RFID Counting over Time-Varying Channels

For many applications that use RFID technology, it is important to count the number of RFID tags accurately. However, the wireless channel between the RFID tags and readers can introduce communication errors, and the error rate may vary significantly over time. No existing protocol can perform RFID counting robustly (i.e., maintaining the estimation quality) over time-varying channels. In this paper, we design RRC, a Robust RFID Counting protocol that offers provable guarantees on estimation quality over time-varying channels. Specifically, regardless of how the communication errors occur, the final output generated by RRC is always a standard (e, δ) estimate of the correct count n. Furthermore, the expected amount of time needed by RRC is O(Y + 1/2 + (log log n) ² ) for a constant 6, where Y is the number of communication errors encountered by RRC. This makes the efficiency of RRC asymptotically near-optimal.