Performance analysis of hybrid ALOHA/CDMA anti-collision scheme for RFID systems over fading channels

This paper proposes and theoretically investigates the efficiency of a hybrid ALOHA/CDMA anti-collision scheme for passive radio frequency identification (RFID) systems. The decorrelating detector is supposed to be used at RFID reader, while each tag is assumed to assign with a Gold code and responds to the reader in a randomly selected time slot. The tag identification is performed considering the influence of both code collisions and detection errors due to fading channels. The system efficiency, which is defined as the average number of successfully detected tags over a slot, is theoretically derived. Computer simulations are also performed to validate the theoretical analysis. In the numerical results, we evaluate the performance of the tag identification procedure with system parameters that maximize the system efficiency. We also confirm the superiority of the proposed system in comparison with conventional ALOHA-based ones.