经典RFID介绍

UHF 900Mhz
~7m
Supply Chain
μwave 2.4Ghz
10m
Traffic Toll
Presentation Objectives:
• Explain technical principles behind RFID • Provide overview of RFID technology • Discuss:
Note: 64 bit versions also defined, 256 bit version under definition
Generic Tag Architecture
(Highly Simplified) Wrຫໍສະໝຸດ te PathReceiver
Antenna
D G
S
Memory
Protocol Engine
* Class 1 Gen 2 is still in development, expected to close in Q4, 2004
Class 0 Protocol
Backscatter
Class 0 Tag Backscatter Frequency
Modulation Format
North America
Tag Details
LF Freq. Range 125 - 134KHz Read Range 10 cm
HF
13.56 MHz 1M
UHF
866 - 915MHz 2-7 M
Microwave
2.45 - 5.8 GHz 1M
Market share
Coupling
74% Magnetic
17% Magnetic
into tag
Electronic Product Code
Header - Tag version number EPC Manager - Manufacturer ID Object class - Manufacturer’s product ID Serial Number - Unit ID With 96 bit code, 268 million companies can each categorize 16 million different products where each product category contains up to 687 billion individual units
• Reduce cost (man power, shipping mistakes) • Increase sales (keep shelves full) • DoD Total Asset Visibility Initiative
Source of data: EDN – October 2004 - “Reading Between the Lines” Brian Dipert
3.3 Mhz for data “1” 2.2 Mhz for data “0” FSK
Typical data stored in tag: • 96 bit EPC code • 24 bit kill code • 16 bit Cyclic Redundancy Check (CRC)
Reader/tag communication modes: 1. Start up signals (power up tags and sync. with them) 2. Tree Traversal (read individual tags) 3. Communication (send commands to tags)
RFID Overview
Greg Leeming Intel Corporation
11/8/2004
Radio Frequency IDentification
• Tag wirelessly sends bits of data when
it is triggered by a reader
6%
3%
Electro magnetic Electro magnetic
Existing standards
Application
11784/85, 14223 18000-3.1, 15693,14443 A, B, and C
EPC C0, C1, C1G2, 18000-6
Smart Card, Ticketing, animal tagging,
Access, Laundry
Small item
Transportation
management, vehicle ID,
supply chain,
Access/Security,
Anti-theft, library, large item transportation management,
supply chain
– Forces driving the adoption of RFID – Challenges RFID deployment must overcome – The future
Agenda
• RFID history • Technical principles • Tag overview • Reader overview • Adoption challenges • The UHF market • The future??
• Far field (UHF, microwave): backscatter. • Modulate back scatter by changing antenna impedance • Field energy decreases proportionally to 1/R
• Boundry between near and far field: R = wavelength/2 pi so, once have reached far field, lower frequencies will have lost significantly more energy than high frequencies
throughput See above
$ 8 bit password Reader broadcasts partial OID
? 32 bit
Authentication and
password and
Encryption
concealed
mode
Global Standard
No
No No Yes
Tags
Types of Tags
– Passive • Operational power scavenged
from reader radiated power
– Semi-passive • Operational power provided by battery
– Active • Operational power provided by battery - transmitter built
Read Only
Read & Write Read & Write Read & Write
Tag Privacy Cost
$$ 24 bit password
$$
See above
Security
Reader broadcasts OID or Anonymous modes with reduced
• Absorption by non-conductive materials significant problem for microwave frequencies
Source of data: “Introduction to RFID” CAENRFID an IIT Corporation
• Harry Stockman October 1948 Paper – Communication by means of
reflected power ( The proceedings of the Institute of Radio Engineers)
• First RFID Patent - 1973 • Auto-ID center founded at MIT – 1999
Data rates: fast and slow defined: fast ( 12.5 micro sec bit period) and slow (62.5 micro second bit period) --- either 20% or 100% modulation depths
Class 0 Signaling
Focus of this presentation is on UHF
Four main frequencies:
Frequency Distance
Example Application
LF
125khz
Few cm
AutoImmobilizer
HF 13.56Mhz
1m
Building Access
Default Class 0 Reader Communication Sequence
Tag power up, reset, and calibration process
Reader power up
Tag Singulation Process
RFID History
• First Bar code patents – 1930s • First use of RFID device – 2nd world war – Brittan used RFID-like