an introduction to rfid technology · 2007. 10. 3. · led to new passive rfid designs based on...

1536-1268/06/$20.00 © 2006 IEEE ■ Published by the IEEE CS and IEEE ComSoc PERVASIVEcomputing 25

R F I D T E C H N O L O G Y

An Introduction to RFID Technology

In recent years, radio frequency identifica-tion technology has moved from obscurityinto mainstream applications that helpspeed the handling of manufactured goodsand materials. RFID enables identification

from a distance, and unlike earlier bar-code tech-nology (see the sidebar), it does so without requir-ing a line of sight.1 RFID tags (see figure 1) sup-port a larger set of unique IDs than bar codes and

can incorporate additional datasuch as manufacturer, producttype, and even measure envi-ronmental factors such as tem-perature. Furthermore, RFID

systems can discern many different tags located inthe same general area without human assistance.In contrast, consider a supermarket checkoutcounter, where you must orient each bar-codeditem toward a reader before scanning it.

So why has it taken over 50 years for this tech-nology to become mainstream? The primary rea-son is cost. For electronic identification tech-nologies to compete with the rock-bottom pricingof printed symbols, they must either be equally

low-cost or provide enough added value for anorganization to recover the cost elsewhere. RFIDisn’t as cheap as traditional labeling technologies,but it does offer added value and is now at a crit-ical price point that could enable its large-scaleadoption for managing consumer retail goods.Here I introduce the principles of RFID, discussits primary technologies and applications, andreview the challenges organizations will face indeploying this technology.

RFID principles Many types of RFID exist, but at the highest

level, we can divide RFID devices into two classes:active and passive. Active tags require a powersource—they’re either connected to a poweredinfrastructure or use energy stored in an inte-grated battery. In the latter case, a tag’s lifetime islimited by the stored energy, balanced against thenumber of read operations the device mustundergo. One example of an active tag is thetransponder attached to an aircraft that identi-fies its national origin. Another example is aLoJack device attached to a car, which incorpo-rates cellular technology and a GPS to locate thecar if stolen.

However, batteries make the cost, size, and life-time of active tags impractical for the retail trade.Passive RFID is of interest because the tags don’trequire batteries or maintenance. The tags alsohave an indefinite operational life and are smallenough to fit into a practical adhesive label. A pas-sive tag consists of three parts: an antenna, a semi-

RFID is at a critical price point that could enable its large-scale adoption.What strengths are pushing it forward? What technical challenges andprivacy concerns must we still address?

Roy WantIntel Research

About the Review ProcessThis article was reviewed and accepted before Roy Want became IEEE

Pervasive Computing’s editor in chief. It went through our standard peer-

review process and was accepted 28 Nov. 2005. —M. Satyanarayanan

conductor chip attached to the antenna,and some form of encapsulation.

The tag reader is responsible for pow-ering and communicating with a tag.

The tag antenna captures energy andtransfers the tag’s ID (the tag’s chipcoordinates this process). The encap-sulation maintains the tag’s integrity

and protects the antenna and chip fromenvironmental conditions or reagents.The encapsulation could be a small glassvial (see figure 2a) or a laminar plasticsubstrate with adhesive on one side toenable easy attachment to goods (see fig-ure 2b).

Two fundamentally different RFIDdesign approaches exist for transferringpower from the reader to the tag: mag-netic induction and electromagnetic(EM) wave capture. These two designstake advantage of the EM propertiesassociated with an RF antenna—thenear field and the far field. Both cantransfer enough power to a remote tagto sustain its operation—typicallybetween 10 �W and 1 mW, dependingon the tag type. (For comparison, thenominal power an Intel XScale processorconsumes is approximately 500 mW,and an Intel Pentium 4 consumes up to50 W.) Through various modulationtechniques, near- and far-field-based sig-nals can also transmit and receive data.1

26 PERVASIVEcomputing www.computer.org/pervasive


Figure 1. Three different RFID tags—theycome in all shapes and sizes.

E ver since the advent of large-scale manufacturing, rapid iden-tification techniques have helped speed the handling ofgoods and materials. Historically, printed labels—a simple, cost-

effective technology—have been the staple of the manufacturing

industry. In the 1970s, labeling made a giant leap forward with

the introduction of Universal Product Code bar codes, which

helped automate and standardize the identification process. Bar

codes are also cheap to produce, but they have many limitations.

