The bar code tracking system involves the use of bar coding to code each and every fixed asset that an organization wants to manage and track. The codes are entered into a PC module which can then be used to record an asset's movement and performance, from purchase to disposal, and also generate reports on the same. On a change of location and during relocation, the bar coded asset is tracked using a hand-held terminal. This data is then updated in the PC module. The technology used is simple yet powerful and allows the organization to have complete control over various types of assets, big or small. The system has various components:

RFID

RFID is a technology that offers many more benefits compared to other identification technologies such as bar coding and magnetic stripe.

This emerging technology is not new in fact; it is currently being used, in numerous applications throughout the world. Originally, implemented during World War II to identify and authenticate allied planes, this was known as Friend or Foe. RFID is still being used today for the same purposes.

The main component of this technology is the transponder/tag1, which in most cases comprises of a chip and antenna mounted onto a substrate or an enclosure. The chip consists of a processor, memory and radio transmitter. These transponders communicate via radio frequency to a reader, which has its own antennas. The readers can interface through wired or wireless medium to a main computer. Transponders are also known as smart or radio tags. The memory will vary, depending on the manufacturer, from just a few characters to kilobytes.

Either Transponders can be Read Only (R/O) which are pre-programmed with a unique identification or they can be Read Write (R/W) for applications that require data to be stored in the transponder and can be updated dynamically. Another form of transponder is Write Once Read Many times (WORM). This will allow for an identification number to be written to the transponder once. The information is stored in the memory, it cannot be changed but the transponder can be read many times.

The two most common types of RFID technologies are Active and Passive. Active RFID transponders are self powered and tend to be more expensive than Passive. Having power on board allows the tag to have greater communication distance and usually larger memory capacity. The most common application for Active RFID is for highway tolls.

As for Passive RFID transponders, which are available with chips and without chips, they have no internal power source therefore require external power to operate. The transponder is powered by an electromagnetic signal that is transmitted from a reader. The received signal will charge an internal capacitor on the transponder, which in turn will then supply the power required to communicate with the reader.

Some of the most common uses of Passive RFID today are for animal identification, waste management, security and access control, work-in-process, asset tracking and electronic commerce.

Whether we are talking about Active or Passive RFID, the features and benefits are the same.

The following details for some of the benefits:

It is important to take the environment into consideration when implementing RFID. For example metal, electrical noise, extreme temperatures, liquids and physical stress can create a challenge and may affect performance.

Today, most implementations involve passive technology. For this reason, this document is based solely on passive RFID. There are different frequency bands which passive technology operates within.

Low and High RFID operate on the inductive coupling principle. That is, the energy is transferred from the reader to the tag through shared magnetic field. The amount of transferred energy is proportional to the size of the transmitting and receiving antennas as well as the tag ability to operate at the resonance frequency. The resonant frequency is a state in which the impedance is at its minimum, allowing for maximum current flow in the circuit. The resonance frequency is a function of the inductance and capacitance of the tag circuit. The quality of a resonant circuit is measured by Q factor. The higher the Q factor, the higher the amount of energy transfer. Although higher energy transfer is desirable, the higher Q factor results in reduced bandwidth.

UHF RFID tags communicate with the reader using the backscatter principle. This is the same technique used in radar technology. The term backscatter refers to the portion of the transmitted signal that is reflected back 180 degrees opposite the direction of the incident signal, as opposed to random scattering that is lost in the space. The tag will send back data by means of varying the load of the received signal. The reader senses the varying field and demodulates the signal to retrieve tag data.

Of all the various frequency bands RFID operates within, there isn't one that can address all applications. In essence, there is no super RFID frequency band in other words "one frequency does not fit all." For this reason, the next three sections wil review the most common passive RFID frequencies.

LOW FREQUENCY (LF) PASSIVE RFID

Passive LF RFID has been utilized in several industries for many years. The most common frequencies used are 125 kHz and 134.2 kHz.

One of the key features of LF RFID is that it is not as affected by surrounding metals. This makes it ideal for identifying metal items such as vehicles, equipment, tools and metal containers. The reading range can vary from a few centimeters to a couple of meters depending on the size of the transponders and the reader being used.

Transponders come in various form factors, from glass transponders, to wedge and disks of various sizes. Other form factors available are cards and cylindrical. These different form factors allow for the transponder to be embedded into most materials, except for metal. Other form factors such as keyfobs can also be customized.

LF RFID also penetrates most materials, such as water and body tissue. The limitations are that if used in industrial environments, electric motors may interfere with the LF system.

Due to the size of the antenna required, the LF transponders are typically more expensive than High Frequency transponders. This limits the frequency to applications where the transponders can be re-used.

