TK3 - Chapter 3 - Technische Universität Darmstadt

TK3 - Chapter 3 - Technische Universität Darmstadt

Technische Universität Darmstadt
Telecooperation
TK3: Ubiquitous (& Mobile) Computing
RFID & Smart Items
Erwin Aitenbichler, Max Mühlhäuser
Copyrighted material; for TUD student use only
Dr. Erwin Aitenbichler
Prof. Dr.
Dr. M.
M. Mühlhäuser
Mühlhäuser
Prof.
Telekooperation
Telekooperation
©
©
RFID and Smart Items
2
Dr. Erwin Aitenbichler
Prof. Dr.
Dr. M.
M. Mühlhäuser
Mühlhäuser
Prof.
Telekooperation
Telekooperation
©
©
RFID and Smart Items
• RFID: Radio Frequency IDentification
– Passive RFID Tags
• Powered from the reader only
• Signal strength decreases with d4
• Cheapest class of tags
– Active RFID Tags
• Includes power source (battery, ...)
• Continuously emits its ID without
triggering from reader
– Semi-active RFID Tags
• Includes power source (battery)
• Similar to passive tag
• Uses battery to power chip
• Smart Item
– Active
– Plus „information processing component“
3
Prof. Dr. M. Mühlhäuser
Telekooperation
©
RFID Applications
• Worldwide RFID market: ~$5.5bn (2009)
• RFID applications (in order of market share 2005)
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Transportation
Security/access control
Supply chain management
Asset management
Toll collection
Automobile immobilisers
Real time location systems
Rental item tracking
Baggage handling
Animal tracking
Point of sale
• Next: Fastest Growing RFID Modernizing Applications
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Prof. Dr. M. Mühlhäuser
Telekooperation
©
RFID: Fastest Growing
1. Contactless Payment
– Contactless Smart Card
• e.g., TUD-Card
– Mobile phones with
NFC (Near-Field Communication)
• not only „passive“ - allows
management apps on phone
• widespread in Korea
2. Item-level Tracking
– Anti-counterfeit tagging for
pharmaceuticals, airplane spare parts,
alcohol, fashion, ...
– WHO: global value trade in counterfeit
pharmaceuticals is US $32~46 billion
3. Baggage Handling
– Air transport baggage control: tracking,
sorting, identifying luggage and cargo
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Prof. Dr. M. Mühlhäuser
Telekooperation
©
RFID: Fastest Growing
4. Case & Pallet Tracking
– Wal-mart and supply-chain partners
reduce out-of-stocks through case
and pallet tagging
5. Asset Management
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spare parts tracking
tool management
reusable container management
laundry tracking
library management systems
document tracking
6. Contactless Ticketing
– Seoul public transport replaced
450 million printed paper tickets/year
with RFID cards
– Access control for ski lifts, etc.
much more comfortable with RFID
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Prof. Dr. M. Mühlhäuser
Telekooperation
©
RFID: System Components
• RFID System
– RFID Reader
– RFID Reader Antenna
– RFID Transponder
• RFID Transponder (= Tag)
– Chip
– Coupling element
(coil or antenna)
– Housing
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Prof. Dr. M. Mühlhäuser
Telekooperation
©
RFID: Ranges and Coupling
• Close coupling systems
– Use very small ranges (<= 1cm)
– Also called: close coupling systems
– Transponder must be inserted into reader or positioned on surface
– Greater amount of power can be provided
– Applications:
• Contactless Smart Card for payment functions
• Door locking systems
• Remote coupling systems
– Read ranges of up to 1m
– Almost always based on Inductive Coupling
– Have 90% market share
• Long-range systems
– Typical read ranges: 3m with passive tags, 15m with active tags
– Electromagnetic Backscatter Coupling or SAW-Transponders
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Prof. Dr. M. Mühlhäuser
Telekooperation
©
RFID: Inductive Coupling
Reader
Tags
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Prof. Dr. M. Mühlhäuser
Telekooperation
RFID: Inductive Coupling
©
• Typical frequencies: <135kHz (λ=2400m), 13.56MHz (λ=22.1m)
• Distance reader-tag << λ:
– Operates in the near field of antenna
– EM-field may be treated as simple magnetic alternating field
– „transformer-type coupling“ btw. reader and transponder antennas
• Transponders comprise of
– Microchip
– Large area coil antenna
• Power supply to passive transponders
– Reader (continuously) sends a strong carrier signal
– Transponder‘s self resonant frequency = read frequency
– Transponder draws energy from magnetic field
– Near field -> Power drops with 60dB/decade
– Range limited to ~1m
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Prof. Dr. M. Mühlhäuser
Telekooperation
RFID: Inductive Coupling
©
• Data transfer: Transponder -> Reader
• Load Modulation
– Transponder modulates data
by switching a load resistor on/off
– Impedance change noticeable at reader
– Requires highly complex circuitry at
reader (remember Listen-while-talk!)
