RFID Tags
Transcription
RFID Tags
RFID Application Overview and Testing Requirements Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements RFID allgemein verständlich Dipl.-Ing. Hardy Zissel Leiter AutoID / RFID Testcenter, TH Wildau Tel.: +49 3375 508 453, [email protected] Ingenieurbüro Zissel, Königs Wusterhausen Tel.: +49 3375 209005, [email protected] Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Agenda 1. RFID Communication Systems, Standards, and Applications 2. RFID Signal Overview at UHF Frequency Band 3. RFID Signal Analysis (Reader/Interrogator and Tag) 4. RFID Measurement Solutions Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements What’s RFID? Radio Frequency IDentification •Definition of RFID devices –Portable size –Data storage memory in IC chip –Capable of contactless communication •RFID features –Communicates longer distances than barcode; tolerant of dirt and interference –Communicates more data in readable, rewriteable IC chip •Some advantages compared with barcode –Uses in automated check-out with lower costs –Eliminates human error factors for improved information quality –Enables individual item recognition for traceability and tracking Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements RFID Communication Definitions Forward link: transmission from Reader to Tag Reader (Interrogator) (“base station”) Tag Return link: transmission from Tag to Reader (“mobile station”) Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements RFID Systems Description Tags Readers/Interrogators Hardy Zissel Matthias Weilhammer Thomas Giehm • Wireless transducer with antenna • Tag physical design dependent on end-use RFID Testing Requirements RFID Tags - Active • Active • On-board power source and transmitter • Higher range (<100 m), but more expensive • More reliable in difficult RF environs • May contain memory on-board • Battery life to 10 years • Transponder or Beacon Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements RFID Tags - Passive • Passive • Use power induced by the magnetic field of the reader, or battery-assist (passive-assist) • Cheaper • Potentially unlimited life span • Better reliability, especially in difficult physical environs • May contain memory on-board • Read distance: ~10 cm to <10m • Size: smaller than a coin, as thin as paper Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements RFID - Technologien Wirkprinzipien und Eigenschaften werden maßgeblich von der Arbeitsfrequenz bestimmt 125 KHz (LF) reine magnetische Kopplung, Lastmodulation, Reichweite 3 – 5 cm 13,56 MHz (HF) reine magnetische Kopplung, Resonanz, Lastmodulation, 60 cm 868 MHz (UHF) elektromagnetische Kopplung, Resonanz, frei fliegende Welle, Rückantwort auf eigener Frequenz, Reichweite passiv ca. 8 m, aktiv > 100 m 2,45 GHz (SHF) siehe UHF, für Spezialanwendungen, meist aktiv (mit Batterie) Ing.-Büro Zissel, www.zissel.com Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Tags—Inductive vs. Radiative (Backscatter) Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements 125 KHz (LF) Wirkungsweise transformatorisches Prinzip „auseinanderziehen“ der Trafowicklungen reine magnetische Kopplung, unbeeinflusst von Wasser u. anderen diamagnetischen Materialien geringe Datenrate Ing.-Büro Zissel, www.zissel.com Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Praxisbeispiel 125 Khz – transformatorisches Prinzip Glastransponder für die Injektion in Lebewesen Ing.-Büro Zissel, www.zissel.com Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements 13,56 MHz (HF) Wirkungsweise transformatorisches Prinzip mit Resonanz verbessertes transformatorisches Prinzip resonante Schwingkreise ohne Eisenkern günstigere Feldverteilung mit geringerer Energie Ing.-Büro Zissel, www.zissel.com Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Praxisbeispiele 13,56 MHz Schlüsselanhänger, Wäsche-Tag, Smartlabel Ing.-Büro Zissel, www.zissel.com Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements 868 MHz (UHF) Wirkungsweise H- und E – Feld, frei fliegende Wellen reiner Funkbetrieb über ablösende Welle (Wellenlänge ~ 0,34m) Nutzung von H- und E-Feld große Reichweiten (einige Meter) Ing.-Büro Zissel, www.zissel.com Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Praxisbeispiele 868 MHz Label und Hardtags (passiv) Inlay für Label von UPM für Papier, Kunststoff Metalltag mit Stahlgehäuse von ZISSEL für Metallbehälter 12 m Reichweite Transponder mit Metallgehäuse und Kunststoffüberzug von ZISSEL für Personen in Medizin und Sport Ing.