including indicative of wheth-er each of the plurality of passive wireless transpondershave successfully transmitted to one another in a definedorder.[0047] The machine-executable instructions that maycause the controller to transmit a first signal to at leastone neighboring passive wireless transponder respon-sive to receipt of an interrogation carrier wave by theantenna may further cause the controller to: transmit afirst signal which includes at least one unique identifierthat uniquely identifies a respective neighboring passivewireless transponder.[0048] The machine-executable instructions that maycause the controller to transmit a first signal to at leastone neighboring passive wireless transponder respon-sive to receipt of an interrogation carrier wave by theantenna may further cause the controller to: transmit afirst signal which omits any unique identifiers that unique-ly identify any neighboring passive wireless transpond-ers. The machine-executable instructions that maycause the controller to transmit a first signal to at leastone neighboring passive wireless transponder respon-sive to receipt of an interrogation carrier wave by theantenna may further cause the controller to: transmit afirst signal which includes a unique identifier that uniquelyidentifies the passive wireless transponder.[0049] A method of operation may be summarized asincluding repeatedly providing an interrogation carrierwave to the plurality of passive wireless transponders,the interrogation carrier wave which causes the passive

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wireless transponders to transmit to at least one neigh-boring passive wireless transponder; receiving informa-tion from at least one of the plurality of passive wirelesstransponders, the received information indicative ofwhether each of the passive wireless transponders havesuccessfully transmitted to at least one respective neigh-boring passive wireless transponder in response to eachinterrogation carrier wave; and determining whethereach of the passive wireless transponders have success-fully transmitted to at least one respective neighboringpassive wireless transponder in response to each inter-rogation carrier wave. The passive wireless transpond-ers may be grouped in pairs, each passive wireless trans-ponder of a respective one of the pairs opposed to oneanother across an edge of a selectively openable pas-sage, and receiving information from at least one of theplurality of passive wireless transponders, the receivedinformation indicative of whether each of the passivewireless transponders have successfully transmitted toat least one respective neighboring passive wirelesstransponder in response to each interrogation signal in-cludes receiving information form at least one passivewireless transponder of each pair, the received informa-tion indicative of whether the passive wireless transpond-ers of the respective pair successively communicatedwith one another. The passive wireless transpondersmay be grouped in pairs, each passive wireless trans-ponder of a respective one of the pairs opposed to oneanother across an edge of a selectively openable pas-sage, and repeatedly providing an interrogation signal tothe plurality of passive wireless transponders includesproviding the interrogation signals which, for each paircause at least a first passive wireless transponder of apair to transmit an addressed signal to a second passivewireless transponder of the pair. The passive wirelesstransponders may be grouped in pairs, each passivewireless transponder of a respective one of the pairs op-posed to one another across an edge of at least one flap,and determining whether each of the passive wirelesstransponders have successfully transmitted to at leastone respective neighboring passive wireless transpond-er in response to each interrogation signal includes, foreach pair determining whether at least one of the passivewireless transponders of the pair has successfully trans-mitted to the other one of the passive wireless transpond-ers of the pair in response to each interrogation signal.The passive wireless transponders may be grouped inpairs, each passive wireless transponder of a respectiveone of the pairs opposed to one another across an edgeof at least one flap, and determining whether each of thepassive wireless transponders have successfully trans-mitted to at least one respective neighboring passivewireless transponder in response to each interrogationsignal includes, for each pair determining whether at leastone of the passive wireless transponders of the pair hassuccessfully transmitted to the other one of the passivewireless transponders of the pair in response to eachinterrogation signal which encodes a defined command.

The passive wireless transponders may be grouped inpairs, each passive wireless transponder of a respectiveone of the pairs opposed to one another across an edgeof a selectively openable passage, the pairs spaced fromone another such that a nearest neighbor of anyone ofthe passive wireless transponders is the other wirelesspassive transponder of the pair, and determining whethereach of the passive wireless transponders have success-fully transmitted to at least one respective neighboringpassive wireless transponder in response to each inter-rogation signal includes, for each pair determining wheth-er at least one of the passive wireless transponders ofthe pair has successfully transmitted to the other one ofthe passive wireless transponders of the pair in responseto each interrogation signal. Repeatedly providing an in-terrogation signal to the plurality of passive wirelesstransponders, the interrogation signal which may causethe passive wireless transponders to transmit to at leastone neighboring passive wireless transponder may in-clude repeatedly providing the interrogation signal froman interrogator system. Receiving information from atleast one of the plurality of passive wireless transpondersmay include receiving the information by the interrogatorsystem and determining whether each of the passivewireless transponders have successfully transmitted toat least one respective neighboring passive wirelesstransponder in response to each interrogation signal in-cludes determining by the interrogator system whethereach of the passive wireless transponders have success-fully transmitted to at least one respective neighboringpassive wireless transponder. Receiving informationfrom at least one of the plurality of passive wireless trans-ponders may include receiving the information by a hostprocessor-based system from the interrogator systemand determining whether each of the passive wirelesstransponders have successfully transmitted to at leastone respective neighboring passive wireless transpond-er in response to each interrogation signal includes de-termining by the host processor-based system whethereach of the passive wireless transponders have success-fully transmitted to at least one respective neighboringpassive wireless transponder.[0050] An interrogator system to determine the relativepositions of a plurality of passive wireless transpondersmay be summarized as including a transceiver to providean interrogation carrier wave; a processor communicablycoupled to the transceiver; and a processor-readablenontransitory storage medium including machine execut-able instructions that when executed by the processor,cause the processor to: repeatedly transmit an interro-gation carrier wave to each of a plurality of passive wire-less transponders that causes each of the passive wire-less transponders to transmit a backscatter signal to atleast one neighboring passive wireless transponder; re-ceive information from at least one of the plurality of pas-sive wireless transponders, the information receivedfrom the at least one of the plurality of passive wirelesstransponders indicative of whether each of the passive

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wireless transponders have successfully transmitted toat least one respective neighboring passive wirelesstransponder in response to each received interrogationcarrier wave; and determine based on the received in-formation whether each of the passive wireless trans-ponders have successfully transmitted to at least onerespective neighboring passive wireless transponder inresponse to each received interrogation carrier wave.[0051] The machine readable instructions that maycause the processor to repeatedly transmit an interroga-tion carrier wave to each of a plurality of passive wirelesstransponders, may further cause the processor to: re-peatedly transmit an interrogation carrier wave togrouped pairs of passive wireless transponders, eachpassive wireless transponder of a respective one of thepairs positioned in opposition to one another across anedge of a selectively openable passage; and wherein themachine readable instructions that cause the processorto receive information from at least one of the plurality ofpassive wireless transponders, further cause the at leastone processor to: receive information from at least oneof the plurality of passive wireless transponders, the re-ceived information indicative of whether each of the pas-sive wireless transponders have successfully transmittedto at least one respective neighboring passive wirelesstransponder in response to each interrogation signal in-cludes receiving information form at least one passivewireless transponder of each pair, the received informa-tion indicative of whether the passive wireless transpond-ers of the respective pair successively communicatedwith one another.[0052] The machine readable instructions that maycause the processor to repeatedly transmit an interroga-tion carrier wave to each of a plurality of passive wirelesstransponders, may further cause the processor to: re-peatedly transmit an interrogation carrier wave togrouped pairs of passive wireless transponders, eachpassive wireless transponder of a respective one of thepairs positioned in opposition to one another across anedge of a selectively openable passage; and wherein themachine readable instructions that cause the processorto determine based on the received information whethereach of the passive wireless transponders have success-fully transmitted to at least one respective neighboringpassive wireless transponder in response to each re-ceived interrogation carrier wave, further cause the atleast one processor to: determine for each pair of passivewireless transponders whether at least one of the passivewireless transponders forming the pair has successfullytransmitted to the other one of the passive wireless trans-ponders forming the pair in response to each interroga-tion signal that includes data indicative of an encodeddefined command.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0053] In the drawings, identical reference numbers

identify similar elements or acts. The sizes and relativepositions of elements in the drawings are not necessarilydrawn to scale. For example, the shapes of various ele-ments and angles are not drawn to scale, and some ofthese elements are arbitrarily enlarged and positioned toimprove drawing legibility. Further, the particular shapesof the elements as drawn, are not intended to conveyany information regarding the actual shape of the partic-ular elements, and have been solely selected for easeof recognition in the drawings.

Figure 1 is a schematic diagram illustrating an ex-ample system for providing backscatter communica-tion between each of a number of passive wirelesstransponders, according to one non-limiting illustrat-ed embodiment.Figure 2 is a schematic diagram illustrating an ex-ample substrate including a number of frangible pas-sive wireless transmitters able to backscatter com-municate with at least one other passive wirelesstransmitter in the presence of an interrogation carrierwave, according to one non-limiting illustrated em-bodiment.Figure 3 is a schematic diagram illustrating an ex-ample arrangement of ordered items each includinga passive wireless transmitter able to backscattercommunicate with at least one neighboring passivewireless transmitter in the presence of an interroga-tion carrier wave, according to one non-limiting illus-trated embodiment.Figure 4 is a schematic diagram illustrating an ex-ample arrangement of ordered items each includinga passive wireless transmitter able to backscattercommunicate with at least one neighboring passivewireless transmitter in the presence of an interroga-tion carrier wave, according to one non-limiting illus-trated embodiment.Figures 5A and 5B are schematic diagrams illustrat-ing an example arrangement of at least one pair ofpassive wireless transmitters arranged to detect theopening of an enclosure via backscatter communi-cation in the presence of an interrogation carrierwave, according to one non-limiting illustrated em-bodiment.Figure 6 is a high level logic flow diagram of an illus-trative method for determining the relative spatial re-lationship between passive wireless transponders,according to one non-limiting illustrated embodi-ment.Figure 7 is a high level logic flow diagram of an illus-trative method for determining the presence of anearest neighbor spatial relationship between pas-sive wireless transponders, according to one non-limiting illustrated embodiment.Figure 8 is a high level logic flow diagram of an illus-trative method for determining whether a defined sig-nal has passed sequentially through a number ofneighboring passive wireless transponders, accord-

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ing to one non-limiting illustrated embodiment.Figure 9 is a high level logic flow diagram of an illus-trative method for passing a defined signal sequen-tially through a number of neighboring passive wire-less transponders, according to one non-limiting il-lustrated embodiment.Figure 10 is a high level logic flow diagram of anillustrative method for determining whether neigh-boring passive wireless transponders are main-tained in a proximate spatial relationship over time,according to one non-limiting illustrated embodi-ment.

