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Robust implicit EDF: A wireless MAC protocol for collaborative real-time systems

Published:01 September 2007Publication History
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Abstract

Advances in wireless technology have brought us closer to extensive deployment of distributed real-time 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.

References

  1. Baker, T. P. 1991. Stack-based scheduling of real-time processes. The Journal of Real-Time Systems 3, 1, 67--100. Google ScholarGoogle ScholarDigital LibraryDigital Library
  2. Bao, L. and Garcia-Luna-Aceves, J. J. 2001. A new approach to channel access scheduling for ad hoc networks. In Proceedings of the 7th Annual International Conference on Mobile Computing and Networking (MobiCom 2001). Rome, Italy. ACM Press, New York. 210--221. Google ScholarGoogle ScholarDigital LibraryDigital Library
  3. Benveniste, M., Chesson, G., Hoeben, M., Singla, A., Teunissen, H., and Wentink, M. 2001. EDCF Proposed Draft Text. IEEE Working Document 802.11-01/131r1.Google ScholarGoogle Scholar
  4. Bharghavan, V., Demers, A., Shenker, S., and Zhang, L. 1994. Macaw: A medium access protocol for wireless lans. In Proceedings of ACM Special Interest Group on Data Communications Conference (SIGCOMM 1994). London, England. Google ScholarGoogle ScholarDigital LibraryDigital Library
  5. Buttazzo, G. 1997. Hard Real-Time Computing Systems: Predictable Scheduling Algorithms and Applications. Kluwer Academic Publishers, Boston, MA. Google ScholarGoogle ScholarDigital LibraryDigital Library
  6. Caccamo, M., Zhang, L. Y., Sha, L., and Buttazzo, G. 2002. An implicit prioritized access protocol for wireless sensor networks. In Proceedings of the IEEE Real-Time Systems Symposium (RTSS 2002). Austin, Texas. Google ScholarGoogle ScholarDigital LibraryDigital Library
  7. Crenshaw, T., Tirumala, A., Hoke, S., and Caccamo, M. 2005. A robust implicit access protocol for real-time wireless collaboration. In Proceedings of the 17th Euromicro Conference on Real-Time Systems (ECRTS 2005). Palma de Mallorca, Spain. Google ScholarGoogle ScholarDigital LibraryDigital Library
  8. Cunningham, R. and Cahill, V. 2002. Time bounded medium access control for ad hoc networks. In Proceedings of the Workshop Principles of Mobile Computing (POMC 2002). Toulouse, France. Google ScholarGoogle ScholarDigital LibraryDigital Library
  9. Facchinetti, T., Almeida, L., Buttazzo, G., and Marchini, C. 2004. Real-time resource reservation protocol for wireless mobile ad hoc networks. In Proceedings of the 25th IEEE International Real-Time Systems Symposium (RTSS 2004). Libson, Portugal. Google ScholarGoogle ScholarDigital LibraryDigital Library
  10. Hoke, S. 2004. Wireless distributed control based on RI-EDF MAC protocol. http://pertsserver.cs. uiuc.edu/~mcaccamo/IPC/.Google ScholarGoogle Scholar
  11. Lee, D., Puri, A., Varaiya, P., Sengupta, R., Attias, R., and Tripakis, S. 2002. A wireless token ring protocol for ad-hoc networks. In Proceedings of the IEEE Aerospace Conference. Vol. 3. Big Sky, Montana.Google ScholarGoogle Scholar
  12. Lindgren, A., Almquist, A., and Schelén, O. 2001. Evaluation of quality of service schemes for IEEE 802.11 wireless lans. In Proceedings of the 26th Annual IEEE Conference on Local Computer Networks (LCN 2001). Tampa, Florida. Google ScholarGoogle ScholarDigital LibraryDigital Library
  13. Lindgren, A., Almquist, A., and Schelen, O. 2003. Quality of service schemes for ieee 802.11 wireless lans, an evaluation. Mobile Networks and Applications (MONET) 8, 3, 223--235. Google ScholarGoogle ScholarDigital LibraryDigital Library
  14. Liu, C. L. and Layland, J. W. 1973. Scheduling algorithms for multiprogramming in hard real time environment. Journal of the ACM 20, 1, 40--61. Google ScholarGoogle ScholarDigital LibraryDigital Library
  15. Liu, J. W. S. 2000. Real-Time Systems. Prentice Hall, Inc., Upper Saddle River, New Jersey.Google ScholarGoogle Scholar
  16. Monks, J. P., Bharghavan, V., and Hwu, W. 2001. A power controlled multiple access protocol for wireless packet networks. In Proceedings of 20th IEEE Conference on Computer Communications (INFOCOM 2001). Anchorage, Alaska.Google ScholarGoogle Scholar
  17. Malpani, N., Welch, J. L., and Vaidya, N. 2000. Leader election algorithms in mobile ad hoc networks. In Proceedings of the 4th International Workshop on Discrete Algorithms and Methods for Mobile Computing and Communications (DIALM 2000). Boston, MA. Google ScholarGoogle ScholarDigital LibraryDigital Library
  18. Sobrinho, J. and Krishnakumar, A. 1999. Quality-of-service in ad hoc carrier sense multiple access networks. IEEE Journal on Selected Areas in Communications 17, 8 (August), 1353--1368. Google ScholarGoogle ScholarDigital LibraryDigital Library
  19. Jurdzińkski, T., Kutylowski, M., and Zatopianski, J. 2002. Efficient algorithms for leader election in radio networks. In Proceedings of the 21st Annual Symposium on Principles of Distributed Computing (PODC 2002). Monterey, CA. Google ScholarGoogle ScholarDigital LibraryDigital Library
  20. Tobagi, F. A. and Kleinrock, L. 1975. Packet switching in radio channels: Part ii---the hidden terminal problem in carrier sense multiple-access and the busy-tone solution. IEEE Transactions on Communications 23, 12 (Dec.), 1417--1433.Google ScholarGoogle ScholarCross RefCross Ref
  21. Yang, X. and Vaidya, N. 2002. Priority scheduling in wireless ad hoc networks. In ACM International Symposium on Mobile Ad Hoc Networking and Computing (MobiHoc 2002). Lausanne. Google ScholarGoogle ScholarDigital LibraryDigital Library

