[Cu-wireless] 802.11 & multihop networks

[Sascha Meinrath]

On Wed, 16 Apr 2003, Zachary C. Miller wrote:

> Sascha Meinrath wrote:
> > Is it possible to modify the RTS/CTS protocol so that (as in your example
> > below) when node B gets a RTS from A it says to other nodes "talk amongst
> > yourselves" and they don't communicate with B for the requisite time (but
> > can still commmunicate with each other)?  Or is the problem more
> > complicated, for example, if B doesn't have any ability to filter out the
> > noise from C when it's talking with D?
>
> It is more complicated for the reason you said.

<SNIP>

> I'm guessing changing this would mean hacking the firmware on all the
> radios in the network. Not really something that is going to happen
> outside the domain of theory...so I'd think we'd just have to live
> with it and keep our pods small as we already knew we had to. (Or we
> could change to a heirarchical design with directional antennas... :)

i know dave has done some experimentation with setting transmit power
levels -- finding some way to optimize this (or better yet, automate it)
would help alleviate (though certainly not eliminate) the problem.  do any
of the papers have some sort of algorithm that would let us predict
at about what density we are going to start seeing major deprecation of
the network?  i mean, is this going to be an issue with 10 nodes? 50?
1000?  and how much can we make up by switching to faster transmitting
radios (e.g., replacing our 11Mbs with 54 Mbs transceivers).

this is certainly an issue that we need to keep in mind; but the main
bottleneck right now in building the network is needing funding for
components and volunteers to help install new nodes.  is anyone interested
in installing nodes this sunday?  we have all the equipment and several
sites that could all be added to the network if we had the person-power.

--sascha