The road to a smooth, accelerated RFID rollout requires optimal solutions

Industrial, retail and pharmaceutical applications must be carefully evaluated for performance to find the best fit among RFID technology options By Dirk Morgenroth, NXP Semiconductors Marketing Director, Market Sector RFID, Business Line Identification NXP Semiconductors Austria GmbH Stryria Mikron-Weg 1, 8101 Gratkorn, Austria Tel +43 3124 299 942 Email: [email protected] Abstract: This technical article provides a detailed overview of RFID, including general definition and uses, the standards and regulatory bodies with oversight, the breakdown of multiple frequencies in RFID technology, general industry research, and deployment considerations. The article also discusses the need for industrial, retail, and pharmaceutical industries must carefully evaluate applications to find the best fit among RFID technologies. RFID (Radio Frequency Identification) systems are gaining worldwide acceptance in several high-volume applications that include well established industrial uses, as well as emerging applications for optimizing product flows in the retail supply chain and the securing, authentication and tracking of pharmaceuticals from factory to patient. Industrial applications include RFID tags being used to track work in process in production facilities, asset management of pallets, beer kegs and gas cylinders (high valued reusable items). Another common use is in the manufacturing of laptop PCs to assure that the right components are used to manufacture the ordered laptop with the right performance. In retail supply chain applications, RFID readers located throughout distribution centers and stores are being monitored by corporate in an attempt to maximize inventory utilization and minimize out of stock scenarios. RFID for supply chain

management received an unprecedented boost in 2005 when the world's largest retailer, Wal-Mart, announced plans to integrate the technology into its supply chain. Adoption in the pharmaceutical industry is also well underway, spurred in the U.S. by a 2004 Federal Drug Administration (FDA) report recommending that RFID technology be in widespread use throughout the pharmaceutical industry on a worldwide basis. In part due to the many new application of the use of RFID, and the resulting requirements for the RFID technology needed to maximize the return of investment for companies using the technology, RFID continues to develop based on new standards and improvements in the technology and design. Naming a few of these challenges, they include HF gen 2 standards, Near Field UHF technology, as well as mature and off-the-shelf hardware and sensor technology. RFID basics RFID technology can be broadly divided into passive tags that have no energy source and draw their operating power from the RFID reader and active tags that include a power source, such as a battery in the tag. The battery power source can increase the communication range as well as support logging of sensor data without a reader field being present.

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RFID systems are designed to operate over a variety of frequency ranges. •

Low-frequency (LF): 125 to 134.2 kHz and 140 to 148.5 kHz. Typical applications include immobilization systems in automobiles, retail, and animal identification and tracking through the human food chain.

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High-frequency (HF): 13.56 MHz. Typical applications include tagging of rental items like books or uniforms, public transportation ticketing pharmaceuticals and other item tagging.

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Ultra-high-frequency (UHF): 860 MHz to 960 MHz. Typical applications include fixed asset tracking, baggage handling, and supply chain applications.

Standards and regulatory bodies There is no global public body that governs the frequencies used for RFID on a world wide basis. As a result, countries and regions have chosen independently which frequency bands are reserved for the use of RFID. Fortunately, LF and HF RFID tags can be used globally, with power levels harmonized on a global basis simplifying the design of readers and labels. For UHF frequencies, however, the situation is a bit more challenging as a frequency range of 860 MHz to 960 MHz needs to be used, creating challenges for the unified solutions, part of this issue has been resolved. The remaining hurdles lie in getting the approval for the usage of RFID at UHF in all countries, like in China for example. Although many agencies can be involved in RFID standards, two stand out as the most important: EPCGlobal, an Electronic Product Code (EPC) industry group representing the interests of end users, and the International Standards Organization (ISO) which

represents the technology community and fosters the standardization of technology, assuring end users of multiple sources, interoperability and compatibility of products from different vendors. Multiple frequencies for multiple use cases For reasons of technology availability and maturity LF and HF frequencies have been heavily utilized for RFID rollouts utilizing passive systems. Standardized LF and HF technologies have been available since 1995, while UHF has been available since 2001. A LF system is considered appropriate in applications which are very industrialized and need RFID to operate under very harsh conditions. The LF is immune to electrical noise in the environment and having encryption technology designed into the IC enables communication distances of up to 1.5 metres to be reached. LF is also a technology very suitable for liquids, organic materials and metal applications. Markets which have adopted LF as the major technology are: animal identification, casino chip identification, access control, asset management solutions for gas cylinder, beer kegs and other high valued products. An HF system is considered appropriate in applications where items are tagged and read and write ranges of up to 1.5 metres are required. Encryption algorithms allow for protected data on the IC and EAS features in the tag, making anti theft prevention possible. Typical applications today include tagging of library books, CDs and DVDs, pharmaceutical products for counterfeit prevention and many applications which require a very precise read and write environment. A UHF system is typically used today for applications where great read ranges

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are required, with distances of several meters. Such applications include the identification of pallets and cases, as well as car authentication in a factory for production control purposes as well as for road toll solutions. As UHF is the youngest RFID technology solution for tagging of items in the supply chain environment as well as EAS, however, its solutions are still under development. The relative merits of each frequency range are well known and widely accepted. As with any new technology, many companies are working on stretching and improving the performance of their technology, which is also the case for RFID. LF’s range and performance and costs are being improved with new IC designs and more mature readers in the market. In HF, new encryption algorithms are being used to make the technology even more secure for short ranges, faster protocols are being introduced to improve the reading and anti-collision speed. Additionally, new regulations are being worked on to allow for more power to be used to increase the read and write distance of the HF solutions.

