An improved dynamic framed slotted ALOHA Anti-collision algorithm based on estimation method for RFID systems In order to solve the collision problems between multiple RFID tags and improve the identification efficiency, this work presents an improved dynamic framed slotted ALOHA Anti-collision algorithm forRFID systems. Based on the time slot distribution information, the algorithm estimates the average number of tags in each collision slot and then dynamically sets the frame size for unrecognized tags due to the collision between multiple tags. We theoretically analyzed the time complexity of the proposed algorithm. Simulation results demonstrate that our proposed algorithm outperforms other existing algorithms in the literature in terms of the identification efficiency and the total number of time slots.