Campus Event Calendar
Event Entry
What and Who
Optimality of Video-on-Demand Broadcast
Prof. David G. Kirkpatrick
Ringvorlesung
AG 1, AG 2, AG 3, AG 4, AG 5, SWS
Public Audience
English
Note: We use this to send email in the morning.
Date, Time and Location
Thursday, 9 November 2006
13:00
60 Minutes
E1 3 - Hörsaal Gebäude
016
Saarbrücken
Abstract
The design of efficient protocols for broadcast delivery of
video content
has been an area of active research for more than a decade. The goal
typically is to minimize delay d, before playback can begin, as a
function of the communication bandwidth (and video length).
This talk addresses the intrinsic cost of such communication. In
particular, we describe a simple abstract protocol that minimizes
delay as a function of both server and receiver bandwidth. This is
achieved by partitioning the video into a fixed number of segments,
partitioning the server bandwidth into an equivalent number of equal
bandwidth subchannels, and broadcasting each segment repeatedly on its
own subchannel. (The protocol can be implemented as a concrete discrete
protocol in which movie information is packaged into discrete fixed
length packets using only a modest overhead, measured in terms of increased
delay or server bandwidth).
Our primary contribution is a lower bound on the required (worst-case)
delay
that applies in a very general model of communication. This lower bound
matches
the behaviour of our abstract protocol in the limit as the number of
segments
approaches infinity. We are also able to relate its behaviour to arbitrary
protocols that have a fixed number of segments.
We also consider the intrinsic average delay. While worst-case optimal
protocols are not necessarily average-case optimal, we show that the optimal
average delay is at most a (small) constant factor less than the optimal
worst-case delay, when server and receiver bandwidths are the same.
video content
has been an area of active research for more than a decade. The goal
typically is to minimize delay d, before playback can begin, as a
function of the communication bandwidth (and video length).
This talk addresses the intrinsic cost of such communication. In
particular, we describe a simple abstract protocol that minimizes
delay as a function of both server and receiver bandwidth. This is
achieved by partitioning the video into a fixed number of segments,
partitioning the server bandwidth into an equivalent number of equal
bandwidth subchannels, and broadcasting each segment repeatedly on its
own subchannel. (The protocol can be implemented as a concrete discrete
protocol in which movie information is packaged into discrete fixed
length packets using only a modest overhead, measured in terms of increased
delay or server bandwidth).
Our primary contribution is a lower bound on the required (worst-case)
delay
that applies in a very general model of communication. This lower bound
matches
the behaviour of our abstract protocol in the limit as the number of
segments
approaches infinity. We are also able to relate its behaviour to arbitrary
protocols that have a fixed number of segments.
We also consider the intrinsic average delay. While worst-case optimal
protocols are not necessarily average-case optimal, we show that the optimal
average delay is at most a (small) constant factor less than the optimal
worst-case delay, when server and receiver bandwidths are the same.
Contact
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Veronika Weinand, 11/07/2006 12:36
Veronika Weinand, 10/25/2006 15:08
Veronika Weinand, 10/24/2006 12:47
Veronika Weinand, 10/23/2006 15:06
Veronika Weinand, 10/19/2006 14:54
Veronika Weinand, 10/16/2006 17:07
Veronika Weinand, 10/16/2006 17:05 -- Created document.
Veronika Weinand, 10/25/2006 15:08
Veronika Weinand, 10/24/2006 12:47
Veronika Weinand, 10/23/2006 15:06
Veronika Weinand, 10/19/2006 14:54
Veronika Weinand, 10/16/2006 17:07
Veronika Weinand, 10/16/2006 17:05 -- Created document.