センサネットワーク
Sensor Networks
担当:山内規義教授
Prof. Noriyoshi Yamauchi
June 12, 2008
センサネットワーク
Sensor Networks
担当:山内規義 教授
Prof. Noriyoshi Yamauchi
RFID
Radio Frequency-Identification
RFID
Radio Frequency-Identification
• RFID is a means of identifying a person or
object using a radio frequency
transmission.
The technology can be used to identify,
track, sort or detect a wide variety of
objects.
Communication takes place between a
reader (interrogator) and a transponder
(Silicon Chip connected to an antenna)
often called a tag.
• Tags can either be active (powered by
battery) or passive (powered by the reader
field), and come in various forms including
Smart cards, Tags, Labels, watches and
even embedded in mobile phones.
The communication frequencies used
depends to a large extent on the
application.
The various features of RFID systems
• TransponderはTRANSmitter(送信機)と
resPONDER(応答機)からの合成語で、受
信した電気信号を中継送信したり、受信信号
に何らかの応答を返す機器の総称
RFID
Example
Security
Immobilizer(Texas Instruments’ )
Other
Library
Sushi
Region MAP
Available & Practical RFID Frequencies
The frequency ranges used for RFID systems range from the
myriametric range below 135kHz, through short wave and
ultrashort wave to the microwave range, with the highest
frequency being 24GHz. In the frequency range above
135kHz the ISM bands available worldwide are preferred
Typical RFID System
Structure of RFID
RFID System
• In a typical system tags are attached to objects. Each
tag has a certain amount of internal memory (EEPROM)
in which it stores information about the object, such as
its unique ID (serial) number, or in some cases more
details including manufacture date and product
composition. When these tags pass through a field
generated by a reader, they transmit this information
back to the reader, thereby identifying the object. Until
recently the focus of RFID technology was mainly on
tags and readers which were being used in systems
where relatively low volumes of data are involved.
RFID
• Every object to be identified in an RFID system will need
to have a tag attached to it. Tags are manufactured in a
wide variety of packaging formats designed for different
applications and environments. The basic assembly
process consists of first a substrate material (Paper,
PVC, PET...), upon which an antenna made from one of
many different conductive materials including Silver ink,
Aluminum and copper is deposited. Next the Tag chip
itself is connected to the antenna, using techniques such
as wire bonding or flip chip. Finally a protective overlay
made from materials such as PVC lamination, Epoxy
Resin or Adhesive Paper, is optionally added to allow the
tag to support some of the physical conditions found in
many applications like abrasion, impact and corrosion.
RFID Packaging
RFID Packaging
• In terms of computational power, RFID tags are quite
dumb, containing only basic logic and state machines
capable of decoding simple instructions. This does not
mean that they are simple to design! In fact very real
challenges exist such as, achieving very low power
consumption, managing noisy RF signals and keeping
within strict emission regulations. Other important circuits
allow the chip to transfer power from the reader signal
field, and convert it via a rectifier into a supply voltage.
The chip clock is also normally extracted from the reader
signal. Most RFID tags contain a certain amount of NVM
(Non volatile Memory) like EEPROM in order to store
data.
RFID Packaging
How RFID Tags Communicate
• In order to receive energy and communicate with a reader, passive
tags use one of the two following methods shown in fig 7. These are
near field which employs inductive coupling of the tag to the
magnetic field circulating around the reader antenna (like a
transformer), and far field which uses similar techniques to radar
(backscatter reflection) by coupling with the electric field. The near
field is generally used by RFID systems operating in the LF and HF
frequency bands, and the far field for longer read range UHF and
microwave RFID systems. The theoretical boundary between the
two fields depends on the frequency used, and is in fact directly
proportional to l/2p where l = wavelength. This gives for example
around 3.5 meters for an HF system and 5 cm for UHF , both of
which are further reduced when other factors are taken into account.
Energy and information transfer
between reader and tag
RFID Reader
RFID Reader and Label Printer
UID
Unique item Identification
• UID is the set of data for tangible assets
that is globally unique and unambiguous,
ensures data integrity and data quality
throughout life, and supports multi-faceted
business applications and users.
• EPC (Electronic Product Code)
• ONS (Object Name Service)
EPC
Electronic Product Code
• In October 1999 the Auto-ID center was
created in the Department of Mechanical
Engineering by a number of leading figures at
MIT . The potential benefits of RFID tags had
been identified long before, what was stopping
the adoption of the technology in the supply
chain was the cost of the tags.
ONS
Object Name Service
• ONS matches the EPC code to
information about the product via a
querying mechanism similar to the DNS
(Domain Naming system) used in the
internet, which is already proven
technology capable of handling the
volumes data expected in an EPC RFID
system. The ONS server provides the IP
address of a PML Server that stores
information relevant to the EPC.
Major Areas of RFID
•
•
•
•
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Access Control
Container Security
Container Identification and Location
Activity Tracking
Regulatory Compliance
Contactless Smart Cards
Available standards for contactless smart cards
Standards
Card type
Approximate range
ISO / IEC 10536
Close coupling
0~2mm
ISO / IEC 14443
Proximity coupling
0~10cm
ISO / IEC 15963
Vicinity coupling
0~1m
The various smart cards
ID-1 card
ISO 7810
Smart cards
ISO 7816
Contactless
smart cards
CICC
close cpl.
ISO 10536
Memory
card
contact
Processor
card
Processor
card
PICC
proximity
ISO 14443
Memory
Card
13.56 MHz
contactless
VICC
vicinity cpl.
ISO 15693
Processor
Card
13.56 MHz
RICC
remote cpl.
ISO ???
Memory
Card
13.56 MHz
Memory Card (battery)
2.4 / 5.8 GHz
Dual interface card
Family of (contactless and contact) smart cards,
with the applicable standards
Structure of Contactless Smart Cards
Suica
Suica
•
ICテレホンカードとSuica
•
非接触ICカードの開発は、1980年代から始められましたが、日本での本格的な普及が始
まったのは、つい最近で、1999年に運用が開始されたNTTのICテレホンカードが日本にお
ける実用化第1号です。
ちなみに、ICテレホンカードは、利用者が増えないことなどから、2006年3月末でサービス
が終了しました。一方、2001年にサービスを開始した、JR東日本の非接触ICカードを利用
したプリペイド乗車券であるSuicaは、着実に利用者を増やし、サービス開始から3年とかか
らずに、1,000万枚を発行しました。
Suicaは、乗車券としてだけなく、電子マネーとしても用途を広げ、利用可能な場所は、駅の
中から、駅の外へと着実に広がっています。Suicaの爆発的ともいえる普及により、非接触
ICカードは、注目を浴び始めました。JR東日本のSuicaに続き、JR関西のICOCA、スルッと
KANSAIのPiTaPa、JR東海のTOICAといった交通系の非接触ICカードの運用が開始され
たほか、2007年3月18日には、首都圏の私鉄やバスなどで利用できるPASMOの運用も始
まります。
FeliCaは、のちに携帯電話などに内蔵できるように設計された「モバイルFeliCa」というバリ
エーションも登場し、すでに、携帯電話にとって必須の機能と言っても過言でないでしょう。
ちなみに、FeliCaのコアとなるICチップで数えると(FeliCaとモバイルFeliCaの合計に相当)、
2005年10月の時点で、1億個を出荷したことが発表されました(※FeliCaやモバイルFeliCa
と、これらを使用している各種のサービスについては、次回、詳しく触れます)。
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