Robust Implicit EDF: A Wireless Mac Protocol for Collaborative Real-Time Systems

Tanya L. Crenshaw, Spencer Hoke, Ajay Tirumala, Marco Caccamo

Research output: Contribution to journalArticlepeer-review


Advances in wireless technology have brought us closer to extensive deployment of distributed realtime embedded systems connected through a wireless channel. The medium-access control (MAC) layer protocol is critical in providing a real-time guarantee. We have devised a real-time wireless MAC protocol, robust implicit earliest deadline first, or RI-EDF. Packets are transmitted according to EDF scheduling rules, offering a protocol that implicitly avoids contention. In the event of a packet loss or a node failure, every node has the opportunity to recover the schedule based on a static recovery priority, offering a protocol that is robust with no central point of failure. We demonstrate in simulations that RI-EDF provides better goodput and lower packet loss than existing protocols like 802.11 PCF and EDCF. In our implementation and distributed control test-bed, we show that RI-EDF provides better throughput than the TinyOS MAC-layer protocol. Overall, RI-EDF provides predictable temporal behavior with minimal impact on node failures, packet losses, and noise in the channel.

Original languageEnglish (US)
Number of pages1
JournalACM Transactions on Embedded Computing Systems
Issue number4
StatePublished - 2007


  • Earliest deadline first
  • Reliability
  • medium-access control
  • real time
  • wireless

ASJC Scopus subject areas

  • Software
  • Hardware and Architecture


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