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White Paper

A BASIC INTRODUCTION TO RFID TECHNOLOGY AND ITS

USE IN THE SUPPLY CHAIN

January 2004

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TABLE OF CONTENTS

EXECUTIVE SUMMARY .................................................................................................3

INTRODUCTION TO RFID ............................................................................................4

HOW RFID WORKS ......................................................................................................5

RFID systems..............................................................................................................5Communication............................................................................................................ 5

Anti-collision .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... ... .... .... .... . 5

RFID BUILDING BLOCKS.............................................................................................6

RFID Tags............................................................................................................................................................... 6Packaging ................................................................................................................... 6Examples of different formats............ ........ ......... ........ ......... ......... ........ ......... ........ ....... 6Tag Cost .....................................................................................................................6

Tag ICs ......................................................................................................................8Tag Classes ................................................................................................................ 8Selecting a tag............................................................................................................. 9

Active and passive tags .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... .... ... .... .... ... 10How tags communicate .............................................................................................. 11Tag Orientation (polarization)...................................................................................... 13Tag standards............................................................................................................ 14

RFID Readers.......................................................................................................................................................17Handheld Readers ..................................................................................................... 18

RFID Label Printers............................................................................................................................................18

Reader Antennas ................................................................................................................................................19

RFID TECHNOLOGY IN THE SUPPLY CHAIN............................................................ 20

Definition of the Supply Chain. .................................................................................... 20How will RFID help improve supply chain efficiency........ ........ ......... ........ ......... ......... ... 20The main benefits of RFID in the supply chain. ........ ......... ........ ......... ........ ......... ........ . 20

THE EPC ELECTRONIC PRODUCT CODE................................................................ 22

EPC Origins ..........................................................................................................................................................22

EPC layout ............................................................................................................................................................22

EPC infrastructure..............................................................................................................................................23Middleware or Savant Software.................................................................................. 24Object Name Service (ONS)....................................................................................... 24Physical Markup Language (PML)............................................................................... 24How the EPC will automate the supply chain ............................................................... 25

SECURITY IN RFID SYSTEMS................................................................................... 26

CONCLUSION ............................................................................................................ 27

ABOUT THE AUTHOR................................................................................................. 27

APPENDIX A .......................................................................................................... 28

More about Near and Far fields ........ ......... ........ ......... ......... ........ ......... ........ ......... ...... 28

APPENDIX B ........................................................................................................ 30

EIRP and ERP Power Emissions ................................................................................ 30

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Executive Summary

In2003RFIDseemedtohaveappearedfromnowhere,andintothespotlightasoneofthehottest technologies around. Everyone from journalists, analysts, VCs, technologycompanies and retail giants like Wal-Mart were making public statements, mandates,predicationsandinvestments,basedonthepromisethatRFIDwassettorevolutionizetheglobalsupplychainonascalenotseensincetheinternetrevolutioninthe1990s.Equallysurprising isthatRFIDisnot new,itsbeenaround forwellover10 years, and isalreadyinuseinapplicationslikeaccesscontrolandtransport.Whilsttherehavebeenmanyfalsestartsandpromisesinthepast,whathasmadethedifferencethistimearound,isthecreation of the EPC (electronic product code) coupled with lower tag costs, and themandated adoption of RFID by Wal-Mart and Tesco for all their suppliers by 2005-6.

Furthermore,theEuropeanParliamenthasannouncedlegislationwhichobligesallgoodstobe traceable throughout the supply chain by2005. These initiatives, andothers like therecentUS-DODannouncementsarenowdrivingthemarketandincitingmanycompaniesto

developstrategiesforRFIDcompliance.TheuseofRFIDcombinedwiththeEPCpromisestoprovidedataaboutproductsneveravailablebefore.ManyitemsproducedwilleventuallyhavetheirownuniqueIDnumbers.Allparts of thesupply chain includingmanufactures,distributors and retailerswill beabletohave instant access to information about an individual product. RFID is not expected toreplacebarcodessimplybecausetagsarestilltooexpensiveeventhoughtheirpriceshavefallen to around 20 cents in volume versus0.2 cents for a bar code label. Adoption is

thereforelikelytohappenfirstatthePaletteandCratelevel,thenastechnologyadvancesandcostsreducefurther,wecanexpecttoseetagsonmoreandmorehighvalueitems.ThewideadoptionofRFIDacrossthesupplychainwillbringsignificantbenefitsleadingtoreducedoperationalcostsandhenceincreasedprofits.Manyanalystssuggestthatthiswill

happeninthreeprimaryareas.

Reducedinventoryandshrinkage Benefitfromareductioninstoreandwarehouselaborexpenses Areductioninout-of-stockitems

Withsomuchhighprofilebacking,momentumandindisputablebenefits,canRFIDfail?Mostanalyststhinknot,butareawareofthemanyobstacles,misconceptionsandissuestoberesolvedonthewayincluding;

Tagpricesandefficiencies HarmonizationofRFIDstandards, Interoperabilitythroughoutthesupplychain

ITinfrastructuretohandlelargevolumesofdata Changeofworkandlaborpractices Sharedcostofdeployment Privacyissues

ThispaperisaimedatbothtechnicalandbusinessprofessionalswhowanttounderstandhowRFIDbasicallyworks,thevariousbuildingblocksandthepotentialthetechnologyhasforthesupplychain.FinallyIhopethatitwillalsoshedlightonsomeofthemysteriesandconfusionsurroundingRFIDandallthatitpromises.

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Introduction to RFID

Ingeneralterms,RFID(RadioFrequencyIdentification)isameansofidentifyingapersonorobjectusingaradiofrequencytransmission.Thetechnologycanbeusedtoidentify,track,sort or detect a wide variety of objects.Communication takes placebetween a reader(interrogator)andatransponder (SiliconChipconnectedtoanantenna)oftencalledatag.Tagscaneitherbeactive(poweredbybattery)orpassive(poweredbythereaderfield),andcomeinvariousformsincludingSmartcards,Tags,Labels,watchesandevenembeddedin

mobile phones. The communication frequencies useddepends to a large extent on theapplication, and range from 125KHz to 2.45 GHz. Regulations are imposed by mostcountries(groupedinto3Regions)tocontrolemissionsandpreventinterferencewithotherIndustrial,ScientificandMedicalequipment(ISM).

Table 1. Most commonly used RFID frequencies for passive tags Performance overview

LF HF UHF MicrowaveFrequencyRange

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How RFID works

Figure 1. Typical RFID system

RFID systemsInatypicalsystemtagsareattachedtoobjects.Eachtaghasacertainamountofinternalmemory (EEPROM) inwhich itstoresinformation abouttheobject, suchasits unique ID

(serial) number, or in some casesmore details includingmanufacture date andproductcomposition.Whenthesetagspassthroughafieldgeneratedbyareader,theytransmitthisinformationbacktothereader,thereby identifyingtheobject.UntilrecentlythefocusofRFIDtechnology was mainly on tags and readers whichwere being used in systems whererelativelylowvolumesof dataare involved.ThisisnowchangingasRFID inthesupplychainisexpectedtogeneratehugevolumesofdata,whichwillhavetobefilteredandrouted

to thebackend ITsystems.To solve this problem companies have developed specialsoftwarepackagescalledsavants,whichactasbuffersbetweentheRFIDfrontendantheITbackend.SavantsaretheequivalenttomiddlewareintheITindustry.

