rfid application overview and testing requirements · 2009-07-28 · franco canestri -july 2007...
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Franco Canestri -July 2007 RFID Testing Requirements
presented by:
Franco Canestri and Hiromi Matsuoka
Agilent Technologies Sales & Services
GmbH & Co.KG
Böblingen, Germany
and
Agilent Technologies Signal Analysis Division
Kobe, Japan
RFID Application Overview
and Testing Requirements
Franco Canestri – July 2007 RFID Testing Requirements
Agenda
1. RFID Communication Systems, Standards, and Applications
– What’s RFID?
– Reader/Interrogator and Tag
– Frequency bands and applications
2. RFID Signal Overview at UHF Frequency Band
– Various standards at UHF band RFID
– ASK Modulation
– Line coding
3. RFID Signal Analysis (Reader/Interrogator and Tag)
– Measurements for Reader/Interrogator
– Measurements for Tag and RFID systems
4. RFID Measurement Solutions
Franco Canestri – July 2007 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
Franco Canestri – July 2007 RFID Testing Requirements
RFID Communication Definitions
Reader
(Interrogator)
Tag
Forward link:
transmission from
Reader to Tag
Return link:
transmission from Tag
to Reader(―base station‖)
(―mobile station‖)
Franco Canestri – July 2007 RFID Testing Requirements
RFID Systems Description
Readers/Interrogators
Tags
• Wireless transducer with antenna
• Tag physical design dependent on
end-use
Franco Canestri – July 2007 RFID Testing Requirements
RFID Readers (Interrogators)
• Includes antenna, transceiver, and
decoder
• Many usage models:– Periodic requests to inquire about any tag in
the vicinity
– activate upon detection
– activate upon request
• Read range, memory variable
• Data stored for collection, or passed to
the data processor
Franco Canestri – July 2007 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
Franco Canestri – July 2007 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
Franco Canestri – July 2007 RFID Testing Requirements
Tags—Inductive vs. Radiative (Backscatter,
Remote Propagation)
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
Radiative
InductiveBased on Magnetic
couple principle
Franco Canestri – July 2007 RFID Testing Requirements
Tags—Inductive vs. Radiative (Backscatter)
From June 2005 High Frequency Electronics
Copyright © 2005 Summit Technical Media
Franco Canestri – July 2007 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 What do I do?
Franco Canestri – July 2007 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
Franco Canestri – July 2007 RFID Testing Requirements
Identifying Tags
Reader talk first (RTF)
• Multiple tags receive power
•Only the tag which is queried responds
―You talk first, then
everyone else decrement ‖
…1 3 0 7
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
―OK tag #2, download‖
Tag talk first
(TTF)•As soon as tag is
illuminated, tag
talks
•Active tags talk all
the time, for short
periods
Franco Canestri – July 2007 RFID Testing Requirements
Frequency Bands and Applications
Wall
13.56 MHz
900 MHz Multi-path
Leakage
Wall
Reader/Interrogator
Long distance and wide
coverage
• Read multiple tags at a time
• Issues from multi-path and fading
Easier RF design
• Tolerant of influence from water and
metals
• Short distance communication
Frequency 13.56 MHz (HF) 900 MHz (UHF)
Application Item tracking, electronic payment,
building security
Item tracking
Places to use Shop shelves, cash desk, ticket gate Logistics center, warehouse
Standards ISO 18092, 14443, 15693 EPCglobal Class1 Gen2
ISO 18000-6
Franco Canestri – July 2007 RFID Testing Requirements
Agenda
1. RFID Communication Systems, Standards, and Applications
– What’s RFID?
