EPCglobal Class 1 Generation 2 For Users

Introduction
EPCglobal was formed in 2003 to take the activities of the AutoID Laboratories forward into a non-profit standards framework supporting use of RFID in the supply chain and other applications. As part of this mission, EPCglobal is seeking to create a single worldwide standard for the UHF reader-tag air interface. This second-generation standard was developed in 2004 and became publicly available in 2005 [1]; it has also been submitted to the International Standards Organization (ISO) with the intention that it should become part of the ISO-18000 series of RFID standards, as ISO18000-6C.

Numerous vendors have announced upgrades for existing RFID readers, and new reader models, to support second-generation ("Gen 2") tags, and by the end of 2005 several tag manufacturers were able to supply Gen 2 tags in quantity. In this application note, we will try to provide an introduction to those parts of the standard that directly affect users, to help them understand what the terminology means and make optimal use of the new capabilities provided by second-generation tags and readers.

Overview: Protocol Challenges and Gen 2 Solutions
Any passive RFID protocol must provide certain basic functions:

• a set of modulations and symbols for binary bits that are understood by the reader and tag
• preambles, packet structures, and timing conventions that enable tags and readers to synchronize to each other's clock, and recognize commands and data
• a minimal subset of commands and responses that make it possible to read tag identifying numbers (which will generally be EPCglobal-compliant electronic product codes, EPCs, for Gen 2 tags), and optionally to write new IDs and other information to tag memory
• provisions for allocating the wireless medium when more than one tag is in the field of a reader, in order to resolve potential collisions between tags contending to transmit information back to the reader

Let's look at how the EPCglobal Gen 2 standard deals with these challenges. Many of the more technical aspects of the standard are transparent to most users, and will be only briefly reviewed here.