RFID PRINCIPLES AND APPLICATIONS

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• RFID PRINCIPLES AND APPLICATIONS

Peter H. Cole Professor of RFID Systems at the
University of Adelaide and Director of the
Auto-ID Laboratory _at_ Adelaide
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Good news Heckling is encouraged
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What we aim to convey

• Some physical or mathematical principles
  necessary to establish feasibility
• The sense of excitement
• Some important themes will recur
• No pages full of algebra

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Outline

• RFID and the supply chain
• The emerging EPC technology
• The key concepts
• Physics of RFID
• RFID systems
• Coupling calculations
• RFID protocols
• The work of Auto-ID Labs
• Conclusions

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• PART 1
• RFID AND THE SUPPLY CHAIN

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Tag reading
The black spot
Normally a very weak reply is obtained
Some application illustrations will be given
shortly
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Traffic Monitoring
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Waste Collection
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Example applications

• What can you do with this technology ?
• Supply chain benefits
• Reduce out of stocks, reduce inventory, speed up
  delivery, check freshness, track and trace,
  produce to demand, identify sources of diversion,
  identify counterfeiting, theft prediction, faster
  recalls
• Consumer benefits
• Direct order from home, smart appliances, (e.g.
  microwave, washing machine, refrigerator), smart
  healthcare, assisted living
• New and less expected benefits
• Customized products, smart recycling,
  checkout-less stores

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The supply chain
Global Supply Chain
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• PART 2
• THE EMERGING EPC TECHNOLOGY

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The Auto-ID Center

• Global, industry funded research program
• Massachusetts Institute of Technology (1999)
• Cambridge University (2000)
• University of Adelaide (2001-2002)
• Japan, China, Switzerland (2003)
• Mission
• Create the internet of things
• Research for the benefit of mankind

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About the Center

• End User Sponsors Include
• Procter Gamble, Gillette, Uniform Codes Council
  (UCC), CHEP International, EAN International,
  International Paper, Philip Morris Group, Johnson
  Johnson, Wal-Mart, Yuen Foong Yu, United States
  Postal Service, Westvaco, Unilever,
  Kimberly-Clark, Tesco, Coca-Cola, Knight Ranger,
  Dai Nippon Printing, Department of Defense,
  United Parcel Service
• Vendor Sponsors Include
• NCR, Savi Technologies, Sun Microsystems, Flint
  Ink, Markem, Invensys, Sensormatic, Cashs,
  Rafsec, Flexchip, Alien Technology, Philips
  Semiconductor, SAP, Checkpoint, ThingMagic,
  Accenture, AC Nielson, Avery Denison, Ember
  Corporation, PWC, Accenture
• Trade Bodies
• AIM Global, GCI, GMA, FMI, NACS, NACDS, AIM,
  POPAI, IMRA, ARTS, UTSA

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The Auto-ID Center Vision

• The internet of things
• Physical objects connected via the internet
• Simple identifying labels on objects
• Unlimited associated data in a data base
• Connections via an intranet or the internet
• Freely available world wide standards
• High performance protocols and software
• A scalable system not choked by expansion

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Metamorphosis

• Auto-ID Center
• Terminated 31/10/2003
• Spawned two organisations
• Auto-ID Labs
• MIT, Cambridge (UK), Adelaide, Fudan (China),
  Keio (Japan), St Gallen/ETHZ (Switzerland) and in
  2005 ICU (Korea)
• EPCglobal

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• PART 3
• THE KEY CONCEPTS

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Key concepts then

• The Electronic Product Code (EPC)
• Tags bearing it and readers reading it
• The Object Name Service (ONS)
• The Physical Mark-up Language (PML)
• Smart scalable networking for the physical world
• The savant, an event manager and router

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Key concepts now

• Electronic product code
• Formats for various applications
• ID system
• Tags and readers
• EPC middleware
• Replaces the savant
• ALE engine and interfaces
• Performs filtering a data routing for clients

• Discovery services
• ONS discovery service
• Discovery services for events
• EPC information services
• Enables users to securely exchange information
  with trading partners

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Use of electromagnetic fields

