lecture 5 rfid technologies - hoseipropagation characteristics are different in each frequency band...
TRANSCRIPT
Lecture 5
RFID Technologies
What’s RFID and What’s It for?
RFID Categories and Working Mechanisms
RFID Frequencies and Features
RFID Anti-Collision Techniques
What is RFID - Video 1
BiometricSystems
Smart Cards
RFID
OpticalCharacter
Recognition(OCR)
BarcodeSystems
Auto-ID
Object Auto-Identification Technologies
RFID is one technology to identify an object
RFID
RFID - Radio Frequency IDentification
A radio-based data capture technology that can be used to electronically identify, track, and store information contained on a “tag” that is attached to or embedded in an object, such as a key, an animal, a cloth – almost all physical objects!!
What do RFID Tags look like?
Types of RFID Tags
Active RFID Tag – with a battery
Passive RFID Tag – without a battery
Semi-Active/Semi-Passive– with a battery
– but working conditionally
RFID Tag Components
Antenna Power Supply
RF Transmitter
RF Receiver
Control Unit
Microchip
With
Memory
(10011...0)
ID Number
ID Code
Tag Integrated Circuit (IC)Tag Antenna
An Example of Passive Tag
RFID Tag Memory
Read-only tags Tag ID is assigned at the factory during manufacturing
Can never be changed
No additional data can be assigned to the tag
Write once, read many (WORM) tags Data written once, e.g., during packing or manufacturing
Tag is locked once data is written
Similar to a compact disc or DVD
Read/Write tags
Tag data can be changed over time
Part or all of the data section can be locked
RFID Reader
RFID Reader is a device to – Communicate with tag
– Read/write code from/into tag
– Supply power to passive tag
– Internal/External Antenna
– Connections to other machines
RFID
Reader
Reader AntennaRFID Tag
Serial Port
CPU
Power
SupplyRAM
Flash
RF Board
Interface
GPIO
Ethernet
WLANTag
Antenna
Electromagnetic Waves
Computer/ServerSmartphone
RFID
Tag
Communications btw Reader & Tag
Inductive Coupling – 電磁誘導方式 Short comm. distance
Propagation Coupling– 電波方式 Long comm. distance
RFID
Reader
Coil/Antenna
RFID
Tag
IC Chip
Coil
Antenna
RFID
Reader
Antenna
Antenna
Inductive Coupling
Propagation Coupling
Reader-TagCommunications
Time
Time
Power Change
ParametersCommandPreamble
Reader sending
Tag processing & sendingTag changing & receiving
Reader receiving
Tag 1
Reader
Tag 2
Tag 3
Interrogation zone
Interrogation Zone – Readable Distance
x
x
Tag 1
Reader
Tag 2
Tag 3
Various Shapes of
Interrogation zone
Reader’s Direction
Interrogation Zone – Readable Distance
Propagation characteristics are different in each frequency band
LF HF VHF UHF SHF EHFMF
UV
1 MHz1 kHz 1 GHz 1 THz 1 PHz 1 EHz
infrared visible
X raysGamma rays
902 – 928 Mhz
2.4 – 2.4835 Ghz
5.725 – 5.785 Ghz
ISM band WLAN
30kHz 300kHz 3MHz 30MHz 300MHz 30GHz 300GHz
10km 1km 100m 10m 1m 10cm 1cm 100mm
3GHz
Frequency and Communications
LF HF VHF UHF SHF EHFMF
30kHz 300kHz 3MHz 30MHz 300MHz 30GHz 300GHz3GHz
Radio Frequency for RFID
119~136kHz13.56MHz
315MHz
418MHz
433MHz
860MHz
|
960MHz
2.45GHz
5.8GHz
RFID Frequency Available in Japan
UHF Frequency in Different Countries
Advantages Relative freedom from regulatory limitations
Suited for applications reading small amounts of data at slow speeds and minimal distances
Penetrates materials well (water, tissue, wood, aluminum)
RFID in 119~136 KHz (LF)
Disadvantages: Does not penetrate or transmit around
metals (iron, steel)
Small amounts of data & slow read speeds
Large Antennas compared to higher frequency
Minimal Range
Thicker (than 13.56 MHz)
Advantages Suited for applications requiring reading small amounts of data in
near distances
Penetrates water/tissue well
Simpler antenna design (fewer turns of the coil); lower costs to build
Higher data rate (than 125 kHz--but slower than higher MHz systems)
Thinner tag construction (than 125 kHz)
Popular Smart Card frequency
RFID in 13.56 MHz (HF)
Disadvantages: Does not penetrate or transmit around metals
Large Antennas (compared to higher frequencies)
Larger tag size than higher frequencies
Reading Range of ≈ 0.5~1 m
Advantages Effective around metals
Best available frequency for distances of >1m
Tag size smaller than 13.56 MHz
Smaller antennas
Good non-line-of-sight
High data rate; Large amounts of data
Controlled read zone via antenna directionality
RFID in 300~960 MHz (Lower Range UHF)
Disadvantages: Does not penetrate water/tissue
Regulatory issues (differences in frequency,
channels, power, and duty cycle)
Advantages Tag size smaller than inductive or lower range UHF
Range: greater range than inductive w/o battery
More bandwidth than lower range UHF (more frequencies to hop)
Smaller antennas than lower range UHF or inductive
High data rate
Good non-line-of-sight communication
Can transmit large amounts of data more quickly
Controlled read zone via antenna directionality
Effective around metals with tuning adaptations
RFID in 2.45 GHz (UHF)
Disadvantages: More susceptible to electronic noise than lower UHF bands, e.g. 433
