usb wifi ad-hoc mode suggestions?

usb wifi ad-hoc mode suggestions?

[Greg Johnson]

I'm working on a project where we need to use a USB wifi adapter in ad-hoc
mode.

We've been struggling with this.  Is there a 'standard' known solid way to
do this?  What products and/or chipsets and Linux drivers should we be
looking at?

We're trying the zd1211 with the zd1211rw driver and the mac80211 stack,
which doesn't seem to have ad-hoc support currently, but their web site says
it should be easy to add.

Any suggestions would be *greatly* appreciated!  We are a bit stuck on this.

Thanks in advance,

Greg Johnson


       
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Re: usb wifi ad-hoc mode suggestions?

[Pavel Roskin]

Hello!

Quoting Greg Johnson <gregfjohnson@yahoo.com>:

> I'm working on a project where we need to use a USB wifi adapter in ad-hoc
> mode.
>
> We've been struggling with this.  Is there a 'standard' known solid way to
> do this?  What products and/or chipsets and Linux drivers should we be
> looking at?

Two suggestions:

1) at76_usb, available in wireless-2.6/everything (Atmel USB).

2) linux-wlan-ng - separate project, may need updating for the latest  
kernels.  Supports Prism based USB devices.

Both Atmel and Prism devices are 802.11b only and may be hard to find,  
but they would definitely work.

> We're trying the zd1211 with the zd1211rw driver and the mac80211 stack,
> which doesn't seem to have ad-hoc support currently, but their web site says
> it should be easy to add.

That's another approach you can take.  At least you have the hardware,  
and it should be 802.11g capable.  All you need is to fix the code.

-- 
Regards,
Pavel Roskin

Re: usb wifi ad-hoc mode suggestions?

[Daniel Drake]

Greg Johnson wrote:
> We're trying the zd1211 with the zd1211rw driver and the mac80211 stack,
> which doesn't seem to have ad-hoc support currently, but their web site says
> it should be easy to add.

If you have coding resources on your hands, all that needs to be done is 
for someone to look at the ad-hoc handling code in the vendor driver and 
port it over the mac80211 driver. Diving into the vendor driver is a bit 
of a challenge though.

Daniel

Re: usb wifi ad-hoc mode suggestions?

[Michael Buesch]

On Saturday 06 October 2007 19:48:47 Daniel Drake wrote:
> Greg Johnson wrote:
> > We're trying the zd1211 with the zd1211rw driver and the mac80211 stack,
> > which doesn't seem to have ad-hoc support currently, but their web site says
> > it should be easy to add.
> 
> If you have coding resources on your hands, all that needs to be done is 
> for someone to look at the ad-hoc handling code in the vendor driver and 
> port it over the mac80211 driver. Diving into the vendor driver is a bit 
> of a challenge though.

btw: Does the device also support AP mode?

-- 
Greetings Michael.

Re: usb wifi ad-hoc mode suggestions?

[Greg Johnson]

--- Michael Buesch <mb@bu3sch.de> wrote:

> On Saturday 06 October 2007 19:48:47 Daniel Drake wrote:
> > Greg Johnson wrote:
> > > We're trying the zd1211 with the zd1211rw driver and the mac80211 stack,
> > > which doesn't seem to have ad-hoc support currently, but their web site
> says
> > > it should be easy to add.
> > 
> > If you have coding resources on your hands, all that needs to be done is 
> > for someone to look at the ad-hoc handling code in the vendor driver and 
> > port it over the mac80211 driver. Diving into the vendor driver is a bit 
> > of a challenge though.
> 
> btw: Does the device also support AP mode?

At this point we would be happy with any USB wifi chipset, any driver,
and either AP mode or ad-hoc mode.  Do I sound desperate?  ;-)

We would be OK with 802.11B for now, but would need to be able to get
a reasonably reliable supply of wifi chips.

The Linux processor we are running on is an XSCALE, rather than a vanilla
X86, which is another contraint.  (In retrospect, I think we should have
gone with a vanilla x86, because then we could have gone with ndiswrapper
or similar.)

We had tried the driver zd1211-driver-r83, and that seems to work OK on our
xscale box in client mode talking to an access point.  And, it would allow
itself to be configured in ad-hoc mode.  But, it dropped 90+% of ping
packets in ad-hoc mode, to say nothing of trying to transfer actual data.

I downloaded and built ZD1211LnxDrv_2_21_0_0.tar.gz, and that seems to work
OK on my x86 laptop, but it failed miserably on our xscale.  (We are running
the xscale in big-endian, and the driver seems to have lots of byte-ordering
assumptions wired into it.)  (I have only tested it in client mode on my
laptop; don't even know if it works in ad-hoc mode yet.)  If
ZD1211LnxDrv_2_21_0_0.tar.gz works ok in ad-hoc mode on an x86 laptop,
we could possibly try fixing the byte-ordering problems with ntohs() etc.
and get it working on the xscale processor.  Another somewhat daunting
possibility would be to try to build a little-endian xscale linux kernel,
play with redboot to get little-endian bootloader etc. ;-(

If we can port ad-mode into zd1211rc/mac80211, that would be ideal from
our standpoint.  But that seems like a really large and difficult and
time-consuming task.

At this point we are getting desperate and are sorta trying to explore
the whole space and see if we can come up with any solution at all.

Greg


> 
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> Greetings Michael.
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Re: usb wifi ad-hoc mode suggestions?

[Greg Johnson]

IZD1211LnxDrv_2_21_0_0.tar.gz seems to work pretty well in ad-hoc mode based
on a few brief tests.  Pings seemed solid and reliable, and I transfered a
300-meg file with no problems at all.

So, it might be possible to hack on that driver to solve byte ordering issues
on the xscale processor.

Greg



       
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