DETAILED DESCRIPTION

[0054] In the following description, certain specific de-tails are set forth in order to provide a thorough under-standing of various disclosed embodiments. However,one skilled in the relevant art will recognize that embod-iments may be practiced without one or more of thesespecific details, or with other methods, components, ma-terials, etc. Communications systems and protocols thatare well known to those of skill in the communicationsarts or are readily available in the form of standards orsimilar guidance documents have not been shown or de-scribed in detail to avoid unnecessarily obscuring de-scriptions of the embodiments. Additionally, time-of-flight, time-of-arrival, or differential time-of-arrival basedposition or location determination methods that are wellknown to those of skill in the communications arts havenot been shown or described in detail herein. Addition-ally, detailed specifications of well known electronic com-ponents such as passive radio frequency identification("RFID") transducers, RFID interrogators, radio frequen-cy receivers, radio frequency transceivers, processors,nontransitory storage or memory, communication and/orswitching protocols and the like have not been shown ordescribed in detail.[0055] Unless the context requires otherwise, through-out the specification and claims which follow, the word"comprise" and variations thereof, such as "comprises"and "comprising," are to be construed in an open, inclu-sive sense that is as "including, but not limited to."[0056] As used in this specification and the appendedclaims, the singular forms "a," "an," and "the" include plu-ral referents unless the content clearly dictates other-wise. It should also be noted that the term "or" is generallyemployed in its sense including "and/or" unless the con-tent clearly dictates otherwise. Reference throughout thisspecification to "one embodiment" or "an embodiment"means that a particular feature, structure or characteristicdescribed in connection with the embodiment is includedin at least one embodiment. Thus, the appearances ofthe phrases "in one embodiment" or "in an embodiment"in various places throughout this specification are notnecessarily all referring to the same embodiment. Fur-thermore, the particular features, structures, or charac-teristics may be combined in any suitable manner in one

or more embodiments.[0057] The headings and Abstract of the Disclosureprovided herein are for convenience only and do not in-terpret the scope or meaning of the embodiments.[0058] Figure 1 shows an illustrative system 100 forproviding backscatter waves 102 by any number of pas-sive wireless transducers 104 responsive to illuminationby an interrogation carrier wave 106. Any number of pas-sive wireless transducers 104a-104n (collectively "trans-ducers 104") are illuminated by the interrogation carrierwave 106 generated by a radio frequency generator 108such as a radio frequency identification ("RFID") interro-gator. Each transducer 104 includes at least an antenna,an RF front end, and a communicably coupled controlcircuit. Each transducer 104 may optionally include anontransitory storage media communicably coupled tothe antenna and/or control circuit. Upon receipt of theinterrogation carrier wave 106, the RF front end derivespower from the interrogation signal or carrier wave topower the transducer. The transducers 104 backscattera portion of the incident energy received via the interro-gation carrier wave 106 as backscatter wave 102. Thetransducer may impose data or information on the back-scatter wave. For example, the transducers may imposeor encode a unique identifier of the transponder on thebackscatter wave 102.[0059] For example, upon receiving an interrogationcarrier wave 106 generated by an RF transmitter 108, afirst transducer 104a generates a backscatter wave 102areceivable by any number of second transducers 104b-104n and optionally by a receiver 110 disposed in a read-er or interrogator device 112. Similarly, each of the sec-ond transducers 104b-104n also generates a respectivebackscatter wave 102b-102n. The backscatter waves102a-102n generated by each of the respective trans-ducers 104a-104n provides a communicable couplingbetween the transducers 104. Information, for exampledata indicative of a unique transducer identifier may thusbe exchanged between transducers 104. Using suchcommunications, each transducer 104 is able to detect,identify, or otherwise "learn" those other transducers 104with which a communicable coupling is possible (i.e.,those "other" transducers that can be considered "in theneighborhood" of, or neighboring, the respective trans-ducer).[0060] In some instances, each transducer 104n back-scatters a respective backscatter wave 102n having dataor information modulated thereon that is uniquely indic-ative of the respective transducer 104n backscatteringthe backscatter wave 102n. In at least some instances,a reader or interrogator 112 may receive the backscatterwave 102n containing the information. In other instances,the backscatter wave 102n may carry or otherwise in-clude modulated data representative of information,commands, and/or instructions communicated betweensome or all of the transducers 104a-104n, or betweensome or all of the transducers 104a-104n and a receiver110 in a reader or interrogator 112. In some instances,

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the backscatter wave 102 provided by each transducer104 may be limited in range or signal strength such thatonly a nearest neighbor transducer 104 is able to receivethe backscatter wave 102. In other instances, the back-scatter wave 102 provided by each transducer 104 maybe limited in range or signal strength such that only limitednumber of transducers (e.g., nearest and "next nearest"neighboring transducers) are able to receive the back-scatter wave 102.[0061] The transducers 104a-104n can include anytype or style of current or future developed passive, wire-less, radio frequency transducer. At its most basic, eachtransducer 104 includes at least an antenna and a com-municably coupled control circuit arranged or configuredsuch that a portion of an incident interrogation carrierwave 106 within a particular, defined, radio frequencyband causes the transducer 104 to generate a backscat-ter wave 102 which is broadcast via the antenna. As dis-cussed above, in some instances, one or more nontran-sitory storage media may be communicably coupled tothe control circuit. Such nontransitory storage media mayinclude volatile and/or non-volatile nontransitory memo-ry. Such storage media may be read-only or read/writecapable. Non-limiting examples of such memory include:read only memory (ROM), random access memory(RAM), dynamic random access memory (DRAM), elec-trically erasable programmable read only memory (EEP-ROM), and flash memory. In some instances, the storagemedia stores or otherwise retains data representative ofan identifier unique to the transducer 104. In at least someinstances, the data representative of the identifier uniqueto the transducer 104n may be modulated onto the back-scatter wave 102n by the control circuit.[0062] The control circuit may have the capability toexecute one or more machine executable instruction setsupon energization by a received interrogation carrierwave 106. In some instances, all or a portion of the ma-chine executable instruction set may be stored in the non-transitory storage coupled to the control circuit. In otherinstances, all or a portion of the machine executable in-struction set may be encoded or otherwise transportedas a signal modulated on the incoming interrogation car-rier wave 106. In yet other instances, all or a portion ofthe machine executable instruction set may be encodedor otherwise transported as a signal modulated on abackscatter wave 102n generated by another transducer104n. Where such a received backscatter wave 102ncontains modulated information including one or morecommands or machine executable instruction sets exe-cutable by a transducer control circuit, the control circuitin the recipient transducer 104 can extract and executethe received instructions.[0063] In addition to backscattering its own wave 102,some or all of the transducers 104 may also beneficiallyreceive backscatter waves generated by other, neigh-boring, transducers. Where the received backscatterwave carries modulated information identifying the trans-ducer 104n responsible for backscattering the wave,

such may be used by the recipient transducer 104 touniquely identify the neighboring transducer 104n. Eachtransducer 104 may use the properties or parameters ofeach received backscatter wave 102 to determine oneor more aspects of the relative spatial relationship be-tween the transducer 104 and the other, neighboring,transducer(s) 104 backscattering the received waves102. Such backscatter wave properties or parametersmay include, but are not limited to, received signalstrength ("RSSI") and/or time-of-flight ("TOF"). For ex-ample, transducer 1 04a may receive three backscatterwaves 102b, 102c, and 102d backscattered respectivelyby transducers 104b, 104c, and 1 04d. Based on thereceived signal strengths of the backscatter waves 102b,102c, and 1 02d, the transducer 104a can determinetransducer 104c is physically closest (i.e., highest RSSI),104d is physically next closest, and 104b is physicallymost distant (i.e., lowest RSSI).[0064] In another example, transducer 104a may back-scatter a wave 102a including defined information or datathat is received by transducers 104b, 104c, and 104d. Inturn, each of transducers 1 04b-1 04d backscatters arespective wave 102b, 102c, and 102d that includes in-formation or data identifiable to transponder 104a. Thebackscatter waves 102b, 102c, and 102d are receivedby transducer 104a at different times based on the rela-tive distance between transducer 104a and each of trans-ducers 104b, 104c, and 104d. Using the time-of-flight(i.e., the time required for the waves 102b, 102c, and102d backscattered by transducer 104a to return to trans-ducer 104a), transducer 104a determines the relative lo-cation and/or distance to each of the transducers 104b-104d.[0065] The transmitter 108 can include any device orsystem capable of generating an interrogation carrierwave 106 in the radio frequency or microwave frequencyspectrum. The interrogation carrier wave 106 is gener-ated at a frequency and phase sufficient to wirelesslytransfer or otherwise impart at least a portion of the en-ergy of the interrogation carrier wave 106 to one or moretransducers 104 via the RF front end of the transducer.In at least some instances, the transmitter 108 generatesonly the interrogation carrier wave without modulating orotherwise imposing data in the form of a signal on theinterrogation carrier wave 106. In other instances, thetransmitter 108 generates the interrogation carrier wave106 with information in the form of a signal modulated orotherwise imposed on the interrogation carrier wave 106.At least a portion of the information (e.g., data, com-mands, combinations of data and commands) that ismodulated on the interrogation carrier wave 106 is re-ceived by the transducers 104.[0066] The receiver 110 can include any device or sys-tem capable of receiving some or all of the waves 102a-102n backscattered by the transducers 104a-104n re-sponsive to the receipt of the interrogation carrier wave106 generated by the transmitter 108. In some instances,the transmitter 108 and the receiver 110 may be partially

