Interference Avoidance Algorithms for Passive RFID Systems Using Contention-Based Transmit Abortion

The performance of a passive RFID system in a dense multi-reader environment is limited by both reader-to-reader interference and reader-to-tag interference. In this paper, we formulate a practical RFID system model which takes into account the non-linear demodulation of the tags and the transmission spectrum of the readers. Using this model, we derive a novel linear programming formulation to obtain the optimum communication probability of the readers for a given reader deployment scenario. We then propose two novel distributed interference avoidance algorithms based on the detect-and-abort principle for multi-channel readers which can effectively mitigate the reader-to-tag interference as well as the reader-to-reader interference. Computer simulations show that the proposed algorithms can improve the successful communication probability and fairness among readers in dense reader environments, compared with the conventional listen-before-talk algorithm. key words: RFID, reader collision, collision avoidance