They require a clear line of sight between the reader and tag, can

be obscured by grease and nearby objects, and are hard to read in

sunlight or when printed on some substrates. RFID is an alternative

labeling technology that has also been around for decades.

The British employed RFID principles in World War II to identify

their aircraft using the IFF (Identification Friend or Foe) system. In

the 1960s, Los Alamos National Laboratory carried out work

more closely related to modern RFID in its effort to explore access

control. It incorporated RFID tags into employee badges to auto-

matically identify people, limit access to secure areas, and make

it harder to forge the badges. Niche domains have also used

RFID in various applications, such as to identify animals, label

airline luggage, time marathon runners, make toys interactive,

prevent theft, and locate lost items.

Regardless of these applications, RFID technology remained rel-

atively obscure for many years. Now, however, three major organi-

zations are pioneering its large-scale adoption: Wal-Mart, Tesco,

and the US Department of Defense. Each aims to offer more com-

petitive pricing by using RFID to lower operational costs by

streamlining the tracking of stock, sales, and orders. When used in

combination with computerized databases and inventory control,

linked through digital communication networks across a global set

of locations, RFID can pinpoint individual items as they move

between factories, warehouses, vehicles, and stores.

RFID: From Obscurity to Wal-Mart

Near-field RFIDFaraday’s principle of magnetic induc-

tion is the basis of near-field couplingbetween a reader and tag. A reader passesa large alternating current through areading coil, resulting in an alternatingmagnetic field in its locality. If you placea tag that incorporates a smaller coil (seefigure 3) in this field, an alternating volt-age will appear across it. If this voltage isrectified and coupled to a capacitor, areservoir of charge accumulates, whichyou can then use to power the tag chip.

Tags that use near-field coupling senddata back to the reader using load mod-ulation. Because any current drawn fromthe tag coil will give rise to its own smallmagnetic field—which will oppose thereader’s field—the reader coil can detectthis as a small increase in current flow-ing through it. This current is propor-tional to the load applied to the tag’s coil(hence load modulation).

This is the same principle used inpower transformers found in most homestoday—although usually a transformer’sprimary and secondary coil are woundclosely together to ensure efficient powertransfer. However, as the magnetic fieldextends beyond the primary coil, a sec-ondary coil can still acquire some of theenergy at a distance, similar to a reader

and a tag. Thus, if the tag’s electronicsapplies a load to its own antenna coil andvaries it over time, a signal can be encodedas tiny variations in the magnetic fieldstrength representing the tag’s ID. Thereader can then recover this signal bymonitoring the change in current throughthe reader coil. A variety of modulationencodings are possible depending on thenumber of ID bits required, the datatransfer rate, and additional redundancybits placed in the code to remove errorsresulting from noise in the communica-tion channel.

Near-field coupling is the moststraightforward approach for imple-menting a passive RFID system. This iswhy it was the first approach taken andhas resulted in many subsequent stan-dards, such as ISO 15693 and 14443,and a variety of proprietary solutions.However, near-field communication hassome physical limitations.

The range for which we can use mag-netic induction approximates to c/2πf,where c is a constant (the speed of light)and f is the frequency. Thus, as the fre-quency of operation increases, the dis-tance over which near-field couplingcan operate decreases. A further limi-tation is the energy available for induc-tion as a function of distance from the

reader coil. The magnetic field drops offat a factor of 1/r3, where r is the sepa-ration of the tag and reader, along a cen-ter line perpendicular to the coil’s plane.So, as applications require more ID bitsas well as discrimination between mul-tiple tags in the same locality for a fixedread time, each tag requires a higherdata rate and thus a higher operatingfrequency. These design pressures haveled to new passive RFID designs basedon far-field communication.

Far-field RFID RFID tags based on far-field emissions

(see figure 4) capture EM waves propa-gating from a dipole antenna attachedto the reader. A smaller dipole antenna inthe tag receives this energy as an alter-nating potential difference that appearsacross the arms of the dipole. A diodecan rectify this potential and link it to acapacitor, which will result in an accu-mulation of energy in order to power itselectronics. However, unlike the induc-tive designs, the tags are beyond therange of the reader’s near field, and infor-mation can’t be transmitted back to thereader using load modulation.

