1 The reader collision problem occurs when the signal from one reader interferes with the signal from other readers. Solutions like RTS-CTS are not applicable because a reader may communicate with multiple tags simultaneously. In this paper, we describe Pulse, a distributed protocol to reduce reader collisions. The operation of the Pulse protocol is based on periodic beaconing on a separate control channel by the reader, while it is reading the tags. The protocol functions effectively with fixed as well as mobile RFID readers. We show, using simulation in QualNet, that using Pulse protocol, the throughput (overall read rate) is increased by as high as 98%(with 49 readers) as compared to “Listen Before Talk” (CSMA) and by 337%(with 9 readers) as compared to Colorwave. We also present an analytical model for our protocol in a single hop scenario.
Shailesh M. Birari, Sridhar Iyer