An introduction to EPC Gen 2 tags
Apr 02, 2005
With much talk about the Generation 2 Electronic Product Code (EPC) tag, here we list a range of the most important things you need to know about it and answers to your questions. Gen 2 tags were ratified in December 2004 and are expected to be approved by ISO as part of the 18000 series by the end of this year. Gen 2 tags are intended to work better globally by taking into account regional frequency differences.
- Speed of operation: compared to previous class 1 EPC tags, generation 2 tags will be able to approximately write to about 7 tags per second (versus 4) and read about 1,000 tags per second (versus 300)
- Security: the tag has a 32bit password versus 8bit, tag memory and reading can be password protected, and the tag has a kill feature which can not be reversed once activated
- There are three interrogator operation modes for generation 2 tags:
1. Single interrogator mode (no other interrogators present)
2. Multi interrogator mode (up to 49 interrogators in 1 square km)
3. Dense interrogator mode (more than 50 interrogators in 1 square km)
These are necessary to prevent interrogators from interfering with each other. In single and multi modes, interrogators can use the available spectrum to send and receive data. In dense mode, interrogator signals are kept separate from tag signals. This can be considered in a simplified way as interrogators transmitting on "even" pulses and tags responding on "odd" pulses. This tackles the interference problems with previous versions. Interrogators can detect the number of interrogators and change mode appropriately, but those with old hardware that do not support this functionality will need to be replaced - just one reader not following this rule in a dense environment would cause significant interference problems.
- Since ratification, companies are developing the tags and the first samples will be delivered this month. However, it will take time to receive enough tag units to properly test them and design appropriate readers supporting all the functions of gen 2, initially readers may not provide full functionality for the standard. Volume tags may be ready by the fourth quarter of 2005.
- Gen 2 tags are more power efficient meaning they should work better in tougher environments such as with the presence of metal and fluids
Gen 2 is, however, a bloated design compared to the concept of a simple read only tag. However, it is a necessary one to bridge regional differences and provide a robust solution for the limited RFID infrastructure in place today. RFID is an evolving technology and no doubt at some point generation 3 will become the focus.