• Coupling is via electromagnetic fields
• There is little margin for poor performance
• We must understand their properties

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• PART 4
• THE PHYSICS OF RFID

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The field vectors

• A full theory of electrodynamics, including
  the effects of dielectric and magnetic materials,
  must be based on the four field vectors
• Electric field vector E
• Magnetic field vector H
• Electric flux density vector D
• Magnetic flux density vector B

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Material state vectors
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Laws in differential form
Vortex
Source
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Electromagnetic propagation
Electric current creates a vortex of magnetic
field
Magnetic field creates a vortex of electric field
Electric field creates a vortex of magnetic field
Propagation
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Electromagnetic waves

• They propagate with the velocity of light
• (Light is an electromagnetic wave)
• Velocity c is 300,000,000 m/s
• Wavelength - frequency relation is c fl
• But not all electromagnetic fields are
  propagating waves some are just local energy
  storage fields

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Boundary Condition electric field
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Boundary Condition magnetic field
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The basic laws how they work

• Gausss law
• Electric flux deposits charge
• Electric field cannot just go past a conductor,
  it must turn and meet it at right angles
• Faradays law
• Oscillating magnetic flux induces voltage in a
  loop that it links

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Near and far field distributions
Electric field launched by an electric dipole
There is also a magnetic field not shown
Note the differences between near and far fields
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Fields of a Magnetic Dipole(oh dear, I lied)
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Near and far fields

• The far field is an energy propagating field
• Appropriate measure of strength is 0.5 h H2
  (power flowing per unit area)
• The near field is an energy storage field
• Appropriate measure of strength is reactive power
  per unit volume 0.5 w m0H2
• Near field - far field boundary is l/2p
• Examples 100 kHz 500m 10 MHz 5m 1000 MHz 50mm

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The radian sphere

• At br 1, r l/2p, and
• The phase factor e-jbr is one radian
• Inside this sphere the near field predominates
• Outside this sphere the far field predominates

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• PART 5
• RFID SYSTEMS

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Issues in RFID Design

• Active or passive
• Operating frequency
• Electric or magnetic fields
• Material or microelectronic

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The usual way backscatter

• The most popular technology
• Tag contains a microcircuit and an antenna
• Tag is powered by the interrogation beam
• Frequency of that beam is chosen for good
  propagation
• Tag contains an internal oscillator
• Frequency of that oscillator is chosen for low
  power consumption

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Microelectronic Backscatter

• Concept can be applied from 10 MHz to 10,000 MHz
• Low propagation loss points to coupling using the
  far field
• Low power consumption requires a low frequency
  microcircuit
• Reply is by modulation of the interrogation
  frequency

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Relevant Issues

• Range is determined largely by the ability to
  obtain sufficient rectified voltage for the label
  rectifier system
• High quality factor resonance becomes important
  in small tags
• Reply is at sidebands of the interrogation
  frequency

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Interesting features

• Near and far fields
• Energy storage in the near field
• Energy propagation in the far field
• Radian sphere (rl/2p) is the boundary

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Label antennas

• Magnetic field free space
• Magnetic field against metal
• Electric field free space
• Electric field against metal
• Electromagnetic field
• Very small antennas respond to either the
  electric field or the magnetic field
• Somewhat larger antennas respond to both

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Planar printed coil
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Ferrite cored solenoid
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Electric field bow tie
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Electric field box structure
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Electromagnetic field antenna

• Dimensions are no longer a small fraction of a
  wave length
• Operating principles are less clear

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• PART 6
• COUPLING CALCULATIONS

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Field creation structures

• Near magnetic field
• Made by current carrying loops
• Near electric field
• Made by charged electrodes
• Far electromagnetic field
• Made by propagation from an originally near field

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Far field coupling theory
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Near field coupling theory 1
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Near field coupling theory 2
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Near field coupling theory 3
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Measures of exciting field
In the far field
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Significant conclusions

• Coupling volumes for well shaped planar electric
  and magnetic field labels are size dependent and
  similar
• Radiation quality factors for both types of label
  formed within a square of side L are size
  dependent and similar
• These are calculated results for sensibly shaped
  antennas

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Optimum operating frequency
The optimum frequency for operation of an RFID
system in the far field is the lowest frequency
for which a reasonable match to the radiation
resistance of the label antenna can be achieved,
at the allowed size of label, without the label
or matching element losses intruding.
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• PART 7
• RFID PROTOCOLS

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What is a protocol?

