RFID Tags

RFID Application Overview
and Testing Requirements
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
RFID allgemein verständlich
Dipl.-Ing. Hardy Zissel
Leiter AutoID / RFID Testcenter, TH Wildau
Tel.: +49 3375 508 453, hardy.zissel@th-wildau.de
Ingenieurbüro Zissel, Königs Wusterhausen
Tel.: +49 3375 209005, hardy.zissel@zissel.com
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Agenda
1. RFID Communication Systems, Standards, and Applications
2. RFID Signal Overview at UHF Frequency Band
3. RFID Signal Analysis (Reader/Interrogator and Tag)
4. RFID Measurement Solutions
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
What’s RFID?
Radio Frequency IDentification
•Definition of RFID devices
–Portable size
–Data storage memory in IC chip
–Capable of contactless communication
•RFID features
–Communicates longer distances than barcode; tolerant of dirt and interference
–Communicates more data in readable, rewriteable IC chip
•Some advantages compared with barcode
–Uses in automated check-out with lower costs
–Eliminates human error factors for improved information quality
–Enables individual item recognition for traceability and tracking
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
RFID Communication Definitions
Forward link:
transmission from
Reader to Tag
Reader
(Interrogator)
(“base station”)
Tag
Return link:
transmission from Tag
to Reader
(“mobile station”)
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
RFID Systems Description
Tags
Readers/Interrogators
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
• Wireless transducer with antenna
• Tag physical design dependent on
end-use
RFID Testing Requirements
RFID Tags - Active
• Active
• On-board power source and
transmitter
• Higher range (<100 m), but more
expensive
• More reliable in difficult RF environs
• May contain memory on-board
• Battery life to 10 years
• Transponder or Beacon
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
RFID Tags - Passive
• Passive
• Use power induced by the magnetic
field of the reader, or battery-assist
(passive-assist)
• Cheaper
• Potentially unlimited life span
• Better reliability, especially in difficult
physical environs
• May contain memory on-board
• Read distance: ~10 cm to <10m
• Size: smaller than a coin, as thin as
paper
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
RFID - Technologien
Wirkprinzipien und Eigenschaften werden maßgeblich von der
Arbeitsfrequenz bestimmt
125 KHz (LF)
reine magnetische Kopplung, Lastmodulation, Reichweite 3 – 5 cm
13,56 MHz (HF)
reine magnetische Kopplung, Resonanz, Lastmodulation, 60 cm
868 MHz (UHF)
elektromagnetische Kopplung, Resonanz, frei fliegende Welle,
Rückantwort auf eigener Frequenz,
Reichweite passiv ca. 8 m, aktiv > 100 m
2,45 GHz (SHF)
siehe UHF, für Spezialanwendungen, meist aktiv (mit Batterie)
Ing.-Büro Zissel, www.zissel.com
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Tags—Inductive vs. Radiative (Backscatter)
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
125 KHz (LF) Wirkungsweise
transformatorisches Prinzip
„auseinanderziehen“ der Trafowicklungen
reine magnetische Kopplung, unbeeinflusst von Wasser u.
anderen diamagnetischen Materialien
geringe Datenrate
Ing.-Büro Zissel, www.zissel.com
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Praxisbeispiel
125 Khz – transformatorisches Prinzip
Glastransponder für die Injektion in Lebewesen
Ing.-Büro Zissel, www.zissel.com
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
13,56 MHz (HF) Wirkungsweise
transformatorisches Prinzip mit Resonanz
verbessertes transformatorisches Prinzip
resonante Schwingkreise ohne Eisenkern
günstigere Feldverteilung mit geringerer Energie
Ing.-Büro Zissel, www.zissel.com
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Praxisbeispiele
13,56 MHz
Schlüsselanhänger, Wäsche-Tag, Smartlabel
Ing.-Büro Zissel, www.zissel.com
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
868 MHz (UHF) Wirkungsweise
H- und E – Feld, frei fliegende Wellen
reiner Funkbetrieb über ablösende Welle (Wellenlänge ~ 0,34m)
Nutzung von H- und E-Feld
große Reichweiten (einige Meter)
Ing.-Büro Zissel, www.zissel.com
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Praxisbeispiele
868 MHz Label und Hardtags (passiv)
Inlay für Label von UPM
für Papier, Kunststoff
Metalltag mit Stahlgehäuse von
ZISSEL
für Metallbehälter
12 m Reichweite
Transponder mit Metallgehäuse
und Kunststoffüberzug von ZISSEL
für Personen in Medizin und Sport
Ing.-Büro Zissel, www.zissel.com
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Aktuelle Projekte des Ingenieurbüros Zissel:
Intelligentes Regal für Bibliotheken
-
Bücherregal für Zeitschriften
-
In Zusammenarbeit mit TH Wildau
-
Liefert präzise Daten über die Nutzung der Zeitschriften innerhalb der Bibliothek
-
Ideal für Optimierung des Zeitschriftenbestandes
Generierung der Richtlinie VDI4478-1 zur Bestimmung der Qualität von
Sicherungsgates
-
Ideal für die Nutzung in Bibliotheken (gesamter Bücherbestand)
-
Einheitlicher vergleichbarer Qualitätsstandard
-
Gut für Ausschreibungen
-
Soll anschließend in die ISO überführt werden
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Tags—Inductive vs. Radiative (Backscatter,
Remote Propagation)
Radiative
Current in tag from the reader allows
the tag to radiate
• Frequencies above VHF
• Reader and tag can be read from
further away
• Subject to fading, reflection, etc
• Higher data rates
Inductive
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
The Challenges of RFID
Suppose…you are all tags
•
•
•
•
You are all blindfolded
You are nearly deaf
You talk by whispering
You can’t hear each other
Suppose…I’m a reader
•
•
•
•
•
•
I’m blindfolded
I don’t know who is in the room
I need to yell so you can hear me
If two of you talk at once, I can’t understand you
I’m not allowed to say your name
I may hear many others like me screaming in the
same room
I need to identify everybody in the room
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
What do I do?