CommunicationThecommunicationprocessbetweenthereaderandtagismanagedandcontrolledbyoneof several protocols, such as the ISO15693 and ISO18000-3 forHForthe ISO18000-6,andEPCforUHF.Basicallywhathappensisthatwhenthereaderisswitchedon,itstartsemittingasignalattheselectedfrequencyband(typically860-915MHzforUHFor13.56MHzforHF).

Anycorrespondingtag inthevicinityofthereaderwilldetectthesignalanduse theenergyfrom it towake up andsupply operatingpower toits internal circuits.Once theTaghasdecodedthesignalasvalid,itrepliestothereader,andindicatesitspresencebymodulating(affecting)thereaderfield.

Anti-collisionIfmanytagsarepresentthentheywillall replyatthesame time,whichatthereaderendisseen asa signal collision and an indication ofmultiple tags.The reader manages this

problem by using an anti-collision algorithm designed to allow tags to be sorted andindividuallyselected.Thereare manydifferenttypesofalgorithms(BinaryTree,Aloha....)which are defined as part of the protocol standards. The number of tags that can beidentifieddependson thefrequencyandprotocolused,andcantypically rangefrom50tags/sforHFandupto200tags/sforUHF.Onceatagisselected,thereaderisabletoperformanumberofoperationssuchasreadthetagsidentifiernumber,orinthecaseofaread/writetagwriteinformationtoit.Afterfinishingdialogingwiththetag,thereadercantheneitherremoveitfromthelist,orputitonstandby

untilalatertime.Thisprocesscontinuesundercontroloftheanticollisionalgorithmuntilalltagshavebeenselected.

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RFID Building Blocks

RFID Tags.PackagingEveryobject tobe identifiedinanRFIDsystemwillneedtohaveatagattachedtoit.Tagsaremanufacturedinawidevarietyofpackagingformatsdesignedfordifferentapplicationsand environments. Thebasicassemblyprocess (seeFig4.) consistsof first a substratematerial (Paper,PVC,PET...),uponwhichanantennamade from oneofmany differentconductivematerialsincludingSilverink,Aluminumandcopperisdeposited.NexttheTagchipitself is connectedto theantenna,usingtechniquessuchaswirebondingorflip chip(seeFig4.).FinallyaprotectiveoverlaymadefrommaterialssuchasPVClamination,EpoxyResinorAdhesivePaper,isoptional lyaddedtoallowthetagtosupportsomeofthephysicalconditionsfoundinmanyapplicationslikeabrasion,impactandcorrosion.

Fig 2. Basic Tag Assembly

Examples of different formats

Creditcardsizeflexiblelabelswithadhesivebacks Tokensandcoins Embeddedtagsinjectionmoldedintoplasticproductssuchascases Wristbandtags

Hardtagswithepoxycase Keyfobs

TagsdesignedspeciallyforPalettesandcases Papertags

Tag CostThetypeofmaterialsandassemblymethodsusedtopackagetagsimpactdirectlyonthefinal cost ( around 30%), and tosome extent on the communication performance.Inthesupplychain,thecostoftagsisoneofthemainconsiderationsformassadoption,withthe5centtagbeingthemuchtalkedabouttarget.Howtoachievethisfigureiscurrentlyoneofthegreatdebates.Traditionallychipdiesizehasalwaysbeenthekeyfocus,andICcompanies

havemanagedtogetdiesizes(chiparea)downtoaround0.3mm2forUHFchips,resultinginamanufacturingcostofabout1-2centsdependingontheSiliconprocess.Thisleaves3centsfortherest!whichiswheretherealchallengenowseemstolie.Therearesolutionsin

PVC

PET

PAPER .

Substrate Antenna

Copper

ALU

Conductive Ink .

Chip

Flip chipconnection

Antenna

Wire

Gold

bumpsChipSurface

Overlay

PVC

Epoxy Resin

AdhesivePaper

.

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thepipelinefromcompanieslikeAlienTechnologyandPhilipsSemiconductors,whomhavebothdevelopednewchipassemblytechniqueswhichwhenusedwiththeverylargevolumes(billions of tags) expected in the supply chainpromises to optimize costs to the levelsrequiredinordertoreachthe5centgoal.

Fig 3. HF (13.56 MHz) Tag examples

Paperlabelswithconductivesilverinkantennas Flexiblelabelwithanaluminumantenna

-

Courtesy of ASK

Courtesy of Inside Contactless

Fig 4. UHF (860 930 MHz) tag examples

Courtesy of MATRICS

Courtesy of IPICO

Coil on chip Tags (image courtesy of Maxell)

A new and fascinating development for tags is based on havingtheantennadepositeddirectlyontothetagchipssurface.Althoughthecommunicationdistanceislimitedtoaround

3mm,theresultisamicroscopictagwhichcanbeconcealedforexampleinbanknotes,as

proposedrecentlybyHitachi-Maxell.BothMaxellandInsidecontactlesshavedevelopedworkingversionsofthesetagsatUHF,HF(Maxell)andHF(Inside).

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Tag ICs

Fig 5. Basic Tag IC architecture

RFID tag ICs are designed and manufactured using some of the most advancedandsmallestgeometrysiliconprocessesavailable.Theresultisimpressive,whenyouconsiderthatthesizeofaUHFtagchipisaround0.3mm2i.e.aboutthesizeofthesquarebelow

Intermsofcomputationalpower,RFIDtagsarequitedumb,containingonlybasiclogicandstatemachinescapableofdecodingsimpleinstructions.Thisdoesnotmeanthattheyaresimple to design! In fact very real challenges exist such as, achieving very low powerconsumption,managing noisy RF signals and keepingwithin strictemissionregulations.Other important circuitsallow thechip to transferpower from the reader signal field, andconvertitviaarectifierintoasupplyvoltage.Thechipclockisalsonormallyextractedfrom

thereadersignal.MostRFIDtagscontainacertainamountofNVM(NonvolatileMemory)likeEEPROMinordertostoredata.Theamountofdatastoreddependsonthechipspecification,andcanrangefromjustsimpleIdentifier numbers of around 96bits tomore information about theproductwith upto32Kbits.However,greaterdatacapacityandstorage(memorysize)leadstolargerchipsizes,andhencemoreexpensivetags.In1999TheAUTO-IDcenter(nowEPCGlobal)basedattheMIT(MassachusettsInstituteofTechnology)intheUS,togetherwithanumberofleadingcompanies, developed the idea of an unique electronic identifier code called the EPC(ElectronicProductCode).TheEPCissimilarinconcepttotheUPC(UniversalProductCode)usedin barcodestoday.Havingjusta simplecodeofupto256bitswouldleadto

smallerchipsize,andhencelowertagcosts,whichisrecognizedasthekeyfactorforwidespreadadoptionofRFIDinthesupplychain.TagsthatstorejustanIDnumberareoftencalledLicensePlateTags

Tag ClassesOneofthemainwaysofcategorizingRFIDtagsisbytheircapabilitytoreadandwritedata.

Thisleadstothefollowing4classes.EPCglobalhasalsodefinedfiveclasseswhicharesimilartotheonesbelow.

