The National Grid node will be participating in an Access Grid broadcast of the following seminar organized by Nanyang Technological university (NTU).

"Wifi Service Differentiation"

Assistant Professor Ilenia Tinnirello
University of Palermo

7 July 2006 (Friday)
1000 hours @ The Big One
National Grid Office, I2R Building
21 Heng Mui Keng Terrace
Singapore 119613

Abstract

The problem of quality of service support in wireless LAN is a theme of current interest. Several solutions have been currently debated in
literature in order to protect time-sensitive traffic from best-effort one, through simulations and analytical studies.

According to the EDCA proposal, which is a completely distributed solution, the service differentiation is provided by giving probabilistically a higher number of channel access grants to stations involved in real-time applications. To this purpose, the MAC parameter settings (CWmin/AIFS) of each contending station can be tuned opportunely.

In this talk, we face the problem of the EDCA MAC parameter tuning in the common scenario in which a given number of low-rate delay-sensitive traffic flows share the channel with some stations, with different priority, involved in data transfer.

Our contribution is threefold: a simulation study about MAC parameter effects, an analytical study about the network optimizations, and an experimental study about the support of QoS in actual scenarios. First, we show the different effects of contention window and inter frame times tunings, by enlightening that each solution has different side effects in terms of bandwidth availability for the best effort stations and we propose a very simple solution to make automatic the optimal CWmin/AIFS joint settings. Second, we show the inaccuracy of some common EDCA models and propose a new approach for the EDCA analysis. Third, through a custom-mad network interface, equipped with a programmable MAC including the EDCA extensions, we show that commercial 802.11 cards show a large performance spread due to not standard implementations and discuss the consequences for the support of QoS.

Speaker

Ilenia Tinnirello has been Assistant Professor at the University of Palermo since January 2005. She received the Laurea degree in Electronic Engineering and the Ph.D. on Communications, respectively in April 2000 and February 2004, under the supervision of Prof. Giuseppe Bianchi. She spent 2004 as Visitor Researcher at the Seoul National University, Korea, where she collaborated with Professor Sunghyun Choi. Her research activity has been mainly focused on wireless networks and in particular on Multiple access algorithms with quality of service provisioning; cross-layer interactions between access solutions and physical layer; mobility management and load balancing in wireless packet networks.

Ilenia Tinnirello has been involved in various national and international research projects: project PRIN RAMON (2001-2002); project
FIRB PRIMO (2002-2004); european project ITEA-MAGELLAN (2004-2006); projet PRIN MIMOSA (2006-2007). She also served as Technical Program Commettee memberand as referee for several international IEEE/ACM journals and conferences.

Admission is Free. All are Welcome