EPCglobal Class-1 Generation 2 UHF RFID Todd Humes, CTO Impinj, Inc. 501 N 34th Street, Suite 100 Seattle, WA 98103
[email protected]
An RFID Chip
More transistors than the processor in a 1985 IBM PC-AT Lower power consumption than a honeybee’s brain
RFID Hardware Overview Wafers
Tags
Reader
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RFID is Old, what’s New • New standards at UHF (900 MHz) vs HF (13.56MHz) • UHF - 10X range of HF RFID • Faster data rates – up to 640kbps
• But, presents many new challenges:
• How to identify and read/write single tags from hundreds within a reader field... • Tag and reader RF interference... • Security.... • Tag data processing...
• Solution - EPCglobal Gen2 standard
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RFID Systems Network layer
RFID Reader
Air Interface
Tag
Tag
IP
RFID Reader
Tag
Network Tag
RFID Reader Example data exchange: Forward
Link parameters
Link rates and encoding formats
Return
Tag inventory
Singulation parameters, tag identification 5
Tag Identification • Suppose…you are all tags • • • •
You You You You
are all blindfolded are nearly deaf talk by whispering 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
What do I do? 6
Reader Environments • Operating Environment • A region within which a reader’s RF transmissions are attenuated by less than 90dB (roughly a sphere with a 1km radius)
• Single-reader environment • A single reader operating in the environment
• Multiple-reader environment • # of simultaneously active readers < # of available channels • Example: 10 readers operating in 50 channels
• Dense-reader environment • # of simultaneously active readers # of available channels • Example: 50 readers operating in 50 channels
Readers require knowledge of operational deployment and the ability to adjust their RF parameters for a given environment ie. One non-dense reader in a dense reader deployment will spoil the whole frequency plan
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Air Interface Control Gen2 features
Purpose
S/W Control
Tag selection and identification
Singulation control and options for faster inventories
Q-algorithm, Boolean selection, truncated replies
Dense reader mode
Allows for a large number of closely spaced readers with minimal interference and optimized data rate for high noise or high speed comm
Forward link options – DSBASK, SSB-ASK, PR-ASK Return link options – Baseband or subcarrier backscatter
Sessions
Multiple readers talk within same tag population
Choice of four sessions
e.g. dock door reader + handheld Variable data rates
Link closure in varied environments
Configure forward link (Tari, pulsewidth) and reverse link (preamble type, data rate, encoding - FMO or Miller)
Kill and access password
Security
Password validation and management
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