Figure 1. Metals, field characteristics and tag construction are challenging for NF UHF

HF and LF tags tend to have typical coil configurations where the tag size directly relates to the read range. The tags are less sensitive to the materials they are attached to and as such the label designs are basic and generic. UHF tags, however, come in many different configurations as they need to be optimized to the material the labels are attached to. This is largely due to the fact that the propagated UHF signals interact with tagged articles or adjacent materials more strongly that HF or LF. There are also differences in designs when using UHF in the far field mode or near field mode, again see pictures.

In UHF until recently only Far Field UHF technology has been available, making identification of fluids and other organic material virtually impossible. Today the industry is working on Near-Field UHF (NF UHF) to help identify problematic materials/products. With NF UHF, read distances of approximately 30 cm can be achieved, allowing for some item level tagging. Figure 1 provides an overview of the performance of LF, HF, and UHF systems across several key areas. Tag construction will be discussed in the next few paragraphs.

Fig 2. A sampling of UHF tag configurations

While FF UHF is today clearly understood, the main work is being conducted in optimizing hardware and software to solve application specific requirements, such as improving read rates of tags on

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cases, optimizing the reader fields and working on the harmonization of regulations to allow UHF to be used on a world wide basis. Over the last year research has begun on NF UHF to analyze how this technology can be used to achieve item-level tagging, and combinations with FF UHF. Industry research With these scenarios as a backdrop, in early 2006, Deutsche Post World Net launched an initiative to evaluate industry usage of RFID across several industries including fashion, pharmaceutical and electronics. Other members of the DHL Innovation Initiative included IBM, Intel, Philips Semiconductors (now NXP Semiconductors) and SAP. By including both HF and UHF systems in its testing and evaluations, the Initiative's goal was to determine optimum RFID solution for various applications within target industries. Key factors being considered were the readability and writability of RFID tags under differing environmental conditions, when applied to the many materials found in a typical logistic environment. Since there does not seem to be one frequency which optimizes the performance of the RFID solutions for all applications, technologies are being investigated to determine which frequency is the most suitable frequency for the application. Many other companies are working on similar tests, for example Metro and Kaufhof in Germany, as well as companies such as Walmart and Target. Deployment considerations Two critical considerations for deployment of RFID systems are privacy and safety.

Privacy issues largely revolve around the range in which the RF signal can be read or written as well as the use of security enhancing technologies like password protection and cryptology and destroy commend where required. Cryptology technologies are well proven and deployed at large for HF, some LF solutions but not yet in UHF solutions. Regarding the read range, since the power of HF RFID signals drops off rapidly from the interrogator antenna, it has an inherent advantage over the far-field operation of typical UHF RFID chips. UHF fields can, however, be contained by using near field coupling between the interrogator antenna and the tag -- the technique used in the aforementioned NF UHF. The following example of HF and NF UHF systems shows that: 1. At the read distances required by the Federal Communications Commission (FCC) for a pharmaceutical application, an HF system has a higher tag excitation. 2. For point of sale (POS) applications, HF systems have better field containment and are therefore less susceptible to the reading of fringe tags. Figure 3 shows that for ranges up to 300 mm, HF has a higher reactive power density (Wvz in the dotted line) than UHF (WvØ in the solid line) and therefore a more robust signal in the region where communication can take place under FCC rules. A more robust signal is associated with more accurate read rates. On the other hand, at ranges larger than 300 mm, NF UHF's higher reactive power density becomes greater than

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HF's which makes it more of a privacy risk. Since the HF signal decays faster, it is also less susceptible to the reading of fringe tags and it is also less susceptible to unauthorized reading of or writing to the tag.

Fig. 3. Reactive power density vs. distance for a pharma application using FCC regulations

Health issues are still a matter of active study by regulatory agencies around the world with each region setting allowable limits to radiation exposure not just for RF but virtually all electromagnetic-field exposure. Allowable exposure is expressed in terms of power density. For a specific system with a known transmit power and frequency, this means that a minimum exposure distance can be calculated. Regulatory bodies also make a distinction between allowable occupational exposure and allowable radiation exposure for the general public. Since the general public is not subject to more or less continuous exposure, the minimum distance is greater than for occupational exposure. Since NF UFH is a relatively new technology in terms of its use in RFID applications, it is not clear as of this time how the health issues will be sorted out. Conclusion Although the deployment of RFID systems has historically been to use either LF or HF frequencies for item-level tagging and UHF for pallet and caselevel tagging, the development of NF UHF has introduced the possibility of

using NF UHF for item-level tagging as well. The industry has reacted to this development by initiating testing scenarios to determine which frequency delivers the highest performance and is most cost effective for different applications. Performance in this context includes not just technical efficiency but the ability to accommodate the privacy, health, and security concerns that are often written into regulations. The industry has also started to move toward a harmonized secondgeneration standard for HF, similar in its intent to the UHF Gen 2 standard already agreed to by EPCGlobal and ISO. Many observers believe, however, that in the final analysis, there is no one-sizefits all solution for RFID. In countries where both HF and UHF frequencies can be utilized, issues such as tag performance repeatability, privacy, reliability, scalability and cost may tip the balance toward one frequency choice or the other. By making both available, system integrators have the option of determining the most appropriate solution and deploying it. Broader usage of both UHF and HF frequencies will allow the industry to accelerate the adoption of RFID technology because companies can adopt and take advantage of the benefits of RFID in their supply chains much more easily. Although there are areas for improvement, RFID has already proven itself to be a reliable, cost-effective technology. Technical hurdles have been surmounted in the past and there will be many developments in the future that will improve the technology's performance. NXP, a leader in developing RFID technology will continue to play a

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leading role in technology development and will help its customers and partners

in the value chain to find the best solution for their application.

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