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or completely integrated into a single device, i.e., a trans-ceiver. In some instances, the transmitter 108 and re-ceiver 110 may be positioned in a single handheld orportable device as exemplified by a handheld RFID in-terrogator. In other instance, the transmitter 108 and re-ceiver 110 may be discrete components located in dif-ferent locations, enclosures, or housings.[0067] The transmitter 108, the receiver 110, or boththe transmitter and the receiver may be communicablycoupled to a communications interface (not shown in Fig-ure 1) that enables communication with a host device120 via one or more intervening networks 122 (e.g., localarea network, enterprise network, wide area network,world-wide network, the Internet). In at least some in-stances, an interrogator 112 that includes both a trans-mitter 108 and a receiver 110 may be a dedicated devicehaving only limited processing speed or capability. Toperform processor intensive computations, the interro-gator 112 may communicate some or all of the data re-ceived from the transponders 1 04a-1 04n to the externalhost device 120. Such data may include for example,received data indicative of the identity of each transpond-er’s "nearest neighbor" transponder or received data in-dicative of the identity of transponder(s) located in a par-ticular transponder’s "neighborhood."[0068] The external host device 120 can include anysystem, devices, or combination of systems and devicescommunicably coupled to one or more communicationsinterfaces capable of bidirectionally exchanging data withthe interrogator 112. In some instances, external hostdevice 120 may be collocated with the interrogator 112.In other instances, the external host device 120 may belocated remote from the interrogator 112. In at least someinstances, one or more networks 122 communicably cou-pled a single external host device 120 to a plurality ofinterrogators 112. One or more nontransitory storage de-vices 124 may be included in or communicably coupledto the external host device 120. The nontransitory stor-age devices 124 may include one or more data stores ordatabases containing transponder identification datasuch as data indicative of unique identifiers associatedwith transponders 1 04a-1 04n.[0069] Figure 2 shows an illustrative system 200 inwhich an object or enclosure 202 (e.g., a cardboard ship-ping container or box) is sealed using an adhesivebacked substrate 204 containing a number of transduc-ers 104. In at least some implementations, each of thetransducers 1 04a-1 04n embedded in the substrate mayinclude one or more frangible or disruptable elementsthat are positioned upon and/or coupled to the substrate204 in a manner such that any attempt to remove or oth-erwise interrupt the continuity of the substrate 204 resultsin the physical and/or electrical destruction of at least oneof the transducers 104. In other instances, the substrate204 includes individual transducers 104a-104n posi-tioned in physical locations beyond which one or moretransducers 104 are unable to recognize or identify a"nearest neighbor." Such positioning may result in the

inability for at least one transducer to identify at least oneof its nearest neighbors in response to any disruption tothe continuity of the substrate (e.g., by cutting or tearing).Such substrates 204 are beneficial in deterring and de-tecting unauthorized access to the interior portion and/orcontents of the enclosure 202.[0070] In a first implementation, an interrogator 112receives backscatter waves 102a-1 02n, each providedby a respective transducer 104a-104n responsive to thereceipt of an interrogation signal 106. In such an imple-mentation, each of the backscatter waves 102a-102n in-cludes data indicative of the identity of the backscatteringtransducer. Upon receipt of the backscattered waves 102a-1 02n, the interrogator 112 and/or external host sys-tem 120 determines whether the data indicative of theidentities of the transducers 104a-104n providing thebackscattered waves 102a-102n compare favorably withstored data indicative of the identities of the transducers104a-104n included in the substrate 204 attached or oth-erwise coupled to the particular enclosure 202. In at leastsome instances, a nontransitory storage medium com-municably coupled to the interrogator 112 or the externalhost system 120. If the interrogator 112 or the externalhost system 120 determines a mismatch or if a numberof transducers 104 exceeding a defined threshold fail torespond, the interrogator 112 at least one human-per-ceptible output capable of alerting a system user of po-tential tampering with the enclosure 202 is provided.[0071] In a second implementation, the transducers104a-104n unidirectionally communicate via backscatterwaves 102a-102n data indicative of a command or similarinformation to each successive nearest neighbor trans-ducer until the command or signal transits a closed looppathway formed by the substrate 204. In at least someinstances, the substrate 204 extends continuouslyaround a perimeter of the enclosure 202. In such instanc-es, the interrogator 112 provides an interrogation carrierwave 106 to a first transducer 104a. Responsive to thereceipt of the interrogation carrier wave 106, the firsttransducer 104a backscatters a wave 102a that includesinstructions or other data that causes at least the "nearestneighbor" transducer 104b to backscatter a wave 102bthat includes similar instructions or data. Each subse-quent transducer 104x in turn, backscatters a one-way,"daisy-chain," type wave 102 x that include instructionsor data that cause the next "nearest neighbor" transducer104x+1 to backscatter a wave 102 x+1 containing theinstructions or data. Each transponder 104a-104n includ-ed in the substrate 204 thus passes the instructions ordata to the "nearest neighbor" transponder in a mannersimilar to a "token." The process is repeated sequentiallyuntil the backscatter wave 102n backscattered by the"last" transducer 104n in the substrate is received by thefirst transducer 104a, or until a damaged or displacedtransducer 104 prevents the backscattering of the wave102 that includes the instructions or data to a "nearestneighbor" transponder.[0072] In some instances, upon the return of the in-

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struction, command, or data to the first transponder 104a,the first transponder 104a backscatters a wave 102a re-ceivable by the interrogator 112 that includes data rep-resentative of a "SUCCESS" message. On the otherhand, upon a failure of the instruction, command, or datato return to the first transducer 1 04a within a definedtime interval, the first transponder 104a backscatters awave 102a receivable by the interrogator 112 that in-cludes data representative of a "FAILURE" message. Inturn, the interrogator 112 and/or a communicably coupledexternal host system 120 can provide at least one human-perceptible output capable of alerting a system user ofpotential tampering with the enclosure 202.[0073] In a third implementation, the transducers 104a-1 04n communicate via backscatter waves 1 02a-102n data indicative of instructions or data to each suc-cessive nearest neighbor transducer until the commandor data reaches the "end" of the pathway formed by anopen-ended (i.e., not forming a closed loop) substrate204. In at least some instances, the substrate 204 ex-tends only partially around a perimeter of the enclosure202. In such instances, the interrogator 112 provides aninterrogation carrier wave 106 to a first transducer 104a.Responsive to the receipt of the interrogation carrierwave 106, a first transducer 104a on the substrate 204generates a backscatter wave 102a that includes instruc-tions or other data that causes at least the "nearest neigh-bor" transducer 104b to backscatter a wave 1 02b thatincludes similar instructions or data. Each subsequenttransducer 104x in turn, backscatters a one-way, "daisy-chain," type wave 102 x that includes instructions causingthe next "nearest neighbor" transducer 104x+1 to back-scatter a wave 102 x+1 that includes the instructions ordata. Each transponder 104a-1 04n thus passes the in-structions or data to the "nearest neighbor" transponderin a manner similar to a "token."[0074] The process is repeated sequentially until thedefined "last" transducer 104n in the substrate 204 re-ceives the wave 102 backscattered by its "nearest neigh-bor." The "last" transponder 104n then backscatters awave 102n that includes data representative of the in-structions or data in a reverse direction back to the "near-est neighbor" providing the incoming backscatter wave102n. Each subsequent transducer 104x in turn, back-scatters a one-way, "daisy-chain," type wave 102 x thatincludes instructions causing the next "nearest neighbor"transducer 104x-1 to backscatter a wave 102 x-1 thatincludes the instructions or data to a nearestneighbor" transponder. Each transponder 1 04a-1 04nincluded in the substrate 204 thus passes on two occa-sions (i.e., once in a "forward" direction and once ina "reverse" direction) the instructions or data tothe "nearest neighbor" transponder in a manner similarto a "token." The process is repeated sequentially untilthe wave 102b backscattered by the second transducer104b in the substrate is received by the first transducer104a, or until a damaged or displaced transducer 104prevents the transmission of the backscatter wave 102

containing the instruction or data to a "nearestneighbor" transponder.[0075] In some instances, upon the return of the in-struction, command, or data to the first transponder 104a, the first transponder 104a backscatters a wave 102areceivable by the interrogator 112 that includes data rep-resentative of a "SUCCESS" message. On the otherhand, upon a failure of the instruction, command, or datato return to the first transducer 1 04a within a definedtime interval, the first transponder 104a backscatters awave 102a receivable by the interrogator 112 that in-cludes data representative of a "FAILURE" message. Inturn, the interrogator 112 and/or a communicably coupledexternal host system 120 can provide at least one human-perceptible output capable of alerting a system user ofpotential tampering with the enclosure 202.[0076] Thus, in some instances any alteration to or dis-ruption of the 15 substrate 204 causes the generation bythe interrogator 112 and/or external host system 120 ofan output indicative of tampering with the enclosure 202.In other instances, any alteration to or disruption of thesubstrate 204 interrupts the oneway or bidirectionaltransmission of a backscatter wave 102 that includes in-structions or data in a "daisy-chain" manner between"nearest neighbors" or proximately positioned passivewireless transponders 104. In either event, a failure of apassive wireless transponder 104 to respond with a back-scatter wave 102 provides the interrogator 112 with anindication that the substrate 204 includes damaged ordisplaced transponders 1 04a-1 04n that may indicateunauthorized tampering with the enclosure 202.[0077] Figure 3 shows an illustrative system 300 inwhich a number of objects 302a-302n (collectively "ob-jects 302"), each having a respective passive wirelesstransponder 104a-104n physically coupled thereto, arearranged in a defined order and illuminated by an inter-rogation carrier wave 106 provided by an interrogator112. Each of the passive wireless transponders 104a-104n can include a communicably coupled nontransitorystorage that includes data indicative of a unique identifierassociated with the respective transducer 104. Librarybooks, each containing a uniquely identifiable RFID tagthat are arranged in a defined order on a library shelfprovide but one simple example of such an arrangementof objects 302.[0078] In a first implementation, an interrogator 112receives waves 102a-102n, each backscattered by a re-spective passive wireless transponder 104a-104n re-sponsive to the receipt of an interrogation carrier wave106. In such an implementation, upon receipt of the in-terrogation carrier wave 106, each of the 10 passive wire-less transponders 102a-102n determines, using back-scatter waves 102 the identity of its "nearest neighbor"transponders 104. Thus, as depicted in Figure 3, trans-ponder 104b would receive backscatter waves 102a and102d and identify transponders 104a and 104d as "near-est neighbors." Similarly, transponder 104d would re-ceive backscatter waves 1 02b and 1 02c and identify

