An improved spread slotted ALOHA anti-collision algorithm in RFID system

In the Radio Frequency Identification (RFID) system, the information of tags will collision when there are several tags in the identification process of readers. This paper first introduces the basic principle of collision, and then it mainly analyzes the respective characteristics of time division multiple access (TDMA) and code division multiple access (CDMA). At the same time it introduces the ALOHA algorithm basic on TDMA. On the basis of them this paper puts forward the improved spread slotted ALOHA anti-collision algorithm. This algorithm not only combine with the principle of TDMA and CDMA, but also it use packet retransmission mechanism when tag collision occurs. It means that it groups the tags when the tags collision still occurs, they will be retransmit in the following time slot. It can be seen from the simulation results, the improved algorithm can effectively enhance the throughput and it reduce delay performance of the system.