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While EPCglobal Generation 2 (Gen 2) RFID products have now made their way to market and into the supply chain, the arrival of Gen 2 does not signal the retirement or obsolescence of other RFID protocols. In fact, it will likely be some time before all partners in RFID-enabled supply chains are consolidated on Gen 2. Even then, other RFID protocols will also be in use in other business applications, just as numerous barcode formats are used today. Organizations that print and encode RFID smart labels, or expect to in the future, must plan for an ongoing multiprotocol RFID environment, regardless of their current RFID involvement or expected requirements (Figure 1).

It is clear that multiprotocol environments demand readers that can process multiple protocols. The alternative is to have separate readers for each individual tag protocol that is received. This approach is not only cost-prohibitive, but it would also be a challenge to find enough physical space to install all the necessary hardware.

Management of these devices — especially for upgrades or new components — would also quickly spiral out of control. Some vendors support hardware upgrades to readers to allow them to handle a number of protocols. However, this approach has its drawbacks in that this is not a quick or simple fix, especially because it cannot always be anticipated which protocol will emerge as the dominant industry choice for a given application.

Obviously, multiprotocol readers are a much better option and RFID readers and encoders using software-defined radio (SDR) technology can be the most flexible and cost-effective multiprotocol solutions on the market. Software-defined radios use software to control the RF signal modulation and demodulation, and the transfer of data. Support for frequencies, standards and options are written into the software and are not hardwired into the hardware. Therefore, upgrades and changes are accomplished simply by downloading new software to the device. There is no need to install new components or replace the device itself. SDRs, therefore, have the advantage of providing a relatively simple and expedient way to allow end users to support multiple RFID protocols as they emerge.

Companies that are implementing RFID not only need to choose multiprotocol readers, they need to choose multiprotocol printer/encoders as well. Multiple generations of EPC and ISO tag technologies are expected to coexist for years, even beyond the phased implementation timetables established in EPC compliance tagging protocols. Whole new classes of tags are under development, such as temperature sensor tags. A multiprotocol printer/encoder — again, optimally with software-defined radio architecture — provides protection for RFID investments and a cost-effective migration path to meet future requirements. As with readers, printer/encoders with SDR can be upgraded with a simple download of new protocols as they emerge.

In spite of the fact that it is a standard, Gen 2 itself has a much higher potential for variation in execution by vendors than end users may expect. This is because Gen 2 is written as a robust and flexible standard that can accommodate a broad range of user needs. Gen 2 specifies a variety of basic requirements and then specifies the details of many more optional features. How these options come together in commercial products depends on the choices vendors make and is influenced by any number of factors, including cost, performance or speed to market. Table 1 summarizes some of the key features and enhancements over Generation 1 tags.

In addition to the variability that comes from tag vendors' execution around the standard, other areas also add to differences in RFID offerings. The chips used in Gen 2-compliant tags, for example, vary in memory size and content, rewritability, data security, and other characteristics. Printer/encoders and readers vary by the features they include; how they comply with U.S., European, and other radio regulations; security support; and more.

The fact that tags in numerous configurations are circulating creates the requirement that companies using Gen 2 tags, or applying them for customers, must support a variety of tag types. This rule also applies to RFID technology providers as well — particularly hardware vendors. Printer/encoders can only support features and options built into the RFID chip used in the smart label media. In Gen 2 tags, the tag identification (TID) area in the chip memory encodes the chip manufacturer and chip model number information to identify which optional features are present. Both the smart media and hardware must each support all the desired features. Additionally, the protocol control bits in the UII (formerly called “EPC”) memory bank may be used to specify the size and format of the data stored in the UII memory. In an EPC encoded tag, the format is defined by the EPCglobal Gen 2 tag data standards.

One area to be aware of is that smart media using Gen 2 chips and printer/encoders that separately conform to the same Gen 2 standard are not necessarily physically compatible. Printer/encoders communicate data in a small and specific physical location within the printer/encoder that corresponds to where the tag inlay must be positioned within the label media. The tightly controlled position of the inlay within the printer/encoder is in contrast to most RFID readers, which are configured to broadcast to cover the large area so that all tags in the field will be identified. Users must make sure the smart label media they use is designed to be compatible with their specific brand and model of printer/encoder.

Some of the variables within the Gen 2 standard and printer/encoder considerations that must be considered to ensure maximum performance include:

• Data content

  Gen 2 requires a minimum 96-bit EPC identifier, which is a major change from the 64-bit identifiers common in early EPC tags. The EPCglobal tag data standards for Gen 2 tags also support much larger data structures in expanded UII memory for future applications. Gen 2 specs also allow (as an option) unlimited user tag memory, which organizations at any point in the supply chain can use to add proprietary supplemental data. The additional memory could be used to store lot codes or expiration dates, time and date stamps for transactions, input from temperature sensors, and other information. The presence and size of user memory available varies by the model and manufacturer of the chip used in the smart label inlay (the chip-antenna combination). So one thing to determine when choosing a printer/encoder is whether it can support these expanded data structures (Figure 2).

