This is part of my own research on this subject.
Objective of RFID
The main goal of an RFID system is to carry data on a transponder (tag) that can be retrieved with a transceiver through a wireless connection. The ability to access information through a non-line-of-sight storage in a tag can be utilized for the identification of goods, locations, animals, and even people. Discerning specific information from these tags will have profound impacts on how individuals in commerce and industry keep track of their goods and each other.
Basics of RFID
RFID is an acronym for Radio Frequency Identification. The three basic components of a typical RFID system are an antenna or coil, a transceiver (reader with decoder), and a transponder (tag) with electronically programmed information. In an RFID system, an antenna continuously emits radio signals at a given frequency. When a transponder (that is set to detect that specific frequency) comes into contact with these signals, the badge is activated and communicates wirelessly with the reader through the modulation of transmittance frequencies. Through the use of an antenna, the information that is stored on the transponder can be read or written from the transponder. Typically, the antenna is packaged with the transceiver into a larger structure called a reader (interrogator) that is in charge of the systemâ€™s data communication and acquisition. The data that is obtained and analyzed by the reader can then be transported to a computer through serial, parallel, or bus cables. The general design of a simple RFID system is displayed through the following figure:
Brief History of RFID
RFID technology was invented in 1948, but it was not mainstreamed for commercial applications until the 1980s. One of its first known applications was during World War II, when it was used by the British radar system to differeniate between German aircraft and their own aircraft with attached radio transponders.
Only recently, due to technology advances, have the price points dropped to where RFID is now feasible for companies to adopt. Wal-Mart was among the first commercial enterprises to select RFID technology to achieve improvements in the inventory supply process and theft control. Wal-Mart started the process of implementing RFID throughout its retail distribution chain by requiring its top 100 suppliers to use RFID tags by year-end 2004 on the pallets and cases they shipped to Wal-Mart.
However, due to the status of standards, manufacturers of RFID tags were unable to meet the volume of demand within Wal-Mart’s desired time frame.
Distinguishing Features of RFID
How Tags Work
RFID tags can be characterized as either active or passive. Traditional passive tags are typically in â€œsleepâ€ state until awakened by the readerâ€™s emitted field. In passive tags, the readerâ€™s field acts to charge the capacitor that powers the badge. Due to the strength of the signal that is required, passive tags are most often used for short read-range applications (several inches) and require a high-powered reader. Passive tags are often very light, compact, and have unlimited life spans. However, drawbacks of this technology include limited memory storage (ranging from 32-128 bits) and read-only capabilities. By contrast, active tags are typically powered by an internal battery (that lasts several years) and are utilized for long read-range applications of 3-100 ft. Unlike passive RFID tags, active badges continuously emit a detectable signal and are typically read/write with a total memory capacity of 1MB. Due to these increased capabilities, active tags are heavier, costlier, and have limited life spans.
The transmitted radio frequencies are used to exchange a very brief and small amount of data, the EPC, which is then used to map to information regarding an objectâ€™s unique characteristics such as:
â€¢ This is where I originated: “manufacturing source”
â€¢ This is what I am: â€œpallet carrying boxes of paper towelsâ€ -or-
â€¢ This is what I am: â€œa specific box of paper towelsâ€
â€¢ This is my route tracking: â€œmy mode of transportation; my origination point, my arrival and departure time and location of every stop along the way, and the time I arrived at this final destination pointâ€
â€¢ This is my purchase and restocking information: â€œI was purchased by so and so, on this date, at this price, and I have now left the building â€“ please restock this itemâ€
At this time, tagging is not occurring at the item level in most cases but rather at the pallet and case level. Tagging at item level is being done in some high-price ticket items. Best Buy, for example, is beginning to use item-level tagging for items like computers. The plan is to migrate down to the item level in the entire supply chain as it becomes economically feasible.
The data structure for the EPC has been defined by the EPC global organization. The data structure lays out the data fields and what information they carry, the size of the data fields and how they are digitally encoded.
How Readers Work
A reader has a field (a distance range) within which it can query via radio waves for whatever tags may be present. The reader follows a protocol that is intended to enable it to avoid duplicate reads but capture all tags present within its range.
There is a large variation in reader capabilities, ranging from how many tags a reader can capture within a specific time period to more complicated tasks like filtering and communicating with a product database. Readers have to be matched to tag type: active or passive class: 0 (read only) or class 1 (read/write), gen 1 or gen 2 tags. Some readers can capture multiple tag types. Readers communicate with tags over radio waves and by following a specific RFID communications protocol.
The implementation challenge with readers is determining how many you need and their ideal placement in your physical facility. Poorly placed readers can result in creating duplicate reads of tags when their read range overlaps (some readers have special edge software to address this problem). Or, you can end up with the opposite result with missed item reads when they are located too far away from the tagged items.
The capabilities of the RFID system are also very dependent on the carrier frequency at which information is transported. Due to government regulation, different parts of the electromagnetic spectrum are assigned for different purposes. The three frequency ranges that typically distinguish RFID systems are low, intermediate, and high. There are currently eight frequency bands in use around the world for RFID application. These frequency ranges and associated information describing typical system characteristics and areas of application are explained through the following table:
Table 1: Frequency Bands and Applications
Short to medium read range
Low reading speed
Short to medium read range potentially inexpensive medium reading speed
Long read range
High reading speed
Line of sight required
Railroad car monitoring
Toll collection systems
RFID Use in Supply Chain Management
When you hear the term RFID used today it most commonly refers to the burgeoning business application for managing and tracking supply chains, especially in the materials, manufacturing, and retail industries. The supply chain business objective is to use RFID technology to not only take the just-in-time inventory concept to its next performance level but to support additional information functions … from streamlining the product recall process and reducing theft and fraud, to further improving the type and quantity of product marketing information.
Advantages of RFID
The novelty of RFID technology is its ability to transport information along significant distances and through a myriad of mediums. For instance, tags can be read through environmental conditions like snow, fog, and ice and visual challenges like paint, furniture, and even walls. This unique non-line-of-sight technology thus has an inherent advantage over the typical optical technologies used in such systems like barcodes. RFID tags can also be read in challenging circumstances at remarkable speeds, in most cases responding in less than 100 milliseconds. The read/write capability of an active RFID system is also a significant advantage in interactive applications. As a result, although a relatively expensive technology, RFID is truly a superior means of automated data collection and identification.
What RFID is Today and What RFID Hopes to Be Tomorrow
Current: Simply stated RFID can be an effective replacement technology of UPC bar codes. Because no line of sight is required. RFID can be used more easily by retail chains than today’s bar code.
Future: RFID has an almost unlimited potential in what it could track. It could track an item throughout its lifecycle. Such applications might include keeping records of maintenance and repairs or tracking personal data such as medical records and passport information. A tag could be attached to an inanimate object or embedded under a person’s skin.
But the potential of RFID, depends on how well the standards definitions are adopted, their realization into actual equipment components, how expensive they are, and how they are received by the purchasing public.