wlan interface (was: first play with new XO 1.5 machines)

Albert Cahalan acahalan at gmail.com
Fri Oct 30 01:23:56 EDT 2009

On Thu, Oct 29, 2009 at 12:17 PM, Daniel Drake <dsd at laptop.org> wrote:
> 2009/10/26 Albert Cahalan <acahalan at gmail.com>:

>>> The issue is that A and B are both hosting their own networks, they
>>> are both beacon masters, spewing beacons based off their own clocks.
>> How is this any different than the mesh situation?
> Exactly how the XO-1 mesh functions on this level is frustratingly
> unknown, but when I did a couple of simple observations once before,
> the clocks appear to synchronize with the neighbours.
>> Which clock? Do you mean one for the individual bits, or one
>> for packet-level time division?
> I mean the clock in the 802.11 MAC sublayer. This defines the basis of
> the timing synchronization function (TSF) which is a core part of
> 802.11. Without synchronized clocks, nodes cannot communicate.

I talked with one of the 802.11 experts I know. He's quite sure
that there should be no problem on Atheros hardware at least.
He has no problem transmitting arbitrary packets at arbitrary
times and no problem receiving packets either. The only limit
is that you get just one channel at a time.

I'll check with a couple of the other experts I know.

The TSF stuff  looks like an optimization that you don't really need,
except perhaps when sending to a receiver that stops listening
at certain times. Lame hardware misses out, no surprise.

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