Real Time Communications over 802.11: RT-WMP

Ad-hoc networks usually support best-effort traffic and occasionally some kind of quality of service (QoS). However, there are some applications, which generally involve cooperative control, with hard real-time traffic requirements where strict deadlines must be met. To meet deadlines, the communication network has to support the timely delivery of inter-task messages. This is the case, for example, of applications involving cooperative robot teams, such as those used for rescue tasks in hostile environments, emergencies or disaster recovery, where a wired backbone is in-feasible or economically unviable. In this paper, we present RT-WMP, a novel protocol that allows wireless real-time traffic in relatively small mobile ad-hoc networks using the low-cost commercial 802.11 technology. The protocol is based on a token-passing approach and message exchange is priority based. Moreover, support for frequent topology changes is provided through the sharing of a matrix that describes link quality amongst the members of the network.

[1]  A. S. Krishnakumar,et al.  Quality-of-service in ad hoc carrier sense multiple access wireless networks , 1999, IEEE J. Sel. Areas Commun..

[2]  A. S. Krishnakumar,et al.  Real-time traffic over the IEEE 802.11 medium access control layer , 1996, Bell Labs Technical Journal.

[3]  Jamal N. Al-Karaki,et al.  Quality of service support in IEEE 802.11 wireless ad hoc networks , 2004, Ad Hoc Networks.

[4]  Wei Zhao,et al.  Hard real-time communication in multiple-access networks , 1995, Real-Time Systems.

[5]  C. Siva Ram Murthy,et al.  Providing MAC QoS for multimedia traffic in 802.11e based multi-hop ad hoc wireless networks , 2007, Comput. Networks.

[6]  Tzi-cker Chiueh,et al.  Real-time performance guarantees over wired/wireless LANs , 1998, Proceedings. Fourth IEEE Real-Time Technology and Applications Symposium (Cat. No.98TB100245).

[7]  Lorenzo Donatiello,et al.  Ad hoc networks: a protocol for supporting QoS applications , 2003, Proceedings International Parallel and Distributed Processing Symposium.

[8]  Stavros Tripakis,et al.  A wireless token ring protocol for ad-hoc networks , 2002, Proceedings, IEEE Aerospace Conference.

[9]  Edsger W. Dijkstra,et al.  A note on two problems in connexion with graphs , 1959, Numerische Mathematik.

[10]  David Starobinski,et al.  RTS/CTS-induced congestion in ad hoc wireless LANs , 2003, 2003 IEEE Wireless Communications and Networking, 2003. WCNC 2003..

[11]  Jangeun Jun,et al.  Theoretical maximum throughput of IEEE 802.11 and its applications , 2003, Second IEEE International Symposium on Network Computing and Applications, 2003. NCA 2003..

[12]  Mario Aldea Rivas,et al.  Michael González Harbour: MaRTE OS: An Ada Kernel for Real-Time Embedded Applications , 2001, Ada-Europe.

[13]  S. Liew,et al.  Throughput Analysis of IEEE 802 . 11 Multi-hop Ad hoc Networks , 2007 .

[14]  Giorgio C. Buttazzo,et al.  Dynamic Resource Reservation and Connectivity Tracking to Support Real-Time Communication among Mobile Units , 2005, EURASIP J. Wirel. Commun. Netw..

[15]  Yu-Chee Tseng,et al.  A Priority MAC Protocol to Support Real-Time Traffic in Ad Hoc Networks , 2004, Wirel. Networks.

[16]  Michael González Harbour,et al.  RT-EP: A Fixed-Priority Real Time Communication Protocol over Standard Ethernet , 2005, Ada-Europe.

[17]  Soung Chang Liew,et al.  Throughput analysis of IEEE802.11 multi-hop ad hoc networks , 2007, TNET.

[18]  Linda Bushnell,et al.  Real-time mixed-traffic wireless networks , 2001, IEEE Trans. Ind. Electron..