Improved physical layer collision recovery receivers for RFID readers

Radio Frequency Identification (RFID) systems usually operate in a multiple RFID tag environment. If multiple tags respond simultaneously, a collision occurs and the information is discarded. In this paper, we propose a novel physical layer collision recovery mechanism. We analyse theoretical limits of the inventory time and show how our new method can approach such theoretical maxima. We propose a method that resolves more colliding tags by making collisions less destructive. In this method a postprocessing of the received signal by beamforming is performed. Furthermore, we investigate the influence of the proposed method on the system performance by means of simulations. We show that our method considerably shortens the time necessary to interrogate tags.