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transponders 104b and 104c as "nearest neighbors."Each passive wireless transponder would then backscat-ter a respective wave 102 that includes data indicativeof the identified "nearest neighbors." Continuing with theexample in Figure 3, transponder 1 04b would backscat-ter a signal that includes data indicating transponders104a and 104d as "nearest neighbors." Each of the trans-ponders 104a-104n would backscatter a respective wave1 02a-1 02n that includes similar "nearest neighbor" data.[0079] Upon receipt of the backscattered waves 102a-102n, the interrogator 112 and/or external host system120 determines whether the "nearest neighbor" data pro-vided by each of the transponders 104a-104n comparesfavorably with stored data indicative of the identities ofthe "nearest neighbor" transponders 104a-104n. Re-sponsive to the detection of discrepancies between the"nearest neighbor" data provided by each transponder104a-104n and the stored "nearest neighbor" data, theinterrogator 112 and/or the communicably coupled ex-ternal host system 120 generates one or more human-perceptible alerts.[0080] In a second implementation, each of the trans-ponders 1 04a-1 04n includes a nontransitory storagecontaining data indicative of the identified nearest neigh-bor transponders. Thus, for example, the nontransitorystorage in transponder 1 04b will contain data indicativeof the identity of nearest neighbor transponders 104a and104c. In response to a received interrogation carrier wave106, each transponder 1 04a-1 04n can determine theidentity of one or more "nearest neighbor" transponder104, for example by generating a backscatter wave 102and measuring the received signal strength of backscat-ter waves102 generated by other transponders. After de-termining the identity of one or more nearest neighbortransducers, each transducer 1 04a-1 04n compares theidentity of the determined nearest neighbor transponderwith the stored data indicative of the identity of nearestneighbor transponders.[0081] Responsive to the detection of discrepanciesbetween the determined nearest neighbor transponderdata and the stored nearest neighbor transponder data,a transponder 104 generates a backscatter wave 102that includes data indicative of the discrepancy. For ex-ample, if transponder 104b detects the identities of de-termined nearest neighbors do not include transponders104a and 104c, but instead include transponders 104aand 1 04d, transponder 104b can generate a backscattersignal 102b that includes an error message indicative ofthe discrepancy. In some instances, the error messageprovided by the transponder may include additional dataindicative of the determined nearest neighbors. Respon-sive to the receipt of a backscatter wave 102 includingdata indicative of a discrepancy, the interrogator 206 gen-erates one or more human perceptible alerts. If the trans-ponders 104a-104n provide determined nearest neigh-bor data to the interrogator 206, the interrogator may ad-vantageously identify those objects that are out of orderand may also advantageously identify the appropriate

locations of the misplaced objects.[0082] Figure 4 shows an illustrative system 400 inwhich a number of objects 402a-402n, each having arespective transducer 104a-104n physically coupledthereto, are arranged in a defined two-dimensional orderand illuminated by an interrogation carrier wave 106 pro-vided by an interrogator 206. Each of the transducers104a-104n can include a nontransitory storage that in-cludes data indicative of a unique identifier associatedwith the transducer 104. Shoe boxes, each containing auniquely identifiable RFID tag that are arranged in a de-fined two-dimensional matrix on store shelf provide a sim-ple example of such an arrangement of tagged objects.[0083] In operation, upon receipt of an interrogationcarrier wave 106, each of the transponders 104 can re-spond by firstly generating one or more backscatterwaves 102 to determine the identities of the nearestneighbor transponders, and secondly by communicatinga backscatter wave 102 including data indicative of theidentities of the determined nearest neighbor transpond-ers to the interrogator 206. Upon receiving informationindicative of the nearest neighbor transponders fromsome or all of the transponders 104, the interrogator 206determines the relative spatial relationship between atleast some of the objects 402a-402n based on the re-turned transponder data. In at least some instances, theinterrogator 206 provides the system user with a humanperceptible output (e.g., a display) of the relative spatialrelationship between the objects 402 based on the re-ceived transponder data. In some instances, the interro-gator 206 can advantageously provide the system userwith an indication of the location of a defined object, forexample the location of a specific shoe box on a wallcontaining a large number of physically similar or identi-cal shoe boxes.[0084] In a first implementation, in response to a re-ceived interrogation carrier wave 106, each transponder104a-104n determines the identity of one or more "near-est neighbor" transducers. In such instances, each trans-ponder 104a-104n generates at least one backscatterwave 102 and determines the identity of one or morenearest neighbor transponders, for example using theRSSI or TOF techniques previously discussed. After de-termining the identity of the one or more nearest neighbortransducers, each transducer 104a-104n generates abackscatter wave 1 02a-1 02n that includes data indica-tive of the determined nearest neighbor transducers. Forexample, transducer 402f will generate a backscatterwave 102d including data identifying transponders 104a,104b, 104c, 104e, 104g, 104i, 104j, and 1 04k as nearestneighbor transponders. Each transponder 1 04a-1 04nilluminated by the interrogation carrier wave 106 will per-form a similar determination of the identities of the near-est neighbor transponders and will return the nearestneighbor identities to the interrogator 206 as data includ-ed in a backscatter wave 102a-102n.[0085] The interrogator 206 combines the nearestneighbor identity data received from the transponders

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104a-104n to determine the relative spatial location, po-sition, or configuration of each transponder with respectto at least a portion of the other transponders. Identifyingthe relative location, position, or configuration of eachtransponder advantageously permits the interrogator todetermine the relative spatial location, position or config-uration of the object attached to each transponder. In atleast some instances, each of the transponders 104 mayperform all or a portion of the spatial location, position,or configuration determination and communicate suchdata to the interrogator 206 via data included in a back-scatter wave 106. The interrogator 206 may include oneor more output devices capable of providing the systemuser with an indication of the location of a particular trans-ponder and/or object relative to other transponders orobjects. Thus, for example, an interrogator may advan-tageously permit a warehouse worker to identify a par-ticular item located on a number of stacked shelves con-taining a large number of outwardly similar items.[0086] Figures 5A and 5B show an illustrative system500 in which an enclosure 502 includes one or more dis-placeable members 504a-504n for accessing an internalvolume or space located at least partially within the en-closure 502. Although only one is shown in Figures 5Aand 5B, transponder pairs 510, each including two trans-ponders 104a and 104b, are positioned proximate andacross an edge of a void providing access to the interiorof the enclosure. For example, in Figure 5A, a first trans-ponder 104a is positioned on a removable door 504 anda second transponder 104b is positioned on the enclo-sure 502 such that the transponders 104a and 104b areproximate when the door 504 is in a CLOSED positionand distal when the door 504 is in an OPEN position. Inanother example, in Figure 58, a first sensor 104a is po-sitioned on a first box flap 504a and a second sensor104b is positioned on a second box flax 504b such thatsensors 104a and 104b are proximate when the box flapsare in a CLOSED position and distal when either or bothof the box flaps are in an OPEN position.[0087] Figure 5A shows an interrogator 206 positionedinternal to the enclosure 502, Figure 5B shows an inter-rogator 206 positioned external to the enclosure 502. Ei-ther continuously or periodically, the interrogator 206generates an interrogation carrier wave 106. Upon re-ceiving the interrogation carrier wave 106, the transpond-ers 104a, 104b in each transponder pair 510 determinewhether they are positioned in a "nearest neighbor" orproximate position indicating the displaceable mem-ber(s) 504 is in a CLOSED position and the interior ofthe enclosure 502 is inaccessible. If the transponders104a, 104b are not positioned in a "nearest neighbor" orproximate position, the displaceable member(s) 504 arein an OPEN position and the interior of the enclosure 502is accessible. Thus, the position of the transponders104a, 104b can provide an indication of whether the en-closure 502 has been broached and the interior portionaccessed. One or both transponders 104a, 104b in eachtransponder pair 510 generate a backscatter wave 102a,

102b including data indicative of the nearest neighbortransponder (if any). The interrogator 206 receives thebackscatter signal and generates a signal indicative ofwhether the transponders are physically disposed prox-imate (i.e., in a "nearest neighbor" configuration) or distal(i.e., not in a "nearest neighbor" configuration). The in-terrogator 206 can store in a communicably coupled non-transitory storage data indicative of the relative spatialrelationship (i.e., proximate or distal) of the transponders104 in each transponder pair 510 attached to the enclo-sure 502. Storing data indicative of the relative spatialrelationship of the transponders 104 provides a historicalrecord indicative of an occurrence where the interior ofthe enclosure 502 was accessible. In some instances,the interrogator 206 can communicate an alert to one ormore external devices when a distal relative spatial re-lationship between the transponders 104 in one or moretransponder pairs 510 is detected.[0088] Figure 6 shows a high level method 600 of de-termining the relative spatial position of passive wirelesstransponders 104. A radio frequency generator 108 gen-erates an interrogation carrier wave 106 that illuminatesa number of passive wireless transponders 104a-104n.Responsive to the receipt of the interrogation carrierwave 106, each of the transponders 104a-104n gener-ates a respective backscatter wave 102a-102n. In turn,each of the transponders 104a-104n receives one ormore backscatter waves 102a-102n generated by othertransponders. In at least some instances, the transpond-ers 104a-104n use one or 15 more received backscatterwave properties (e.g., received signal strength or "RSSI")to determine the relative distance between the trans-ponder originating the backscatter wave and the trans-ponder receiving the backscatter wave. In other instanc-es, each transponder 104 broadcasts a backscatter waveto all or a portionof the remaining transponders and measures the time-of-flight of the backscatter signals provided by all or aportion of the remaining transponders to determine therelative distance between the transponder originating thebackscatter wave andthe transponder receiving the backscatter wave. Themethod 600 of determiningthe relative spatial position of a number of passive wire-less transponders commences at 602.[0089] At 604, an external host device 110 receivesfrom each of a number of passive wireless transponders104a-104n a respective backscatter signal 102a-102nthat includes information indicative of at least one neigh-boring passive wireless transponder spatially proximatethe respective passive wireless transponder 104a-104nfrom which the information is received. Such informationmay be modulated on, encoded in, or otherwise carriedby the backscatter wave 102 generated by the respectivetransponder 104.[0090] At 606, using the information indicative of theat least one neighboring passive wireless transponderthat is spatially proximate the respective passive wireless

