The promise of increased functionality in RFID systems created in compliance with the new EPC global Generation 2 (Gen 2) standard creates a foundation for a new era of RFID use in the supply chain. Gen 2 has quickly been established as the RFID technology of choice for many global organisations and their trading partners. It is important to understand however that Gen 2 is a starting point and not the end of RFID supply chain innovation. It may be a surprise to some that there will be significant disparities in performance and capability among Gen 2-compliant products.
Gen 2 creates a platform on which to build interoperable RFID products and systems that will improve inventory management, logistics and retail operations around the world. However, standard-based products don't provide standard performance. Companies will have similar information needs as their competitors, and have comparable business practices, but usage environments are anything but standardized or homogeneous. Gen 2 or any RFID technology won't provide exactly the same performance at any two facilities. That is why it is important to understand the difference between what Gen 2 specifies and the range of performance that compliant Gen 2 products could provide in real-world use. By understanding the Gen 2 performance specifications and how different features will impact real-world performance, users can specify Gen 2 systems that provide the functionality and benefits they need.
Factors that should be taken into account when considering adopting Gen 2 RFID technology include speed, efficiency, reliability, range, security and cost.
Speed
Fundamental to many users of the technology is the ability to read RFID tags quickly and simultaneously. Gen 2 speed requirements were developed and refined based on the needs and experiences of those who used Generation 1 technology. The ability to identify and differentiate items on a high-speed conveyor system is needed in order to carry out efficient sorting, distribution and inventory management.
There is no fixed or minimum speed specification with the Gen 2 standard because reading speeds depends on many variables, including power output, tag density and the RF environment. Gen 2 technical specs should enable readers to perform more than 1,500 tag readings per second in North America and 600 reads per second in Europe, which has more power and bandwidth restrictions.
The Gen 2 spec supports “group select,” an important feature for providing high-speed reading and sorting. It allows RFID interrogators to seek and read select groups of tags (based on data structure) and to ignore others in the read field. It also reduces the amount of data the system must process, for faster reading. Additionally, Gen 2 features new technology called “persistence” that gives tags the ability to remember their status if they lose access to reader power, greatly improving read performance, especially in large tag populations.
Bandwidth efficiency
Wireless bandwidth is limited, highly regulated and must be managed carefully. Gen 2 products can be used throughout the world without a site license, and will provide the range, speed and other performance needed to meet the supply chain application requirements spelled out by users. This overcomes the implementation obstacle of Gen 1 specifications that was developed based on the US Federal Communication Commission (FCC) radio regulations. These regulations were not compatible with other government regulations around the world and therefore required site licenses for users elsewhere in the world.
The Gen 2 standard provides users with some flexibility for how interrogators utilise bandwidth. System performance can be optimised based on the number of RF devices operating in the environment. The standard defines three modes of Gen 2 product operation: single reader, multi-reader and dense reader. Specifications for each mode are intended to provide improved performance in typical usage environments.
The single reader mode specification is intended for implementations where there will be only one interrogator per facility. Single reader provides acceptable performance, but if there is another RF device operating nearby it could pose an interference problem.
Multi reader products are more RF friendly and make more efficient use of bandwidth and manage their transmission more carefully. They can operate in environments with up to 10 readers present without causing significant performance problems.
Dense reader mode is for use in facilities with more than 10 readers, which includes most distribution centers and factories where RFID systems operate. It is the safest choice for implementing EPC equipment and providing the most focused and efficient use of bandwidth, which optimizes performance and protects against interference.
Reliability
The Gen 2 standard makes reading performance more reliable. There are also ways to implement the standard and compliant equipment to further improve data integrity and system reliability.
EPC numbers followed a defined data format, which makes it possible for systems to verify data read from and written to the tag. The Gen 2 standard shifts data checking from the reader (as in Gen 1) to the interface, enabling faster execution. Gen 2 also adds protection against receiving false positive reading, known as ghost tags. Ghost tags are recorded when the reader picks up portions of the data from different tags and interprets them as the identification of a single (non-existent) tag. Additionally, Gen 2 tags will also perform more reliably in a wider range of operating temperatures. The Gen 2 standard adds support to verify data written to tags. Gen 1 technology users experienced lost and corrupt data, and made verification a requirement for the more robust and reliable Gen 2 standard.
Range
User requirements–not standard specifications–dictate the range required from Gen 2 EPC systems. As with speed, there is no range requirement in the Gen 2 standard because of the many variables that affect range, including interference, reader power output, duty cycle (the amount of time the reader can continuously transmit), reader density and more. The Gen 2 specifications enable range to satisfy user-defined supply chain application requirements.
Manufacturers can take advantage of flexibility within Gen 2 specifications to improve reader range. Gen 2 allows, but does not require, spread spectrum radio transmission. Spread spectrum technology broadcasts over multiple channels, which makes efficient use of bandwidth and provides improved range over other transmission techniques.
Security
Standard EPC tags are protected against tampering. The standard protocol includes encryption and requires the tag and reader to create a secure link before data is transmitted, which makes it very difficult to alter the EPC number. Some industries including the retail and consumer goods industries require the disabling of tags in the field so that their data can never be accessed and customer privacy can be adhered to. It also has authentication requirements to prevent unauthorized and accidental disablement of tags.
Gen 2 also supports ‘cloaking’ which enables tags to be set so they will only communicate with authenticated readers. Readers must provide a password before the tag will respond with any communication. Passwords may also be required to write to tags or disable them therefore giving additional security.
Cost
One of the principal motivations for development of the EPC system was to create RFID technology that was cost-effective for use in supply chain operations. Focus was placed on creating specifications to enable the production of low-cost chips and equipment. Initial user experience with Gen 1 EPC technology revealed that low-cost designs had serious limitations when used in real-world operations including reliability, data security and range. The Gen 2 standard was created specifically to satisfy user desires and concerns.
Value is a more important consideration than cost, but is not easily compared among different products without a good understanding of the functionality required from the system. The EPC Gen 2 standard strikes a balance between cost and functionality that should lead to the development of cost-effective products that satisfy real-world application requirements.
Intermec Intellitag Gen 2 RFID systems
With Intermec’s extensive RFID development history and close involvement with EPC global standards development, Intermec is intimately familiar with the Gen 2 standard, the variations of how it can be implemented, and its potential performance in real-world systems. Intellitag Gen 2 systems are designed to move beyond the limitations in the basic Gen 2 standard to provide high-level performance. Many of the optional features that Gen 2 supports are standard in Intellitag Gen 2 products. Intellitag RFID systems provide the following functionality to meet customer’s Gen 2 implementation requirements: dense reader operation, write verification, persistence, range, write protection and tag kill function.
By understanding the disparities in performance, reliability and ease-of-use that different standard-compliant products will produce, Gen 2 users can make the best decisions about the products that will form the foundation of their applications. The most important thing to remember about EPC Gen 2 technology is that “standard” does not mean “equal.”
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