Anti-collision algorithm in RFID

In the radio-frequency identification (RFID) system, tags store unique identifications and are attached to objects; a reader performs the tag interrogation procedure to recognize an object by issuing wireless RF signals to interrogate the identification of the attached tag. Like other wireless communication systems, the RFID system also suffers from the signal interference problem. There are two types of signal interference. One is called the reader collision, which occurs when multiple readers issue signals to same tags simultaneously. The other is called the tag collision, which occurs when multiple tags respond to a reader simultaneously. Collisions hinder and slow down the tag interrogation procedure. Therefore, reader anti-collision and tag anti-collision protocols are required to respectively reduce reader collisions and tag collisions to improve interrogation procedure performance. In this chapter, we introduce existing reader anti-collision and tag anti-collision protocols. We intend to provide not only an extensive survey of the protocols, but also new research directions of them.