The technique designers use for com-mercial far-field RFID tags is back scat-tering (see figure 5). If they design an

JANUARY–MARCH 2006 PERVASIVEcomputing 27

Figure 2. RFID tags based on near-field coupling: (a) a 128 kHz Trovan tag, encapsulated in a small glass vial that’s approximately 1 cm long and (b) a 13.56 MHz Tiris tag (www.ti.com/rfid), which has a laminar plastic substrate (approximately 5 � 5 cm) withadhesive for easy attachment to goods.

(a) (b)

antenna with precise dimensions, it canbe tuned to a particular frequency andabsorb most of the energy that reaches itat that frequency. However, if an imped-ance mismatch occurs at this frequency,the antenna will reflect back some of theenergy (as tiny waves) toward the reader,

which can then detect the energy using asensitive radio receiver. By changing theantenna’s impedance over time, the tagcan reflect back more or less of theincoming signal in a pattern that encodesthe tag’s ID.

In practice, you can detune a tag’s

antenna for this purpose by placing atransistor across its dipole and then turn-ing it partially on and off. As a roughdesign guide, tags that use far-field prin-ciples operate at greater than 100 MHztypically in the ultra high-frequency(UHF) band (such as 2.45 GHz); below



Alternating magnetic field inthe near-field region

Using induction for power coupling from reader to tag andload modulation to transfer data from tag to reader

RFIDreader

RFIDtag

Magnetic fieldaffected by tag data

Binary tag ID

Glass or plasticencapsulation

Near-field region Far-field region

Propagating electromagneticwaves

Power and data

(if tag supportswrite)

Coil

c/2πƒ

Data viachangesin fieldstrength

Figure 3. Near-field power/communication mechanism for RFID tags operating at less than 100 MHz.

Figure 4. RFID tags based on far-field coupling: (a) a 900-MHz Alien tag (16 � 1 cm) and (b) a 2.45-GHz Alien tag (8 � 5 cm).

(a) (b)

this frequency is the domain of RFIDbased on near-field coupling.

A far-field system’s range is limited bythe amount of energy that reaches thetag from the reader and by how sensi-tive the reader’s radio receiver is to thereflected signal. The actual return signalis very small, because it’s the result oftwo attenuations, each based on aninverse square law—the first attenuationoccurs as EM waves radiate from thereader to the tag, and the second whenreflected waves travel back from the tagto the reader. Thus the returning energyis 1/r4 (again, r is the separation of thetag and reader).

Fortunately, thanks to Moore’s lawand the shrinking feature size of semi-conductor manufacturing, the energyrequired to power a tag at a given fre-quency continues to decrease (currentlyas low as a few microwatts). So, withmodern semiconductors, we can designtags that can be read at increasinglygreater distances than were possible afew years ago. Furthermore, inexpensiveradio receivers have been developed with

improved sensitivity so they can nowdetect signals, for a reasonable cost, withpower levels on the order of –100 dBmin the 2.4-GHz band. A typical far-fieldreader can successfully interrogate tags3 m away, and some RFID companiesclaim their products have read ranges ofup to 6 m.

EPCglobal’s work was key to pro-moting the design of UHF tags (seewww.epcglobalinc.org), which has beenthe basis of RFID trials at both Wal-Mart and Tesco (see the sidebar for moreinformation about the trials). EPCglobalwas originally the MIT Auto-ID Center,a nonprofit organization set up by theMIT Media Lab. The center later dividedinto Auto-ID labs, still part of MIT, andEPCglobal, a commercial company. Thiscompany has defined an extensible rangeof tag standards, but its Class-1 Gener-ation-1 96-bit tag is the one receiving themost attention of late. This tag can labelover 50 quadrillion (50 � 1015) items,making it possible to uniquely labelevery manufactured item for the fore-seeable future—not just using generic

product codes. This isn’t necessary forbasic inventory control, but it has impli-cations for tracing manufacturing faultsand stolen goods and for detectingforgery. It also offers the more contro-versial post-sale marketing opportuni-ties, enabling direct marketing based onprior purchases. (I discuss the related pri-vacy concerns later on.)