The following are some of the benefits and limitations of LF RFID:

Currently, most access control systems are based on LF, contact-less cards, or keyfob for security. A read only card can be used simply as identification or a read-write card can be used to maintain access or security information.

The largest user for LF RFID is the automotive industry. Currently, all car immobilizers (key) use a LF transponder embedded into a car key with a reader mounted in the ignition. Other applications are vehicle identification for highway and parking lot access.

Numerous automotive manufactures use LF RFID for work-in-process. Being able to insert a transponder into a pallet or product gives the manufacturer the reliability required and allows the product to be identified and used throughout the manufacturing process.

LF is also used for animal identification, from endangered species, to pets and livestock. Currently, cattle are identified with a bar coded ear tag. This form of identification is unreliable and is not robust enough for the environment.

Dual Frequency Products

Dual frequency products are used in challenging environments where the tags are in close proximity to RF absorbent materials such as people, animals, vegetation, soil, or fluids.

They are ideal for tracking people, animals, documents and paper rolls. They are also well suited to mining and underground applications like marking buried pipes.

Ideal for Lossy Media: These dual frequency products offer the same ability as low frequency RF systems for operating tags in lossy media using the same IP-X multi-read protocol as the IPICO UHF products. The low frequencies used can penetrate through lossy media without the tag antenna detuning and the high attenuation encountered with UHF systems. And compared with other low frequency technologies, IPICO's dual frequency products can achieve much longer reading ranges.

Handles Dynamic Tag Populations Very Well: The IP-X protocol handles dynamic tag populations extremely well allowing up to 120 tags to be read simultaneously, at a rate of up to 30 tags/s. The Reader does not have to complete reading a group before new tags are added.

These dual frequency products employ the same anti-collision algorithm and offer the same high data rates as do IPICO's UHF systems.


HIGH FREQUENCY (HF) PASSIVE RFID

Passive High Frequency (HF) operates at 13.56MHz and is a globally accepted frequency. This means that any system operating at HF can be used globally. However, there are some differences with regulations in the different regions of the world. These differences pertain primarily to power and bandwidth. In North America and Industry Canada, the FCC limits the reader antenna power to three watts while in Europe the regulations allow for four watts.

HF is also the basis of numerous standards such as ISO 14443, 15693, 18000-3. These standards and others will be discussed in more detail in the section V on RFID STANDARDS.

With HF, the signal travels well through most materials including water and body tissue. It is however more affected by surrounding metals compared to Low frequency (LF).

In comparison to LF, the benefits of HF are lower tag costs, better communication speed and the ability to read multiple tags at once.

The length of the antenna is based on the length of the signal wave, thus the higher the frequency the shorter the wavelength. For this reason, there is the flexibility that an antenna for a HF tag is small enough that it can be produced by printing it onto a substrate, using conductive ink, and then affixing the chip.

Tags produced with HF chips are typically less than 1mm in thickness and are available with different sizes of antennas. The larger the tag antenna, the greater the energy capture area the tag has and the greater the communication distance from the reader. Smaller tag sizes may be easier to package into a product but the downside is the reduction of communication distance available.

The capability of the small inlay size allows it to be embedded into labels. Labels with inlays are called smart labels. Using printers with embedded RFID or external readers, smart labels cannot only be printed on; they can also be written to.

With the current power regulations, HF is designed for applications that require a 1m or less of communication range. Orientation of the tags with respect to the reader antenna will have an impact on the communication range. For optimum communication range, both antennas (tag and reader) should be parallel. Having the tag perpendicular to the reader antenna may significantly reduce the communication range.

The higher the frequency, the higher the data throughput and the faster the communications will be between the reader and the tags. This increase in speed allows for the reader to communicate with multiple tags at once. The process of communication with multiple tags is known as Anti-Collision and at HF, a reader can read up to 50 tags per second.

The following are some of the benefits and limitations of HF RFID:

Although most access control systems today are based on LF, using either contact-less cards or keyfobs, HF is becoming the technology of choice for new access control and security systems. The additional memory allows for improved security and the integration of biometrics as part of the security features. Enhanced access control systems have the ability to validate assets, such as computer equipment and other items as one passes through an access control system or portal. Assets embedded with a HF tag can be read and identified within the access control system. Documents and files can easily be identified and tracked as well.

