[OLPC-AU] limits on ad-hoc connections

[James Cameron]

On Thu, Feb 09, 2012 at 01:44:15PM -0600, Daniel Drake wrote:
> On Wed, Feb 8, 2012 at 10:59 PM, James Cameron <quozl at laptop.org> wrote:
> > No, that's not how ad-hoc works. ?I'll simplify and translate for you.
> 
> Your explanation is correct but doesn't exactly match the buggy
> behaviour of our wireless hardware/firmware. As far as I can tell, the
> ad-hoc nodes in our setup make no attempt to synchronize
> clocks/beacons, nor do they stop transmitting their own beacons in the
> presence of another node transmitting beacons too. I guess this is why
> our ad-hoc networks perform slower and less reliably than the XO-1
> mesh, which at least had synchronization.

The ad-hoc nodes also have the duty to transmit an occasional beacon,
not only for timing purposes of the other nodes, but to ensure that any
node that enters the area is aware of the network SSID and avoids
transmitting interference.  From my reading this is psuedo-random.  I
would expect to see many each second from every node, and many many more
each second from whatever node has the main responsibility.

-- 
James Cameron
http://quozl.linux.org.au/