Adopting a standard: The Near-Field CommunicationForum

An important recent developmentopens up new possibilities for morewidespread RFID applications. Since2002, Philips has pioneered an openstandard through EMCA International,resulting in the Near-Field Communi-cation Forum (www.nfc-forum.org). Theforum sets out to integrate active signal-ing between mobile devices using near-field coupling, and it uses an approachthat is compatible with reading existingpassive RFID products. The new NFCstandard aims to provide a mechanismby which wireless mobile devices can


Data (if tag supports data write)

Using electromagnetic (EM) wave capture to transfer power from reader to tag and EM backscatter to transfer data from tag to reader

Binary tag ID Glass or plasticencapsulation

Near-field region Far-field region

Propagating electromagnetic waves(typically UHF)

Antenna dipole

Power

RFIDreader

RFID tag

Data modulatedon signal reflected

by tag

Figure 5. Far-field power/communication mechanism for RFID tags operating at greater than 100 MHz.

communicate with peer devices in theimmediate locality (up to 20 cm), ratherthan rely on the discovery mechanismsof popular short-range radio standards.These standards, such as Bluetooth andWi-Fi, have unpredictable propagationcharacteristics and might form associa-tions with devices that aren’t local.

The NFC standard aims to streamlinethe discovery process by passing wire-less Media Access Control addresses andchannel-encryption keys between radiosthrough a near-field coupling side chan-nel, which, when limited to 20 cm, letsusers enforce their own physical securityfor encryption key exchange. The forumdeliberately designed the NFC standardto be compatible with ISO 15693 RFIDtags operating in the 13.56-MHz band.It also allows mobile devices to read thisalready popular tag standard and to becompatible with the FeliCa and Mifaresmart card standards, widely used inJapan.

In 2004, Nokia announced the 3200GSM cell phone, which incorporates anNFC reader (see figure 6). Although thecompany hasn’t published an extensivelist of potential applications, the phonecan make electronic payments (similarto a smart card) and place calls based onthe RFID tags it encounters. For exam-ple, you could place your phone near anRFID tag attached to a taxi-stand sign,and your phone would call the taxi com-pany’s coordinator to request a taxi atthat location.2 This model offers a closelink between the virtual representationswithin a computer’s memory, such as thepositions of taxis being tracked by thedispatch computer, and the physicalworld, such as signs and people with cellphones. Furthermore, it is a key enablingtechnology for implementing MarkWeiser’s vision of ubiquitous and perva-sive computing.3

A complication for broad adoption ofthe NFC standard is that state-of-the-artEPCglobal RFID tags are based on far-

field communication techniques, work-ing at UHF frequencies. Unfortunately,NFC and EPCglobal standards are fun-damentally incompatible.

Reading colocated tagsOne commercial objective of RFID

systems is to read, and charge for, alltagged goods in a standard supermarketshopping cart as it is pushed through aninstrumented checkout aisle. Such a sys-tem would speed up the checkoutprocess and reduce operational costs.

Even if the RF reading environment foran RFID tag is ideal, it’s still an engi-neering challenge to support multiplecolocated tags. Consider two tags situ-ated next to each other and equidistantfrom the reader. On hearing the reader’ssignal, both would acquire enough powerto turn on and transmit a response backto the reader, resulting in a collision. Thedata from both tags would be superim-posed and garbled.

In CSMA (carrier sense multipleaccess)-based communication networks,such as Ethernet, this is an old probl-em that an anticollision protocol canresolve. In its simplest form, the protocolinserts a random delay between the

beginning of the interrogation signal andthe tag’s response. But a collision mightstill occur, so the reader must initiate sev-eral rounds of interrogation until it hearsall the tags in that area with high prob-ability. The number of rounds used,number of tags present, and duration ofeach tag reply can be used to calculatethe probability of all tags being detected.By modifying the number of rounds, wecan adjust the probability to suit typicaloperation conditions. We can furtherenhance this protocol by preventing tagsthat have already been heard by thereader from responding on the nextround until the current interrogationcycle ends.