AC/DCConverter

Powercontrol

Decoder

EEPROMMemory

Modulator Encoder

Instructionsequencer

Tag antenna

Connections

Chip

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CLASS0 READONLY.FactoryprogrammedThesearethesimplesttypeoftags,wherethedata,whichisusuallyasimpleIDnumber,(EPC) iswrittenonlyonce intothe tagduringmanufacture.Thememory is thendisabledfrom any further updates. Class 0 isalso used todefinea categoryof tagscalledEAS(electronicarticlesurveillance)oranti-theftdevices,whichhaveno ID,andonlyannouncetheirpresencewhenpassingthroughanantennafield.CLASS1 WRITEONCEREADONLY(WORM)FactoryorUserprogrammed

In this case the tagismanufacturedwithnodatawritten into thememory. Datacantheneitherbewrittenby thetagmanufacturerorby theuser onetime.Followingthisnofurtherwritesareallowedandthetagcanonlyberead.TagsofthistypeusuallyactassimpleIdentifiersCLASS2READWRITEThisisthemostflexibletypeoftag,whereusershaveaccesstoreadandwritedataintothetagsmemory.Theyaretypicallyusedasdataloggers,andthereforecontainmorememoryspacethanwhatisneededforjustasimpleIDnumber.

CLASS3 READWRITEwithonboardsensorsThese tagscontainon-boardsensorsforrecordingparametersliketemperature,pressure,andmotion,whichcanbe recordedbywritinginto the tagsmemory.Assensor readingsmustbetakenintheabsenceofareader,thetagsareeithersemi-passiveoractive.CLASS4READWRITEwithintegratedtransmitters.Thesearelikeminiatureradiodeviceswhichcancommunicatewithothertagsanddeviceswithoutthepresenceofareader.Thismeansthattheyarecompletelyactivewiththeirown

batterypowersource.

Table 2. Different tag classes

Class Knownas Memory PowerSource Appl ica t ion0 EAS EPC[1] None EPC Passive Ant-theft ID

1 EPC Read-Only Any Identification

2 EPC Read-Write Any Datalogging

3 SensorTags Read-Write Semi-Passive/Active Sensors4 SmartDust Read-Write Active AdHocnetworking

[1]ThesectiononEPCstandardsevolutionshowsthattheEPCclass0islikelytoevolvetoaread-write

Selecting a tagChoosingtherighttagforaparticularRFIDapplicationisanimportantconsideration,andshouldtakeintoaccountmanyofthefactorslistedbelow:

Sizeandformfactorwheredoesthetaghavetofit?

Howclosewilltagsbetoeachother Durabilitywillthetagneedtohaveastrongouterprotectionagainstregularwearandtear. Isthetagre-usable Resistancetoharshenvironments(corrosive,steam...) Polarizationwhatwillbethetagsorientationwithrespecttothereaderfield Exposuretodifferenttemperatureranges Communicationdistance Influenceofmaterialssuchasmetalandliquids Environment(Electricalnoise,otherradiodevicesandequipment) OperatingFrequency(LF,HForUHF) SupportedCommunicationStandardsandprotocols(ISO,EPC)

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RegionalRegulations(US,EuropeandAsia) WillthetagdataneedtostoremorethanjustanIDnumberlikeanEPC Anti-collision-howmanytagsinthefieldatthesametimeandhowquicklymusttheybe

detected.

Howfastwilltagsmovethroughthereaderfield Readersupportwhichreaderproductsareabletoreadthetag Doesthetagneedtohavesecurity Dataprotectionbyencryption

Fig 6. How passive tags are defined

Active and passive tagsFig6,showsthatthefirstbasicchoicewhenconsideringatagisbetweeneitherpassive,semi-passiveoractive. Passivetagscanbereadatadistanceofupto4-5musingtheUHFfrequencyband,whilsttheothertypesoftags(semi-passiveandactive)canachievemuch

greaterdistancesofupto100mforsemi-passive,andseveralkilometersforActive.Thislargedifferenceincommunicationperformancecanbeexplainedbythefollowing; Passive tags use the reader field as a source of energy for the chip and for

communicationfromand tothe reader.Theavailablepower fromthereaderfield,notonly reduces very rapidly with distance ,but is also controlled by strict regulations,resultingina limitedcommunicationdistanceof 4 -5mwhenusingtheUHFfrequency

band(860Mhz930Mhz). Semi-Passive(batteryassistedbackscatter)tagshavebuiltinbatteriesandthereforedo

notrequireenergyfromthereaderfieldtopowerthechip.Thisallowsthemtofunctionwithmuchlowersignalpowerlevels,resultingingreaterdistancesofupto100meters.Distance is limited mainly due to the fact that tag does not have an integratedtransmitter,andisstillobligedtousethereaderfieldtocommunicatebacktothereader.

Activetagsarebatterypowereddevicesthathaveanactivetransmitteronboard.Unlike

passivetags,activetagsgenerateRFenergyandapplyittotheantenna.Thisautonomyfrom the reader means that they can communicate at distances of over several

kilometers.Thispaperfocusesonpassivetags.Theexperiencegainedbydifferentcompaniesrunningvarioustrailsandevaluationshassofarshown,thatoutofthedifferentRFIDfrequenciesLF,HF,UHFandmicrowave(seefig1).HFandUHFarethebestsuitedtothesupplychain.Furthermore, it is expected that UHF due to its superior read range, will become thedominantfrequency.ThisdoesnotmeanhoweverthatLFandmicrowavewillnotbeusedincertaincases.

Passive

LF, HF

UHFMicrowave

Power source Frequency

Class 0

Class 1

Class 2

18000

Protocol

Paper label

PVC.

Package

256 bits

PropreitarySemi-passive

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Table 3. Comparison of Passive and Active Tags

Advantages Disadvantages Remarks

Passive

Longerlifetime

Widerrangeofformfactors

Tags are more mechanicallyflexible

Lowestcost

Distancelimitedto4-5m(UHF)

Strictlycontrolledby

localregulations

Most widely used inRFIDapplications.

TagsareLF,HForUHF

Semi-Passive

Usedmainlyinrealtimesystems to track highvalue materials orequipmentthroughoutafactory.

TagsareUHF

Active

Greater communication

distance

Canbeusedtomanageotherdevices like sensors (Temp,

pressureetc) Do not fall under the same

strict power regulationsimposedonpassivedevices

Expensive - due tobattery, and tagpackaging

Reliability - impossible

todeterminewhetherabatteryisgoodorbad,

particularly inmultipletransponderenvironments.

Widespread

proliferation of activetransponderspresents

an environmentalhazardfrompotentiallytoxic chemicals inbatteries.

Used in logistics fortrackingof containersontrains,trucksetc..Tags are UHF or

microwave

How tags communicate

NearandFar f ie ldsInordertoreceiveenergyandcommunicatewithareader,passivetagsuseoneofthetwo

followingmethodsshowninfig7.Theseare nearfieldwhichemploysinductivecouplingofthetagtothemagneticfieldcirculatingaroundthereaderantenna(likeatransformer),andfarfieldwhichusessimilartechniquesto radar(backscatterreflection)bycouplingwiththeelectricfield.ThenearfieldisgenerallyusedbyRFIDsystemsoperatingintheLFandHFfrequencybands,andthefarfieldforlongerreadrangeUHFandmicrowaveRFIDsystems.Thetheoreticalboundarybetweenthetwofieldsdependsonthefrequencyused,andisin

factdirectlyproportionalto/2where =wavelength.Thisgivesforexamplearound3.5

metersforanHFsystemand5cmforUHF,bothofwhicharefurtherreducedwhenotherfactorsaretakenintoaccount.(seeTableA-1AppendixA)Note:AmoredetailedexplanationonnearandfarfieldscanbefoundinAppendixA.

