Redundant reader elimination in RFID systems

While recent technological advances have motivated large-scale deployment of RFID systems, a number of critical design issues remain unresolved. In this paper we deal with detecting redundant RFID readers (the redundant reader problem). The underlying difficulty associated with this problem arises from the lack of collision detection mechanisms, the potential inability of RFID readers to relay packets generated by other readers, and severe resource constraints on RFID tags. We prove that an optimal solution to the redundant reader problem is NP-hard and propose a randomized, distributed, and localized approximation algorithm, RRE. We provide a detailed probabilistic analysis of the accuracy and time complexity of RRE and conduct elaborate simulations to demonstrate their correctness and efficiency.