Séminaire INFRES TELECOM ParisTech
Organisateurs:Hugues Randriam &Dario Rossi
Speaker:Aruna Jayasuriya (ITR,Univ. South Australia,Adelaide)
Title:Supporting QoS for Realtime Applications in Wireless Infrastructure Networks
Abstract:In recent years,there has been a rapid growth in deployment and usage of realtime network applications,such as Voice-over-IP,video calls/video conferencing,live network seminars,and networked gaming. At the same time,wireless networking technologies have become increasingly popular with a wide array of devices such as laptop computers,Personal Digital Assistants (PDAs),and cellular phones being sold with built-in WiFi and WiMAX interfaces. For realtime applications to be popular over wireless networks,simple,robust and effective QoS mechanisms suited for a variety of heterogeneous wireless networks must be devised.
To provide guaranteed QoS,an access network should limit load using an admission control algorithm. In this research,we propose a method to provide effective admission control for variable bit rate realtime flows,based on the Central Limit Theorem. Our objective is to estimate the percentage of packets that will be delayed beyond a predefined delay threshold,based on the mean and variance of all the flows in the system. Any flow that will increase the percentage of delayed packets beyond an acceptable threshold can then be rejected. Using simulations we have shown that the proposed method provides a very effective control of the total system load,guaranteeing the QoS for a set of accepted flows with negligible reductions in the system throughput.
We also propose a method to determine the delay-dependent “value”of a packet based on the QoS requirements of the flow. Using this value in scheduling is shown to increase the number of packets sent before a predetermined deadline. We propose a measure of fairness in scheduling that is calculated according to how well each flow’s QoS requirements are met. We then introduce a novel scheduling paradigm,Delay Loss Controlled-Earliest Deadline First (DLC-EDF),which is shown to provide better QoS for all flows compared to other scheduling mechanisms studied.
We then study the performance of our admission control and scheduling methods working together,and propose a feedback mechanism that allows the admission control threshold to be tuned to maximise the efficient usage of available bandwidth in the network,while ensuring that the QoS requirements of all realtime flows are met.
Short Bio: Aruna Jayasuriya is a senior research fellow at the Institute for Telecommunications Research (ITR),University of South Australia. He received his Bachelor of Engineering (electrical and electronic) from University of Adelaide in 1997 and PhD in Telecommunication from University of South Australia in 2002. His current research interests include:QoS in wireless networks,analysis of multihop networks,vehicle-to-vehicle communication networks and opportunistic medium access control for distributed networks.