RFID Testing Requirements
More Challenges of RFID
• Selecting and identifying tags – collision control.
• Multiple readers in area—how to allow for a large
number of closely spaced readers.
• Minimal interference and optimized data rate for high
noise or high speed communications.
Also :
• Sessions—how to handle multiple readers talking within
same tag population
• Variable data rates—Used to handle different needs in
varied environments
• Password, protection and security
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Identifying Tags
1 3 0 7
…
“OK tag #2, download”
“You talk first, then
everyone else decrement ”
Slotted Aloha
•Tags “roll dice” and
announce value
•Tag with 0 value is
allowed to talk
•All tags decrement count
•New tag with 0 is allowed
to talk
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
Reader talk first
(RTF)
• Multiple tags
receive power
Tag talk first
(TTF)
•As soon as tag is
illuminated, tag
talks
•Active tags talk all
the time, for short
periods
•Only the tag which is
queried responds
RFID Testing Requirements
Frequency Bands and Applications
Easier RF design
• Tolerant of influence from water and
metals
Reader/
Interrogator 13.56 MHz
• Short distance communication
Wall
900 MHz
Multi-path
Leakage
Long distance and wide
coverage
• Read multiple tags at a time
Wall
• Issues from multi-path and fading
Frequency
13.56 MHz (HF)
900 MHz (UHF)
Application
Item tracking
Places to use
Item tracking, electronic payment,
building security
Shop shelves, cash desk, ticket gate
Standards
ISO 18092, 14443, 15693
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
Logistics center, warehouse
EPCglobal Class1 Gen2
ISO 18000-6
RFID Testing Requirements
RFID Standards Summary at UHF band
Standard
Direction Modulation
EPCglobal C1
Gen2
(ISO 18000-6
Type C)
ISO 18000-6
Type A
ISO 18000-6
Type B
Forward
Return
DSB-ASK,
SSB-ASK,
PR-ASK
Forward
Return
Tari
Line Coding
6.25/
12.5/25 us
PIE
FM0 / Miller
DSB-ASK
40/80/120
kbps
33 kbps
FM0
DSB-ASK
40/160
kbps
10/40 kbps
Return
Forward
Bit Rate
PIE
Manchester
40/160
kbps
FM0
For standards compliance and interoperability,
need to verify correct configuration of:
Modulation, Bit rate, Tari, Line Coding
ASK: Amplitude Shift Keying
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
RFID Definitions: CW/Burst/Pulse
ASK in Reader/Tag Bursts
Pulse
A single pair of
on/off intervals
A contiguous set of
symbols from a single
transmitter
Burst
This is
actually the
envelope of
the CW signal
This is the tag
using the CW
power
transmitted to
respond
Interrogator Power-On
Entire signal from reader
power turn on until turn off
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Terms – Tari (Interrogator Symbols)
Tari = Type A Reference Interval (ISO / IEC 18000-6-A)
The length of a binary '0' is defined as Tari, and is used as a reference
for several other times in the standard.
• The data rate can vary from 27 to 128 Kbps (Tari from 25 to 6.5
microseconds)
• A binary '0' is a short high level pulse followed by low pulse of equal
length
• A binary '1' is a longer high pulse followed by the same low pulse width
(PW)
This symbol set provides a high average RF power delivered to the tag.
