Collision resolution algorithms for RFID applications

This paper presented a review of modern contention resolution algorithms which combine signal processing tools and scheduling mechanisms, and which are suitable for implementation in RFID systems. We have concluded that in order to minimize the number of transmissions and retransmissions of the contending tags, retransmission diversity algorithms with random selection of orthogonal ID sequences provide an attractive option. Due to the operating frequencies of RFID systems, the most probable method to achieve MPR capabilities is through reader cooperation, which remains as an open research area. Another contribution of this paper is the identification of tag collisions as a method to improve privacy and security. However, despite such security enhancement schemes, single packet transmissions are still susceptible to severe privacy and security attacks that must be solved either by other layers or through a further modification of the MAC procedures.