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  1. Robust implicit EDF: A wireless MAC protocol for collaborative real-time systems

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                Alessandro Berni

                Medium access control (MAC) protocols play an important role in providing quality of service (QoS) and real-time support to distributed networks of embedded systems. Crenshaw et al. propose Robust Implicit Earliest Deadline First (RI-EDF), which is a robust real-time wireless MAC protocol that is implicitly capable of avoiding channel contention. RI-EDF builds on previous work by Caccamo et al. [1] to deliver better goodput and lower packet loss than existing 802.11 MAC protocols. This new MAC protocol is characterized by five key features: no need for clock synchronization; possibility for a node to reclaim bandwidth unused by the predecessor node; no single point of failure; real-time guarantee; and lightweight implementation suitable for application in resource-constrained embedded systems. The paper starts with an overview of related research, and continues with the detailed discussion of the protocol. First, the finite state machine of RI-EDF is provided and assumptions are given, then demonstrations are provided for key properties. Simulation has been used to evaluate RI-EDF against Institute of Electrical and Electronics Engineers (IEEE) 802.11 enhanced distributed coordination function (EDCF) and IEEE 802.11 point coordination function (PCF) protocols, in terms of goodput (ratio of the number of actual data bytes per second transmitted to the available bandwidth), packet loss (percentage of packets sent but not received over the total number of packets transmitted), and missed deadlines (packets received beyond the real-time constraint). Results show that RI-EDF is capable of delivering better performance in conditions of high network load. A power-aware version of RI-EDF is also discussed, based on the differentiation of nodes between sources and sinks; an implementation is presented on TinyOS MICA2 motes. A final discussion on dynamic schedule updates in RI-EDF highlights its fundamental trade off. Unlike IEEE 802.11 EDCF, the table-based scheduling upon which RI-EDF is based does not allow new nodes to instantly join the network. This constraint is functional to the higher-priority requirement of gaining a conflict-free environment for applications with mainly real-time, periodic traffic. Overall, the paper is an interesting development that goes in the direction of providing effective real-time operation of distributed systems and sensor networks. Online Computing Reviews Service

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