Value of bit is dependent on
the length of the pulse =
Pulse Interval Encoding (PIE)
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Terms – Line Coding
(Manchester, FM0)
Example 01011
0
Manchester
FM0
1
0
1
1
Represents
0 = 01
1 = 10
No superposition of DC potential
by switching voltage at bit center
Represents
0 = 01 or 10
1 = 11 or 00
(phase switch at boundary)
Advantages in signal collision and
error detection
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
PIE (Type C) Coding
•Represent data 0 or 1 with pulse time length
(not with voltage level at decision points)
•Variable Tari length by data rate
• Bit value determined by length of pulse, not
amplitude
• To read value, look for PW, (falling, low, rising),
then delta time
• Short length=0; long length=1
Pulse
PW
data-0
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
PW
PW
data-1
PW
PW
data-0
RFID Testing Requirements
RFID Communication Systems
Tag
Reader
(Interrogator)
CW
Operations
Key characteristics
Interrogator transmits CW signal ON
and OFF
Quite low power level from passive
Tag
During CW ON period, Reader sends
request signal to Tag
Different line coding between Reader
and Tag
Tag
receives the CW signal power,
Hardy Zissel
Matthias
WeilhammerIC, and responds to Interrog.
activates
Thomas Giehm
RFID Testing Requirements
UHF band Reader signal (Gen2 DSB-ASK)
Standard defines ripple, rise time, fall
time and pulse width
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Strategies for Avoiding Interference
• Frequency multiplex (manual or auto)
• Listen before talk
• Time multiplex (duty cycle transmit)
• Frequency hopping spread spectrum (FHSS)
• Direct sequence spread spectrum (DSSS)
• Chirp pulses (SAW filters)
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
U.S. FCC EPCglobal Regulations
Must use either FHSS (Frequency-Hopping Spread-Spectrum) or DSSS (DirectSequence Spread-Spectrum)
FHSS
•Requires pseudo-random sequence to choose ordering for channel hopping
•Requires equal use of 50 channels, with average time no greater than 0.4 sec on
each channel during 20 sec time period if 20dB bandwidth is less than250 kHz
ORequal use of 25 channels, with average time no greater than 0.4 sec on
each channel during 10 sec time period if 20dB bandwidth is greater than or
equal to250 kHz
DSSS
•Requires 6dB bandwidth of at least 500 kHz
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Summary of RFID Challenges
• ASK based modulation not that simple
– Tari, bit rate, T1/T2, Trise/Tfall
• Spurious Requirements to co-exist with Cellular
system
– -60 to -80 dBm/100kHz
• Collision Avoidance under Multi-Reader/Dense Reader
Environment
• Multi-path/Fading
– Especially UHF tag even w/ slow movement
• Integration into Mobile Phone; Mobile Phone as Tag or
Reader (example: Near-Field Communication, NFC)
– Today; 13.56MHz RFID Tag (FeliCa), QR code reader
– Future; 300MHz/900MHz/2.4GHz RFID reader
• Mobile Phone-like production
– Tx Power Calibration
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Required measurements for Reader, Tag and
RFID systems
Reader/Interrogator Measurements
- Signal Analysis for standard compliance
- Modulation depth, rise/fall time, demodulated bits
- Radio Regulation Test
- For all commercial product under local regulations (FCC, ETSI, TELEC etc.)
Tag and RFID System Measurements
- Radio traffic conditions (Reader and tag response, burst measurements)
- Signal analysis for troubleshooting (burst/inter-burst timing, error
analysis, demodulation)
- Tag sensitivity and operating frequency
- Transmission performance (level, distance, interoperability)
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Reader/Interrogator Measurements
– in time domain
Time domain analysis is required
on-ripple
overshoot
100%
Higher Threshold
on-ripple
undershoot
off-width
50%
on-width
off-ripple
overshoot
Lower Threshold
0%
on-time
rise time
off-ripple
undershoot
off-time
fall time
Pulse width, Rise/Fall time requirements
for each RFID standard need to be analyzed
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Tag and RFID System Measurements
Need detailed and flexible measurements during Tag/Reader
communication sessionsTag
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Measurements in Data Communications
Establish actual data communications and capture the
signal with antennas and probing.
> Measure tag response and communication timing
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
VSA RFID Modulation Analysis
Traffic conditions
Demod bits
ASK Summary
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
Burst Summary
RFID Testing Requirements
Signal Analysis for Standard Compliance
Easy identification of
bursts in time domain
Demodulated bits
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
Demodulated
waveform
Modulation depth and
time domain analysis
RFID Testing Requirements
Tag and RFID System Measurements
Clear burst identification
with direction indicated
Detect bursts with length
and interval timing
Time length of entire CW power
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Summary and Conclusions on
RFID measurement requirements
• RFID Communication Systems, Standards, and Applications
– RFID tags respond to Reader/Interrogator’s signal power
– Need measurements under multi-path, attenuated signal in the air
• RFID Signal Overview at UHF Frequency Band
– Various standards with parameters like bit rate, tari, line coding
– Pulse rise time and modulation quality need to be analyzed
• RFID Signal Analysis (Reader/Interrogator and Tag)
– Reader/Interrogator : Standard compliance with FFT, Regulation test
with Swept SA
– Tag and RFID systems: Measure low level response with SA
• RFID Measurement Solutions
– Signal Analyzer with Swept-SA and AutoTune plus FFT-based VSA
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements
Thank You for Your Attention !
Hardy Zissel
Matthias Weilhammer
Thomas Giehm
RFID Testing Requirements