Design of a Quaternary Query Tree ALOHA Protocol Based on Optimal Tag Estimation Method

Radio Frequency Identification (RFID) technology is one of the most promising technologies in the IoT (The Internet of Things) era. Many RFID systems have been used in supermarkets or warehouses. There are two challenges for RFID anti-collision algorithms. The first challenge is accurately estimating the number of tags; the other is improving the efficiency of RFID systems. This paper proposes an optimal tag estimation method in which tags respond to the reader in assigned time slots instead of responding randomly. In order to improve the performance of the RFID system, a 4-ary query tree Additive Link On-line HAwaii (ALOHA) protocol is presented that combines the merits of query tree algorithm and frame slotted ALOHA, and avoids their weaknesses. Simulation results show that the proposed algorithm has a higher tag identification efficiency compared to other dynamic frame slotted ALOHA algorithms, and it can overcome the tag starvation phenomenon, because it traces each tag until all of them are identified successfully.