– Reader/Interrogator and Tag
– Frequency bands and applications
2. RFID Signal Overview at UHF Frequency Band
– Various standards at UHF band RFID
– ASK Modulation
– Line coding
3. RFID Signal Analysis (Reader/Interrogator and Tag)
– Measurements for Reader/Interrogator
– Measurements for Tag and RFID systems
4. RFID Measurement Solutions
Franco Canestri – July 2007 RFID Testing Requirements
RFID Standards Summary at UHF band
For standards compliance and interoperability, need to verify correct configuration of:
Modulation, Bit rate, Tari, Line CodingASK: Amplitude Shift Keying
Standard Direction Modulation Bit Rate Tari Line Coding
EPCglobal C1
Gen2
(ISO 18000-6
Type C)
Forward DSB-ASK,
SSB-ASK,
PR-ASK
6.25/
12.5/25 us
PIE
Return 40/80/120
kbps
FM0 / Miller
ISO 18000-6
Type A
Forward DSB-ASK 33 kbps PIE
Return 40/160
kbps
FM0
ISO 18000-6
Type B
Forward DSB-ASK 10/40 kbps Manchester
Return 40/160
kbps
FM0
Franco Canestri – July 2007 RFID Testing Requirements
RFID Definitions: CW/Burst/PulseASK in Reader/Tag Bursts
Interrogator Power-On
Burst
Pulse
Entire signal from reader
power turn on until turn off
A single pair of
on/off intervals
A contiguous set of
symbols from a single
transmitter
This is
actually the
envelope of
the CW signal
This is the tag
using the CW
power
transmitted to
respond
Franco Canestri – July 2007 RFID Testing Requirements
Key Challenges for UHF band RFID
Communication systems: Radio waves (potential interference
from other UHF radio services)
Places to use: Logistics center, warehouse (All over the world)
Example use cases:
US – WALMART ordered to attach RFID tags for top 300 suppliers
Hong Kong – Used in HK Airport for baggage tracking
Japan – Started in May 2006 at electric mass merchandisers
Baggage control system in April 2007
Some known issues:
– Standard compliance to communicate various Tags and Readers
– Impact from multi-path, fading
– Receiver sensitivity of tags and reader with attenuated signal in the air
Franco Canestri – July 2007 RFID Testing Requirements
Terms – Bit Rate or Symbol Rate
―Bit Rate‖ used in many standard docs.
―Bit‖ means encoded ASK modulated waveform.
―Symbol‖ means same as ―Bit‖ sometimes.
―Symbol‖ appears in the standard docs, but not as often as ―Bit.‖
bit
data-0 (s1) of Miller (M=4)
Franco Canestri – July 2007 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)
Franco Canestri – July 2007 RFID Testing Requirements
Terms – Line Coding
(Manchester, FM0)
Example 01011
0 1 0 1 1
Manchester
FM0
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
Franco Canestri – July 2007 RFID Testing Requirements
PIE (Type C) Coding
Pulse
•Represent data 0 or 1 with pulse time length
(not with voltage level at decision points)
•Variable Tari length by data rate
data-0 data-1 data-0
PW PW PW PWPW
• 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
Franco Canestri – July 2007 RFID Testing Requirements
RFID Communication Systems
Operations
Interrogator transmits CW signal ON and OFF
During CW ON period, Reader sends request signal to Tag
Tag receives the CW signal power, activates IC, and responds to Interrog.
CW
Reader
(Interrogator)
Tag
Key characteristics
Quite low power level from passive Tag
Different line coding between Reader and Tag
Franco Canestri – July 2007 RFID Testing Requirements
UHF band Reader signal (Gen2 DSB-ASK)
Standard defines ripple, rise time, fall
time and pulse width
Franco Canestri – July 2007 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)
Franco Canestri – July 2007 RFID Testing Requirements
U.S. FCC EPCglobal Regulations
Must use either FHSS (Frequency-Hopping Spread-Spectrum) or DSSS (Direct-Sequence 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 than 250 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 to 250 kHz
DSSS
• Requires 6dB bandwidth of at least 500 kHz
Franco Canestri – July 2007 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 ReaderEnvironment
• 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
Franco Canestri – July 2007 RFID Testing Requirements
Agenda
1. RFID Communication Systems, Standards, and Applications
– What’s RFID?
– Reader/Interrogator and Tag
– Frequency bands and applications
2. RFID Signal Overview at UHF Frequency Band
– Various standards at UHF band RFID
– ASK Modulation
– Line coding
3. RFID Signal Analysis (Reader/Interrogator and Tag)
– Measurements for Reader/Interrogator
– Measurements for Tag and RFID systems
4. RFID Measurement Solutions
Franco Canestri – July 2007 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)
Franco Canestri – July 2007 RFID Testing Requirements
Reader/Interrogator Measurements
– in time domain
on-time
on-width
off-width
rise time fall time
off-time
on-ripple overshoot
on-ripple undershoot
off-ripple overshoot
off-ripple undershoot
Higher Threshold
Lower Threshold
50%
100%
0%
Time domain analysis is required
Pulse width, Rise/Fall time requirements
for each RFID standard need to be analyzed
Franco Canestri – July 2007 RFID Testing Requirements
950 MHz ―Spectrum Regulation Test‖
Conformance Tests
Q: What equipment is needed for Radio Regulation Tests?