Contact-less Smart Cards or RFID cards are going to be the credit cards of next generation. Credit card companies have been testing HF RFID based on ISO 14443 standards for some time. We should start seeing the deployment of these new cards in the next few years, once retail terminals are upgraded to support RFID capabilities. One of the main reasons for the switch to contact-less smart cards is primarily to the ruggedness and consistent performance levels associated with RFID. When a tag is embedded into a card or other form factors, the tag is essentially protected from the surrounding environment. As for the readers, they can also be encased and protected from the surrounding environment. The second reason for the switch to RFID is the additional memory the tags can store. This allows for better security and protection of privacy issues. By using biometrics and personalized access number improved security can be accomplished.

Numerous sports teams and events are using HF RFID for payment and access. Most ski hills in Europe use the technology for convenience and prevention from fraud. The next world cup scheduled for 2006 in Germany will be using tickets embedded with HF inlays.

HF is also a solution for identifying products, such as cases and pallets. The communication range of HF limits the type of warehouse or logistics applications. For retail or for applications that do not require long communication distances, HF is a very good solution.

High Frequency RFID is an ideal solution for applications that require lower cost identification and the ability to read multiple tags at once at a distance of 1meter or less.

ULTRA HIGH FREQUENCY (UHF) PASSIVE RFID

Ultra High Frequency is referred to the frequency range 300 MHz to 3 GHz in the radio spectrum. RFID technology has been developed in different regions of this band, specifically, 433 MHz, 860 -956 MHz, and 2.45 GHz.

UHF coming to prominence in the RFID market place is a fairly recent phenomena compared to the more established High Frequency (13.56 MHz) and Low Frequency (125-134.2 kHz) technologies. HF is a robust technology, which works well for item management applications, but fails where read ranges of beyond 1m is required. UHF vendors are targeting the supply chain market where longer read distances are required.

Technically speaking, RFID in the UHF range differs from High Frequency systems in a number of ways. UHF operates, primarily, in 860-956 MHz range allowing for shorter antennas and longer read distances. Reader-Tag communication is implemented using backscatter technology. In this method, tag communicates with the reader by modulating the received signal and radiating it back to the reader. This scheme is fundamentally different than Inductive-coupling method used in HF systems. Moreover, the anti collision (simultaneous reads) feature implementation in UHF is achieved using a protocol based on bit broadcasting as opposed to HF protocol that operates based on the time-slot concept. This allows for higher number of tags to be read simultaneously in the UHF range, typically 200 tags as opposed to 50 tags with HF systems.

Although the UHF RFID addresses some shortcomings of the HF RFID, primarily in terms of read range, it has to contend with its own limitations and challenges. Today's UHF systems do not work in the presence of liquids whereas HF and LF work fairly well in such environments. Metal poses a serious challenge for any RFID implementation, more so in the UHF range. Moreover, longer read distance becomes a disadvantage in applications such as banking and access control.

The following are some of the benefits and limitations of UHF RFID:

There are complicating factors that have somewhat hindered faster progress in the UHF RFID market. As mentioned above, UHF technology suffers from lack of standards and regulations. ISO and EPC Global are the main bodies that work to draw standards and specifications for UHF RFID. However, at times, these two organizations seem to be moving in competing paths, resulting in duplication of efforts and confusion in the market place. This has caused some major vendors and users to delay their entry into the RFID market.

EPC Global is a major driving force in the RFID space. It is the successor to Auto ID Inc., which was incepted in collaboration between the academia and consumer product industry. EPC Global's vision is to identify every single item across the supply chain and eventually every object in the world with a unique Electronic Product Code (EPC). Although their stated mission seems to be ambitious at present, pilot projects are underway in supply chain applications. EPC Global is preparing specifications for all different RFID technologies. However, its primarily work has been concentrated in the UHF range. That is because EPC Global is mainly sponsored by consumer product industry. Retailers and manufacturers such as Wal-Mart, Gillette, and Proctor & Gamble see immediate benefits from using RFID in their distribution operations. They believe UHF, due to its longer read range, is more suitable for supply chain management at the pallet and to some degree at the case level.

Amongst all different types of RFID technologies, UHF has been the focus of the media in recent months mainly because of Wal-Mart's announcing its intentions to implement RFID. Wal-Mart has committed to the use of UHF technology in its distribution centers and has mandated its suppliers to follow suit. Another major user of RFID is Department of Defense (DoD), one of the earliest users of RFID in their logistical operation. DoD has recently renewed its commitment to full implementation of RFID in its logistics. Although DoD has not tied its RFID implementations to a specific frequency, it is anticipated that UHF will be the dominant technology to be employed.

RFID industry is on the verge of a breakthrough. The market has passed its infancy and there is no doubt that this technology is going to revolutionize the way we live. RFID will add intelligence to objects and that will change the way humans interact with them. There is no single RFID technology capable of working in all the applications. Different RFID technologies will be complementing each other, each serving functions that most suit its characteristics.