Radio frequency identification.

Radio frequency identification (RFID) is a group of technologies used to identify or track electronic devices (RFID tags or transponders), typically applied to or incorporated into products, animals, or even persons, using radio waves or electromagnetic fields. RFID systems have various applications, with the most prevalent one being enterprise supply chain management to improve the efficiency of inventory tracking and management, as RFID transponders complement bar codes (allowing the reading from several meters, even beyond the line of sight), and may one day even take their place. Other uses include payment services (for example public transportation, toll roads, season parking tickets, ski tickets, proximity smart cards), asset and inventory tracking, patient identification in hospitals, animal identification, library systems, anti-theft technologies, or even race timing. The main reasons for blocking its even more widespread utilization are privacy and security related issues, originating from the wireless nature of the technology. Technological challenges and development directions include robust collision resolution (caused by simultaneously transmitting transponders or readers), the mitigation of the privacy concerns, and the creation of more intelligent chips (by adding cryptographic algorithms, new sensors, more memory, and processing power to the transponders) while retaining miniaturization and cost-efficiency efforts. In this chapter, we will start by briefly summarizing the history of radio frequency identification systems. After that, we will introduce the components of such systems and classify them based on programmability, data capacity, frequency, and reading distance, as well as power supplement and reply transfer methods. We will describe the various coupling types used in RFID systems, present the common coding schemes and modulations, and give an overview of the standardization efforts. This chapter will focus on collision detection and resolution algorithms and conclude by practical suggestions on RFID system selection for different tasks. DOI: 10.4018/978-1-60960-732-6.ch023