A: Swept-tuned spectrum analyzer, Signal generator, Power
meter, AutoTune feature (transient signals) on Spectrum An.
Q: Can FFT-based VSA be used for Radio Regulation
Tests?
A: Not recommended because of following risks.
1. Inspection agency uses swept-tuned spectrum analyzer
2. Conformance test is described with VBW, detector mode,
sweep time, which are not applicable in FFT-based VSA
For best correlation, use a swept-tuned spectrum analyzer with
AutoTune capability
Franco Canestri – July 2007 RFID Testing Requirements
Tag and RFID System Measurements
Reader/Interrogator
Tag behaviorResponding correctly to Reader signals?
How long to respond to Reader signals?
Burst amplitude, duration?
Signal analysis for troubleshootingCheck the impact from interference
Investigate null Tag response
Tag sensitivityReceived signal level required
for reliable response?
Operating frequency?
Distance of reliable communication?
Behavior due to interference (reflection,
multi-path, etc.)
Need detailed and flexible measurements during Tag/Reader
communication sessions
Tag
Franco Canestri – July 2007 RFID Testing Requirements
Measurements in Data Communications
Reader/Interrogator
Establish actual data communications and capture the signal
with antennas and probing.
> Measure tag response and communication timing
Tag
Franco Canestri – July 2007 RFID Testing Requirements
Summary of required measurements
Reader/Interrogator Tag and RFID system
- Standards
compliance
- Radio traffic
condition
- Troubleshooting
- Radio
Regulation Tests- Tag sensitivity
- Operating frequency
FFT
(VSA)
Swept
SA
Use both FFT-based VSA with Spectrogram and Swept SA
to cover all measurement needs
Franco Canestri – July 2007 RFID Testing Requirements
Agenda
1. RFID Communication Systems, Standards, and Applications
– What’s RFID?
– Reader/Interrogator and Tag
– Frequency bands and applications
2. RFID Signal Overview at UHF Frequency Band
– Various standards at UHF band RFID
– ASK Modulation
– Line coding
3. RFID Signal Analysis (Reader/Interrogator and Tag)
– Measurements for Reader/Interrogator
– Measurements for Tag and RFID systems
4. RFID Measurement Solutions
Franco Canestri – July 2007 RFID Testing Requirements
Burst Summary
Demod bits
ASK Summary
VSA RFID Modulation Analysis
Traffic conditions
Franco Canestri – July 2007 RFID Testing Requirements
Signal Analysis for Standard Compliance
Easy identification of
bursts in time domain
Demodulated bits
Demodulated
waveform
Modulation depth and
time domain analysis
Franco Canestri – July 2007 RFID Testing Requirements
Tag and RFID System Measurements
Detect bursts with length
and interval timing
Time length of entire CW power
Clear burst identification
with direction indicated
Franco Canestri – July 2007 RFID Testing Requirements
Tag Sensitivity
Interrogator
signal
Tag response Level difference
Check the Interrogator power level, tag response, and level difference
> Swept SA can detect lower noise power level
than FFT-based VSA
Franco Canestri – July 2007 RFID Testing Requirements
What’s the best analyzer for RFID?
Swept-tuned Spectrum Analyzer with AutoTune
Spectrum analysis with the fastest sweep up to 26.5 GHz
High dynamic range
Great level and frequency accuracy
FFT-based VSA S/W
Multiple domain analysis in time, frequency, and phase
Spectrogram, digital wireless modulation analysis
SW operates with scope/logic analyzer/simulation
Swept-tuned Signal Analyzer
with AutoTune and with
integrated VSA S/W option
Franco Canestri – July 2007 RFID Testing Requirements
Test Equipment needed in RFID Applications
(from : Canestri, F. “Radio-Frequency Identification (RFID): General Application Overview
and Testing Challenges” - 2007 – submitted Paper)
Reader with
transmitting antenna Passive or Active
RFID Tag
on object to identify
R-C circuit
to groud
Short
switch Termination
AutoTuned Spectrum Analyzers
- with integrated VSA Software
- with integrated Spectrograms
- with AutoTune functionality
EDA SW solutions
Vector Network Analyzers
Signal generators
Circuits Analyzers
Logic Analyzers
Oscilloscopes
Multi-meters
Circuit Analyzers
Logic Analyzers
R T
Franco Canestri – July 2007 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