• Load Modulation with Subcarrier
– Voltage fluctuations at reader
caused by transponder are very small
compared to reader carrier, e.g.,
• Reader output voltage: 100V
• Feedback from transponder: ~10mV
• -> Drop: 80dB
– Transponder modulates data on subcarrier
with fS and then uses load modulation
-> this creates two sidebands on fT
– Reader can easily separate fT ± fS from fT and decode data
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Prof. Dr. M. Mühlhäuser
Telekooperation
RFID: EM Backscatter Coupling
©
• Electromagnetic Backscatter Coupling
Passive Tag
Active Tag
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Prof. Dr. M. Mühlhäuser
Telekooperation
RFID: EM Backscatter Coupling
©
• Typical frequencies:
– UHF: 868, 915 MHz
– Microwave: 2.5, 5.8 GHz
• Allows construction of antennas with far smaller dimensions and
greater efficiency
• Power supply to transponder
– Estimated with free space path loss
– Need ~50µW to operate chip on transponder
– If reader‘s transmission power = 0.5W,
then path loss must be <=40dB
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Prof. Dr. M. Mühlhäuser
Telekooperation
RFID: EM Backscatter Coupling
©
• Electromagnetic Backscatter Coupling
– EM waves are reflected by objects greater than λ/2
• most prominently, the radar utilizes this principle
– In particular, objects in resonance with the reader signal reflect well
– The reflection characteristic can be influenced by altering the load
connected to the antenna
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Prof. Dr. M. Mühlhäuser
Telekooperation
RFID: SAW-Transponder
©
• Surface acoustic wave (SAW) transponder
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Uses piezoelectic effect (and has no chip)
Interdigital Transducer converts voltage to surface wave and vice versa
Transponder ID (16-32 bit) determined by placement of reflectors
Typical frequency: 2.45 GHz
Reading range: 1-2m (at permitted transmission powers)
15
Prof. Dr. M. Mühlhäuser
Telekooperation
RFID: Data Transmission
©
• Reader -> Transponder
– Often uses Pulse-Pause Coding: bits encoded in pulse lengths
– Well-suited for passive tags, because only short power interruptions
• Transponder -> Reader
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Prof. Dr. M. Mühlhäuser
Telekooperation
RFID: Anticollision
©
• Anticollision / Multiple Access
• When the reader polls, all transponders answer -> collision
– Problems very similar to that in Wireless Networks
– Short-range readers usually do not support anticollision at all
• RFID anticollision methods (examples)
– Transponder-driven
• ALOHA, Slotted ALOHA
– Transponders send at a random time, repetition time differs slightly
– Assumption: not many tags, short duration of transmission
-> low collision probability
– Reader-driven
• Binary search algorithm
– Uses binary search to identify one transponder after the other
• Dynamic binary search algorithm
– More efficient for multibyte IDs
– Allows to limit the number of bytes transmitted
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Prof. Dr. M. Mühlhäuser
Telekooperation
RFID Anticollision: Binary Search
©
Manchester Code
• Assumptions
– All transponders send in sync
– The precise bit positions of collisions are recognizable by reader
– Further, this example assumes load modulation with subcarrier
• Manchester code allows to detect collisions
– Rising edge indicates 0, falling edge indicates 1
– Missing edge indicates collision
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Prof. Dr. M. Mühlhäuser
Telekooperation
RFID Anticollision: Binary Search
©
• Transponder commands sent to the transponders:
– REQUEST(searchId)
• If the transponderId <= searchId, then the transponder
replies with its transponderId
– SELECT(id)
• The transponder with the specified id becomes active
for the following read/write requests
– UNSELECT
• Removes the selection and mutes the selected
transponder. It will not even respond to further
REQUEST commands
– READ/WRITE
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Prof. Dr. M. Mühlhäuser
Telekooperation
RFID Anticollision: Binary Search
• Example: 4 Transponders
Command
Reply
REQUEST(11111111)
1X1X001X
• yields 8 possibilities:
*) transponder actually exists
Transponder
ID
1
10110010
2
10100011
3
10110011
4
11100011
©
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Prof. Dr. M. Mühlhäuser
Telekooperation
RFID Anticollision: Binary Search
©
• Algorithm to identify all transponders:
while true:
send REQUEST(maxId)
receive(id)
while id contains ‘X‘:
replace highest ‘X‘ with ‘0‘ and set all lower bits ‘1‘
send REQUEST(id)
receive(id)
foundTag(id)
send SELECT(id) ...