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transponder 104a-104n from which the information is re-ceived, the external host device 110 determines the rel-ative position of the passive wireless transponders 104.For example, if transponder 104a returns a backscatterwave 102a that includes data indicative that transponder104c is spatially proximate, transponder 104c returns abackscatter wave 102c that includes data indicative thattransponder 104e is spatially proximate, and transponder104e returns a backscatter wave 102e that includes dataindicative that transponder 104g is spatially proximate,the external host device 110 can deduce the relative spa-tial position of the transponders is A-C-E-G. The method600 of determining the relative spatial position of anumber of passive wireless transponders concludes at608.[0091] Figure 7 shows a high level method 700 of de-termining by each of a number of passive wireless trans-ponders the relative spatial position of one or more otherspatially proximate passive wireless transponder(s) 104.Each of a number of passive wireless transponders 104a-104n receives an interrogation carrier wave 106. Re-sponsive to the receipt of the interrogation carrier wave106, each of the transponders 104a-104n generates arespective backscatter wave 102a-102n. Based on oneor more backscatter wave 102a-102n properties or pa-rameters, each of the transponders 104a-104n deter-mines which of the other passive wireless transpondersrepresent spatially proximate neighboring transponders.In some instances, received signal strength or "RSSI" isused by the transponder to determine which of the othertransponders is spatially proximate. In other instances,the time of flight of a backscatter wave returned by eachof the other transponders is used by the transponder todetermine which of the other transponders is spatiallyproximate. The method 700 of determining by each of anumber of passive wireless transponders the relativespatial position of one or more other spatially proximatepassive wireless transponder(s) commences at 702.[0092] At 704, each of a number of passive wirelesstransponders 104a- 104n receives an interrogation car-rier wave 106 provided by an RF generator 108. In re-sponse to receiving the interrogation carrier wave, eachtransponders 104a-104n generates a respective back-scatter wave 102a-102n. In at least some instances, thebackscatter wave 102 generated by each transponder104 may include information such as a unique identifierassigned to the respective transponder 104 generatingthe backscatter wave 102. Based on one or more prop-erties or parameters of each received backscatter wave102, each transponder 104 determines which of the otherpassive wireless transponders represent spatially prox-imate neighboring transponders. In some instances, re-ceived signal strength or "RSSI" is used by the trans-ponder to determine which of the other passive wirelesstransponders is spatially proximate. In other instances,the time of flight of a backscatter wave returned by eachof the other passive wireless transponders is used by thetransponder to determine which of the other passive wire-

less transponders is spatially proximate.[0093] At 706, each of the passive wireless transpond-ers 104a-104n generates a respective backscatter wave102a-102n that includes information indicative of theidentity of one or more other spatially proximate trans-ponders as determined at 704. The method 700 of de-termining by each of a number of passive wireless trans-ponders the relative spatial position of one or more otherspatially proximate passive wireless transponder(s) con-cludes at 708.[0094] Figure 8 shows a high level method 800 of de-termining interruptions in a known sequence of passivewireless transponders based on the sequential rebroad-cast of a backscatter wave from transponder to neigh-boring transponder in a defined sequence. A number ofpassive wireless transponders 104 may be physicallyconfigured such that neighboring transponders 104 arearranged in a known or defined order. For example, anumber of passive wireless transponders 104a-104nmay be coupled to a substrate in a known or definedorder. In at least some instances, the substrate may in-clude a material such as an adhesive backed tape usefulfor sealing packages prior to placing the packages intocommerce and the passive wireless transponders 104can include frangible passive wireless transponders thatare rendered inoperable if damaged (e.g., cut through)or if the substrate is forcibly removed from a surface (e.g.,torn off a package). Such an implementation advanta-geously provides an indication of tampering with the sub-strate and/or the item to which the substrate is attached.[0095] In some instances, the substrate 204 may beapplied about the continuously about a perimeter of apackage 202 such that the ends of the substrate "meet"or otherwise fall adjacent to each other. In such instanc-es, the passive wireless transponders 104a-104n dis-posed in the substrate form a "loop" about the packageand the backscatter waves 102 sequentially communi-cated by each transponder 104 to a neighboring trans-ponder 104 will work their way in a single direction aroundthe loop back to the originating or "first" transponder thatinitiated the sequential transmission of the backscatterwave 102.[0096] In other instances, the substrate 204 may beapplied to only a portion of the perimeter of a packageand the ends of the substrate do not meet or otherwisefall adjacent to each other. In such instances, the passivewireless transponders 104a-104n disposed in the sub-strate form an open loop and the backscatter waves 102sequentially communicated by each transponder 104 toa neighboring transponder 104 will work their way fromthe transponder at the first end of the substrate to thetransponder at the second end of the substrate 204. Insome instances, the backscatter waves 102 sequentiallycommunicated by each transponder 104 to a neighboringtransponder 104 will work their way from the transponderat the first end of the substrate to the transponder at thesecond end of the substrate 204 and back the transpond-er at the first end of the substrate 204. The method of

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determining interruptions in a known sequence of pas-sive wireless transponders based on the sequential re-broadcast of a backscatter wave from transponder toneighboring transponder in a defined sequence com-mences at 802.[0097] At 804, an interrogation carrier wave 106 is pro-vided to a number of passive wireless transponders104a-104n arranged in a defined series, sequence, orconfiguration. Responsive to the receipt of the interroga-tion signal 106, a first passive wireless transponder 104acommunicates a backscatter wave 102a to a neighboringtransponder 1 04b, which in turn communicates a back-scatter wave 102b to a neighboring transponder 104c,and so on. A damaged or missing transponder 104 inter-rupts the sequential transmission of the backscatter wave102. In at least some instances, a respective nontransi-tory storage media communicably coupled to each trans-ponder 104 can store data indicative of the source of thereceived backscatter wave 102.[0098] At 806, at least one of the passive wirelesstransponders 104 generates a respective backscatterwave 102 that includes data indicative of whether eachof the passive wireless transponders have successfullytransmitted to a respective neighboring passive wirelesstransponder in a defined order. In some implementations,such a backscatter wave 102 is communicated to theinterrogator by the "first" or originating transponder 104.Such a transponder may be positioned at the first end ofa substrate attached to a first object in a defined seriesof objects. In such instances, the first transponder 104can generate the backscatter signal responsive to receiv-ing from a neighboring transponder a backscatter wave102 indicative of a successful sequential transmission ofthe backscatter wave 102 by a defined sequence of trans-ponders 104a-104n.[0099] At 808, using the information included in thebackscatter wave 102 provided by the first transponder104, the external host device 110 determines whethereach of the passive wireless transponders have success-fully transmitted to a respective neighboring passive wire-less transponder in a defined order or sequence. In atleast some implementations, the external host device cangenerate one or more human perceptible alarms or an-nunciations to indicate a failure to transmit in the definedorder or sequence. The method of determining interrup-tions in a known sequence of passive wireless transpond-ers based on the sequential rebroadcast of a backscatterwave from transponder to neighboring transponder in adefined sequence concludes at 810.[0100] Figure 9 shows a high level method 900 of de-termining by a passive wireless transponder 104 whetherthe sequential rebroadcast of a backscatter wave by aknown sequence or arrangement of transponders hasbeen interrupted. The method of determining by a pas-sive wireless transponder 104 whether the sequential re-broadcast of a backscatter wave by a known sequenceor 10 arrangement of transponders has been interruptedcommences at 902.

[0101] At 904, an interrogation carrier wave 106 is re-ceived by a first passive wireless transponder 104a. Thefirst passive wireless transponder 104a is a member ofa plurality of passive wireless transponders 104a-104narranged in a defined series, sequence, or configuration.[0102] At 906, responsive to the receipt of the interro-gation signal 106, the first passive wireless transponder104a communicates a backscatter wave 102a to a neigh-boring transponder 104b, which in turn communicates abackscatter wave 102b to a neighboring transponder104c, and so on. A damaged or missing transponder 104interrupts the sequential transmission of the backscatterwave 102.[0103] At 908, the first passive wireless transponder104a receives a second signal, such as a second back-scatter wave 102 generated by a spatially proximate orneighboring passive wireless transponder 104. The sec-ond backscatter wave 102 includes data indicative ofwhether each of a plurality of passive wireless transpond-ers which includes at least the first passive wireless trans-ponder 104a and at least the spatially proximate or neigh-boring passive wireless transponder 104, have success-fully transmitted a backscatter wave 102 to one anotherin a defined order. The method of determining by a pas-sive wireless transponder 104 whether the sequential re-broadcast of a backscatter wave by a known sequenceor arrangement of transponders has been interruptedconcludes at 910.[0104] Figure 10 shows a high level method 1000 ofdetermining the relative positions of a plurality of passivewireless transponders 104a-104n by repeatedly provid-ing an interrogation carrier wave 106 from a radio fre-quency generator 110 to the plurality of passive wirelesstransponders 104a-104n. In some implementations, pas-sive wireless transponders 104a-104n may be positionedat defined locations in, on, or about an enclosure 502.Such positioning may provide an indication of undesiredaccess to the interior portion of the enclosure. For exam-ple, passive wireless transponders 104a-104n may bepositioned in pairs 510 on an exterior or interior surfaceproximate an opening (e.g., door, box flaps) providingaccess to an interior space of an enclosure 502. Uponinterrogation, if both passive wireless transponders ineach transponder pair 510 indicate placement proximatethe other transponder in the transponder pair 510, suchindicates the integrity of the enclosure 502 has not becompromised. On the other hand, should one or both ofthe passive wireless transponders in a transponder pairindicate placement distal from the other transponder inthe transponder pair 510, such indicates a potential com-promise of enclosure 502 integrity.[0105] An interrogator 206, positioned internal or ex-ternal to the enclosure 502 may repeatedly provide aninterrogation carrier wave 106 to the plurality of passivewireless transponders 104 positioned in, on, or about theenclosure 502. Data indicative of the relative physicalposition of some or all of the passive wireless transpond-ers (e.g., proximate, distal) may be stored by the inter-

