Survey, Nomenclature and Comparison of Reader Anti-Collision Protocols in RFID

Radio-frequency identification (RFID) has attracted a great deal of attention, due to its wide range of applications in the fields of logistics and supply chain, medicine, inventory, stock, asset management etc. Mobile readers in RFID have become available, while stationary readers are becoming more functional. In a workplace where readers are deployed densely, multiple RFID readers try to access the same tag at the same time. The situation, where multiple readers are in each others interference region, reader-to-tag communication, leads to a reader collision problem and thus inhibits the communication with the tag. Passive tags are cheaper and are widely used, but they lack frequency selectivity. In such an environment, the problems of reader-to-reader and reader-to-tag collision occur, which lead to the reduction of the efficiency and reliability of the RFID system, resulting in the misreading or failure to read the tag and an increase in the tag interrogation time. The existing standards do not allow this problem to be overcome efficiently. Hence, many reader anti-collision algorithms have been proposed in the literature. We survey the existing works on RFID reader collisions and compare their proposed solutions, based on their performances.