RFID Reader Anticollision Protocols for Dense and Mobile Deployments

The rapid development of RFID (Radio Frequency IDentification) technology has allowed its large adoption and led to increasing deployments of RFID solutions in diverse environments under varying scenarios and constraints. The nature of these constraints ranges from the amount to the mobility of the readers deployed, which in turn highly affects the quality of the RFID system, causing reading collisions. Although several solutions were proposed to engage the issue of reading collision, few were ever concerned with the densification and/or mobility of readers. This paper proposes two distributed TDMA (Time Division Multiple Access) approaches designed to reduce these collisions through local coordination between neighboring devices for different scenarios tested here. The first proposal is based on a reservation phase organized between readers with different priority levels given to readers depending on their previous success. The second one takes advantage of the particular case of RFID collisions, allowing a local and mutual decision of each reader to access or not tags in their vicinity. Simulations were run over different stressful environments in terms of tag/reader density and mobility, proving that our proposals achieved the best performance in terms of throughput, collision avoidance and coverage delay when compared to other collision reducing schemes