The design argues for the use of active tags for better monitoring of devices over longer distances, while operating them in a transmit only mode. Power lost in idle listening is conserved by eliminating the receiver entirely from the tags. More details on this project are available here.
Related publications:
- RollCall : The Design For A Low Cost And Power Efficient Active RFID Asset Tracking System
Gautam Bhanage, Yu Zhang, Yanyong Zhang, Trappe Wade, and Rich Howard
Proceedings of Eurocon 2007, 2007. [.pdf]