Re: [Madwifi-devel] Selecting 5MHz channel width

[Mark G. <gol...@gm...>]

On 1/19/07, Mark Goldstein <gol...@gm...> wrote:
> >From: Pavel Roskin <proski@gn...> - 2006-12-21 18:36
> >On Fri, 2006-12-22 at 04:11 +0200, Nick Kossifidis wrote:
> >> As far as i know atheros cards don't go that low, what cards are you
> >> talking about ?
>
> > There are flags for 10 MHz and 5MHz channels in hal/ah.h, called
> > CHANNEL_HALF and CHANNEL_QUARTER respectively. When HAL returns the
> > channel list, it's supposed to set those flags.
>
> > I think the only way to select the channel width is to select the
> > channel with such width. However, I don't see any userspace interface
> > allowing to find out the channel width.
>
> I have similar question. We have Atheros-based cards for Public Safety
> band (4.9 GHz), where it is also possible to use half- and quater-rate
> channels.
> Atheros driver under Windows has these options and Client Utility
> allows selection of bandwidth.
>
> This card works OK with madwifi in 4.9 band, but only on full-rate (20
> MHz) channels.
> The card reports 4.9 band channels for all bandwidth.
> Now, 10 and 20 MHz channels have the same numbers, so if one selects
> this channel, it works as 20 MHz. There are channels that could only
> be 5 MHz (e.g. 15). But when I select this channel, the card seems not
> working.
> If I have 2 cards under windows, I can create ad-hoc connection e.g.
> on channel 15 with 5 MHz mode. But when one card works under Linux
> with madwifi (latest version), neither it could see the second card,
> nor the second one could see it.
>
> I guess, there should be some HAL API to set bandwidth.
>

To be more accurate, Atheros Client Utility allows selection of the
channel and bandwidth for STA when starting Ad-Hoc mode. It is also
the channel the STA will stay on if it did not find any other Ad-Hoc
device to connect to.
Otherwise channel and bandwidth selection makes sense for AP and
monitoring modes only.
Maybe some iwpriv options like setting of wireless mode?

-- 
Mark Goldstein