センサネットワークSensor Networks

担当：山内規義教授Prof. Noriyoshi Yamauchi

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

RFIDRadio Frequency － Identification

RFIDRadio 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 R ＦＩＤ 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

UIDUnique 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)

EPCElectronic 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.

ONSObject 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

• Access Control

• Container Security

• Container Identification and Location

• Activity Tracking

• Regulatory Compliance

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

Available standards for contactless smart cards

contact

contactless

ID-1 cardISO 7810

Smart cardsISO 7816

Contactless smart cards

CICCclose cpl.

ISO 10536

Memory card

Processor card

MemoryCard

13.56 MHz

Dual interface card

Processor card

Memory Card (battery)2.4 / 5.8 GHz

MemoryCard

13.56 MHz

ProcessorCard

13.56 MHz

RICCremote cpl.

ISO ???

VICCvicinity cpl.ISO 15693

PICCproximity

ISO 14443

Family of (contactless and contact) smart cards, with the applicable standards

The various smart cards

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）。