Time Modeling with NS2 in UHF RFID Anti-Collision Protocols

Abstract

In UHF RFID systems, many collisions happen due to the numerous tag responses generated by the inventory process. This is a serious worry faced by the RFID technology which can limit RFID system performances. As a matter of fact, the extra identification delays added by these collisions and the extra energy consumed can bring a waste of bandwidth to the interrogation process. Considering these collisions has been identified as a critical task in RFID systems. Indeed, the efficiency of tag identification is related to the performance of the algorithm of anti-collision, which is implemented on the tag and the reader. To evaluate this performance, an RFID module has already been developed in the NS2 Simulator. This NS2 RFID module implements an RFID system based on the Q-Algorithm of EPC global Radio-Frequency Identification Protocols Class1 Generation-2 Standard (EPC C1 Gen2). The focus of this module is the network layer and its mechanisms for anticollision. In this paper, we propose an optimization of the time model of this NS2 RFID module. This optimization is based on the use of several slots time durations. First, we validate our RFID module model by simulation with NS2 and comparison with theoretical results. Secondly, we conduct a performance evaluation of two recent RFID anti-collision algorithms (Q+ and Split Q-Algorithm), evaluate their performances with this novel model and compared them to the Q-Algorithm of the EPC C1 Gen2 standard. By evaluating the performance of these protocols in our RFID module, we validate that the Split Q-Algorithm and the Q+ minimize the Q-Algorithm identification time. Our new model much more realistic in terms of timing can be of great help in further investigating the performance of the Q-Algorithm and for actual UHF RFID systems performance analysis.