Fig 7. Two different ways of Energy and information transfer between reader and tag

S

N

a

Reader

Magnetic Field (near field)Inductive cou lin

LF and HF

a

Reader

UHF

Electric Field (far field)Backscatter

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LF, HF TagsTagsatthesefrequenciesuseinductivecouplingbetweentwocoils(readerantennaandtagantenna - seefig7)inordertosupplyenergyto thetagandsendinformation.Thecoilsthemselvesareactually tunedLC circuits,whichwhensettotherightfrequency(ex;13.56

MHz),willmaximize theenergytransferfrom readerto tag. Thehigherthe frequency theless turns required (13.56MHztypicallyuses3 to5 turns).Communicationfromreadertotag occurs by the readermodulating(changing)its fieldamplitudeinaccordancewiththedigital information to be transmitted (base band signal). The result is the well knowntechniquecalledAMorAmplitudeModulation.Thetagsreceivercircuitisabletodetectthemodulatedfield,anddecodetheoriginalinformationfromit.However,whilstthereaderhasthepowertotransmitandmodulateitsfield,apassivetagdoesnot.Howiscommunicationthereforeachievedbackfromtagtoreader?.Theanswerlies inthe inductivecoupling.Justasinatransformerwhenthesecondarycoil(tagantenna)changestheloadandtheresultisseeninthePrimary(readerantenna).The

tagchipaccomplishesthissameeffectbychangingitsantennaimpedanceviaaninternalcircuit,whichismodulatedatthesamefrequencyasthereadersignal.Infactitsalittlemorecomplicatedthanthisbecause,iftheinformationiscontainedinthesamefrequencyasthereader,thenitwillbeswampedbyit,andnoteasilydetectedduetotheweakcouplingbetweenthereader andtag.Tosolvethisproblem, therealinformationisofteninsteadmodulatedintheside-bandsofahighersub-carrierfrequencywhichismoreeasilydetectedbythereader.

Fig 8. Creation of two higher frequency side-bands

UHF tagsPassivetagsoperatingattheUHFandhigherfrequenciesusesimilarmodulationtechniques

(AM)aslowerfrequencytags,andalsoreceivetheirpowerfromthereaderfield.Whatisdifferent however, is the way that energy is transferred, andthe design ofthe antennasrequiredtocaptureit.Wehavealreadymentionedthatthisisachievedusingthe farfield,whichisin facttheregioninElectromagneticTheorywheretheelectricandmagneticfield

components of a conductor (antenna) breakaway, and propagate into free spaceas acombinedwave.Atthispoint,thereisnofurtherpossibilityofinductivecouplinglikeinHFsystems,becausethemagneticfieldisnolongerlinkedtotheantenna.Transmissionofthiswaveinthefarfieldisthebasisofallmodernradiocommunication.Insomesystemssuchastransmissionlines(coaxialcables),thepropagationofthesewavesisrestrictedasmuchaspossibleviaspecialshieldingastheyconstituteapowerloss.Forantennasitstheinverse,propagationisencouraged.Whenthepropagatingwavefromthereadercollideswithatagantennaintheformofadipole (seefig7),partoftheenergyisabsorbedtopowerthetagandasmallpartisreflectedbacktothereaderinatechniqueknownasback-scatter.Theory

showsthatfortheoptimalenergytransferthelengthofthedipolemustbeequalto/2,which

fc =13.56 MHz

fsub = 212 KHz

fc =13.772 MHzfc =13.348 MHz

Reader Carrier signal0 dB

-80 dB

Modulation Informationin subcarrier side bands

Si nal

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givesa dimensionof around16cm.In reality the dipole ismade upof two /4lengths.Deviatingfromthesedimensionscanhaveaseriousimpactonperformance.Justasforlowerfrequencytagsusingnearfieldinductivecoupling,apassiveUHFtagdoes

nothavethepowertotransmitindependently.Communicationfromtagtoreaderisachievedbyalteringtheantennainputimpedanceintimewiththedatastreamtobetransmitted.Thisresultsinthepowerreflectedbacktothereaderbeingchangedintimewiththedatai.e.itis

modulated.Fromanapplicationspointofview,usingthetechniqueoffarfieldback-scattermodulationintroducesmanyproblemsthatarenotsoprevalentinHFandlowerfrequencysystems.Oneofthemostimportantoftheseisduetothefactthatthefieldemittedbythereaderisnotonlyreflectedbythetagantenna,butalsobyanyobjectswithdimensionsintheorderofthewavelengthused.Thesereflectedfields,ifsuperimposedonthemainreaderfieldcanleadtodampingandevencancellation.

Tag Orientation (polarization)

How tags are placed with respect to the polarization of the readers field can have asignificanteffectonthecommunicationdistanceforbothHFandUHFtags,resultinginareducedoperatingrangeofupto50%,andinthecaseofthetagbeingdisplacedby90(seefig 9), notbeing able to read the tag . The optimal orientationforHFtags isfor the twoantennacoils(readerandtag)tobeparalleltoeachotherasshownbelowinfig4.UHFtagsareevenmoresensitivetopolarizationduetothedirectionalnatureofthedipolefields.Theproblem of polarization can be overcome to a large extent by different techniquesimplementedeitheratthereaderortagasshownintable4below.Table 4. Managing the problem of tag orientation

Reader -Antenna Tag UHF-AntennaCircularfieldpolarization HF - Antennas physically placed at

different locations with in different

orientations(XYZ) twoantennas90outofphasewitheach

other 3DTunnelreaders

UHFTwoantennaspolarized90outofphaseegMatricsdoubledipole

Fig 9. HF Tag orientation with different antenna configurations

Tagreadable

TagUn-readable

Reader

Antenna

1- D field,90 tag

orientations

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Tag standards

Avery importantaspectofRFID technologyaretheassociatedstandardsandregulations.

They are designed to ensure safe operation with respect to other electricalandradioequipment,andguaranteeinteroperabilitybetweendifferentmanufacturersreadersandtags.Regulationsaremainlyconcernedwithreaderpoweremissionsandallocationoffrequencybands, whilst standards like the ISO (International StandardsOrganization) definetheAirinterfacecommunicationbetweenReader->TagandTag->Reader,andincludeparameterssuchas;

Communicationprotocol SignalModulationtypes

Datacodingandframes DataTransmissionrates Anti-collision (detectionand sorting ofmany tags intheReaderf ieldatthesame

time)

Reader

Antenna

3 - D field,

90 tag

orientations

Mux

Reader

Antenna2 - D field,90 tag

orientations

0 90

Phase splitter

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ThehistoryofRFIDstandardsoverthelast10yearshasunfortunatelybeenfarfromideal,leadingtotoomanyvariationsandconfusion.ThesituationforthesupplychainandItemmanagementisnodifferentduetothetwoairinterfacestandardscurrentlybeingproposedbyISOandtheEPCglobal(seebelow).Someinitiativesareunderwaytotryandharmonizethetwointooneglobalstandard,whichwouldcertainlybetherecommendedwaytoensurethewidespreadadoption,andhighvolumesofRFIDtagswithinthesupplychain.

