A survey on RFID anti-collision strategies: From avoidance to recovery

By adopting appropriate anti-collision strategies, radio frequency identification (RFID) technology can realize fast and contactless reading of multiple tags, significantly improving identification efficiency and accuracy. Traditional anti-collision strategies commonly employ a collision avoidance policy that operates at the MAC layer. The principle of this strategy involves coordinating communication between multiple tags and readers through a series of algorithms. However, in large-scale and intensive scenarios, an increased likelihood of signal collisions occurs within the system due to the growing number of tags, and the traditional strategy fails to adapt to these scenarios. To further address the collision problem in RFID systems in severe environments, researchers have proposed collision recovery-based anti-collision strategies. This strategy leverages the physical layer characteristics of RFID signals, aiming to resolve the collision issue in the system through signal recovery or parallel decoding. In this work, we initially discuss the collision problem in RFID systems. Subsequently, a review of recent works based on collision avoidance strategies is presented and synthesized. After that, we review anti-collision strategies based on collision recovery, classifying and analyzing collision recovery schemes from various perspectives. Ultimately, we provide an outlook of future research directions for this technology.