-Büro Zissel, www.zissel.com Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Aktuelle Projekte des Ingenieurbüros Zissel: Intelligentes Regal für Bibliotheken - Bücherregal für Zeitschriften - In Zusammenarbeit mit TH Wildau - Liefert präzise Daten über die Nutzung der Zeitschriften innerhalb der Bibliothek - Ideal für Optimierung des Zeitschriftenbestandes Generierung der Richtlinie VDI4478-1 zur Bestimmung der Qualität von Sicherungsgates - Ideal für die Nutzung in Bibliotheken (gesamter Bücherbestand) - Einheitlicher vergleichbarer Qualitätsstandard - Gut für Ausschreibungen - Soll anschließend in die ISO überführt werden Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Tags—Inductive vs. Radiative (Backscatter, Remote Propagation) Radiative Current in tag from the reader allows the tag to radiate • Frequencies above VHF • Reader and tag can be read from further away • Subject to fading, reflection, etc • Higher data rates Inductive Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements The Challenges of RFID Suppose…you are all tags • • • • You are all blindfolded You are nearly deaf You talk by whispering You can’t hear each other Suppose…I’m a reader • • • • • • I’m blindfolded I don’t know who is in the room I need to yell so you can hear me If two of you talk at once, I can’t understand you I’m not allowed to say your name I may hear many others like me screaming in the same room I need to identify everybody in the room Hardy Zissel Matthias Weilhammer Thomas Giehm What do I do? RFID Testing Requirements More Challenges of RFID • Selecting and identifying tags – collision control. • Multiple readers in area—how to allow for a large number of closely spaced readers. • Minimal interference and optimized data rate for high noise or high speed communications. Also : • Sessions—how to handle multiple readers talking within same tag population • Variable data rates—Used to handle different needs in varied environments • Password, protection and security Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Identifying Tags 1 3 0 7 … “OK tag #2, download” “You talk first, then everyone else decrement ” Slotted Aloha •Tags “roll dice” and announce value •Tag with 0 value is allowed to talk •All tags decrement count •New tag with 0 is allowed to talk Hardy Zissel Matthias Weilhammer Thomas Giehm Reader talk first (RTF) • Multiple tags receive power Tag talk first (TTF) •As soon as tag is illuminated, tag talks •Active tags talk all the time, for short periods •Only the tag which is queried responds RFID Testing Requirements Frequency Bands and Applications Easier RF design • Tolerant of influence from water and metals Reader/ Interrogator 13.56 MHz • Short distance communication Wall 900 MHz Multi-path Leakage Long distance and wide coverage • Read multiple tags at a time Wall • Issues from multi-path and fading Frequency 13.56 MHz (HF) 900 MHz (UHF) Application Item tracking Places to use Item tracking, electronic payment, building security Shop shelves, cash desk, ticket gate Standards ISO 18092, 14443, 15693 Hardy Zissel Matthias Weilhammer Thomas Giehm Logistics center, warehouse EPCglobal Class1 Gen2 ISO 18000-6 RFID Testing Requirements RFID Standards Summary at UHF band Standard Direction Modulation EPCglobal C1 Gen2 (ISO 18000-6 Type C) ISO 18000-6 Type A ISO 18000-6 Type B Forward Return DSB-ASK, SSB-ASK, PR-ASK Forward Return Tari Line Coding 6.25/ 12.5/25 us PIE FM0 / Miller DSB-ASK 40/80/120 kbps 33 kbps FM0 DSB-ASK 40/160 kbps 10/40 kbps Return Forward Bit Rate PIE Manchester 40/160 kbps FM0 For standards compliance and interoperability, need to verify correct configuration of: Modulation, Bit rate, Tari, Line Coding ASK: Amplitude Shift Keying Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements RFID Definitions: CW/Burst/Pulse ASK in Reader/Tag Bursts Pulse A single pair of on/off intervals A contiguous set of symbols from a single transmitter Burst This is actually the envelope of the CW signal This is the tag using the CW power transmitted to respond Interrogator Power-On Entire signal from reader power turn on until turn off Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Terms – Tari (Interrogator Symbols) Tari = Type A Reference Interval (ISO / IEC 18000-6-A) The length of a binary '0' is defined as Tari, and is used as a reference for several other times in the standard. • The data rate can vary from 27 to 128 Kbps (Tari from 25 to 6.5 microseconds) • A binary '0' is a short high level pulse followed by low pulse of equal length • A binary '1' is a longer high pulse followed by the same low pulse width (PW) This symbol set provides a high average RF power delivered to the tag. Value of bit is dependent on the length of the pulse = Pulse Interval Encoding (PIE) Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Terms – Line Coding (Manchester, FM0) Example 01011 0 Manchester FM0 1 0 1 1 Represents 0 = 01 1 = 10 No superposition of DC potential by switching voltage at bit center Represents 0 = 01 or 10 1 = 11 or 00 (phase switch at boundary) Advantages in signal collision and error detection Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements PIE (Type C) Coding •Represent data 0 or 1 with pulse time length (not with voltage level at decision points) •Variable Tari length by data rate • Bit value determined by length of pulse, not amplitude • To read value, look for PW, (falling, low, rising), then delta time • Short length=0; long length=1 Pulse PW data-0 Hardy Zissel Matthias Weilhammer Thomas Giehm PW PW data-1 PW PW data-0 RFID Testing