An Enhanced Method of Estimating Number of Tags Using Signal Strength Properties in RFID Systems

Radio frequency identification (RFID) is a wireless communication technology that provides automatic identification and data collection. In the application of RFID systems with large number of tags, many tags may respond to the reader in the same time. Thus, enhanced anti-collision algorithms are required to have fast multiple tag identification process. Thus, several anti-collision algorithms are developed mainly in two different areas: ALOHA based algorithm and tree based algorithm. These algorithms help to achieve better identification performance, by adjusting the frame size closer to the optimum size. There are many methods to select the appropriate frame size based on the number of collided slots, the collision ratio or the maximum throughput. In this paper a new method is introduced by using the characteristics of the received signal by the reader.