RollCall : The design for a low-cost and power efficient active RFID asset tracking system

One of the most compelling and immediate applications of pervasive computing would be to use RF technology to support low-cost, long-lived and continual tracking of assets. Unfortunately, initial solutions have not yet led to widespread deployment. We believe that meeting the economic and system requirements of this application requires a redesign of the tag, the transmission protocol, and the algorithms used by basestations to identify tags, all with the underlying goal of reducing cost and power consumption through simplification. In this paper, we propose a new inventory tracking system, called RollCall, in which a transmit-only RFID tag will be attached to every item, and these tags will report their presence to the readers periodically by broadcasting the tag IDs so that a missing tag/item can be quickly identified. The power conservation obtained from short transmissions on a very simple MAC layer combined with the hardware cost and size reduction from having a simple radio stack on the tag provides considerable economic, dimensional and tag lifetime benefits. In this paper, we present the design and architecture of the RollCall system, and conduct preliminary studies to examine the feasibility of building such a system by tweaking off-the-shelf signal processing algorithms. Initial studies and simulation results suggest that it is possible to monitor about 5000 tags in a store with networked basestations at a low error rate with an extended tag life time of at least a year based on conservative estimates with non-custom tag radio and micro-controllers.