Identification processes that rely on AIDC technologies are significantly more reliable and less expensive than those that are not automated. The most common AIDC technology is bar code technology, which uses optical scanners to read labels. Most people have direct experience with bar codes because they have seen cashiers scan items at supermarkets and retail stores. Bar codes are an enormous improvement over ordinary text labels because personnel are no longer required to read numbers or letters on each label or manually enter data into an IT system, they just have to scan the label. The innovation of bar codes greatly improved the speed and accuracy of the identification process and facilitated better management of inventory and pricing when coupled with information systems. RFID represents a significant technological advancement in AIDC because it offers advantages that are not available in other AIDC systems such as barcodes. RFID offers these advantages because it relies on radio frequencies to transmit information rather than light, which is required for optical AIDC technologies. A type of AIDC technologies clearly describes Figure 1. Like bar codes in an earlier time, RFID is the next revolution in AIDC technology. Most of the advantages of RFID are derived from the reliance on radio frequencies rather than light (as is required in optical technology) to transmit information. This characteristic means that RFID communication can occur: Without optical line of sight, because radio waves can penetrate many opaque materials, At greater speeds, because many tags can be read quickly, whereas optical technology often requires time to manually reposition objects to make their bar codes visible, and
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Over greater distances, because many radio technologies can transmit and receive signals more effectively than optical technology under most operating conditions.
Figure 1. Type of AIDC technologies
1.1. Radio frequency identification Radio frequency identification (RFID) is a form of automatic identification and data capture (AIDC) technology that uses electric or magnetic fields at radio frequencies to transmit information. An RFID system can be used to identify many types of objects, such as manufactured goods, animals, and people. Each object that needs to be identified has a small object known as an RFID tag affixed to it or embedded within it. The tag has a unique identifier and may optionally hold additional information about the object. Devices known as RFID interrogators (also called readers) wirelessly communicate with the tags to identify the item connected to each tag and possibly read or update additional information stored on the tag. This communication can occur without a line of sight and over greater distances than other AIDC technologies [1]. 1.1.1. RFID system components RFID systems can be very complex, and implementations vary greatly across industries and sectors. For purposes of discussion in this document, an RFID system is composed of up to three subsystems: An RF subsystem, which performs identification and related transactions using wireless communication, An enterprise subsystem, which contains computers running specialized software that can store, process, and analyze data acquired from RF subsystem transactions to make the data useful to a supported business process, and An inter-enterprise subsystem, which connects enterprise subsystems when information needs to be shared across geographic or organizational boundaries [3]. Every RFID system contains an RF subsystem, and most RFID systems also contain an enterprise subsystem (Figure 2). An RFID systems supporting a supply chain is a common example of an RFID system with an inter-enterprise. In a supply chain application, a tagged product is tracked throughout its life cycle, from manufacture to final purchase, and sometimes even afterwards (e.g., to support service agreements or specialized user applications).
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Figure 2. RFID system architecture
1.1.2. RF Subsystem To enable wireless identification, the RF subsystem consists of two components: RFID tags (sometimes referred to as transponders), which are small electronic devices that are affixed to objects or embedded in them. Each tag has a unique identifier and may also have other features such as memory to store additional data, environmental sensors, and security mechanisms. RFID interrogators (often called readers), which are devices that wirelessly communicate with tags to identify the item connected to each tag and possibly associate the tagged item with related data.[2] Both the tag and interrogator are two-way radios. Each has an antenna and is capable of modulating and demodulating radio signals. Figure 3 shows a simple RF subsys