Based On Slotted Aloha Rfid Tag Anti-collision Algorithm

Due to the merits of long communication distance, fast speed and large information capacity, the radio-frequency identification (RFID) is becoming a promising technology recently. This paper systematically analyses the existing RFID anti-collision algorithms and suggest improvement so as to reduce collisions between tags, and accelerate identification speed.Firstly, we introduce the existing anti-collision algorithms and establish a simulation model implementing the ISO18000-6C Protocol, and determine the simulation parameters under China channel regulation.Secondly, we analyze the existing Slotted ALOHA algorithms based on the presumption that all slots have equal length. Then an improved frame size determining method by introducing an unequal slot-length index is proposed accordingly.Thirdly, the Grouping strategy and the dynamic algorithms in dynamic environment, are discussed. The simulation results shows that the Grouping strategy can not improve the performance of existing algorithms, and dynamic algorithm Lower Bound SBS improves the identification speed by 10/s compared with static algorithm Lower Bound FBF when more than 300 tags are present under the forward/backward transmission data rate of 125/60kb/s.Fourthly, we propose a novel ALOHA-based medium access control (MAC) protocol, BIS, in which the time consumption of the empty slots has been largely reduced through empty slot scanning and dynamic frame size adjustment by combining Bit-Slot and ID-Slot algorithm. Simulation results show that the identification speed of the proposed protocol is 500/s under under the forward/backward transmission data rate of 80/100kb/s.Finally, the performance of unequal slot-length index and dynamic algorithm are implemented and tested in the UHF reader (based on the Intel Tilden R1000 reader chip).