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  • Research Article
  • Open Access

ASAP: A MAC Protocol for Dense and Time-Constrained RFID Systems

  • 1Email author,
  • 2,
  • 2 and
  • 3
EURASIP Journal on Wireless Communications and Networking20072007:018730

  • Received: 16 October 2006
  • Accepted: 21 June 2007
  • Published:


We introduce a novel medium access control (MAC) protocol for radio frequency identification (RFID) systems which exploits the statistical information collected at the reader. The protocol, termed adaptive slotted ALOHA protocol (ASAP), is motivated by the need to significantly improve the total read time performance of the currently suggested MAC protocols for RFID systems. In order to accomplish this task, ASAP estimates the dynamic tag population and adapts the frame size in the subsequent round via a simple policy that maximizes an appropriately defined efficiency function. We demonstrate that ASAP provides significant improvement in total read time performance over the current RFID MAC protocols. We next extend the design to accomplish reliable performance of ASAP in realistic scenarios such as the existence of constraints on frame size, and mobile RFID systems where tags move at constant velocity in the reader's field. We also consider the case where tags may fail to respond because of a physical breakdown or a temporary malfunction, and show the robustness in those scenarios as well.


  • Information System
  • Radio Frequency
  • Statistical Information
  • Medium Access Control
  • System Application


Authors’ Affiliations

Qualcomm, San Diego, CA 92121, USA
Wireless Communications and Networking Laboratory, Department of Electrical Engineering, Pennsylvania State University, University Park, PA 16802, USA
Philips Research, Eindhoven, 5621, The Netherlands


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© Girish Khandelwal et al. 2007

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.