An Evaluation of UHF RFID Anti-Collision Protocols with NS2

Abstract

Radio frequency identification (RFID) has become an enabling and a promising technology for the proliferation of the Internet of Things (IoT) and its implementation. An RFID system front-end is composed of many tags that are identified by one or more readers. The significant issue in RFID system is how to limit the anti-collisions that occur between readers and tags when identifying and reading tags data. A Dynamic Framed Slotted ALOHA (DFSA) mechanism for UHF RFID passive tags was proposed by the EPC Global Class-1 Generation-2 standard (EPC C1 Gen2). In this mechanism the 'Q- algorithm' is used to dynamically update the size of the frame based on the number of unidentified tags. Many researchers have evaluated the Q-Algorithm and proposed many enhancements to ameliorate it and to have better read performances. However, a design of an anti-collision scheme plays a major role in determining a protocol performance. In order to measure a protocol performance, a variety of factors could be used. In this paper we have compared two recent enhancements of the Q-Algorithm with the original one used by the EPC C1 Gen2 standard. We have implemented protocols in NS2 simulator and conduct the comparison based on three factors which are system efficiency, collision ratio and the marginal identification cost. Not only the strengths and weaknesses of the protocols measured were shown by the results, but also the importance of evaluating all relevant performance factors was highlighted especially when comparing anti-collision protocols.