A Novel Anti-Collision Scheduling Protocol for RFID-based Wireless Localization

In an active RFID based wireless localization system, usually a number of RFID readers are required to generate localization beacon broadcasts from which a RFID tag can collect multiple RSSI measurements and forward them to a localization server for calculating the location of the tag. Such operations should be done from time to time when the tag is moving. Collisions may happen at the tag if the readers send the beacon broadcasts at the same time or at the server if the tags forward the measurements at the same time. In this paper, we present a novel hybrid slotted anti-collision scheduling protocol for such RFID-based wireless localization of mobile tags by considering tag mobility and treating the existing tags and newly entered tags differently. In the proposed protocol, a time frame consists of a reader beaconing phase, a sequential polling phase for existing tags, and a tree-splitting anti-collision measurement forwarding phase for newly entered tags. Because the existing tags do not participate in the third phase for competition, we are able to improve the time efficiency and the QoI (Quality of Information) of the localization. Analysis and simulation results verify the performance of the proposed protocols. Keywords—RFID; wireless localization; collision avoidance; tree-splitting algorithm; quality of information