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rogator 206 in a communicably coupled nontransitorystorage. Date and time data indicative of the date andtime the relative physical position of some or all of thepassive wireless transponders was obtained may alsobe stored in the nontransitory storage. Such advanta-geously provides a history of the relative position of someor all of the plurality of passive wireless transponders. Insome instances, the interrogator 206 can transmit oneor more signals that include data indicative of the relativephysical position of some or all of the passive wirelesstransponders to one or more remote devices via a com-municably coupled communications interface. The meth-od 1000 of determining the relative positions of a pluralityof passive wireless transponders 104a-104n by repeat-edly providing an interrogation carrier wave 106 from aradio frequency generator 110 to the plurality of passivewireless transponders 104a-104n commences at 1002.[0106] At 1004, an interrogator 206 positioned internalor external to the enclosure 502 repeatedly provides atleast an interrogation carrier wave to some or all of aplurality of passive wireless transponders 104a-104n po-sitioned in, on, or about an enclosure 502. In at leastsome instances, at least a portion of the transponders104a-104n may be positioned in pairs with each trans-ponder 104 in the pair disposed on opposing surfaces ofa movable member 504a-504b providing access to aninterior portion of the enclosure 502. Such positioningpermits detection of movement of movable member504a-504b which may indicate an attempt to access theinterior portion of the enclosure 502. The interrogatormay provide such interrogation carrier waves 106 on aperiodic, intermittent, or continuous basis.[0107] At 1006, responsive to the receipt of the inter-rogation carrier wave 106 by some or all of the pluralityof passive wireless transponders 04a-104n, each of thepassive wireless transponders 104 generates a back-scatter signal 102 to determine the identity of anotherphysically proximate nearest neighbor transponder. If themoveable members 504a, 504b are proximate each oth-er, the identity of the physically proximate nearest neigh-bor transponder is the other transponder in the pair 510.Some or all of the plurality of passive wireless transpond-ers generate at least one backscatter wave 102 contain-ing information indicative of the identity of the other pas-sive wireless transponder determined to be physicallyproximate the respective transponder 104 (if any).[0108] At 1008, the interrogator 206 determines wheth-er each of the plurality of passive wireless transpondershave successfully transmitted to at least one neighboringpassive wireless transponder in response to each inter-rogation carrier wave 102 received by the plurality of pas-sive wireless transducers 104a-104n. In some instances,the interrogator 206 determines whether each of the plu-rality of passive wireless transponders 1 04a-1 04n havesuccessfully transmitted to at least one neighboring pas-sive wireless transponder.[0109] In other instances, each of the plurality of trans-ponders 104a-104n compares data indicative of the

neighboring passive wireless transponder stored in acommunicably coupled nontransitory storage with thedata indicative of the determined neighboring passivewireless transponder. In such instances, some or all ofthe passive wireless transponders 104a-104n may com-municate information indicative of the comparison results(i.e., MATCH or NO MATCH) to the interrogator 206 viaa backscatter wave 102 generated by the respectivetransducer. The method 1000 of determining the relativepositions of a plurality of passive wireless transponders104a-104n by repeatedly providing an interrogation car-rier wave 106 from a radio frequency generator 110 tothe plurality of passive wireless transponders 104a-104nconcludes at 1010.[0110] Also for example, the various methods may in-clude additional acts, omit some acts, and may performthe acts in a different order than set out in the variousflow diagrams. The use of ordinals such as first, secondand third, do not necessarily imply a ranked sense oforder, but rather may only distinguish between multipleinstances of an act or structure.

Claims

1. An interrogator system to determine the relative po-sitions of a plurality of passive wireless transpond-ers, the interrogator system comprising:

a transceiver (112) to provide an interrogationcarrier wave (106); anda processor (120) communicably coupled to thetransceiver,characterized in that the interrogator systemfurther comprises:

a processor-readable nontransitory storagemedium including machine executable in-structions that when executed by the proc-essor, cause the processor to:

receive information from each of a plu-rality of passive wireless transponders(104) that each comprises at least oneunique identifier and each identifies atleast one neighboring passive wirelesstransponder (104) that is spatially prox-imate the respective passive wirelesstransponder (104) from which the infor-mation is received, wherein at least onesaid neighboring passive wirelesstransponder identifies another of theplurality of passive wireless transpond-ers (104) which is spatially proximateto the at least one said neighboring pas-sive wireless transponder; anddetermine a relative position of each ofthe passive wireless transponders with

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respect to one another based at leastin part on the information received fromeach passive wireless transponders.

2. The system of claim 1 wherein the machine execut-able instructions that cause the processor to receiveinformation from each of a plurality of passive wire-less transponders further cause the processor to:

receive information from each of a plurality ofpassive wireless transponders located about anenclosure;determine based on the received informationwhether tampering with the enclosure has oc-curred; andresponsive to a determination that tamperingwith the enclosure has occurred, generate a hu-man perceptible output indicative that tamperingwith the enclosure has occurred.

3. The system of claim 1 wherein the machine execut-able instructions that cause the processor to receiveinformation from each of a plurality of passive wire-less transponders further cause the processor to:

receive information from each of a plurality ofpassive wireless transponders located about anpackage;determine based on the received informationwhether tampering with the package has oc-curred; andresponsive to a determination that tamperingwith the package has occurred, generate a hu-man perceptible output indicative that tamperingwith the package has occurred.

4. The system of claim 1 wherein the machine execut-able instructions that cause the processor to receiveinformation from each of a plurality of passive wire-less transponders further cause the processor to:

receive information from each of a plurality ofpassive wireless transponders located acrossat least one packaging flap;determine based on the received informationwhether tampering with the package has oc-curred; andresponsive to a determination that tamperingwith the package has occurred, generate a hu-man perceptible output indicative that tamperingwith the package has occurred.

5. The system of claim 1 wherein the machine execut-able instructions further cause the processor to:

compare information received information fromeach of a plurality of passive wireless transpond-ers with stored data indicative of a defined array;

anddetermine whether any of the passive wirelesstransponders are out of order with respect to thedefined array.

6. The system of claim 1 wherein the machine execut-able instructions further cause the processor to:

generate a virtual map of the plurality of passivewireless transponders, the virtual map repre-sentative of the relative spatial positions of thepassive wireless transponders with respect toeach other.

7. A method of operation of a passive wireless trans-ponder (104a), the method characterized in thatthe method comprises the step of:

in response to receipt of an interrogation carrierwave, receiving information from each of anumber of other passive wireless transpondersby the passive wireless transponder (104a)wherein at least one (104b) of the other passivewireless transponders (104b-n) are spatiallyproximate to the passive wireless transponder(104a) and each of the other passive wirelesstransponders (104b-n) identify another of theother passive wireless transponders (104b-n)that is spatially proximate to at least one of theother passive wireless transponders (104b-n);andtransmitting information identifying each of theother passive wireless transponders as a neigh-boring passive wireless transponder that is spa-tially proximate to the respective passive wire-less transponder from which the information isreceived in order to determine a relative positionof each of the other passive wireless transpond-ers.

8. The method of claim 7, further characterized in thatthe method comprises:

categorizing at least one of the other passivewireless transponders as a neighboring passivewireless transponder.

9. The method of claim 8 wherein categorizing at leastone of the other passive wireless transponders as aneighboring passive wireless transponder includescategorizing at least one of the other passive wire-less transponders as a neighboring passive wirelesstransponder based at least in part on a signalstrength of a signal received by the passive wirelesstransponder from one of the other passive wirelesstransponders.

10. The method of claim 8 wherein categorizing at least

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one of the other passive wireless transponders as aneighboring passive wireless transponder includescategorizing at least one of the other passive wire-less transponders as a neighboring passive wirelesstransponder based at least in part on a signalstrength of a signal received by the passive wirelesstransponder from one of the other passive wirelesstransponders relative to a signal strength of a signalreceived by the passive wireless transponder fromother ones of the other passive wireless transpond-ers.

11. The method of claim 8 wherein categorizing at leastone of the other passive wireless transponders as aneighboring passive wireless transponder includescategorizing at least one of the other passive wire-less transponders as a neighboring passive wirelesstransponder based at least in part on a time-of-flightof a signal received by the passive wireless trans-ponder from one of the other passive wireless trans-ponders.

12. The method of claim 8 wherein categorizing at leastone of the other passive wireless transponders as aneighboring passive wireless transponder includescategorizing at least one of the other passive wire-less transponders as a neighboring passive wirelesstransponder based at least in part on a time-of-flightof a signal received by the passive wireless trans-ponder from one of the other passive wireless trans-ponders relative to a time-of-flight of a signal re-ceived by the passive wireless transponder from oth-er ones of the other passive wireless transponders.

13. The method of claim 8 wherein transmitting informa-tion identifying at least one of the other passive wire-less transponders as a neighboring passive wirelesstransponder includes backscattering an interroga-tion carrier wave received from an interrogator sys-tem with the information encoded in the backscat-tered signal.

14. An interrogator system to determine the relative po-sitions of a plurality of passive wireless transpond-ers, the interrogator system comprising:

a transceiver to provide an interrogation carrierwave; anda processor communicably coupled to the trans-ceiver;characterized in that the interrogator systemfurther comprises:

a processor-readable nontransitory storagemedium including machine executable in-structions that when executed by the proc-essor, cause the processor to:

transmit an interrogation carrier waveto each of a plurality of passive wirelesstransponders that causes each of theplurality of wireless transponders totransmit a backscatter signal to a neigh-boring passive wireless transponder ina defined order;receive information from at least one ofthe plurality of passive wireless trans-ponders, the information received fromthe at least one of the plurality of pas-sive wireless transponders indicative ofwhether each of the passive wirelesstransponders have successfully trans-mitted to a respective neighboring pas-sive wireless transponder in the definedorder; anddetermine based on the received infor-mation whether each of the passivewireless transponders have success-fully transmitted to a respective neigh-boring passive wireless transponder inthe defined order.

15. The system of claim 14 wherein the machine-exe-cutable instructions that cause the processor totransmit an interrogation carrier wave to each of aplurality of passive wireless transponders furthercause the processor to:

transmit an interrogation carrier wave to each ofa plurality of passive wireless transponders thatcauses each of the plurality of wireless trans-ponders to successively transmit a commandusing a backscatter signal to a defined sequenceof passive wireless transponders.