Using another anticollision approach,the EPCglobal class-1 standard imple-ments an algorithm based on a QueryTree protocol. The reader starts an inter-rogation cycle by asking which of theID space’s top branches (modeled as abinary tree) contain tags. The algorithmrecursively repeats for each subtreebranch, but if a particular subtree doesn’tgenerate a reply, the reader won’t con-sider any of its branches and subtrees inthe remaining search space. In otherwords, that branch is pruned from thebinary tree. After a short time, all tagspresent will respond to the reader indepth-first-search order. EPCglobal sys-tems using this anticollision algorithmcan potentially read 500 colocated tagsper second.

Enabling a distributed memoryrevolution

Another distinguishing feature ofmodern RFID is that tags can contain farmore information than a simple ID.They can incorporate additional read-only or read-write memory, which areader can then further interact with.

Read-only memory might containadditional product details that don’tneed to be read every time a tag is inter-rogated but are available when required.



Figure 6. The Nokia 3200 cell phone features a Near Field Communicationsreader. From the front, it looks like anordinary cell phone, but on the back, youcan see the reader coil molded into thehousing. (figure courtesy of Nokia)

For example, the tag memory might con-tain a batch code, so if some productsare found to be faulty, the code can helpfind other items with the same defects.

Tag memory can also be used toenable tags to store self-describing infor-mation. Although a tag’s unique ID canbe used to recover its records in an onlinedatabase, communication with the data-base might not always be possible. Forexample, if a package is misdirected dur-ing transportation, the receiving organi-zation might not be able to determine itscorrect destination. Additional destina-tion information written into the tagwould obviate the need and cost of afully networked tracking system.

Other RFID applications take advan-tage of read-write memory available insome tag types. Although the size of thesememories is currently small—typically200 to 8,000 bits—it’s likely to grow inthe future and be used in creative ways.These tags could lead to a distributedmemory capability embedded in our sur-roundings. If locations in a city weretagged with RFID,4 a reader could writemessages directly into the tag. This mightbe used for historical data or for updatesabout nearby services.

Additionally, tags in commercial prod-ucts could contain ownership history. Forexample, a tag attached to secondhandconsumer goods might tell you about theprevious owners and when and where theproduct changed hands. This is similarto the providence documentation thatoften accompanies antiques of value;using RFID to extend this kind of track-ing to everyday items could provide con-sumers with greater confidence in theirsecondhand purchases.

Time stamps can also be stored in anRFID memory alongside other data thathas been written there. For example, iftwo writes occur sequentially but sepa-rated in time, the second write musthave occurred after the first write. If areader were trying to forge the writing

time of the second write, the first writeat least constrains when the forgery hasoccurred to after the first time stamp.Unfortunately, passive RFID doesn’thave the continuous power needed tosupport an onboard clock, so timestamps couldn’t be derived from the tagitself. However, the readers—poweredfrom the infrastructure or from batter-

ies in a handheld unit—could containan electronic clock and write timestamps alongside other data written intothe tag.

RFID that incorporates sensing One of the most intriguing aspects of

modern RFID tags is that they can con-vey information that extends beyonddata stored in an internal memory andinclude data that onboard sensors cre-ated dynamically.5 Commercial versionsof RFID technology can already ensurethat critical environmental parametershaven’t been exceeded. For example, ifyou drop a package on the floor, theimpact might have damaged the enclosedproduct. A passive force sensor can sup-ply a single bit of information that canbe returned along with an RFID tag’s ID,alerting the system about the problem.

Another application of RFID sensing isin relation to perishable goods. Typically,items such as meat, fruit, and dairy prod-ucts shouldn’t exceed a critical tempera-ture during transportation or they won’tbe safe for consumption. An RFID tem-perature sensor could both identify goodsand ensure they remain within a safetemperature range. The KSW TempSensRFID tag was designed explicitly for this

purpose (see www.ksw-microtec.de/www/startseite_en.php).

Antitamper product packaging isanother application domain for RFIDsensing. Most modern consumable prod-ucts are protected by a packaging tech-nology that clearly shows customers if theproduct has been tampered with. A sim-ple binary switch (sensor) can be incor-

porated into an RFID tag, perhaps a thinloop of wire extending from the tagthrough the packaging and back to thetag. If tampering occurs, the wire breaksand shows up as a tamper bit when thetag is read during checkout. In this way,a store can ensure that it only purveystamper-free items. Furthermore, at eachpoint in the supply chain, you can checkindividual products for tamper activity,making it easier to find the culprits.

