Abstract:
IEEE 802.11 has emerged as the dominant standard in the wireless LAN market.
The next challenge facing this technology is how to provide different grades
of service over the same wireless channel shared by all hosts. To this end,
we consider capture, a well known concept stipulating that even in the
event of a collision, a frame can be correctly decoded if the received
power is sufficiently higher than that of the interference. Conceptually,
it is therefore possible to achieve service differentiation by simply allowing
hosts to transmit at different power levels, a capability that is increasingly
being accomodated by the vendors in their products. We develop a Markov model
for the IEEE 802.11 DCF in a network with dual transmission power over a
Rayleigh-fading channel, and use it to evaluate the resulting performance,
in terms of the key metrics of throughput and delay. In particular, we
explore how the performance of the service classes depends on the proportion
of stations in each class and the transmission power ratio. Results show that,
counter-intuitively, this dependence is non-monotonic.
Biography:
Mahbub Hassan is Associate Professor in the School of Computer Science and
Engineering, University of New South Wales, Sydney, Australia, and a seconded
Principal Researcher at National ICT Australia. He authored/edited three
books on network protocol and quality of service related topics. He is the
co-author/editor (with Raj Jain) of the recently published Prentice Hall book
"High Performance TCP/IP Networking". He serves in the editorial board of
Computer Communications journal and previously served as Associate Editor for
IEEE Communications Magazine.