Lecture 5. RFID Technologies

Transcription

1 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

2 Object Auto-Identification Technologies Barcode Systems Biometric Systems Auto-ID Optical Character Recognition (OCR) Smart Cards RFID RFID is one technology to identify an object

3 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!!

4 What do RFID Tags look like?

5 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

6 RFID Tag Components Antenna Power Supply RF Transmitter RF Receiver Control Unit Microchip With Memory ( ) ID Number ID Code Tag Antenna Tag Integrated Circuit (IC) An Example of Passive Tag

7 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

8 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 Serial Port Ethernet WLAN GPIO RAM Flash CPU Power Supply RF Board Interface Antenna Tag Reader Antenna RFID Tag Computer /Server Smartphone RFID Reader Electromagnetic Waves

9 RFID Reader and Antenna What is RFID - Video 2

10 Communications btw Reader & Tag Inductive Coupling 電磁誘導方式 Short comm. distance IC Chip RFID Reader Coil/Antenna RFID Tag Coil Antenna Propagation Coupling 電波方式 Long comm. distance RFID Reader Antenna RFID Tag Antenna

11 Inductive Coupling

12 Propagation Coupling

13 Reader-Tag Communications Reader sending Reader receiving Preamble Command Parameters Time Time Power Change Tag changing & receiving Tag processing & sending

14 Interrogation Zone Readable Distance Tag 1 Tag 3 x Reader x Interrogation zone Tag 2

15 Interrogation Zone Readable Distance Tag 1 Tag 3 Reader Tag 2 Various Shapes of Interrogation zone Reader s Direction

16 Frequency and Communications ISM band WLAN Mhz Ghz Ghz LF MF HF VHF UHF SHF EHF 30kHz 300kHz 3MHz 30MHz 300MHz 3GHz 30GHz 300GHz 10km 1km 100m 10m 1m 10cm 1cm 100mm infrared visible 1 MHz 1 khz 1 GHz 1 THz 1 PHz 1 EHz UV X rays Gamma rays Propagation characteristics are different in each frequency band

17 Radio Frequency for RFID LF MF HF VHF UHF SHF EHF 30kHz 300kHz 3MHz 30MHz 300MHz 3GHz 30GHz 300GHz 119~136kHz 13.56MHz 315MHz 418MHz 433MHz 2.45GHz 860MHz 960MHz 5.8GHz

18 RFID Frequency Available in Japan

19 UHF Frequency in Different Countries

20 RFID in 119~136 KHz (LF) 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) 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 MHz)

21 RFID in MHz (HF) 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 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

22 RFID in 300~960 MHz (Lower Range UHF) Advantages Effective around metals Best available frequency for distances of >1m Tag size smaller than MHz Smaller antennas Good non-line-of-sight High data rate; Large amounts of data Controlled read zone via antenna directionality Disadvantages: Does not penetrate water/tissue Regulatory issues (differences in frequency, channels, power, and duty cycle)

23 RFID in 2.45 GHz (UHF) 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 Disadvantages: More susceptible to electronic noise than lower UHF bands, e.g. 433 MHz, MHz Shared spectrum with others -- microwave ovens, WLAN, TV, Requires non-interfering, "good neighbor" tactics

24 RFID in 5.8 GHz (SHF) Advantages Less used frequency range Less congested band/less interference 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

25 Frequency, Size and Performance

26 RFID Comparisons in Different Frequencies LF HF UHF SHF Band 132KHz 13.56MHz 315 MHz 418MHz 433MHz 868MHz 915/960M 2.4GHz Frequency Range Detail Passive Tag Range Active Tag Range Range adjustment KHz Very Short inches MHz 42 Very Short ~1M MHz 65 Very Short ~1M MHz 10mW ERP Very Short ~1M MHz, 10% 10mW ERP Very Short ~1M MHz 25mW ERP 1% Very Short ~1M MHz Short M MHz Very Short <2M Short Short Long 2 Long 2 Long 2 Long Long Long Very Good 3 Good Fair Fair Fair Poor Poor Poor Propagation through materials Transmission / Acquisition Speed Excellent 3 Very Good Good 2 Good 2 Good 2 Fair Fair Poor SLOW (10s of Tags / s) FAST (1000s of Tags / s) /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 KHz is the only band with Very Good range adjustment and propagation characteristics Copyright 2007 Accenture

27 The Tag Collision Problem Preamble Command Parameters Time Answer Time Power Change Tag Interrogation zone x Reader Tag collision problem: collision occurs when multiple tags respond to the same reader simultaneously 27

28 One-Reader Multi-Tags Collision Tag Reader M Bottles M Tags M Replies at the same time Collision of replied waves Cannot identify which RFID

29 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

30 Tree Algorithm Concept Who has 1? 10? 0? 00? 01??

31 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 10* Read/reply time slots (TS) 1TS 010* 011* 1110* 1111* 13TS Time

32 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, and Reader

33 Main Specifications of RFID Tags Tag frequency 125KHz 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 kbytes +); Read-Only, Read/Write or WORM Tag price Cheaper (10 yen) to expensive (10,000 yen)

34 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

35 RFID Brief History in Japan

36 Annual Sell in JAISA (Japan) Japanese RFID Market Japanese RFID Price Japanese RFID Year

37 Homework 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!!