RFID reader collision problem: performance analysis and medium access

Abstract

The RFID reader collision problem, in which an RFID reader's interrogation is interfered by other concurrent readers' transmission, is considered an important issue to reliable operation and thus to the wide‐spread deployment of RFID networks. In this paper, we present modeling and analysis of the RFID reader collision problem. We observe asymmetry between an RFID reader's and a tag's communication capabilities and develop an RFID radio model based on the asymmetry. By the model, we characterize the spatial reuse of RFID reader networks, and derive concurrent interrogation distance beyond which readers can transmit simultaneously without causing collision and the carrier sense threshold corresponding to the distance. We also examine the dual‐channel mode where available bandwidth is divided into two channels by which reader‐to‐tag communication and tag‐to‐reader communication are separated. We analyze and evaluate the performance of the dual‐channel mode in terms of spatial reuse and interrogation completion time. Copyright © 2010 John Wiley & Sons, Ltd.

Trade-off between maximum cardinality of collision sets and accuracy of RFID reader-to-reader collision detection

“…The antenna gains of the tags are set to 1 dBi. The power reflection coefficient of the tag is [11]. The distance between a reader and the queried tag |x − t| is set to 5 m. Besides, the background power is considered negligible.…”

“…The model proposed in [11] considers the common situation in which the same channel is used for reader-totag query communication and for tag-to-reader response communication. The power of the signal that tag t receives when it is interrogated by reader x is…”

“…I x is evaluated in [11] considering the readers deployed according to the hexagonal constellation shown in Figure 1. Reader x is at the origin of the i and j axes.…”

“…Consequently, UHF RFID systems are easy to suffer from the interference generated during simultaneous interrogation activities [10]. In this case, a reader can suffer a reader-to-reader collision due to the interference generated by the simultaneous operations of other RFID readers [11]. When the reader queries a tag, the reader-to-reader interference is too strong with respect to the weak signals received from the tag, thus compromising the interrogation.…”

SA-PSO based optimizing reader deployment in large-scale RFID Systems

“…The collision problem can be divided into reader collision (Li et al, 2014;Yoon and Vaidya 2012;Yu et al, 2011) and tag collision (Namboodiri and Gao 2010;La Porta et al, 2011). As shown in Fig.…”