Table 5. ISO 18000 Information Technology AIDC Techniques-RFID for Item Management - Air

Interface

18000 1 Part 1 Generic Parameters for Air Interface Communications for Globally Accepted

Frequencies 18000 2 Part 2 Parameters for Air Interface Communications below 135 KHz

18000 3 Part 3 Parameters for Air Interface Communications at 13.56 MHz 18000 4 Part 4 Parameters for Air Interface Communications at 2.45 GHz

18000 5 Part 5 Parameters for Air Interface Communications at 5.8 GHz

18000 6 Part 6 - Parameters for Air Interface Communications at 860 930 MHz

Table 6. EPCglobal standards evolution:

Protocol Frequency Description

Class0 UHF Read-only,factoryprogrammed

Class0Plus UHF Read-writeClass1 HF,UHF WORM,(Write-once,readmany)

Class1,G2

UHF

WORM; can be used globally;merges Classes 0 and 1 andperhapsISO18000-6

Class2 UHF Aproposedread-writetagSource: RFID Journal Jan 2004 issue

Regional Regulations and Frequency Allocation

RFID tags and readers fall under the category of short range devices (SRDs), whichalthoughtheydonotnormallyrequirealicense,theproductsthemselvesaregovernedbythe laws and regulations which vary from country to country. Today, the only globallyacceptedfrequencybandistheHF13.56MHz.ForpassiveUHFRFIDtheproblemismuchmorecomplicatedasfrequenciesallocatedinsomecountriesarenotallowedinothers,duetotheirproximitytoalreadyallocatedbandsfordevicessuchasmobilephonesandalarms.ThisdiscontinuityhasresultedintheITU(InternationalTelecommunicationsUnion)dividingtheworldintothreeregulatoryregions,thesebeing;

REGION 1: Europe, Middle East, Africa and the former Soviet Union including Siberia

REGION 2: North and South America and Pacific east of the International Date Line

REGION 3: Asia, Australia and the Pacific Rim West of the International date line

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The main regulatory bodies in the different regionsREGION1 :IntheUSA,theFederalCommunicationsCommission(FCC).

For UHF regulations see the FCC-Part 15 (15.249).whichcanbe foundat the followingwebsite:http://www.access.gpo.gov/nara/waisidx_01/47cfr15_01.html

AllocatedUHFband(902-928MHz), MaxPoweremission4WEIRP-FrequencyHopping

REGION2:InEurope,CEPT(EuropeanConferenceofPostalandTelecommunications)has

theresponsibilityoffrequencyassignmentandoutputpower.

ForUHF regulationsseepublicationERCREC70-73whichcanbe foundat thefollowingwebsitehttp://www.ero.dk/doc98/official/pdf/rec7003e.pdf

AllocatedUHFfixedband(869.3869.65MHz)

Poweremissionslimitedto500mWEIRP (expectedtobeenhancedto2Win2004) Readersmustoperatewithina10%dutycycleNoFrequencyorchannelhopping

,REGION3:InJAPAN,(MPHPT)MinistryofPublicManagement,HomeAffairs,Postsand

Telecommunication.

Regulation:JapaneseRadioLaw.ReferstoARIB(StandardsAssociationofRadioIndustriesandBusiness

JapanhasonlyrecentlyannouncedtheallocationofaUHFfrequencyat950MHz

ERP and EIRPThese aretwo reference parametersused todefine thepermittedradiated power inRFsystems.TheyareoftenquotedinRFIDreaderandtagspecifications.TheUStendstouseEIRPandEuropeERP.

TherelationshipbetweenthetwoisdefinedasEIRP=ERP*1.64MoreinformationaboutERPandEIRPcanbefoundinAppendixB-

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RFID Readers

HFReader UHFEPCReader

Courtesy of SAMSYS

Readers or interrogators as theyare sometimes called, area keyelementin anyRFIDsystem,andwillthereforebepartoftheproductevaluationandselectionprocess.UpuntiltherecentsurgeindevelopmentsforthesupplychainandEPCtags,readersweremainly

usedin accesscontrolsystemsandother lowvolumeRFIDapplications,whichmeantthattheproblemoftreatingverylargenumbersoftagsandhighvolumesofdatawasnotsuchaserious issue. This is now of course all changing, and many reader manufacturers arestartingto developnextgenerationproductstohandletheapplicationproblemsthatwillbespecifictothesupplychainandEPCinfrastructure.

Main Criteria for readers

Operating Frequency (HF or UHF) some companies are developing Multi-frequencyreaders

ProtocolAgilitySupportfordifferentTagProtocols(ISO,EPC,proprietary)Most

companiesofferMulti-protocolsupport,butdonotsupportall!

Differentregionalregulations

-UHFfrequencyagility902930MHzintheUSand869MHzinEurope-PowerRegulations:4WattsintheUSand500mWinEurope

-ManageFrequencyHoppingintheUSandDutyCycleinEurope

Networkingtohostcapability:- TCP/IP-WirelessLAN(802.11)

-EthernetLAN(10baseT)

-RS485

Abilitytonetworkmanyreaderstogether- viaconcentrators

-viamiddleware

AbilitytoupgradethereaderFirmwareinthefield - viainternet

-viaHostinterface

Managingmultipleantennas- Typically4antennas/reader

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- Howantennasarepolledormultiplexed

Adaptingtoantennaconditions -Dynamicauto-tuning

Interfacetomiddlewareproducts

DigitalI/Oforexternalsensorsandcontrolcircuits

Handheld Readers

Thesereadersareusedformanualinterventionwhereatagmayneedtobechecked,oreven updatedoff line. Industrial grade products for HFexist today from companies likePSIONTEKLOGIX.UHFproductsdoexist,butaremainlyeitherbasedaroundcommercialPDAdevices,whichalthoughtheyfunction,arenotclassedasindustrialgradeproducts.

RFID enabled HF Hand Held reader - Courtesy of PSION TEKLOGIX

RFID Label Printers

RFIDcompatiblelabelprintersaredesignedtoprogramdataintothepaperlabel-tags,as

theypassthroughthemachinefornormalprinting.TheprinterhasaninbuiltUHForHF(orboth)reader,capableoffirstrunningabasicfunctionalitycheckonthetag,forwhichifitfails,proceedstoprintavisiblerejectsignonthetagspapersurface.Tagswillneedtohavethecorrect reel format for specific printers. RFID label printers like the one shown fromPRINTRONIXbelowarecapableofprintingandprogrammingatanaveragethroughputof1.5labels/s,dependingonthelengthofthelabel.

Courtesy of PRINTRONIX

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Reader AntennasInanRFIDsystem, reader antennasare often themost tricky part todesign in. For low

powerproximityrange(

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RFID technology in the Supply chain

Definition of the Supply Chain.

The supply chain is a complex multi-stage processwhich involveseverythingfrom theprocurementofrawmaterialsusedtodevelopproducts,andtheirdeliverytocustomersviawarehousesanddistributioncenters.Supplychainsexistinbothservice,manufacturingandretailorganizations.Although,thecomplexityof thechainmayvarygreatlyfromindustryto

industryandfirmtofirm.Supplychainmanagement(SCM)canbeseenasthesupervisionofinformationand financesofthesematerials,astheymovethroughthedifferentprocesses,bycoordinatingandintegratingtheflowswithinandamongthedifferentcompaniesinvolved.Theefficiencyofthesupplychainhasadirectimpactontheprofitabilityofacompany.Itisnosurprisethereforetofindthatmanylargecorporatecompanieshavemadeitakeypartoftheirstrategy,andinvestedheavilyinsoftwaresystems(ERP,WMS..)andITinfrastructuredesignedtocontrolinventory,trackproductsandmanageassociatedfinance.

How will RFID help improve supply chain efficiencyRFIDwillbringanewdimensiontosupplychainmanagementbyprovidingamoreefficientwayofbeingabletoidentifyandtrackitemsatthevariousstagesthroughoutthesupplychain.Itwillallowproductdatatobecapturedautomatically,andthereforebemorequicklyavailableforusebyotherprocessessuchasASN,stockmanagementandrealtimebilling.

