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3/21/2013 RFID Overview Greg Leeming Intel Corporation 11/8/2004 Radio Frequency IDentification • Tag wirelessly sends bits of data when it is triggered by a reader • Power source not required for passive tags… a defining benefit • Superior capabilities to barcode: – Non Line of Sight Distance Frequency – Hi-speed, multiple reads – Can read and write to tags 125khzID Few cm – LFUnit specific Example Application AutoImmobilizer HF 13.56Mhz 1m Building Access UHF 900Mhz ~7m Supply Chain μwave 2.4Ghz 10m Traffic Toll Four main frequencies: Focus of this presentation is on UHF 1 3/21/2013 Presentation Objectives: • Explain technical principles behind RFID • Provide overview of RFID technology • Discuss: – Forces driving the adoption of RFID – Challenges RFID deployment must overcome – The future Agenda • • • • • • • RFID history Technical principles Tag overview Reader overview Adoption challenges The UHF market The future?? 2 3/21/2013 RFID History • First Bar code patents – 1930s • First use of RFID device – 2nd world war – Brittan used RFID-like technology for Identify- Friend or Foe • Harry Stockman October 1948 Paper – Communication by means of reflected power ( The proceedings of the Institute of Radio Engineers) • First RFID Patent - 1973 • Auto-ID center founded at MIT – 1999 – Standardization effort taken over by EPC Global (Electronic Product Code) • Current thrust primarily driven by Wal-Mart and DoD – Automate Distribution: • Reduce cost (man power, shipping mistakes) • Increase sales (keep shelves full) • DoD Total Asset Visibility Initiative Source of data: EDN – October 2004 - “Reading Between the Lines” Brian Dipert Basic Operational Backscatter Principles InductiveTag Coupling TAG Reader Reader N TAG S • • • • Near field (LF, HF): inductive coupling of tag to magnetic field circulating around antenna (like a transformer) • Varying magnetic flux induces current in tag. Modulate tag load to communicate with reader • field energy decreases proportionally to 1/R3 (to first order) Far field (UHF, microwave): backscatter. • Modulate back scatter by changing antenna impedance • Field energy decreases proportionally to 1/R Boundry between near and far field: R = wavelength/2 pi so, once have reached far field, lower frequencies will have lost significantly more energy than high frequencies Absorption by non-conductive materials significant problem for microwave frequencies Source of data: “Introduction to RFID” CAENRFID an IIT Corporation 3 3/21/2013 Tags Types of Tags – Passive • Operational power scavenged • from reader radiated power – Semi-passive • Operational power provided by battery – Active • Operational power provided by battery - transmitter built into tag 4 3/21/2013 Electronic Product Code Header - Tag version number EPC Manager - Manufacturer ID Object class - Manufacturer’s product ID Serial Number - Unit ID With 96 bit code, 268 million companies can each categorize 16 million different products where each product category contains up to 687 billion individual units Note: 64 bit versions also defined, 256 bit version under definition Generic Tag Architecture (Highly Simplified) Write Path Antenna Receiver D G Memory S Protocol Engine 5 3/21/2013 Tag Details LF HF UHF Microwave Freq. Range 125 - 134KHz 13.56 MHz 866 - 915MHz 2.45 - 5.8 GHz Read Range 10 cm 1M 2-7 M 1M Market share 74% 17% 6% 3% Coupling Magnetic Magnetic Electro magnetic Electro magnetic Existing standards 11784/85, 14223 18000-3.1, 15693,14443 A, B, and C EPC C0, C1, C1G2, 18000-6 18000-4 Application Smart Card, Ticketing, animal tagging, Access, Laundry Small item management, supply chain, Anti-theft, library, transportation Transportation vehicle ID, Access/Security, large item management, supply chain Transportation vehicle ID (road toll), Access/Security, large item management, Competing UHF Protocols (EPC only) Read Rate Read or Read/Write Tag Cost Class 0 NA: 800 reads/sec EU: 200 reads/sec Read Only $$ Class 0+ NA:800 reads/sec EU:200 reads/sec Read & Write $$ Class 1 NA:200 reads/sec EU: 50 reads/sec Read & Write Class 1 Gen 2* (UHF Gen2) NA:1700 reads/sec EU: 600 reads/sec Read & Write Privacy Security Global Standard Reader broadcasts OID or Anonymous modes with reduced throughput No See above See above No $ 8 bit password Reader broadcasts partial OID No ? 32 bit password and concealed mode Authentication and Encryption Yes 24 bit password * Class 1 Gen 2 is still in development, expected to close in Q4, 2004 6 3/21/2013 Class 0 Protocol Backscatter Typical data stored in tag: • 96 bit EPC code • 24 bit kill code • 16 bit Cyclic Redundancy Check (CRC) North America Class 0 Tag Backscatter Frequency 3.3 Mhz for data “1” 2.2 Mhz for data “0” Modulation Format FSK Reader/tag communication modes: 1. Start up signals (power up tags and sync. with them) 2. Tree Traversal (read individual tags) 3. Communication (send commands to tags) Data rates: fast and slow defined: fast ( 12.5 micro sec bit period) and slow (62.5 micro second bit period) --- either 20% or 100% modulation depths Class 0 Signaling 7 3/21/2013 Default Class 0 Reader Communication Sequence Tag power up, reset, and calibration process Tag Singulation Process Reader power up Repeated after each frequency hop Reset: 800 micro sec uninterrupted continuous wave Oscillator calibration: 8 116 micro sec pulses Data calibration: 3 pulses ( data “0”, data “1”, data “null”) Single Binary Transversal Once tag has been singulated, reader can send commands to it or begin next BT cycle Tag Singulation Process read individual tag from group of all tags in range of reader • Basic process: • All tags within range of reader backscatter their MSB to the reader. • Reader responds with either a 1 or a 0. • If tag bit equals reader bit, tag backscatters the next bit in it’s code . If instead, tag bit does not equal reader bit, tag goes mute for remainder of singulation. • Process continues until reader has completely read a single tag. • Reader conducts consecutive singulations until all tags in its range are read. • Reader can interrupt the singulation process to send commands to a single tag, a subset of all tags in range, or globally to all tags in range. 8 3/21/2013 Readers UHF Reader Standards GEO / Country Frequency Band North America 900 – 930 MHz EMEA 866 – 868 MHz Korea 908.5 – 914 MHz Australia 918 – 926 MHz China (PRC) TBD Japan Transmitter TBD North America Output Freq. Band 902 – 928 Mhz Output Power 4 watts EIRP TX Channel step 500Khz Hop frequency 2.5 to 20 times per second TX Channels 902.75, 903.25, …, 927.25Mhz Modulation Typically ASK –- 20% to 100% modulation depth Note: EIRP = 1.64X ERP (Effective Radiated Power) 9 3/21/2013 Reader Implementation Challenges • Reader must deliver enough power from RF field to power the tag • Reader must discriminate backscatter modulation in presence of carrier at same frequency • 70db magnitude difference between transmitted and received signals • Interference between readers • Hugh volume of tag data – readers need to filter data before releasing to enterprise network Possible UHF Reader RF Processor DAC MicroController Power Control Host Device Crystal VCO Baseband & Protocol PA Coupler PLL Coupler RFID READER RF Module DAC FPGA Regulation ADC AGC Filters I/Q Demod Filter Coupler Power Detect Transmit path Receive Path Frequency Synthesizer Digital 10