[Sugar-devel] GSoC Proposal: Multimedia Broadcasting

[Geza Kovacs]

On Fri, 2009-04-03 at 13:52 +0200, Martin Langhoff wrote:
> On Fri, Apr 3, 2009 at 1:45 PM, Geza Kovacs <gkovacs at mit.edu> wrote:
> > the local Icecast streaming server over HTTP. Surely you must agree that
> > that is possible?
> 
> And very *quickly* saturate the available bandwidth :-/
> 
> Our deployment scenarios have lots of laptops. Groups of 20, 30 or
> even 50 kids per classroom. Deployments will have maybe 1 AP per 50
> XOs. And you cannot assume that it's your app the only thing happening
> in the network.
> 

True, network saturation would become an issue if all those 50 laptops
were tuned into a stream. However, if such is the case, in very large
classrooms where this would be an issue, the teacher need not broadcast
the viewing invite to every student in the classroom; rather, say, a
student in each pair or group of 3-5 or so would receive the invite,
place their laptop in the center, and the others in the group would be
able to view that screen using their eyeballs. By doing so, even in a
large class only roughly 10 laptops will be viewing a stream at once,
which, given that this is will likely be VGA-resolution video, shouldn't
be too much of a burden on the wifi network. This is somewhat similar to
the approach taken by TEAL (introductory physics teaching) at MIT; there
are multiple screens at the sides of the rooms, but they are placed such
that there is a single screen that several students to view, rather than
a single screen for each student.

> RF saturation is a _very_ real problem. We had some horror stories
> with early 802.11s issues, part implementation, part our own errors in
> not considering the network as something that we could saturate or
> break.
> 
> So - breaking news: dense wifi networks have (by definition almost)
> horrid bandwidth, and are trivial to saturate to the point that they
> become useless.
> 
> Wireless is a shared medium -- not a switched one. Think about that :-/
> 
> cheers,
> 
> 
> 
> m