Broadcast Scheduling for Set Requests
Vincenzo Liberatore
CWRU

Advances in wireless and optical communication, as well as in Internet
broadcast protocols, make broadcast methods an effective solution
to disseminate data.
In particular, repetitive server-initiated broadcast (broadcast disks)
is an effective technique in wireless systems and is a scalable solution
to relieve Internet hot spots.
A critical issue for the performance of broadcast disks is the schedule
of the broadcast.
Most previous work focused on a model where each data item is requested
by clients with a certain probability that is independent of past accesses.
In this paper, we consider the more complex scenario where a client accesses
pages in blocks (e.g. a HTML file and all its embedded images),
thereby introducing dependencies in the pattern of accesses to data.
We present simple heuristic that exploit page access dependencies.
We measured the resulting client-perceived delay on multiple Web server traces,
and observed a speed-up over previous methods ranging from 5% to 34%.
We conclude that scheduling for multi-item requests is a critical factor
for the performance of Web-based broadcast disks.