• Write verification

  Zebra printer/encoders have always supported the write verification feature in all classes of tags to prevent unencoded or corrupted smart labels from being put into circulation. If a chip fails to encode properly, “VOID” is printed on the label to indicate it shouldn't be used, and a new label is selected. Printer/encoders can also be set to stop and communicate an error message if encoding problems arise. Although write verification is especially important for compliance tagging applications, it should be performed for all smart label printing/encoding. The Gen 2 specifications have several new methods for verifying data written to tags.

  Another area of consideration is that different tag inlay designs may require different power levels for optimal performance. The amount of power from the encoder required to write data to a tag is a complex function of the inlay's chip type, antenna design, and antenna size. If not enough power is applied, the chip will not be powered up or may have insufficient power for programming, and the data will fail to be encoded. Applying too much power sometimes disables the tag or causes data communication errors. Either way, the smart label will be voided.

• Security

  The Gen 2 protocol uses an optional 32-bit password to access tag data or lock tag data or to permanently disable (kill) a tag. This is much more secure and versatile than the 8-bit password used in Gen 1. Besides the optional use of password protection, user-allocated memory can be safeguarded with flexible locking options. The “permalock” feature permanently locks the data and prevents rewriting. Gen 2 also offers a less restrictive password-protected feature that enables locking to be toggled on and off. Toggling could be used to lock the blank memory to protect it against accidental encoding and preserve it for future use. When an authorized user wants to change or append the data field, he or she would use a password command to turn off the toggle lock. Encoded data could then be protected by the toggle lock or permalock.

Additional data encoded on Gen 2 tags does not necessarily have the same security protection as the tag ID in the TID memory and EPC memory. The Gen 2 standard also supports optional security implementations, including a separate 32-bit password to access the memory block reserved for users. Different security levels can be applied to different portions of tag memory. Password protection, lockable fields, and other security features for optional data may be supported in the tag, encoder and reader.

Data content, write verification and security represent some leading areas of variability within the Gen 2 standard. Chip manufacturers today are producing a range of Gen 2 chips with different functionality and features, all of which are Gen 2-compliant but not necessarily identical to each other in terms of optional features. As a result, it is even more important to match smart label media to the specific make and model of printer/encoder used. Smart label media should not be considered an interchangeable commodity.

The best strategy for managing the complexity in a multiple protocol environment is to develop a flexible, configurable, and upgradable RFID infrastructure. Products with limited feature support or upgrade options will require more frequent replacement and raise the total cost of ownership. Organizations simply can't afford to replace or add equipment every time requirements change. When evaluating printer/encoder and reader products, determine if they meet three key criteria to support a flexible and cost-effective RFID architecture:

1. Provide simultaneous support for multiple RFID protocols (e.g., Gen 1, Gen 2, ISO, etc.).

2. Meet the user's current needs for protocols, options and features.

3. Provide a clear and efficient upgrade path to add new features and protocol support.

All vendors will say they offer an upgrade path, so these claims must be investigated more carefully. Issues to consider include:

• Who will pay for future upgrades?

• If new options and supports are made available for “free,” is installation and support also free?

• How much time and effort will be required to perform the upgrade? Is it simply a firmware upgrade, easily available through the Internet or over the company LAN, or does it require hardware upgrades and on-site or back-to-factory service?

• Can the printer/encoder be adjusted or optimized to support new inlay designs?

• Is adding support for future protocols an “either/or” proposition? That is, if a printer/encoder is “upgraded” to process a new standard, will it lose its ability to encode tags that support different protocols?

• Can the protocol “mix” supported in the company's printers be configured to support all the tag types and chip options in use?

Multiprotocol requirements force users to look beyond initial considerations to determine what costs will be associated with maintaining and upgrading the RFID system. The answers to those questions do more than differentiate vendors — they determine the total cost of ownership for the system and the amount of protection the organization has for its RFID investments.

Although Gen 2 will bring many much-needed improvements in the performance of RFID systems, there will still be a long period in which Gen 2 technology coexists with other standards in the real world. Not only is Gen 2 unlikely to completely displace other RFID technologies, many chip feature variations allowed by the standard itself assures there will be diversity within the Gen 2 user community. In addition, Gen 2 as an emerging standard will experience transitions during the adoption period, until it has matured. Organizations that currently use or will use smart labels need to recognize this diverse RFID environment and plan accordingly. Planning includes developing an understanding of Gen 2 features and variables, and the implications for making equipment purchases. It is important to look beyond the current spec sheets and evaluate vendors and products on their ability to accommodate changes and meet future needs. If equipment is installed that can't simultaneously support Gen 2 and other protocols, or can't support Gen 2 optional features or future upgrades, organizations may be at risk for costly and premature equipment replacement.

Matt Ream is Zebra Technologies' senior manager, RFID Systems. With more than 25 years in the high-tech engineering industry, 13 of them specifically in RFID, Ream is a key player in the company's worldwide RFID product development and strategic planning.

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