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 • • • • • 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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