[MLB-WIRELESS] [TECH] Dipole antennas, and melbwireless structure

[Kim Hawtin]

On Wed, Mar 20, 2002 at 09:34:06PM +1100, Ben Anderson wrote:
> > Ben Anderson wrote:
> > > > >Even more difficult is a 'moving node' -- a node in a car
> > > > >shifting between cells at 100Km/h, could change routing
> > > > >cells every 10 seconds... Being able to maintain a reliable
> > > > >bi-directional connection is going to be *tough*
> > > >
> > > > Yes, mobile applications are really problematic.  If we can
> > > > pull that one off, it'd be interesting. :)
> > >
> > > I think it's do-able, just not trivial :)  It should work,
> > > just with minor interruption - this isn't a major concern to
> > > me, the scalability issues are much more interesting...
> > If the discovery mechanism can cope with new nodes appearing
> > anyway, and works well, then hopefully this would just be a
> > matter of parameters - ie. shorter timeouts, more re-tries, etc
> > - for a mobile protocol.
> Yep, but there's scaling issues if we have to to a route-update
> across the network, for the whole network every second to keep
> track of nodes....

TCP/UDP/IP was not really meant to deal with this ... but,

even mobile type protocols that would deal with this are things like
MANET or MobileMesh ...

the problem with, say, MobileMesh is that you can set the refresh
interval down to, say, a second. then the routing updates will flush
the link up to the surrounding routers, then if its only up for ten
to fiften seconds, the a link down... the routing deamon will not
export the route further, because it could be considered to be
flapping... =/ 

the other problem is that if you've only got say fifteen seconds of
connection at any time in the 'zone', you may not actually get a wireless
connection. so you'll never see the fixed node anyway ...

now if you push up the output power and range of the fixed nodes
that offer connection, such that the time your in the 'zone' is
larger, then the time your 'online' with a particular fixed node,
then your much more likely to get a sesible connection ...

this is the main reason that mobile phones as we know them, work.
its a trade off between, a large enough area, not too much power so
that the base station can still 'hear' the mobile phones ....

yours,

kim
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