RFID: What You Need To Know

by Rod Harrison, Cornerstone Solutions

Wal-Mart will require all pallets and cases to have RFID tags based on the Class 1, version 2 specification of the Electronic Product Code (EPC); it is being developed under the auspices of EPCglobal, a joint venture between the Uniform Code Council and EAN International, charged with commercializing EPC technology. The tag will carry a 96-bit serial number and be field-programmable. Class 1 or Class 0 tags are acceptable, but Wal-Mart would like to see suppliers move to Class 1 version 2 as soon as the specification is ready.

What is the Electronic Product Code (EPC)?

The Auto-ID Center has proposed a new Electronic Product Code as the next standard for identifying products. The goal is not to replace existing bar code standards, but rather to create a migration path for companies to move from established standards for bar codes to the new EPC. To encourage this evolution, we have adopted the basic structures of the Global Trade Item Number (GTIN), an umbrella group under which all existing bar codes fall. There's no guarantee that the world will adopt the EPC, but our proposal already has the support of the Uniform Code Council and EAN International, the two main bodies that oversee international bar code standards. We're also working with other national and international trade groups and standard bodies.

EPC code structure

The EPC is a number made up of a header and three sets of data. The header identifies the EPC's version number; this allows for different lengths or types of EPC later on. The second part of the number identifies the EPC Manager -- most likely the manufacturer of the product the EPC is attached to -- for example, "The Coca-Cola Company." The third, called object class, refers to the exact type of product, most often the Stock Keeping Unit -- for example "Diet Coke 330 ml can, US version." The fourth is the serial number, unique to the item -- this tells us exactly which 330 ml can of Diet Coke we are referring to. This makes it possible, for example, to quickly find products that might be nearing their expiration date. Example of EPC: 01.115A1D7.28A1E6.421CBA30A

• 01: version of EPC (8 bit header);

• 115A1D7: manufacturer identifier (28 bits, more than 268 million possible manufacturers);

• 28A1E6: product identifier (24 bits, more than 16 million possible products per manufacturer);

• 421CBA30A: item serial number (36 bits, more than 68 billion possible unique items per product).

EPC Compliant tag classes

The difference between Class 0 and 1 is in the data structure and operation. Class 0 tags are read only. Class 1 tags are one-time writeable. The EPC standards call for five classes of tags. The following outlines the roadmap for the EPC tag class type:

Class Type Operation

0 Read Only

1 Write Once, Read Many

2 Read/Write

3 Read/Write Battery Enhanced for Long Range

4 Read/Write Active Transmitter

Widely used RFID ISO Standards in use today

• ISO 14443 for "proximity" cards and ISO 15693 for "vicinity" cards, both recommend 13.56 MHz as its carrier frequency. These standards feature a thinner card, higher memory space availability and allow numerous cards in the field to be read almost simultaneously using anti-collision, bit masking and time slot protocols.

• ISO 14443 proximity cards offer a maximum range of only a few inches. It is primarily utilized for financial transactions such as automatic fare collection, bank-card activity and high-security applications. These applications prefer a very limited range for security.

• ISO 15693 vicinity cards offer a maximum usable range of out to 28 inches from a single antenna or as much as 4 feet using multiple antenna elements and a high-performance reader system.

ISO Standards for RFID Air Interface Competing with EPC.

• 18000 – 1 Part 1 – Generic Parameters for Air Interface Communication for Globally Accepted Frequencies;

• 18000 – 2 Part 2 – Parameters for Air Interface Communications below 135 KHz;

• 18000 – 3 Part 3 – Parameters for Air Interface Communications at 13.56 MHz ;

• 18000 – 4 Part 4 – Parameters for Air Interface Communications at 2.45 GHz;

• 18000 – 5 Part 5 – Parameters for Air Interface Communications at 5.8 GHz ;

• 18000 – 6* Part 6 - Parameters for Air Interface Communications at 860 – 930 MHz;

• 18000 – 7** Part 7 - Parameters for Air Interface Communications at 433.92 MHz .

About the author: Rod Harrison, Cornerstone Solutions, can be reached at 260-496-8259.

Recent articles:

Defense Department Scales Down RFID Plan; http://story.news.yahoo.com/news?tmpl=story&u=/cmp/20031209/tc_cmp/16600185

Defense Dept. working to resolve RFID standards issue; http://www.computerworld.com/softwaretopics/erp/story/0,10801,87808,00.html

Wal-Mart to begin phased RFID tag rollout next year; http://www.computing.co.uk/News/1148506.html

Wal-Mart's RFID Deadline: A Chunky Mess; http://www.eweek.com/article2/0,4149,1414163,00.asp

AmEx Expands RFID Payment Trial; http://www.rfidjournal.com/article/articleview/505/1/1/.html

Military's RFID Alternative: IPv6; http://www.rfidjournal.com/article/view/609.html

RFID is big but nobody understands the costs; http://www.usingrfid.com/news/read.asp?lc=k19752px58zu.html


Other articles in this series:

Part 1: The Basics

Part 2: The Frequencies

Part 3: The Standards

Part 4: The Challenges

Part 5: The Rollout

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