A Reader Anti-collision Protocol for RFID-Enhanced Wireless Sensor Networks

Considering rapid developments in the technologies of both radio-frequency identification (RFID) systems and wireless sensor networks (WSN), an integration of the two technologies may lead to the formation of an RFID-enhanced WSN which would possess improved functions and capabilities. In the RFID-enhanced WSN, many reader-enhanced nodes have increasingly been employed. In such networks, RFID data contains a lot of duplication, because the same tag may be read multiple times, and collision may occur among readers, while energy constraints are also a serious problem. These three could in turn cause serious problems. In this paper, we have proposed our CSMA-based algorithm since it is light, efficiently minimizes all kinds of reader collision, and eliminates the duplicate data. For this purpose, we have used a separate control channel and a tag ID forwarding mechanism with a special contend-backoff mechanism based on the residual energy of RFID-enhanced nodes. Simulation consequences prove that our proposed mechanism achieves a smaller number of reader collisions as well as the highest network throughput, compared to existing reader collision reducing schemes.