send UNSELECT
• 1st iteration:
Command
REQUEST(11111111)
Reply
1X1X001X
REQUEST(10111111)
101X001X
REQUEST(10101111)
10100011
SELECT(10100011)
READ
UNSELECT
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Dr. Erwin Aitenbichler
Prof. Dr.
Dr. M.
M. Mühlhäuser
Mühlhäuser
Prof.
Telekooperation
Telekooperation
Barcode vs. RFID
©
©
• Barcode
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Line-of-sight required
Identification of product class
Static information
No additional storage
Simple copying (counterfeit products)
Reading of single items only
extremely cheap
• RFID
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Contactless reading/writing
Unique identification of product instance
Dynamic information
Storage (RO, WORM, or RW)
Copying difficult (RFID with crypto extensions)
Bulk reading
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Dr. Erwin Aitenbichler
Prof. Dr.
Dr. M.
M. Mühlhäuser
Mühlhäuser
Prof.
Telekooperation
Telekooperation
EPC
©
©
• The Electronic Product Code (EPC) standard
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Dr. Erwin Aitenbichler
Prof. Dr.
Dr. M.
M. Mühlhäuser
Mühlhäuser
Prof.
Telekooperation
Telekooperation
RFID in Retailing
©
©
• Cost of Tags
– Chip-based tags: cost is still >10 Euro cents (for >1 million chips)
– Too expensive for broad (item-level) rollout in retailing
– Cheap readonly-tags with printable electronics (in 5 years?)
• Different package units: Pallet, Case, Item
• Back-store: goods receipt, goods issue, consignment, relocation
– pallet and case-level tagging
• Front-store: theft protection, cashing, customer aid
– requires item-level tagging
24
Dr. Erwin Aitenbichler
Prof. Dr.
Dr. M.
M. Mühlhäuser
Mühlhäuser
Prof.
Telekooperation
Telekooperation
©
©
Integrated goods receipt
Supplier
Customer
Vendor
Unload
1
EM = Event
Management - for
Supply Chain
Management (SCM)
4
Compare to
ASN EPCs
4a
AII = Auto ID
Infrastructure
Post
Goods
Receipt
Adv. Ship
Notification
Proof of
Delivery
Create Inbnd
Delivery
Unload Update
SAP EM
Optional
5
SAP
ERP
Register
EPCs
3
Inbound Delivery
2
6
ERP = Enterprise Resource Planning
25
Dr. Erwin Aitenbichler
Prof. Dr.
Dr. M.
M. Mühlhäuser
Mühlhäuser
Prof.
Telekooperation
Telekooperation
©
©
EPCIS architecture
• EPC information service (EPCIS)
PML
Server
PML
Server
PML
Server
6
5
3
7
ONS-Server
Middleware
4
(Enterprise)
Information
System
2
1
Reader
Product
26
Dr. Erwin Aitenbichler
Prof. Dr.
Dr. M.
M. Mühlhäuser
Mühlhäuser
Prof.
