Fall 2001

*Note the special date and time*

Tuesday 11:40  Goldwater 510

(Supported in part by the Systems Science and Engineering Research Center)

Seminar Schedule: <http://math.la.asu.edu/~tom/cognition/math+cogsched.html>

Our next meeting of the Mathematics and Cognition seminar will take place on
Tuesday, September 11, at 11:40 PM in GWC 510.  There will be pizza and soft drinks.
Our speaker will be Professor Dr. Martin Reisslein of the Department of Electrical
Engineering, who will speak on the topic:

"Modeling of a Prefetching Protocol for Continuous  Media Streaming"

Abstract.
Streaming of continuous media over wireless links is a notoriously
difficult problem.  This is due to the stringent Quality of Service
requirements of continuous media and the unreliability of wireless
links.  We have developed a streaming protocol for the real-time
delivery of prerecorded continuous media from (to) a central base
station to (from) multiple mobile clients within a wireless cell.  Our
protocol prefetches parts of the ongoing continuous media streams
into prefetch buffers in the clients (base station).  Our protocol
prefetches according to a Join--the--Shortest--Queue policy.  By
exploiting rate adaptation techniques of wireless data packet
protocols, the Join--the--Shortest--Queue policy dynamically
allocates more transmission capacity to streams with small
prefetched reserves.  Our protocol uses channel probing to handle
the location--dependent, time--varying, and bursty errors of
wireless links.  We have evaluated our prefetching protocol through
extensive simulations with VBR MPEG and H.263 encoded video traces.
Our simulations indicate that for bursty VBR video with an average
rate of 64 kbit/sec and typical wireless communication conditions
our prefetching protocol achieves client starvation probabilities on
the order of 0.0001 and a bandwidth efficiency of 90% with prefetch
buffers of 128 kBytes. We are now seeking to develop a stochastic
model of the prefetch protocol. The goal of the modeling is to gain an
understanding of the fundamental performance trade-offs in the protocol
and to develop admission control rules.