The Slotted-LBT: A RFID Reader Medium Access Scheme in Dense Reader Environments

Optimization of Mobile RFID Platforms: A Cross-Layer Approach.

“…However, ALOHA efficiency is not as high as required in RFID applications, while carrier-sense features are prone to hidden/expose terminal problems and also suffer from complexity issues at the reader side in order to implement the sensing mechanism (Birari & Iyer (2005)). A proposal for a medium access technique for RFID readers is provided in (Quan et al (2008)) and is referred to as Slotted-LBT (S-LBT). Based on carrier-sensing or LBT, this algorithm makes use of several channels, and in case the selected channel is sensed as busy, a new channel is considered for the transmission.…”

Randomized Multi-Channel Interrogation Algorithm for Large-Scale RFID Systems

“…Since V r ⊆ I r ∪ S r for each r ∈ R, if neither type 1 nor type 2 reader-to-tag collisions occur, then reader-to-reader collision will not happen either. Thus, the set V r does not appear in (8). It is easy to verify that if τ r (N r ) > T/2 for all r ∈ R, then we can simply set γ r,n = 1 for each r ∈R and any n ∈I r .…”

“…FDFA ALGORITHM Although the utilities in (11) are concave functions in P succ r for α >0, problem (P1) is not a convex optimization problem with respect to p, due to the product forms in (8). Thus, finding the optimal solutions of problem (P1) is not easy in general.…”

“…We start by first comparing the FDFA algorithm with DIA [7], S-LBT [8], and random and naive algorithms [6] in terms of the average probability of a successful interrogation among all readers (i.e., the ratio of the successfully interrogated tags compared to the total number of tags in the system). The simulation time is 1,000 sec.…”

“…Therefore, it is of interest to design distributed randomized interrogation schemes such that each reader randomly selects the start time of its interrogation rounds and its operating channel to reduce the probabilities of reader-to-tag and readerto-reader collisions. Related algorithms include naive, random, and carrier sensing protocols [6], the distributed interference avoidance (DIA) algorithm with detect and abort [7], and the slotted listen-before-talk (S-LBT) scheme [8]. However, given the heuristic nature of all of these algorithms, some may not be able to fully utilize the potential capacity of RFID systems.…”