RASPberry: A stable reader activation scheduling protocol in multi-reader RFID systems

Recent technological advances have motivated large-scale deployment of RFID systems. RFID readers are often static and carefully deployed in a planned manner. However, the distribution and movements of tags are often dynamically changed and unpredictable. We study a challenging problem of scheduling the activation of the readers without collision such that the system can work in a stable way in the long term. Here a schedule is stable if at any time slot, the number of total unread tags is bounded from above with high probability under this scheduling. In this paper, we propose a stable reader activation scheduling protocol, RASPberry, in multi-reader RFID systems. We analytically prove that our scheduling protocol, RASPberry, is stable if the arrival rate of tags is less than the processing rate of all readers. In RASPberry, at any time slot, a reader can determine its status using only information of readers within a local neighborhood. To the best of our knowledge, this is the first work to address the stability problem of reader activation scheduling in RFID systems. Our extensive simulations show that our system performs very well.