• Signalling waveforms
• Command set
• Operating procedure
• A back end interface
• whereby the identities of a population of tags
  in the field of a reader may be determined, and
  the population otherwise managed.

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Constraints on protocols

• Electromagnetic compatibility regulations
• Differ with frequency range and jurisdiction
• Some convergence is occurring
• Reader to reader interference
• Readers confusing tags
• Readers blocking other reader receivers
• Simplicity (as reflected in chip size)
• Maybe that influences reliability as well

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Auto-ID Center protocols

• The Auto-ID Center defined
• The Class 1 UHF protocol
• The Class 1 HF protocol
• The Class 0 UHF protocol
• EPCglobal has defined in addition
• Generation 2 UHF protocol

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Why are they different?

• Different field properties at HF and UHF
• Near and far field different field confinement
• Different field penetration in materials
• Different silicon circuit possibilities and costs
• Different electromagnetic regulations
• Read only memory technologies enable
  miniaturisation
• A high performance UHF system was available and
  was modified by the Center to manage privacy
  concerns

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Protocols the major divide

• Tree walking
• More forward link signalling
• Prolonged periods of interrupted signalling
• Partial information of tag population remains
  relevant
• Adaptive round (terminating aloha)
• Less forward link signalling
• Long periods of un-modulated reader carrier
• Reader signalling is less
• No information from one response about others

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Characteristics similarities

• Both can select subsets of tags for participation
• Overt selection may reveal what is selected
• Forms of less overt selection are possible
• Tag sleeping has a role in both

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Tree scanning concepts
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Adaptive round concepts

• Labels reply once per round, in randomly chosen
  slots
• A group of n slots forms a round
• The number of slots in a round varies as needed
• Tags with already collected replies are moved to
  slot F, or silenced in some way.

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Adaptive round concepts 2

• What we saw was the Class 1 Generation 1 HF
  protocol
• Adaptive round concept now appears in may places
• Next protocol is a complex example of an adaptive
  round

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The C1G2 protocol

• Labels have an adjustable probability of replying
  on each query or repeated query
• Probability is adjusted to about a third
• Empty slots, singly occupied slots and multiply
  occupied slots are roughly equi-probable
• A wide range of forward and reverse signalling
  parameters are defined
• Some of them allow for narrow band reply
  signalling separated from the interrogation
  carrier

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C1G2 Features

• Tag must be able to communicate from 860 MHz to
  960 MHz
• Tags must understand 3 different modulation
  schemes
• Double Sideband Amplitude Shift Keying DSB-ASK
• Single Sideband Amplitude Shift Keying SSB-ASK
• Phase Reversal Amplitude Shift Keying PR-ASK
• Coding is by Pulse Interval Encoding (PIE)
• TgtR data rates 40, 80, 160, 320 and 640 kbits
• Selection
• Access Kill Passwords
• EPC up to 256 bits
• Dense reader channelised signalling

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Interrogator/tag operations and tag state
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Inventory

• Reader Talks First
• Sets up communication parameters, defines a round
• Round Size (Q value), slots are numbered from 0
  to 2Q-1
• Tags select a slot within a round to offer a
  reply
• Tag States
• Ready
• Arbitrate
• Reply
• Acknowledge
• Open
• Secured
• Killed

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Replies
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• PART 6
• CURRENT DEVELOPMENTS

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Auto-ID Center accomplishment

• By September 2003
• Tag reading protocols
• UHF Class 1
• UHF Class 0
• HF Class 1
• Tags (commercial chips to all protocols
  available)
• Savant
• Data filtering and event management software
  system
• Version 1 distributed, version 2 in development
• Field trial
• Three phases, then nearing completion
• PML
• Two phases of development
• Establishment of research laboratories
• USA, England, Australia, China, Japan, Switzerland

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Transformation to Laboratories and EPCglobal

