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What is EPC in RFID Tag?

  • Abhishek Shukla
  • Jan 03, 2024
  • RFID
What is EPC (Electronic Product Code)?

“EPC, short for Electronic Product Code, is a 96-bit code that is electronically encoded in RFID tags to identify various kinds of trade products including retail items such as apparel, shoes, food items..”

The idea of a unique product code for each and every product being sold in the market was a great way to globally recognize a product but it has the backing of an earlier invention named barcode. 

In 1949, the idea of a barcode came from a 27-year-old man named Norman Joseph Woodland when he drew four lines on Miami Beach sand. That’s for sure a great invention story that I like. Woodland who became an engineer at IBM received the first patent, US Patent #2,612,994, for 1D barcode, alongside Bernard Silver (an electrical engineer at Drexel, Philly) on October 7, 1952. It was in the form of concentric circles. 

Some 20 years later another IBMer, George Laurer, came up with the idea of UPC (Universal Product Code) when he was assigned the task of developing barcodes that can be used in grocery stores, in 1974. Based on Woodland’s barcode, UPC was created. It is Laurer’s legacy that, as per a GS1 report in 2019, UPC barcodes were scanned more than 6 billion times a day. 

UPC-12 barcodes have been in use for decades now. You can see it on milk cartons, cookies, apparel, shoes, vegetables, electronic items, toys, furniture, and millions more. 

These barcodes contain a 12-digit identification code that tells you about the company name and product no., which uniquely identifies the product. 

The first 6 and sometimes the first 9 digits are termed as company prefix, which is assigned by a nonprofit, say GS1 (previously Uniform Code Council), and the remaining digits are for product details. One can apply for a unique company prefix from the local GS1 office.

Barcoding has been the most successful technology and universally accepted for over a few decades but it only provides product identification. With the changing customer expectations and large-scale inventory that businesses now keep, identifying products is just not enough but tracking each item and pallet is also pertinent. So what do we do? We use RFID (Radio Frequency Identification) and EPC (Electronic Product Code).

What is an Electronic Product Code (EPC)?

EPC, short for Electronic Product Code, is a 96-bit code that is electronically encoded in RFID tags to identify various kinds of trade products including retail items such as apparel, shoes, food items, and healthcare items such as medicines, vaccine vials, medical instruments, and electronic products such as home appliances, TVs, etc. 

The idea to use RFID tags to identify objects as a marker, a ubiquitous RFID, and using the internet to download information about the product came from David Brock in 1998. He discussed it with Sanjay Sarma, who was a researcher at MIT.

The Distributed Intelligent Systems Center (DISC), the research project both Sanjay and David were working on later became the MIT- AutoID Center (co-founded by Sanjay Sarma, Sunny Siu, Dr. Daniel Engels, and Kevin Ashton).

The EPC was a numbering scheme and once the structure of the number was decided, it was named EPC (Electronic Product Code), a 96-bit identifier with four following fields:

  • 1. Version number
  • 2. Manufacturer number
  • 3. Product number
  • 4. Serial number

Sanjay Sarma, in his own words, says that it wouldn’t have been possible if he hadn’t met Kevin Asthton who was working at Proctor and Gamble at the moment and was trying to get retailers to use RFID. Kevin had been working on a problem that retailers often faced: OUT OF STOCKS. The fast-selling items were out of stock for more than 10% of the time which often meant loss of billions of dollars in sales.

In a whitepaper titled ‘The Virtual Electronic Product Code’authored in 2002, by David L. Brock pointed out, “The Electronic Product Code (EPC), as originally conceived, was intended as a method for uniquely identifying physical objects.”   

It was to become a universal system like UPC but internet-based.

He added, “Coupled with the electronic tags (ETAGS), the Object Name Service (ONS), and the Physical Markup Language (PML), the EPC provided a universal system for automatically identifying products and linking these to networked information.”

This is how RFID could provide detailed information about tagged products as well as connect physical objects to a digital world. 

EPC for Assets and EPC for Trade Items are Different 

Since RFID tags are also used in asset management, for tagging items for various asset management applications, as well as inventory management, these RFID tags aren’t necessarily encoded with standard EPC (by GS1, provided for trade items). Instead, these tags are encoded with customized EPC data, stored in the EPC memory bank of the RFID chip within the tags.

Many RFID tag manufacturing companies now use RFID chips with 96 bits and 128 bits of EPC memory. For example, RFID chips manufactured by Alien Technology, Alien Higgs 9, and by Impinj, Impinj Monza R6 support 128-bit EPC. 

The EPC memory bank in RFID tag chips is writable, just like the User memory bank, meaning businesses can customize the tag with desired data to fit their needs, encoding the tag with product details, manufacturer’s details, expiration, etc.

Low-Cost RFID Tags and EPC
When Kevin Ashton approached retailers, around 1999, with his solution to the ‘OUT OF STOCK’ problem in the form of RFID (Radio Frequency Identification) technology, retailers gave him a list of reasons why they wouldn’t go for it. Kevin Ashton was working on RFID projects extensively in London and when he met Sanjay Sarma and David Brock, his vision of a retail supply chain using RFID technology for obvious reasons. 

After the invention of EPC at AutoID-centre, MIT, another problem was the huge costs of RFID tags. At the moment, the lowest cost tags were at .50 USD to 1 USD, and for retailers, it was a problem. Retailers have been using barcodes for decades for item identification and inventory management but they had limited use and used once in a product’s lifetime, during checkout. RFID offered more benefits when it came to the identification of products over the lifetime, from manufacturing to supply chain and inventory and POS. 

In a paper ‘Radio Frequency Identification and the Electronic Product Code’, authored by Sanjay, David, and Daniel in December 2001, they argued that for Radio Frequency Identification to be truly successful, it must offer identification and tracking throughout the supply chain. The cost of RFID tags must be less than 10 US cents and preferably under US cents. 

At present, we all are aware that the objectives set by AutoID-centre have been met and we now have low-cost RFID tags within the 5 US cents limit. EPC played a crucial role here. 

To reduce the cost, the tags cannot use batteries and readers must work on maximum power output as permissible in various countries. The size of the IC chip must also be small to reduce the costs. EPC provided a successful way to encode all the required data inside the tag while keeping the cost low. EPC reduces the IC’s area and power requirements by reducing the memory burden. 

EPC also allows the development of a low-cost anti-collision mechanism that is used in tags. Tag collisions happen when two tags try to respond to a reader simultaneously, in the same frequency band. The interference thus causes the reader to not read any of them. Reader collisions are also a phenomenon where two readers nearby interrogate the same tag, confusing it. Readers also blind each other sometimes and the weak response from the tag cannot be detected by either. 

Anti collision mechanism as developed by AutoID-centre uses the structured numbering system of the EPC and offers bitmasking during tag number reads. It also tries to keep the logic on the tag’s IC to 1000 gates or less. This means readers can rapidly select and read EPCs that belong to a particular manufacturer.

To, summarize, EPC has been a revolutionary invention that made it possible to employ RFID-based identification and tracking in retail stores, supply chains, and inventory management. AutoID-centre and its researchers Sanjay Sarma, David Brock, Daniel Engels, Sunny Siu, along with Kevin Ashton played an important role in the development of EPC and now it has changed the entire product identification mechanism globally. EPC is globally accepted and various organizations such as Universal Code Council, EAN International, the US Department of Defense and US Postal Service, retailers like Walmart, Gillette, Unilever, P&G, and Pepsico have made it possible with trials and funding, and support, back in the day.


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  • Created on Sep 27, 2023

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