Privacy concernsRFID has received much attention in

recent years as journalists, technolo-gists, and privacy advocates havedebated the ethics of its use. Privacyadvocates are concerned that eventhough many of the corporations con-sidering RFID use for inventory track-ing have honorable intentions, withoutdue care, the technology might beunwittingly used to create undesirableoutcomes for many customers.

The inherent problem is that radio-based technologies interact throughinvisible communication channels, so wedon’t know when communication isoccurring. Consider a clothing store thatlabels its garments with RFID tags. Fromthe store’s perspective, this improves


Another application of RFID sensing is in relation

to perishable goods. An RFID temperature

sensor could both identify goods and ensure

they remain within a safe temperature range.

inventory stock checks, because employ-ees can quickly catalog the contents ofvarious racks and bins, even when cus-tomers have mixed up the clothes. Also,employees can perform fast periodicstock checks to detect thefts, which isn’tusually an easy task.

However, if the store fails to remove atag at the point of purchase, it’s possibleto track customers every time they wear

the tagged clothing. Vendors—includingvendors other than the original seller—could learn where the customer shops tobetter target the person with direct-mar-keting techniques. Even more troubling,a criminal might track consumers, judg-ing their wealth based on purchases, pos-sibly targeting them for theft.

Although the potential for RFID mis-use is high, undesirable scenarios can beturned into potentially useful ones. Forexample, if clothes were tagged, wash-ing machine manufacturers could inte-grate RFID readers into the doors oftheir machines, making them aware ofall items selected for washing. Themachines could then choose the appro-priate washing cycle and possibly warnyou about incompatible garments thatmight result in color runs.

The current focus, however, remainson the potential for misuse. A growingcloud of public and media concern forcedBenetton, a well-known clothing store,to hastily retreat after it announced plansto use RFID tags in its stores.6 Concernalso surfaced when the US governmentannounced plans to put RFID tags intopassports to make them easier to check atborders and harder to forge. Privacy

advocates argued that covert readersmight steal the information, enablingidentity theft.7 The passport scheme isstill going forward, but the governmentis modifying its implementation toaddress public concerns.

EPCglobal has addressed some ofthese concerns by designing a kill switchin their tags that lets vendors perma-nently disable a tag at the point of sale.

Vendors then wouldn’t have to removethe tag itself, which might be woven intoa garment and (deliberately) difficult toremove. Of course, concerns still existthat vendors might become complacentand that not all stores would be vigilantabout disabling the tags. An insidiousnumber of tags could still become partof our daily activities, which could laterbe exploited for criminal purposes.

RSA’s proposed solution is the conceptof a blocker tag8—a modified RFID tagthat takes advantage of EPCglobal’s anti-collision protocol. The blocker tagresponds to each interrogation such thatit appears that all possible tag IDs arepresent, so the reader has no idea whattags are actually nearby. Perhaps havingsimple countermeasures to prevent tagmisuse is exactly what we need to over-come privacy concerns.

Remaining challengesThree main issues are holding back

RFID’s widespread adoption, the first ofwhich is cost. Although RFID tags arenow potentially available at prices as lowas 13 cents each, this is still much moreexpensive than printed labels. (As of Sep-tember 2005, Alien Technologies (www.

alientechnology.com) could supply RFIDtags for 12.9 cents each in quantities of1 million.)

Market analysts can’t agree on theprice tipping point—will it be a 10-cent,5-cent, or 1-cent tag? Consider a 50-centcandy bar—if you replace a bar code(which costs nothing because you canprint it on the wrapper) with a 10-centRFID tag, then you might not have anyremaining profit. Consequently, RFIDtags are likely to have their first deploy-ments with high-profit items. Of course,when adoption does take hold, it couldrapidly accelerate as mass productiondrives down prices.