• Transformed
• 26 October 2003
• Auto-ID Labs
• Performs fundamental research related to EPC
  System
• Builds communities not already using EPC System
• EPC Global
• Manages and develops standards
• Markets EPC System

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The Auto-ID Laboratories
In March 2005 the seventh laboratory was
established at ICU in Korea
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Laboratories research program

• Seven laboratories around the world
• Associate laboratories are contemplated
• Flagship research projects
• Anti counterfeiting
• Sensor networks
• Aerospace and automotive
• Additional laboratory research projects

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EPCglobal network outline

• Discovery services
• ONS discovery service
• Discovery services for events
• EPC information services
• Enables users to securely exchange information
  with trading partners

• Electronic product code
• Formats for various applications
• ID system
• Tags and readers
• EPC middleware
• Replaces the savant
• ALE engine and interfaces
• Performs filtering a data routing for clients

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EPC Event Layers
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EPCIS Concepts
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Possible Retailer Implementation
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Capture Application
Manufacturer
Retailer
Dist Ctr
Dist Ctr
Store
Tagging Station
Operational Apps
Palletizer
Dock Portal
Dock Portal
Dock Portal
Backroom Receipt
Rack
Impact Doorway
EPCIS Events
Commission Observe
Observe Aggregate
Observe Shipment
Observe Receipt
ObserveDisaggregate
Observe Restock
Observe Putaway
Observe Shipment
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EPCglobal network roles and interfaces
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• PART 7
• SOME ADELAIDE RESEARCH

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Bode-Fano Limit
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Bode-Fano Limit (cont)
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Bode-Fano Limit (cont)

• Allocated bandwidths
• USA
• 902-928 MHz 4W EIRP FHSS
• CEPT Countries
• 865.6 867.6 MHz 2W ERP LBT
• South Africa
• 865.6 867.6 MHz 2W ERP LBT (coming)
• 917-921 MHz 4W EIRP FHSS
• China
• 917 922 MHz 2W ERP (Temporary licence can be
  applied)
• Australia
• 920 926 MHz 4W EIRP (Temporary licence can be
  applied)

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Bode-Fano Limit (cont)

• 3 different cases considered

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Bode-Fano Limit (cont)

• Assume R 1 k?, C 1 pF
• R 10 k?, C 1 pF (for less power
  consuming tag chip in practice)

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Interesting questions

• Merging of EAS and Data tags
• Security and authentication
• Turning on battery operated tags
• Low power consumption
• Zero power consumption

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Transmitter operated systems

• A small voltage or a large is generated from the
  transmitted power
• A low power consumption circuit, or a zero power
  consumption circuit, detects that event
• Quality factor and detuning issues arise

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Experiments on detuning
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Low and high power sweeps
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A low voltage turn on circuit

• Sensitivity about 5 mV
• Power consumption few nA

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Zero power turn on concept

• Low frequency magnetic field vibrates a magnet
• Piezoelectric converter generates about a volt

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Electroacoustic conversion modelling

• Variables are
• Torque and angular displacement,
• charge and voltage
• Electro-acoustic parameters for substances known
• Parameters for structures are calculated therefrom

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Eletroacoustic conversion

• Structural parameters appear below

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Structure analysed
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Result

• Turn-on voltage depends on
• Driving magnetic field
• Electro-acoustic parameters
• Some resonance quality factors

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• PART 8
• CONCLUSIONS

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What to take away 1

• Simplicity of passive RFID for identity
• The weakness of the label reply
• Ubiquity of objects in supply chain
• Vision of the Auto-ID Center
• Electric and magnetic field concepts
• Source and vortex concepts
• Frequency wave length relation c fl

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What to take away 2

• Near and far field concepts
• Radian sphere size and significance
• Boundary conditions near metal
• Behaviour of simple antennas
• Varieties of fast reading protocol
• Transformation of Center
• Auto-ID Labs research

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What to take away 3

• EPCglobal networking concepts
• Standardised EPC
• Standardised readers, tags and protocols
• Standardised communication between roles

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What to take away 4

• The new research targets
• Security and authentication
• Higher functionality tags
• Active tags
• Sensor networks

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• Thank you