Comparison of Bar codes and RFIDBarcodesarepredominatelyusedtodayforidentifyingandtrackingproductsthroughoutthesupplychain.Eventhoughtheycanachieveefficienciesintheorderof90%,therearestillanumberofdeficienciesinthetechnology,forwhichRFID,isabletoprovideabettersolution

andfurtheroptimization.

Barcodedef iciency RFIDimprovedsolu t ionLineofSightTechnology AbletoScanandreadfromdifferentanglesand

throughcertainmaterials

Unable to withstand harsh conditions (dust,corrosive),mustbecleanandnotdeformed

abletofunctioninmuchharsherenvironments

NopotentialforfurtherTechnologyadvancement Technology advancement possible due to newchipandpackagingtechniques

Can only identify items generically and not asuniqueobjects

EPCcodewillbeabletoidentifyuniquelytypicallyup-to2

96items

Poortrackingtechnology,laborintensiveandslow Potentialto trackitems inreal timea theymovethroughthesupplychain

The main benefits of RFID in the supply chain.EventhoughRFIDapplicationsarestillattheearlystagesofdeployment,manycompaniesrunningpilotsystemshavebeenabletodemonstratesomeofthesignificantbenefitsthatRFIDpromises.Thereisnodoubtthatmorewillbediscoveredastheindustryadoptsthetechnologyonawiderscale.Thefollowingareexamplesofwhathasbeenidentifiedsofarbythedifferentstudiesandtests/pilotsrecentlycompletedwithinthesupplychain.

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AdvancedShipp ingNot ices(ASN)

RFIDisabletoautomaticallydetectwheneitherapalletorshipmenthasleftthewarehouseorDistributionCenter.ThiswillallowtonotonlygenerateanelectronicASNand notify the recipient, but also tobill clients inreal time insteadofwaitinguntiltheendoftheweekormonth,anddoingabatchoperation.

Shrinkage

Oneofthemajorproblemsinthesupplychainisproductlossorshrinkage,which

can account for anything from 2 to 5 % of stock. The causes mayvaryfrommisplacedorders,employeeandcustomertheftorinefficientstockmanagement.RFIDwithitssuperiortrackingandidentificationcapabilitywillbeableto localizewherelossesareoccurring.

ReturnedGoods

Fullvisibilityandautomationcanbepotentiallyachievedonreturnedgoodstherebyreducingfraud.

Anti -counte rf ei t Illegalduplicationandmanufactureofhighvalueproducts,isoneoftheindustries

mostwellknownproblems.Byintegratingatagintoitems,forexamplethebodyofanexpensiveladieshandbag,RFIDhasthepotentialtoauthenticateaproduct,andcombatthesaleoffalsegoodsontheblackmarkets.

SupplyChaineff iciencyRFID will enable the traceability and reduction in the numberof discrepanciesbetweenwhatasupplierinvoiced,andwhatacustomeractuallyreceived.

Improvedstockmanagement Managingstockisthekeypriorityformanyretailers.Studieshaveshownthatonaverage,productsarenotonthestoreshelves7%ofthetimeduetoinefficiencies

in stock management, which means of course a potential purchase loss.ImplementingRFIDattheitemlevelandonshelveswillgiveanautomaticwayofknowingandmanagingstocklevels.Howeverinordertoachievethisonalargescale,itisrecognizedthat tagswillhavetocomedowninpricetoaround5centsorless,andreaderstoaround100USD.

ReductioninlaborcostsAt DC s (Distribution Centers) labor accounts for nearly 70% of costs. It isestimated that RFIDcould reduce this bynearly 30%by removingtheneedformanualinterventionanduseofbarcodeswhenloadingcasesorstockingpallets.

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The EPC TM Electronic Product Code

At theheart of the currentRFIDbasedtechnologydrive to improvesupplychainefficiencyandreduceoperatingcosts,isTheEPC(ElectronicProductCode).WithoutitanditsmanygiantindustrialbackerslikeWal-Mart,RFIDinthesupplychainwouldstillbewhereitwas5yearsago,atechnologylookingforabusinesscase.Themomentumhasbeentremendous,andhassparkedoneoftheraretechnologyrevolutionswhereendusercompaniesareinthe

drivingseat.

EPC OriginsIn October 1999 the Auto-ID center was created in the Department of MechanicalEngineeringbyanumberofleadingfiguresatMIT.ThepotentialbenefitsofRFIDtagshadbeenidentifiedlongbefore,whatwasstoppingtheadoptionofthetechnologyinthesupply

chainwasthecostofthetags.TheAutoIDrecognizedthatinordertosolvethisproblem,tagsneededtobeassimpleaspossible,andactinsteadaspointerstoinformationheldonserversinthesamewayasinformationisstoredontheinternet.Thisleadto the ideaoftheEPC(ElectronicProductCode)whichwouldprovidefastanddetailedinformationofproductsanywhereinthesupplychain.Thegoalhowever,wasnottoreplacebarcodes,butrathertocreateamigrationpathforcompaniestomovefrombarcodetoRFID.

TheAuto-IDCenterofficiallyclosedonOctober26th,2003.Thefinalboardmeetingwasheldin Tokyo, Japan. The Center had completed its work and transferred its technology toEPCglobal(www.epcglobalinc.org),whichwilladministeranddevelopEPCstandardsgoingforward.

EPC layoutThecodeissimilarto theUPC(UniversalProductCode)usedinbarcodes, andrangesfrom64bitsto256bitswith4 distinct fieldsdescribedbelowin fig10..Whatsets theEPC

apartfrombarcodesisitsserialnumberwhichallowstodistinguishtheuniquenessofanitem,andtrackitthroughthesupplychain.

Fig 10. Layout of an EPC which is 96 bits in length

Header(0-7)bitsTheHeaderis8bits,anddefinesthelengthofthecodeinthiscaseO1indicates

anEPCtype1numberwhichis96bitsinlength.TheEPClengthrangesfrom64to256bits.

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EPCmanager(8-35)bitsWilltypicallycontainthemanufactureroftheProducttheEPCtagisattachedto

ObjectClass(36-59)bits ReferstotheexacttypeofproductinthesamewayaanSKU(StockKeepingUnit)

SerialNumber(6096)bits

Providesauniqueidentifierforupto296products

EPC infrastructure

fig. 11 The basic steps of EPC infrastructure

An EPC is stored into an RFID tag/label

and attached to an item Tag Tag Sensor

Reader scans and reads the EPC Sends Data to a computer running middleware

Reader

Temp.

ePC s

Filter Data Query ONS (Object naming Service)

Manage Readers

Middleware/Savant

ID

Internet PML server

ONS database maps the EPC to a URL

URL points to the location whereinformation is stored using PML

ONS

Database

PML data

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EPC infrastructurewill allow immediate access to information, whichwillnotonlyoptimizeexistingservicessuchASN,butalsohavethepotentialtocreatenewservices,forexample;aretailercouldautomaticallylowerpricesastheexpirydateapproaches,oramanufacturercould recall a specific batch of products duetohealthconcerns,andifneededpinpointsourceoftheproblemdowntoauniqueproduct.

