A simulation-based comprehensive study of the LBT mechanism in RFID networks

Radiofrequency Identification (RFID) installations with passive tags pose the interference problem among readers. Tags require a minimal power-up signal strength sent by the reader to operate and therefore the system is very sensitive to interferences. To face this issue, two mechanisms are used: (a) an anti-collision protocol, which serves to solve tags' collisions, and (b) a network coordination protocol, which coordinates readers operation to avoid them transmitting at the same time (and thus interfering each other). In this paper we address a thorough study of the standardized coordination protocol Listen Before Talk (LBT), which has been issued by the European regulation ETSI 302 208. The goal is describing the network operation in terms of the achievable throughput, by carefully detailing all the critical settings of a real facility: (a) a physical model for the channel which involves precise computations of powers and gains, sensitivities and channel fading, (b) modeling the anti-collision mechanism ISO 18000-6C (Framed Slotted Aloha), (c) precise operation of the LBT according to the ETSI regulation, (d) realistic traffic modeling (batch works), and (e) accurately computing the precise operation among readers. A variety of results is provided, which are mainly in these categories: throughput versus traffic, versus cell layout, versus network layout, versus reader and anti-collision protocol setup. They can be employed by practitioners in real-world application to understand the performance of RFID networks.