Efficient missing tag identification in blocker-enabled RFID systems

Abstract

Due to limited on-chip resources, RFID tags may blindly respond to any readers authorized or not, leading to privacy leakage when sensitive data are exposed. A feasible solution to this problem is deploying blocker tags that emulate and behave like the genuine tags. With this deployment, there is always a virtual tag produced by the blocker tag that responds to the reader when the genuine tag to be protected replies, resulting in irreconcilable collisions and thus preventing privacy-leakage. This paper studies the problem of missing tag identification in blocker-enabled RFID systems. Unlike existing work, the reader in this problem will always get the responses from blocker tags even the genuine tags are lost, which makes the existing solutions unavailable. To address this problem, we propose three efficient protocols. The first is a group-based protocol that splits the entire tag set into three subsets and separately deals with each of them in different ways. The second protocol is called collision-reconciled protocol that turns some useless collision slots into useful singleton slots, increasing slot availability and thereby reducing the execution time. The third protocol is a concurrent missing tag identification protocol that improves the time efficiency of missing-event detection by running grouping and missing identification in parallel rather than in sequence. Theoretical analyses and extensive simulations show that our protocols are far superior to benchmark. For example, our best protocol can improve the identification efficiency by a factor of 6.