Middleware or Savant Software

ThesheerpotentialvolumeofdatacreatedbybillionsofEPCtagswouldveryquicklygrindmost existing companies enterprise software and IT infrastructure to a standstill within amatterofminutes.TheanswertothisproblemismiddlewareorSavants.RFIDsavantsserveasasoftwarebufferwhichsitsalmostinvisiblebetweentheRFIDreaders,andtheserversstoring the product information. Itallowscompaniesto process relativelyunstructuredtagdatatakenfrommanyRFIDreaders,anddirectittotheappropriateinformationsystems.Savantsareabletoperformmanydifferentoperations,suchasmonitortheRFIDreader

devices,managefalsereads,cachedataandfinallyqueryanObjectNamingService(ONS).

Object Name Service (ONS)

ONSmatches theEPC code toinformationabout the product viaa queryingmechanismsimilartotheDNS(DomainNamingsystem)usedintheinternet,whichisalreadyproventechnologycapableofhandlingthevolumesdataexpectedin anEPCRFIDsystem.TheONSserverprovidestheIPaddressofaPMLServerthatstoresinformationrelevanttotheEPC.

Physical Markup Language (PML)WhilsttheEPCisabletoidentifytheindividualproduct,therealusefulinformationiswritteninanewstandardsoftwarelanguagecalledPhysicalMarkupLanguage.PMLitselfisbasedon the widely used and accepted extensible markup language (XML), designed as adocumentformattoexchangedataacrosstheinternet.Itisnotsurprisingtherefore,withsomuchof the infrastructurefor EPCbeingborrowedfrom theinternet(DNS,XML..), that it isoftenreferredtoas theinternetofthings.

PMLisdesignedtostoreanyrelevantinformationaboutaproduct;forexample,

(1) Locationinformation e.g., tag X was detected by reader Y, which is located atloadingdockZ;

(2) Telemetry information [Physical properties of an object e.g., its mass; Physicalpropertiesoftheenvironment,inwhichagroupofobjectsislocated,e.g.,ambienttemperature];

(3) Compositioninformatione.g.,thecompositionofanindividuallogisticalunitmadeupofapallet,casesanditemsTheinformationmodelwillalsoincludethehistoryofthevariousinformationelementslisted above e.g., a collectionof the various single

locationreadingswillresultinalocationtrace.(4) manufacturingandexpirydates

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How the EPC will automate the supply chain (courtesy of EPCglobal and XPLANE) Atthep roducta ssembly-p ackagingl ine.

1.Each Item contains an RFIDtagwhich has a uniqueidentifiercalledanEPCstoredinitsmemory.

2.Items can now be automatically and cost-effectivelyidentified,countedandtracked.Casesand pallets canalsocarrytheirownuniquetags.3.As pallets leave the manufacturer, an RFID readerpositionedattheloadingdockdoorbeamsaradiowavethatwakesupthetags.

4.a) TheTagscommunicatetheirindividualEPCs

tothe reader,which rapidlyswitches themonandoffinsequence(anti-collision),untilallareread.

b) The reader sends the EPC to a computer

calledSavantTM,whichinturn,sendstheEPCovertheinternettoanObjectNamingService(ONS) database, which produces acorrespondingaddress.TheONSmatchestheEPC toanother server (PML), whichhas thefulldetailsabouttheproduct.

c) ThePML(PhysicalMarkupLanguage)server

stores details about the manufacturersproducts.Becauseitknowswheretheproductwasmade, ifan accident involving adefectarises, the source of the problem can betrackedandtheproductsimmediatelyrecalled.

Savant ONS server PML serverComputer

EPC: Look under Can of Cherry

Fxyzz3t0nn;4x;CC Super Cola Inc Soda, shippedFrom Boston,MA

5. At theDistr ibuti onCenterIftheunloadingareacontainsanRFIDreader,theresno need to open the packages and examine theircontents.ASAVANTprovidesacargolist,andthepalletisquicklyroutedtotheappropriatetruck.

6. At theRetailSto re As soon as it arrives , retail systems are updated toinclude every item. In this way storescan locatetheirentireinventoryautomatically,accuratelyandatlowcost.Reader enabled smart shelves can automaticallyordermoreproduct from thesystemandthereforekeepstocktocost-effectiveandefficientlevels.

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Security in RFID Systems

RFIDtagsusedinthesupplychainwillcontaindatarangingfromsimpleIDnumbers(EPC),

tomoreimportantinformationaboutaproduct.Forexampleinthehealthindustry,itcouldbe

thebloodtypeofasample.Themaingoalofanysecuritysystemdesignedtoprotectdatastoredinmediumssuchastags,computerdiskdrives,orsmartcardsisbasicallytopreventanyunauthorizedpersonfrombeingabletoeither;

a) Obtainaccessandlearnthedatacontentsb) Obtainaccessandmodify/corrupt/erasethedatacontentsc) Copythedatacontentstoasimilarstoragedevice(duplicate)

In a completesystem, security of data asdefined abovenot only involves the storagemedium,butalsohowdataiscreatedandtransferredfromahosttothemedium(orvice

versa).Forexample,whenanengineerbrokethesecurityofaFrenchbankcreditcardafewyearsago,hediditnotbycompromisingthechipsecurity,butbyhackingthereaderterminal.

Thefollowingarescenariosthatcouldhappeninthesupplychain.

1) IndustrialSabotagesomebodywithagrievanceagainstacompanydecidestostartcorruptingdataintagsbyusingahandhelddevice,anderasingormodifyingthecontents.

2) IndustrialEspionage Aratherunlawful competitorwouldliketoknowhowmany,

andwhattypeofproductsarebeingmanufactured,andshippedbyyourcompany.Hecouldpossiblyachievethisinthefollowingways

i. Eavesdropping l istening in on longer range communication

systemslikeUHFwhichbroadcastsignals(albeitveryweak)upto

100meters someprotocolshave abasic securitywhichensuresthattheIDNisnevertransmittedcompletelyinonestream.ii. PlacingboguswellconcealedreaderslinkedtoaPCsomewherein

theproximityofthetagsmovingthroughtheproductionlineiii. Usinghandhelddevices

3) Counterfeiting Beingabletoreadorinterceptdatabeingwrittenintoatagwhich

uniquelyidentifiesorcertifiesaproduct.Oncethedataisknown,similarread/writetagscouldbepurchasedandupdatedwiththeauthenticdata,thuscreatingtherealpossibilityofcounterfeitingproductswhicharesupposedtobeprotectedbyatag.

Alltheabovescenariosarepotential risksifnosecurityisimplementedinthetagandreader.The importance attached to protecting data in the supply chain will depend on theapplication, andthe companies strategy towards security. In some cases legislationwill

imposeit.Ofcoursebarcodeswhichareusedtoday,canbeeasilyread,decrypted,andevendestroyed,butnotonthewide-spreadandautomaticscalepossiblewithRFID.Eventhesimplestsecuritycostssiliconarea,andthereforewillimpactonthefinaltagprice.This goes against the current trendof trying to produce the smallest, andcheapest tagpossible.Everycompanyisthereforefacedwiththistradeoffbetweencheaperunsecuredtags,andthepotentialsecurityriskstheyentail.