MHz, 860-930 MHz
Shared spectrum with others -- microwave ovens, WLAN, TV, …
Requires non-interfering, "good neighbor" tactics
Advantages Less used frequency range
Less congested band/less interference
RFID in 5.8 GHz (SHF)
Disadvantages: Not available in U.S. or many other countries
Must orient antennas carefully
Range limited (due to scaling issues/wavelengths)
Chip difficult to build
Expensive
Frequency, Size and Performance
Copyright © 2007
Accenture
LF HF UHF SHF
Band 132KHz 13.56MHz 315 MHz 418MHz 433MHz 868MHz 915/960M 2.4GHz
Frequency
Range Detail
119-136
KHz
72dBuA/m
@10m
13.553-
13.567 MHz
42 dBuA/m
@10m
314.7-
315 MHz
65 dBuV/m
@10m
418.95-
418.975
MHz
10mW ERP
433.050-
434.790
MHz, 10%
10mW ERP
868-
868.6 MHz
25mW ERP
1%
902-960
MHz
2400-
2483.5
MHz
Passive Tag
Range
Very Short
inches
Very Short
~1M
Very Short
~1M
Very Short
~1M
Very Short
~1M
Very Short
~1M
Short 1
3-5 M
Very Short
<2M
Active Tag
Range
Short Short Long 2 Long 2 Long 2 Long Long Long
Range
adjustment
Very Good3
Good Fair Fair Fair Poor Poor Poor
Propagation through materials
Excellent 3 Very Good Good 2 Good 2 Good 2 Fair Fair Poor
Transmission
/ Acquisition
Speed
SLOW (10s of Tags / s) FAST (1000s of Tags / s)
1. 915/960 MHz is the only band that provides Short Range for passive tags (due to regulation)
2. Lower UHF bands (315, 418, 433 MHz) are the only bands that provide Long Range (with active tags), have Good propagation, and can use directional Antennas
3. 132 KHz is the only band with Very Good range adjustment and propagation characteristics
RFID Comparisons in Different Frequencies
Interrogation zoneTag
Tag collision problem:
collision occurs when
multiple tags
respond to the same reader
simultaneously
Reader
27
The Tag Collision Problem
x
Time
Time
Answer
Power Change
ParametersCommandPreamble
One-Reader Multi-Tags Collision
Reader
M Bottles M Tags
M Replies at the same time Collision of replied waves Cannot identify which RFID
Tag
Collision Avoidance Anti-Collision
Multiple tags simultaneously respond to a reader’s query- Results in collision at the reader- Have to distinguish between the tags
Need anti-collision techniques
Collision avoidance mechanisms:- Based on TDMA (Time Division Multi Access)- Probabilistic: Tags return at random times- Deterministic: Reader searches for specific tags
Several approaches for Collision Avoidance- Tree algorithm- Memoryless protocol- Contactless protocol- I-code protocol
Tree Algorithm Concept
0 1
0 1 1
0
0 1
010 011 101
Who has “ “?
010 011 101
Who has “1“?
101
Who has “10“?
101
Who has “0“?
011010
Who has “00“?Who has “01“?
011010
Tree Algorithm
• Reader queries for tags and informs in case of collision• Tags generates 0 or 1 randomly. If 0 then tag retransmits
on next query. If 1 then tag becomes silent and starts incrementing its counter (initially zero)
• Counter incremented every time collision reported and decremented every time identification reported
• Tag remains silent till its counter becomes zero
Reader
Read/reply time slots (TS)
010* 011*
10*
1110* 1111* 1TS 13TS Time
Memoryless Protocol
Reader queries for prefix p
In case of collision, reader queries for p0 or p1
Example: consider tags with prefixes:
00111, 01010, 01100, 10101, 10110 and 10111
Reader
Tag frequency
125KHz - 5.8 GHz
Tag readable distance
Passive: 0.1~5 m; Active: ~100m
Tag size and weight
Small/large, thick/thin, shape, etc.
Tag life
Passive: many years; Active: few years
Tag memory
Size (16 bits - 512 kBytes +); Read-Only, Read/Write or WORM
Tag price
Cheaper (10 yen) to expensive (10,000 yen)
Main Specifications of RFID Tags
RFID Brief History 1939: RFID technology was used extensively by the British in WWII
as a way to track planes and other vehicles with IFF (identification of friend or foe) transponders
1948: “Communication by Means of Relflective Power,” a
Landmark paper by Harry Sockman
1950s: D.B. Harris “Radio Transmission Systems With Modulatable Passive Repsonder”.
1960s: R.F. Harrington advances theory with “Field Measurements Using Active Scatterers”.
1970s: Explosion of RFID research and inventions (Los Alamos Labs, Raytheon, Northwestern University, RCA, Fairchild)
1980s: Worldwide Implementation and deployment of RFID in transportation, personnel access, and agriculture
1990s: Expansion of RFID into retail, electronic toll collection, fuel dispensing, parking and building access, etc.
2000s: RFID has become ubiquitous and mainstream
RFID Brief History in Japan
Annual Sell in JAISA (Japan)
Japanese RFID Market Japanese RFID Price Japanese RFID Year
Access the following websites to learn more about RFID
tags, readers, characteristics, technologies, history,
some applications, etc.
RFID – Wikipedia (Japanese)
RFID – Wikipedia (English)
ICタグ - Wikipedia
RFIDとは?
Check RFID products in Japan market (A List of Makers)
Study RFID Anti-Collision Algorithms (A Survey Article)
Others you like Important to get materials from Web!!
Homework