Requirements RFID Communication Systems Tag Reader (Interrogator) CW Operations Key characteristics Interrogator transmits CW signal ON and OFF Quite low power level from passive Tag During CW ON period, Reader sends request signal to Tag Different line coding between Reader and Tag Tag receives the CW signal power, Hardy Zissel Matthias WeilhammerIC, and responds to Interrog. activates Thomas Giehm RFID Testing Requirements UHF band Reader signal (Gen2 DSB-ASK) Standard defines ripple, rise time, fall time and pulse width Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Strategies for Avoiding Interference • Frequency multiplex (manual or auto) • Listen before talk • Time multiplex (duty cycle transmit) • Frequency hopping spread spectrum (FHSS) • Direct sequence spread spectrum (DSSS) • Chirp pulses (SAW filters) Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements U.S. FCC EPCglobal Regulations Must use either FHSS (Frequency-Hopping Spread-Spectrum) or DSSS (DirectSequence Spread-Spectrum) FHSS •Requires pseudo-random sequence to choose ordering for channel hopping •Requires equal use of 50 channels, with average time no greater than 0.4 sec on each channel during 20 sec time period if 20dB bandwidth is less than250 kHz ORequal use of 25 channels, with average time no greater than 0.4 sec on each channel during 10 sec time period if 20dB bandwidth is greater than or equal to250 kHz DSSS •Requires 6dB bandwidth of at least 500 kHz Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Summary of RFID Challenges • ASK based modulation not that simple – Tari, bit rate, T1/T2, Trise/Tfall • Spurious Requirements to co-exist with Cellular system – -60 to -80 dBm/100kHz • Collision Avoidance under Multi-Reader/Dense Reader Environment • Multi-path/Fading – Especially UHF tag even w/ slow movement • Integration into Mobile Phone; Mobile Phone as Tag or Reader (example: Near-Field Communication, NFC) – Today; 13.56MHz RFID Tag (FeliCa), QR code reader – Future; 300MHz/900MHz/2.4GHz RFID reader • Mobile Phone-like production – Tx Power Calibration Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Required measurements for Reader, Tag and RFID systems Reader/Interrogator Measurements - Signal Analysis for standard compliance - Modulation depth, rise/fall time, demodulated bits - Radio Regulation Test - For all commercial product under local regulations (FCC, ETSI, TELEC etc.) Tag and RFID System Measurements - Radio traffic conditions (Reader and tag response, burst measurements) - Signal analysis for troubleshooting (burst/inter-burst timing, error analysis, demodulation) - Tag sensitivity and operating frequency - Transmission performance (level, distance, interoperability) Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Reader/Interrogator Measurements – in time domain Time domain analysis is required on-ripple overshoot 100% Higher Threshold on-ripple undershoot off-width 50% on-width off-ripple overshoot Lower Threshold 0% on-time rise time off-ripple undershoot off-time fall time Pulse width, Rise/Fall time requirements for each RFID standard need to be analyzed Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Tag and RFID System Measurements Need detailed and flexible measurements during Tag/Reader communication sessionsTag Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Measurements in Data Communications Establish actual data communications and capture the signal with antennas and probing. > Measure tag response and communication timing Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements VSA RFID Modulation Analysis Traffic conditions Demod bits ASK Summary Hardy Zissel Matthias Weilhammer Thomas Giehm Burst Summary RFID Testing Requirements Signal Analysis for Standard Compliance Easy identification of bursts in time domain Demodulated bits Hardy Zissel Matthias Weilhammer Thomas Giehm Demodulated waveform Modulation depth and time domain analysis RFID Testing Requirements Tag and RFID System Measurements Clear burst identification with direction indicated Detect bursts with length and interval timing Time length of entire CW power Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Summary and Conclusions on RFID measurement requirements • RFID Communication Systems, Standards, and Applications – RFID tags respond to Reader/Interrogator’s signal power – Need measurements under multi-path, attenuated signal in the air • RFID Signal Overview at UHF Frequency Band – Various standards with parameters like bit rate, tari, line coding – Pulse rise time and modulation quality need to be analyzed • RFID Signal Analysis (Reader/Interrogator and Tag) – Reader/Interrogator : Standard compliance with FFT, Regulation test with Swept SA – Tag and RFID systems: Measure low level response with SA • RFID Measurement Solutions – Signal Analyzer with Swept-SA and AutoTune plus FFT-based VSA Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements Thank You for Your Attention ! Hardy Zissel Matthias Weilhammer Thomas Giehm RFID Testing Requirements