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

[John Gilmore]

> > 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.
> is that you get just one channel at a time.
> ...
> 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.

It's for power saving.  When 802.11 is used with an access point, the
access point can be asked to buffer up frames for battery powered
stations, and send an indication in its periodic beacons.  The station
wakes up for each beacon and can sleep the rest of the time.  In
addition, 802.11e provides more power-save modes (APSD).  See this
paper:

  http://www.redpinesignals.com/VoWiFi-Implementation-with-Single-Stream-802-11n.pdf

I don't think that XO-1 WiFi chips ever did any power saving.  Don't
know about XO-1.5.

	John