Another important issue is design. Westill need to engineer tags and readers sothat they guarantee highly reliable iden-tification. The solutions must be resilientto all tag orientations, packaging mate-rials, and checkout configurations foundin typical stores. Improved tag antennadesign can solve some of these issues. Tagreaders can also be designed to exhibitantenna diversity by multiplexing theirsignals between several antenna modulesmounted in orthogonal orientations, orby coordinating multiple readers. In thelatter case, we must avoid the reader col-lision problem,9 as interrogation signalswill interfere with each other. A stricttime division scheme would allow mul-tiple readers to be deployed.

The final issue is acceptance. The pressand civil libertarians have raised somegenuine concerns, so it’s important thatwe proceed cautiously to incorporate safe-guards that address the potential for RFIDmisuse. In 2003, Simson Garfinkel pro-posed “An RFID Bill of Rights,”10 whichlaid down a set of guidelines that retail-ers should adhere to in order to protectcitizens’ rights. Currently, no laws regu-late tag use, and legislation might berequired to assure the public. In the mean-time, early adopters such as Wal-Martand Tesco could help defuse concerns bypublicly adopting a similar proposal.



The press and civil libertarians have raised some

genuine concerns, so it’s important that we

proceed cautiously to incorporate safeguards

that address the potential for RFID misuse.

Despite these challenges, RFIDcontinues to make inroadsinto inventory control sys-tems, and it’s only a matter of

time before the component costs fall lowenough to make RFID an attractive eco-nomic proposition. Furthermore, exten-sive engineering efforts are under way toovercome current technical limitationsand to build accurate and reliable tag-reading systems. We might also start tosee economic pressure from the largerdistributors to modify product packag-ing and its associated materials to moreeffectively integrate RFID. Finally, at thisdelicate stage, while major corporationsare trialing the technology, media reac-tion and outspoken privacy groups caninfluence the rules by which we use thetechnology. Given that legislation is nowin place among most of the developedcountries to protect our personal infor-mation held in computers at banks andother organizations, there is no reasonwhy RFID data management can’tacquire a similar code of conduct.

RFID’s potential benefits are large,and we’re sure to see many novel appli-cations in the future—some of which wecan’t even begin to imagine.

REFERENCES1. K. Finkelzeller, The RFID Handbook, 2nd

ed., John Wiley & Sons, 2003.

2. R. Want et al., “Bridging Real and VirtualWorlds with Electronic Tags,” Proc. ACMSIGCHI, ACM Press, 1999, pp. 370–377.

3. M. Weiser, “The Computer for the 21stCentury,” Scientific Am., vol. 265, no. 3,1991, pp. 94–104.

4. T. Kindberg et al., “People, Places, andThings: Web Presence of the Real World,”ACM Mobile Networks & Applications J.,2002, pp. 365–376.

5. R. Want, “Enabling Ubiquitous Sensingwith RFID,” Computer, vol. 37, no. 4,2004, pp. 84–86.

6. E. Batista, “‘Step Back’ for Wireless IDTech?” Wired News, 8 Apr. 2003; www.

wired.com/news/wireless/0,1382,58385,00.html.

7. R. Singel, “American Passports to GetChipped,” Wired News, 19 Oct. 2004;www.wired.com/news/privacy/0,1848,65412,00.html.

8. A. Juels, R.L. Rivest, and M. Szydlo, “TheBlocker Tag: Selective Blocking of RFIDTags for Consumer Privacy,” Proc. 8thACM Conf. Computer and Comm. Secu-rity, ACM Press, 2003, pp. 103–111.

9. D.W. Engels and S.E. Sarma, “The ReaderCollision Problem,” white paper MIT-AUTOID-WH-007, Auto-ID Center, Nov.2001.

10. S. Garfinkel, “An RFID Bill of Rights,”Technology Rev., Oct. 2002, p. 35.

For more information on this or any other comput-ing topic, please visit our Digital Library at www.computer.org/publications/dlib.


the AUTHOR

Roy Want is a principal engineer at Intel Research in Santa Clara, California, andleader of the Ubiquity Strategic Research Project. His research interests includeproactive computing, ubiquitous computing, wireless protocols, hardware design,embedded systems, distributed systems, automatic identification, and micro-electromechanical systems. He received his PhD for his work on “reliable manage-ment of voice in a distributed system” from Cambridge University. He is a Fellow ofthe IEEE and ACM. Contact him at Intel Corp., 2200 Mission College Blvd., SantaClara, CA 95052; [email protected].

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