Patentansprüche

1. Abfragesystem, um die relativen Positionen vonmehreren passiven drahtlosen Transpondern zu be-stimmen, wobei das Abfragesystem Folgendes um-fasst:

einen Sendeempfänger (112), um eine Abfra-geträgerwelle (106) bereitzustellen; undeinen Prozessor (120), der an den Sendeemp-fänger kommunikativ gekoppelt ist,dadurch gekennzeichnet, dass das Abfrage-system ferner Folgendes umfasst:

ein prozessorlesbares nicht flüchtiges Spei-chermedium, das maschinenausführbareAnweisungen enthält, die dann, wenn siedurch den Prozessor ausgeführt werden,bewirken, dass der Prozessor:

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Informationen von jedem der mehrerenpassiven drahtlosen Transponder(104) empfängt, die jeweils mindestenseine eindeutige Kennung umfassenund jeweils mindestens einen benach-barten passiven drahtlosen Transpon-der (104) identifizieren, der räumlich inder Nähe des jeweiligen passivendrahtlosen Transponders (104) liegt,von dem die Informationen empfangenwerden, wobei mindestens einer derbenachbarten passiven drahtlosenTransponder einen weiteren der meh-reren passiven drahtlosen Transpon-der (104) identifiziert, der räumlich inder Nähe des mindestens einen be-nachbarten passiven drahtlosenTransponders liegt; undeine relative Position eines jeden derpassiven drahtlosen Transponder inBezug auf einen weiteren zumindestteilweise anhand der von jedem passi-ven drahtlosen Transponder empfan-genen Informationen bestimmt.

2. System nach Anspruch 1, wobei die maschinenaus-führbaren Anweisungen, die bewirken, dass der Pro-zessor Informationen von jedem von mehreren pas-siven drahtlosen Transpondern empfängt, ferner be-wirken, dass der Prozessor:

Informationen von jedem von mehreren passi-ven drahtlosen Transpondern, die sich um einGehäuse befinden, empfängt;aufgrund der empfangenen Informationen be-stimmt, ob eine Beeinflussung des Gehäusesstattgefunden hat; undals Reaktion auf eine Bestimmung, dass eineBeeinflussung des Gehäuses stattgefundenhat, eine menschlich wahrnehmbare Ausgabeerzeugt, die angibt, dass eine Beeinflussungdes Gehäuses stattgefunden hat.

3. System nach Anspruch 1, wobei die maschinenaus-führbaren Anweisungen, die bewirken, dass der Pro-zessor Informationen von jedem von mehreren pas-siven drahtlosen Transpondern empfängt, ferner be-wirken, dass der Prozessor:

Informationen von jedem von mehreren passi-ven drahtlosen Transpondern, die sich um eineVerpackung befinden, empfängt;aufgrund der empfangenen Informationen be-stimmt, ob eine Beeinflussung der Verpackungstattgefunden hat; undals Reaktion auf eine Bestimmung, dass eineBeeinflussung der Verpackung stattgefundenhat, eine menschlich wahrnehmbare Ausgabe

erzeugt, die angibt, dass eine Beeinflussung derVerpackung stattgefunden hat.

4. System nach Anspruch 1, wobei die maschinenaus-führbaren Anweisungen, die bewirken, dass der Pro-zessor Informationen von jedem von mehreren pas-siven drahtlosen Transpondern empfängt, ferner be-wirken, dass der Prozessor:

Informationen von jedem von mehreren passi-ven drahtlosen Transpondern, die sich zumin-dest über einer Verpackungsklappe befinden,empfängt;aufgrund der empfangenen Informationen be-stimmt, ob eine Beeinflussung der Verpackungstattgefunden hat; undals Reaktion auf eine Bestimmung, dass eineBeeinflussung der Verpackung stattgefundenhat, eine menschlich wahrnehmbare Ausgabeerzeugt, die angibt, dass eine Beeinflussung derVerpackung stattgefunden hat.

5. System nach Anspruch 1, wobei die maschinenaus-führbaren Anweisungen ferner bewirken, dass derProzessor:

Informationen Informationen, die von jedem vonmehreren passiven drahtlosen Transpondernempfangen werden, mit gespeicherten Daten,die eine definierte Anordnung angeben, ver-gleicht; undbestimmt, ob einer der passiven drahtlosenTransponder in Bezug auf die definierte Anord-nung außer Betrieb ist.

6. System nach Anspruch 1, wobei die maschinenaus-führbaren Anweisungen ferner bewirken, dass derProzessor:

eine virtuelle Karte der mehreren passivendrahtlosen Transponder erzeugt, wobei die vir-tuelle Karte für die relativen räumlichen Positi-onen der passiven drahtlosen Transponder inBezug aufeinander repräsentativ ist.

7. Verfahren des Betriebs eines passiven drahtlosenTransponders (104a), wobei das Verfahren da-durch gekennzeichnet ist, dass das Verfahren diefolgenden Schritte umfasst:

als Reaktion auf einen Empfang einer Abfrage-trägerwelle, Empfangen von Informationen vonjedem einer Anzahl von weiteren passivendrahtlosen Transpondern durch den passivendrahtlosen Transponder (104a), wobei mindes-tens einer (104b) der weiteren passiven draht-losen Transponder (104b-n) räumlich in der Nä-he des passiven drahtlosen Transponders

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(104a) liegt und jeder der weiteren passivendrahtlosen Transponder (104b-n) einen ande-ren der weiteren passiven drahtlosen Transpon-der (104b-n) identifiziert, der räumlich in der Nä-he mindestens eines der weiteren passivendrahtlosen Transponders (104b-n) liegt; undSenden von Informationen, die jeden der weite-ren passiven drahtlosen Transponder als einenbenachbarten passiven drahtlosen Transpon-der identifizieren, der räumlich in der Nähe desjeweiligen passiven drahtlosen Transpondersliegt, von dem die Informationen empfangenwerden, um eine relative Position von jedem derweiteren passiven drahtlosen Transponder zubestimmen.

8. Verfahren nach Anspruch 7, das ferner dadurch ge-kennzeichnet ist, dass das Verfahren Folgendesumfasst:

Kategorisieren mindestens eines der weiterenpassiven Transponder als einen benachbartenpassiven drahtlosen Transponder.

9. Verfahren nach Anspruch 8, wobei das Kategorisie-ren mindestens eines der weiteren passiven draht-losen Transponder als einen benachbarten passivendrahtlosen Transponder enthält, mindestens einender weiteren passiven drahtlosen Transponder alseinen benachbarten passiven drahtlose Transpon-der zumindest teilweise aufgrund einer Signalstärkeeines durch den passiven drahtlosen Transpondersvon einem der weiteren passiven drahtlosen Trans-ponder empfangenen Signals zu kategorisieren.

10. Verfahren nach Anspruch 8, wobei das Kategorisie-ren mindestens eines der weiteren passiven draht-losen Transponder als einen benachbarten passivendrahtlosen Transponder enthält, mindestens einender weiteren passiven drahtlosen Transponder alseinen benachbarten passiven drahtlosen Transpon-der zumindest teilweise aufgrund einer Signalstärkeeines durch den passiven drahtlosen Transpondervon einem der anderen passiven drahtlosen Trans-ponder empfangenen Signals in Bezug auf eine Si-gnalstärke eines durch den passiven drahtlosenTransponder von anderen der weiteren passivendrahtlosen Transponder empfangenen Signals zukategorisieren.

11. Verfahren nach Anspruch 8, wobei das Kategorisie-ren mindestens eines der weiteren passiven draht-losen Transponder als einen benachbarten passivendrahtlosen Transponder enthält, mindestens einender weiteren passiven drahtlosen Transponder alseinen benachbarten passiven drahtlosen Transpon-der zumindest teilweise aufgrund einer Laufzeit ei-nes durch den passiven drahtlosen Transponder von

einem der weiteren passiven drahtlosen Transpon-der empfangenen Signals zu kategorisieren.

12. Verfahren nach Anspruch 8, wobei das Kategorisie-ren mindestens eines der weiteren passiven draht-losen Transponder als einen benachbarten passivendrahtlosen Transponder enthält, mindestens einender weiteren passiven drahtlosen Transponder alseinen benachbarten passiven drahtlosen Transpon-der zumindest teilweise aufgrund einer Laufzeit ei-nes durch den passiven drahtlosen Transponder voneinem der weiteren passiven drahtlosen Transpon-der empfangenen Signals in Bezug auf eine Laufzeiteines durch den passiven drahtlosen Transpondervon anderen der weiteren passiven drahtlosenTransponder empfangenen Signals zu kategorisie-ren.

13. Verfahren nach Anspruch 8, wobei das Senden vonInformationen, die mindestens einen weiteren pas-siven drahtlosen Transponder als einen benachbar-ten passiven drahtlosen Transponder identifizieren,enthält, eine Abfrageträgerwelle, die von einem Ab-fragesystem empfangen wird, zurückzustreuen, wo-bei die Informationen in dem zurückgestreuten Sig-nal codiert sind.

14. Abfragesystem, um die relativen Positionen vonmehreren passiven drahtlosen Transpondern zu be-stimmen, wobei das Abfragesystem Folgendes um-fasst:

einen Sendeempfänger, um eine Abfrageträ-gerwelle bereitzustellen; undeinen Prozessor, der an den Sendeempfängerkommunikativ gekoppelt ist;dadurch gekennzeichnet, dass das Abfrage-system ferner Folgendes umfasst:

ein prozessorlesbares nicht flüchtiges Spei-chermedium, das maschinenausführbareAnweisungen enthält, die dann, wenn siedurch den Prozessor ausgeführt werden,bewirken, dass der Prozessor:

eine Abfrageträgerwelle an jeden vonmehreren passiven drahtlosen Trans-pondern sendet, die bewirkt, dass jederder mehreren drahtlosen Transponderein Rückstreusignal an einen benach-barten passiven drahtlosen Transpon-der in einer definierten Reihenfolgesendet;Informationen von mindestens einemder mehreren passiven drahtlosenTransponder empfängt, wobei die In-formationen, die von dem mindestenseinen der mehreren passiven drahtlo-

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sen Transponder empfangen werden,angeben, ob jeder der passiven draht-losen Transponder erfolgreich an einenentsprechenden benachbarten passi-ven drahtlosen Transponder in einerdefinierten Reihenfolge gesendet hat;undaufgrund der empfangenen Informatio-nen bestimmt, ob jeder der passivendrahtlosen Transponder erfolgreich aneinen entsprechenden benachbartenpassiven drahtlosen Transponder inder definierten Reihenfolge gesendethat.