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Conclusion

The interest in RFID as a solution to optimize further the supply chain is gatheringmomentumataneverincreasingpace,withmoreandmorecompaniesannouncingtrials

andmandatestotheirsuppliers.Thetechnologyisstillnotyetwidelyunderstoodorinstalledin the supply chain, and cost/ROI models far from established. Many companies arethereforenowfacedwith thedifficultchoicein decidingwhethertheyshouldbelookingatRFIDnow,orwaitinguntildeploymentismorewidespread.ThereisastrongtemptationtogetcarriedawaybyallthehypeandpublicitysurroundingRFIDtoday,whichisallthemorereason tohave asenseofrealityastowhatitmeanstointegrateRFID,whyyourcompanywould want to do it , and what would be the acceptable time frames for the perceivedbenefits.InvestinginRFIDonthescalerequiredforthesupplychainwillbeaverycostlyexercise,andifnotmanagedcorrectlycouldleadtounnecessarylosses.Thetechnologyisnotplugandplay,andwillhavetobeadaptedtoeachapplication.Furthermore,implementingan

infrastructuretosupportEPCdatacouldhaveaconsiderableimpactonexistingITsystems.EvenatthisearlystageintheadoptionofRFIDinthesupplychain,thereisenoughevidencetodemonstratethatwiththerightstrategies,RFIDwillbringbenefits.Thetechnologyisheretostay,andwilleventuallybecomewidelyadoptedwithinthesupplychain.Thosecompaniesprepared to invest now will not only become theearly winners,butalsobenefitfromtheexperiencebybeingcapableofextendingtheapplicationofRFIDintonewservices

About the Author.Steve Lewis

IsthefounderofLARANacompanysetuptoprovideprofessionalconsultingandmarketingservicesforRFIDtechnology.QualifiedwithamicroelectronicsdegreefromtheuniversityofWales,hehasacombinedexperienceofover20 years in thesemi-conductorandRFIDindustries, having held positions in IC silicon design, product marketing, and businessdevelopment.Heisaveteranoftwosiliconstartups,ES2andINSIDETechnologies,andhas spent the last 8 years working in a wide range of RFIDapplications andmarketsincluding;VehicleKeylessEntrysystems,AccessControl,IDandtransport.

ContactDetails

Email:steve.lewis@laranrfid.com

Website:www.laranrfid.com

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Appendix A

More about Near and Far fields

Up until recently, nearly all passive RFID systems in production were either LF or HF.Designing systems at these frequencies was based on a few equations relating to

inductance,mutualinductanceandtheknowledgethatthemagneticfieldreducedrapidlywith distance (1/r

3). With the recent explosion of RFID in the supply chain came the

recognition thatUHF wouldallow longer read range,andfaster detectionof many tags.EngineersusedtodevelopingLFandHFsystems,arenowfacedwithacompletelydifferentconceptandsetofchallengeswithUHF.OneofthenewconceptsencounteredwhenlookingatUHFforthefirsttime,istheideaoftwo distinct and different regions around an antenna called the near fieldand far field.ElectromagnetictheorydevelopedbyMaxwellinthe19

thcenturyshowsthatanyconductor

(e.g.antenna)suppliedwithanalternatingcurrentproducesavaryingmagneticfield(H-field)whichinturn,producesElectricFieldlines(E-field)inspace.Thisistermedthenearfield.

InthenearfieldboththeEandHfieldsarerelativelystaticwithnopropagation.Theyonlyvary instrengthas thecurrentvaries ,withthemagneticfluxof theH-fieldcomingoutfromtheantenna,andgoingbackin,andtheE-fieldemanatingout-wards.Maxwellalsoprovedthatbeyondthisquasi-staticnear field,both theE-fieldsandH-fieldsatacertaindistance,detachedthemselvesfromtheconductorandpropagatedintofreespaceasa combined

wave,movingatthespeedoflightwithaconstantratioofE/H=120or377.(Ohmsareusedbecause theE-fieldismeasuredinvoltspermeterV/MandtheH-fieldinampspermeterA/M.).Thepointatwhichthishappensiscalledthe farfield.

Fig A-1 Transition region between near and far fields

Becausechangesinelectromagneticfieldsoccurgradually,theboundarybetweenthetwofieldsisnotexactlydefined.Thedistanceatwhichthetwoseparateoutfromthesourceasafixedplanewavecanbemodeledinanumberofways.Thesimpler2-regionmodelshownin

figA-2givesadistanceof /2wherethefalloffis1/r3(dominantfield)and1/r

2inthenear

fieldregion,and1/r inthe far field. The 3-regionmodelismuchmorecomplicatedwithatransitionregionwherecomponentsdecayas1/r,1/r

2and1/r

3..

r /0.1 1.0 10

10

100

1000

10000

Magnetic field

Electric field

Transitional field

Plane waveWave impedence,

OhmsZo = 377Ohms

r

0.011/2

Near Field Far Field

5.0

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Fig A-2 Different Region models

Thedistancemeasureof/2canbeconsideredasareferencepoint,whereifthetagisinaregionmuchlessthan1/20wavelengths,thenwearedefinitelyinthenearfield.Fordistancesgreaterthan5wavelengthswearedefinitelyinthefarfield.ThisisshowninTableA-1

Table A-1 Near and Far field limits

Band NearFieldRegion FarFieldRegion

LF 12Km

HF 110mUHF 1.65m

Microwave 0.25cm

ApplyingsomepracticalsensewecandrawthefollowingconclusionsforRFIDtags

1) AtLF,tagsalwaysworkinthenearfield2) Atmicrowave,tagsalwaysworkinthefarfield3) AtHF,tagsworkinthenearfieldbutsomeintermediate(transition)fieldcomponents

areeffectiveatantennaemissionmeasurementranges.4) AtUHF,passivetagsoperateinthetransitionfieldareaortheFarfield

1/r 1/r 1/r 1/r1/r.1/r

Dominant

Terms

in the region

3- REGION MODEL 2- REGION MODEL

FAR FIELD NEAR FIELD NEAR FIELD FAR FIELD

TRANSITION

ZONE

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APPENDIX B

EIRP and ERP Power Emissions

EIRP(EquivalentIsotropicRadiatedPower)EIRPrefers totheproductof thepowersuppliedtotheantennaandtheantennagaininagivendirectionrelativetoanisotropicantennaAnIsotropicantennaisonewhichradiatespowerequallyinalldirections(e.gasphere)ERP(EffectiveRadiatedPower)ERPreferstotheproductofthepowersuppliedtotheantenna anditsgainrelativetoahalf-wavedipoleinagivendirection.

EIRP=ERPx1.64

Comment:Itwouldmakemoresenseofcoursetojusthaveoneharmonizedpowerterm,eitherERPorEIRP,howeveras isoften the casewith International standards, its not always easy toachieve.

Here is an extract from a recent BloonstonLaw Telecom Update from the FCC on thissubject.

ERP/E IRP issues:

Although theCommissionrecommended in the 2000BiennialReviewReportthatarule-makingproposalbeinitiatedtoconsiderusingequivalentisotropicallyradiatedpower(EIRP)exclusively in Commission rules, it now tentatively concludes that the costs ofimplementation and potential for greater confusion that would likely be associated withmaking a wholesale conversion from effective radiated power (ERP)limitsto EIRPlimits,

outweigh the potential benefits to those licensees whodonotpossess thescientificorengineeringexpertisetodistinguishbetweenthetwostandards.Additionally,theagencystates that theconversion fromERPtoEIRPisasimplecalculation.Such a change in the rules would require extensive modif ications, not only for theCommission(e.g.,reprogrammingtheULS,amendinginternationalagreementsnegotiatedin termsof ERP,etc.),butalso for licensees, frequency coordinators,manufacturers,and

othersinthewirelessindustry.Moreover,becauseanEIRPlimitisalwaysalargernumberthantheequivalent ERP limit, theFCC believes that restating all ERPlimitsas EIRPlimitscouldlikelycausesomeentities(e.g.,licensees,frequency;coordinators,etc.)tomistakenlythinkthattheCommissionhasincreasedthepermittedpower