A cardinality estimation scheme for the number of unknown RFID tags under unreliable channels

In recent years, RFID technologies have been widely used in real-life applications, including supply chain manage-ment, warehouse tracking, etc. One of the concerns is the estimation of the number of interested tags. The existence of unknown tags will affect normal operation and management for RFID systems. Existing protocols for estimating the number of unknown tags generally assume ideal communication channels. In practice, there may exist environment interference that affects the transmission from tags to a RFID reader. In this paper, we study the problem of estimating the number of unknown tags under unreliable channels, and propose a cardinality estimation scheme CEUT(Cardinality Estimation for Unknown Tags under unreliable channels). The reader collects responses from all tags after running the Aloha protocol. The number of non-empty slots in the response frame increases due to the presence of unknown tags is designed based on the number of empty slots in the predicted frame converted into non-empty slots in the response frame and the channel noise parameter. The simulation results show that, under the unreliable channel, the estimation result scheme yielded by CEUT is more robust than other existing schemes, and can achieve therequired estimation accuracy.