Reliable identification of RFID tags using multiple independent reader sessions

Abstract

Radio Frequency Identification (RFID) systems are gaining momentum in various applications of logistics, inventory, etc. A generic problem in such systems is to ensure that the RFID readers can reliably read a set of RFID tags, such that the probability of missing tags stays below an acceptable value. A tag may be missing (left unread) due to errors in the communication link towards the reader e.g. due to obstacles in the radio path. The present paper proposes techniques that use multiple reader sessions, during which the system of readers obtains a running estimate of the probability to have at least one tag missing. Based on such an estimate, it is decided whether an additional reader session is required. Two methods are proposed, they rely on the statistical independence of the tag reading errors across different reader sessions, which is a plausible assumption when e.g. each reader session is executed on different readers. The first method uses statistical relationships that are valid when the reader sessions are independent. The second method is obtained by modifying an existing capture-recapture estimator. The results show that, when the reader sessions are independent, the proposed mechanisms provide a good approximation to the probability of missing tags, such that the number of reader sessions made, meets the target specification. If the assumption of independence is violated, the estimators are still useful, but they should be corrected by a margin of additional reader sessions to ensure that the target probability of missing tags is met.Index Terms-Missing tag problem, set cardinality estimation, error probability estimation, RFID networks

A Multiple Hashing Approach to Complete Identification of Missing RFID Tags

“…Actually there is another type of "missing" tag problem [21], in which the "missing" tags represent the tags that are left unread due to errors in the communication link towards the reader, e.g., caused by the obstacles in the radio path. In other words, the study in [21] investigated the problem of tag identification (i.e., reading the tag IDs) in a scenario with non-perfect communication channels.…”

“…In other words, the study in [21] investigated the problem of tag identification (i.e., reading the tag IDs) in a scenario with non-perfect communication channels. The authors studied how to minimize the probability of missing (miss-reading) a tag, which is different from the missing tag identification problem addressed in this study.…”

Who stole my cheese?: Verifying intactness of anonymous RFID systems

“…An intactness verification protocol can ei- 23 ther (1) re-identify present tags through collecting their IDs 24 and compare the collected IDs against the registered ones, 25 or (2) directly access the registered IDs on the server and 26 design efficient polling schemes [9]. Existing work adopts 27 the latter toward scalability in large systems, falling into 28 two categories-probabilistic detection that detects the event 29 of absence with certain probability [9,11], and deterministic 30 identification that accurately pinpoints the IDs of absent tags 31 if any [10,[12][13][14][15][16]. 32 This paper aims to verify the intactness of anonymous 33 RFID systems without tag IDs as a priori (Section 2).…”

Probabilistic optimal tree hopping for RFID identification

“…Second, it assumes that the tag population remains static for the lifetime of tags as each tag is hard coded with some other tags' IDs. The second scheme is to run an identification protocol on the same population several times until probability of missing a tag falls below a threshold [7,10]. They estimate the probability of missing a tag based upon the number of tags that were identified in some runs of the protocol but not in others.…”

“…While we can use the C1G2 compliant scheme proposed in [7,10] to make TH reliable, i.e., repeatedly run TH until the required reliability is achieved. We observe that in this scheme, the leaf nodes in the binary tree are queried multiple times.…”