An Efficient Collision Detection Scheme for Generation-2 RFID Systems

In radio-frequency identification (RFID) systems, tag collision resolution is a significant issue for fast tag identification. Dynamic framed slotted ALOHA (DFSA) is one of the most widely used algorithms to resolve tag collision. Collision detection (CD) plays an important role in determining the efficiency of DFSA-based algorithms because most DFSA-based algorithms determine the next frame size according to the number of collided slots in the current frame. Existing CD methods do not respond quickly enough to detect a collision and have difficulty in distinguishing a collision from noise, resulting in a degradation of system efficiency. This paper presents a CD scheme based on the EPCglobal Class-1 Generation-2 protocol to improve CD efficiency. This scheme enables fast and accurate CD by detecting the number of pulses transmitted by tags. The effectiveness and practical feasibility of the scheme is verified by simulation and implementation. Performance evaluation results show that the proposed scheme achieves faster identification speed than the conventional methods, especially under noise conditions.