32nd IEEE Conference on Local Computer Networks (LCN 2007)
Real-Time Communication in IEEE 802.11 Networks: Timing Analysis and a Ring Management Scheme for the VTP-CSMA Architecture
Dublin, Ireland
October 15-October 18
ISBN: 0-7695-3000-1
Keeping up with the timing constraints of real-time traffic in wireless environments is a hard task. One of the reasons is that the real-time stations have to share the same communication medium with stations that are out of the sphere-ofcontrol of the real-time architecture. That is, with stations that generate timing unconstrained traffic. The VTP-CSMA architecture targets this problem in IEEE 802.11 wireless networks. It is based on a Virtual Token Passing procedure (VTP) that circulates a virtual token among real-time stations, enabling the coexistence of real-time and non realtime stations in a shared communication environment. The worst-case timing analysis of the VTP-CSMA mechanism shows that the token rotation time is upper-bounded, even when the communication medium is shared with timing unconstrained stations. Additionally, the simulation analysis shows that the token rotation mechanism behaves adequately, even in the presence of error-prone communication channels. Therefore, the VTP-CSMA architecture enables the support of real-time communication in shared communication environments, without the need to control the timing behavior of every communicating device. A ring management procedure for the VTP-CSMA architecture is also proposed, allowing real-time stations to adequately join/leave the virtual ring. This ring management procedure is mandatory for dynamic operating scenarios, such as those found in VoIP applications.
Citation:
Ricardo Moraes, Paulo Portugal, Stefano Vitturi, Francisco Vasques, Pedro F. Souto, "Real-Time Communication in IEEE 802.11 Networks: Timing Analysis and a Ring Management Scheme for the VTP-CSMA Architecture," lcn, pp.107-116, 32nd IEEE Conference on Local Computer Networks (LCN 2007), 2007