15. System nach Anspruch 14, wobei die maschinen-ausführbaren Anweisungen, die bewirken, dass derProzessor eine Abfrageträgerwelle an jeden vonmehreren passiven drahtlosen Transpondern sen-det, ferner bewirkt, dass der Prozessor:

eine Abfrageträgerwelle an jeden von mehrerenpassiven drahtlosen Transpondern sendet, diebewirkt, dass jeder der mehreren passivendrahtlosen Transponder erfolgreich einen Be-fehl unter Verwendung eines Rückstreusignalsan eine definierte Folge von passiven drahtlo-sen Transpondern sendet.

Revendications

1. Système interrogateur servant à établir les positionsrelatives d’une pluralité de transpondeurs passifssans fil, le système interrogateur comprenant :

un émetteur-récepteur (112) servant à fournirune onde porteuse d’interrogation (106) ; etun processeur (120) couplé en communicationà l’émetteur-récepteur,le système interrogateur étant caractérisé ence qu’il comprend en outre :

un support de stockage non transitoire lisi-ble par processeur comportant des instruc-tions exécutables par machine qui, une foisexécutées par le processeur, amènent leprocesseur à :

recevoir des informations depuis cha-cun d’une pluralité de transpondeurspassifs sans fil (104) comprenant cha-cune au moins un identificateur uniqueet identifiant chacune au moins untranspondeur passif sans fil (104) voi-sin qui est proche spatialement dutranspondeur passif sans fil (104) res-pectif depuis lequel les informations

sont reçues, au moins un dit transpon-deur passif sans fil voisin identifiant unautre de la pluralité de transpondeurspassifs sans fil (104) qui est prochespatialement dudit au moins un dittranspondeur passif sans fil voisin ; etétablir une position relative de chacundes transpondeurs passifs sans fil parrapport à un autre en fonction en partieau moins des informations reçues de-puis chaque transpondeur passif sansfil.

2. Système selon la revendication 1, dans lequel lesinstructions exécutables par machine amenant leprocesseur à recevoir des informations depuis cha-cun d’une pluralité de transpondeurs passifs sans filamènent en outre le processeur à :

recevoir des informations depuis chacun d’unepluralité de transpondeurs passifs sans fil pla-cés autour d’un contenant ;établir, en fonction des informations reçues, s’ily a eu tentative d’effraction du contenant ; ets’il est établi qu’il y a eu tentative d’effraction ducontenant, générer une sortie perceptible parl’homme indiquant qu’il y a eu tentative d’effrac-tion du contenant.

3. Système selon la revendication 1, dans lequel lesinstructions exécutables par machine amenant leprocesseur à recevoir des informations depuis cha-cun d’une pluralité de transpondeurs passifs sans filamènent en outre le processeur à :

recevoir des informations depuis chacun d’unepluralité de transpondeurs passifs sans fil pla-cés autour d’un emballage ;établir, en fonction des informations reçues, s’ily a eu tentative d’effraction de l’emballage ; ets’il est établi qu’il y a eu tentative d’effraction del’emballage, générer une sortie perceptible parl’homme indiquant qu’il y a eu tentative d’effrac-tion de l’emballage.

4. Système selon la revendication 1, dans lequel lesinstructions exécutables par machine amenant leprocesseur à recevoir des informations depuis cha-cun d’une pluralité de transpondeurs passifs sans filamènent en outre le processeur à :

recevoir des informations depuis chacun d’unepluralité de transpondeurs passifs sans fil pla-cés en travers d’au moins un rabat d’emballage ;établir, en fonction des informations reçues, s’ily a eu tentative d’effraction de l’emballage ; ets’il est établi qu’il y a eu tentative d’effraction del’emballage, générer une sortie perceptible par

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l’homme indiquant qu’il y a eu tentative d’effrac-tion de l’emballage.

5. Système selon la revendication 1, dans lequel lesinstructions exécutables par machine amènent enoutre le processeur à :

comparer des informations des informations re-çues depuis chacun d’une pluralité de transpon-deurs passifs sans fil à des données mémori-sées indiquant un réseau défini ; etétablir si l’un quelconque des transpondeurspassifs sans fil est hors service par rapport auréseau défini.

6. Système selon la revendication 1, dans lequel lesinstructions exécutables par machine amènent enoutre le processeur à :

générer une carte virtuelle de la pluralité detranspondeurs passifs sans fil, la carte virtuellereprésentant les positions spatiales relativesdes transpondeurs passifs sans fil les uns parrapport aux autres.

7. Procédé de fonctionnement d’un transpondeur pas-sif sans fil (104a), le procédé étant caractérisé ence qu’il comprend les étapes consistant à :

en réponse à la réception d’une onde porteused’interrogation, recevoir, par le transpondeurpassif sans fil (104a), des informations depuischacun d’un certain nombre d’autres transpon-deurs passifs sans fil, au moins un (104b) desautres transpondeurs passifs sans fil (104b-n)étant proche spatialement du transpondeur pas-sif sans fil (104a) et chacun des autres trans-pondeurs passifs sans fil (104b-n) identifiant unautre des autres transpondeurs passifs sans fil(104b-n) qui est proche spatialement d’au moinsun des autres transpondeurs passifs sans fil(104b-n) ; ettransmettre des informations identifiant chacundes autres transpondeurs passifs sans fil com-me un transpondeur passif sans fil voisin qui estproche spatialement du transpondeur passifsans fil respectif depuis lequel les informationssont reçues dans le but d’établir une positionrelative de chacun des autres transpondeurspassifs sans fil.

8. Procédé selon la revendication 7, le procédé étantcaractérisé en outre en ce qu’il comprend l’étapeconsistant à :

catégoriser au moins un des autres transpon-deurs passifs sans fil comme un transpondeurpassif sans fil voisin.

9. Procédé selon la revendication 8, dans lequel l’étapeconsistant à catégoriser au moins un des autrestranspondeurs passifs sans fil comme un transpon-deur passif sans fil voisin comporte l’étape consis-tant à catégoriser au moins un des autres transpon-deurs passifs sans fil comme un transpondeur passifsans fil voisin en fonction en partie au moins d’uneintensité de signal d’un signal reçu par le transpon-deur passif sans fil depuis un des autres transpon-deurs passifs sans fil.

10. Procédé selon la revendication 8, dans lequel l’étapeconsistant à catégoriser au moins un des autrestranspondeurs passifs sans fil comme un transpon-deur passif sans fil voisin comporte l’étape consis-tant à catégoriser au moins un des autres transpon-deurs passifs sans fil comme un transpondeur passifsans fil voisin en fonction en partie au moins d’uneintensité de signal d’un signal reçu par le transpon-deur passif sans fil depuis un des autres transpon-deurs passifs sans fil relative à une intensité de si-gnal d’un signal reçu par le transpondeur passif sansfil depuis d’autres parmi les autres transpondeurspassifs sans fil.

11. Procédé selon la revendication 8, dans lequel l’étapeconsistant à catégoriser au moins un des autrestranspondeurs passifs sans fil comme un transpon-deur passif sans fil voisin comporte l’étape consis-tant à catégoriser au moins un des autres transpon-deurs passifs sans fil comme un transpondeur passifsans fil voisin en fonction en partie au moins d’untemps de vol d’un signal reçu par le transpondeurpassif sans fil depuis un des autres transpondeurspassifs sans fil.

12. Procédé selon la revendication 8, dans lequel l’étapeconsistant à catégoriser au moins un des autrestranspondeurs passifs sans fil comme un transpon-deur passif sans fil voisin comporte l’étape consis-tant à catégoriser au moins un des autres transpon-deurs passifs sans fil comme un transpondeur passifsans fil voisin en fonction en partie au moins d’untemps de vol d’un signal reçu par le transpondeurpassif sans fil depuis un des autres transpondeurspassifs sans fil relatif à un temps de vol d’un signalreçu par le transpondeur passif sans fil depuisd’autres parmi les autres transpondeurs passifssans fil.

13. Procédé selon la revendication 8, dans lequel l’étapeconsistant à transmettre des informations identifiantau moins un des autres transpondeurs passifs sansfil comme un transpondeur passif sans fil voisin com-porte l’étape consistant à rétrodiffuser une onde por-teuse d’interrogation reçue depuis un système inter-rogateur, les informations étant codées dans le si-gnal rétrodiffusé.

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14. Système interrogateur servant à établir les positionsrelatives d’une pluralité de transpondeurs passifssans fil, le système interrogateur comprenant :

un émetteur-récepteur servant à fournir une on-de porteuse d’interrogation ; etun processeur couplé en communication àl’émetteur-récepteur ;le système interrogateur étant caractérisé ence qu’il comprend en outre :

un support de stockage non transitoire lisi-ble par processeur comportant des instruc-tions exécutables par machine qui, une foisexécutées par le processeur, amènent leprocesseur à :

transmettre une onde porteuse d’inter-rogation à chacun d’une pluralité detranspondeurs passifs sans fil, ame-nant chacun de la pluralité de transpon-deurs passifs sans fil à transmettre unsignal de rétrodiffusion à un transpon-deur passif sans fil voisin dans un ordredéfini ;recevoir des informations depuis aumoins un de la pluralité de transpon-deurs passifs sans fil, les informationsreçues depuis ledit au moins un de lapluralité de transpondeurs passifs sansfil indiquant si chacun des transpon-deurs passifs sans fil a transmis avecsuccès à un transpondeur passif sansfil voisin respectif dans l’ordre défini ; etétablir, en fonction des informations re-çues, si chacun des transpondeurspassifs sans fil a transmis avec succèsà un transpondeur passif sans fil voisinrespectif dans l’ordre défini.

15. Système selon la revendication 14, dans lequel lesinstructions exécutables par machine amenant leprocesseur à transmettre une onde porteuse d’inter-rogation à chacun d’une pluralité de transpondeurspassifs sans fil amènent en outre le processeur à :

transmettre une onde porteuse d’interrogationà chacun d’une pluralité de transpondeurs pas-sifs sans fil, amenant chacun de la pluralité detranspondeurs passifs sans fil à transmettreavec succès une commande, au moyen d’un si-gnal de rétrodiffusion, à une séquence définiede transpondeurs passifs sans fil.

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REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the reader’s convenience only. It does not form part of the Europeanpatent document. Even though great care has been taken in compiling the references, errors or omissions cannot beexcluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description

• US 2007115125 A1 [0004] • WO 2007035863 A2 [0005]