Telekooperation
Telekooperation
©
©
EPCIS architecture
• Process of getting product information
– Send EPC to Object Naming Service (ONS)
to obtain address of PML server
• ONS works similar to DNS
– Send EPC to PML server to obtain PML
document with product description
• Physical Markup Language (PML)
<class>
<system>Scientific</system>
<type>Variety</type>
<name>Malus S. Red Delicious Group</name>
</class>
<class>
<system>Internal</system>
<type>Produce</type>
<name>Apple <code>A2-L109A</code></name>
</class>
<class>
<system>Apple Growers Group</system>
<type>Produce Class</type>
<name>Red Delicious
<code>USAGG-0010198</code>
</name>
</class>
– proposed as a general, standard means
for describing physical objects and
environments for industrial, commercial and consumer applications
– Example: A batch of "Red Delicious" apples is harvested and assigned
an EPC code 01.081958.0094FE.008ED81C. This code references a PML
file describing the batch and identifies it with a number of classes
• scientific designation
• internal produce number used by the producer
• Apple Growers industry number
27
Dr. Erwin Aitenbichler
Prof. Dr.
Dr. M.
M. Mühlhäuser
Mühlhäuser
Prof.
Telekooperation
Telekooperation
Smart Items
©
©
• Definition
– Real world object
– Local data (e.g. ID, temperature, position)
– Communication interface
• Enabling Technologies
– Barcode and RFID (identification)
– Sensors, actuators, MEMS (object state)
– Infrared / ultrasound sensors, GPS (location)
– WLAN, GSM, Bluetooth, IrDA (wireless comm.)
• Opportunities & Challenges
– Integrate real world objects directly into
business processes
– New business processes & models
– New requirements for enterprise software
– Lack of standards
28
Dr. Erwin Aitenbichler
Prof. Dr.
Dr. M.
M. Mühlhäuser
Mühlhäuser
Prof.
Telekooperation
Telekooperation
Smart Items
©
©
• Sensing and applications
– Location: Position of an item in a (manufacturing) process
– Temperature: Monitor sensitive, dangerous & perishable goods
– Acceleration: Sensitive goods, e.g. hard drives
– Motion: Item stored or being processed
– Pressure: Sensitive goods, e.g. chemical drums
– Humidity: Perishable goods, e.g. food
– Light intensity: Sensitive goods, e.g. photo chemicals
– Mechanical stress: e.g., proper handling of containers
• Communication
– Communication with the infrastructure
• e.g., reader gates provide connection to enterprise backend
– Item-to-item communication
• Smart items can also react directly
• e.g., barrels with certain chemicals must not be co-located
29
Dr. Erwin Aitenbichler
Prof. Dr.
Dr. M.
M. Mühlhäuser
Mühlhäuser
Prof.
Telekooperation
Telekooperation
Aware Goods
©
©
• Aware Goods
– Sensors (temperature, acceleration, …)
– Local memory
– Intermittent connection to backend
– Goal: End-to-End Quality Management:
Integrate Shipping/Transport of Goods
into Enterprise QM Processes
• Example: ESYS – MINIDAN
– Temperature logging
– Temperature range: -40°C to +85°C
– Accuracy: 0.1°C or 0.5°C
– Storage: 16.000 to 32.000 values
depending on resolution
– IR communication
30
Dr. Erwin Aitenbichler
Prof. Dr.
Dr. M.
M. Mühlhäuser
Mühlhäuser
Prof.
Telekooperation
Telekooperation
End-to-End Quality Management
©
©
31
Prof. Dr. M. Mühlhäuser
Telekooperation
CoBIs
©
• CoBIs = Collaborative Business Items
• Increase workplace safety in
chemical, oil, gas industry
• Hazardous goods management
– Storage limit exceeded?
– Safe storage environment?
– Incompatible Goods?
• CoBIs uses wireless sensor nodes
– Peer-to-peer operation
– Ultrasound communication allows
to measure distances
• CoBIs have embedded rule sets and
notify the infrastructure about violations
32
Dr. Erwin Aitenbichler
Prof. Dr.
Dr. M.
M. Mühlhäuser
Mühlhäuser
Prof.
Telekooperation
Telekooperation
Summary: RFID & Smart Items
©
©
• RFID
– RFID Applications: market, fastest growing fields
– RFID system components
– Ranges and Coupling
• Inductive Coupling
• Electromagnetic Backscatter Coupling
• SAW-Transponders
– Data Transmission
– Anticollision: Binary Search
– RFID in Retailing
• Smart Items
– Sensing and Applications
– Aware Goods
– CoBIs
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