FCC RFID Workshop RFID Discussions September 7, 2004 Kevin Powell, Symbol Technologies
RFID Market Direction Convergence around the Electronic Product Code (EPC) as the standard Wal-Mart's RFID-Using Suppliers to Exceed 100 Pilots with eight key suppliers eWeek June 14, 2004 Defense Department will require its suppliers to put RFID tags on shipments by January 2005 to better manage its inventory. Aviation Week EPC Pallet and case tagging mandates – PASSIVE tags Defining the Gen 2 Standard
The Goal is Asset Visibility … Everywhere!
EPC Standards Glossary
Class 0 (available):
Generation 1, protocol 0
Factory programmed ID
Class 1 (available):
Generation 1, protocol 1
Write Once ID
UHF Generation 2 (future):
Single Gen2 protocol
Variety of memories & features
First products in 2005
Readers and Antennas AR400 Reader High Performance Antenna General Purpose Antenna SR400 Reader
Handheld with RFID
Same ruggedness and ergonomic as the MC-9000G Antenna (front-mounted) and additional electronics add the ability to read and write either EPC Class 0 or Class 1 RFID tags Integrated wireless networking RFID 2D bar code “ all in one” 1D bar codes & simultaneously
EPC-Compliant RFID Tags Plastic Tag Carton Tag Glass Tag Concrete Tag Plastic Bottle Tag Generic Tag Variety of tags for different materials and applications Class 0/0+
Basics - RFID System A tag stores information and exchanges it by radio signal Passive RFID Tag Reader commands the tag & simultaneously listens for responses RF modulator Memory Power recovery Digital logic Radio Signal RFID Protocols RF demodulator Oscillator All in 10 microwatts! } Three EPC Communication Protocols for UHF EPC Class 0 (Invented by Matrics) EPC Class 1 (Invented by Alien Technologies) EPC Gen2 under development
Passive RFID System Design
Passive Tag Constraints
Battery-less – RF field powered ONLY, thus:
Total consumed power < 10 W (10M range), and
Simple demodulator (amplitude – 1bit/Hz style)
Simple modulator (1 transistor – square wave out)
Backscatter (modulated RCS) only Tx method
Passive Tag Results
Very wide band response (effective antenna BW) in receiver as well as backscatter(but at low levels)
Confined to relatively inefficient reader modulation encoding methods (simple tag demod).
Passive RFID System Design
Must energize tag (transmit) while in receive mode
= Receive –50dBm while transmitting +30dBm
Avoid noise sources
Reader transmit & receive circuitry
Other backscatter sources, ie fluorescent lighting
Extremely low noise design necessary to properly receive tag signals while transmitter is on.
Detect and avoid other high power RF devices.
Shift receiver away from noise sources.
RFID Frequency Sources Reader Tx Reader CW Fluorescent 20-40kHz Tag - baseband Tag – Gen2 Subcarriers Channel Edge Channel Edge Tag – Class 0 Subcarriers
Passive RFID Trends
Better tag designs/protocols = lower power
Note – Fluorescent interference approx –60dBm
2008 2006 2004 2002 2000 Year -87dBm 6 W +30dBm 100’ -82dBm 11 W +30dBm 75’ -75dBm 25 W +30dBm 50’ -60dBm 100 W +30dBm 25’ -45dBm 600 W +30dBm 10’ Rdr Rx Tag field Rdr pwr Tag Dist
Reader signals interfere with tag signals at thousands of feet separation.
Reader signals interfere with other reader transmissions at less than 100 feet.
80-100 dB range between Reader and Tag leads design to a separation of disparate power levels such that:
Reader signals ONLY contend w/ other readers
Tag signals ONLY contend with other tags
As technology improves tag distances, the impact of noise (self, and fluorescent) becomes severe; the available technology is near the limit.
Technology improvement comes on the heels of the ability to remove the tag response from noise.
Request - allow readers on even channels, tag response on odd channels (or similar) as an optional channel use model.