5GHz 802.11n USB Adapter

5GHz 802.11n USB Adapter

[Jason Andryuk]

I am looking for a linux-supported dual band 802.11n USB Adapter that
can operate at both 2.4GHz and 5GHz.

According to wireless.kernel.org, it seems like the possibilities are:
carl9170/ar9170, rt2800usb and maybe ath9k_htc.

Atheros involvement with linux development is appealing, so I would
prefer an adapter based on their chips.  I also have the feeling their
drivers are more mature than the Ralink ones.

The carl9170 wiki page mentions "It's worth mentioning that the chip
was designed, produced and sold in the early 802.11n-draft period.
Compatibility will always be an issue."  So a product based on the
finalized 802.11n standard is more desirable.

For ath9k_htc, ar7010 devices with the ar9280 radio should support
dual bands.  However, the wiki does not list any devices with that
chip aside from the generic Atheros VID/PID.  Are dual band ar7010 USB
devices commercially available in the US?

Are there any limitations for rt2800usb devices?  The wiki is short on
information as is rt2x00.serialmonkey.com.  Does rt2800usb support AP
mode like rt2800pci?

Are their any other drivers/devices I have overlooked and should consider?

Recommendations of specific devices are appreciated.

Thanks,

Jason

Re: 5GHz 802.11n USB Adapter

[Helmut Schaa]

Am Samstag, 8. Januar 2011 schrieb Jason Andryuk:
> Are there any limitations for rt2800usb devices?  The wiki is short on
> information as is rt2x00.serialmonkey.com.  Does rt2800usb support AP
> mode like rt2800pci?

rt2800usb does not support bc- and mc- buffering (rt2800pci does). Hence,
powersaving stations might experience problems when using rt2800usb in AP
mode.

Helmut

Re: 5GHz 802.11n USB Adapter

[Kalle Valo]

Helmut Schaa <helmut.schaa@googlemail.com> writes:

> Am Samstag, 8. Januar 2011 schrieb Jason Andryuk:
>> Are there any limitations for rt2800usb devices?  The wiki is short on
>> information as is rt2x00.serialmonkey.com.  Does rt2800usb support AP
>> mode like rt2800pci?
>
> rt2800usb does not support bc- and mc- buffering (rt2800pci does). Hence,
> powersaving stations might experience problems when using rt2800usb in AP
> mode.

If some hardware models don't support broadcast/multicast buffering in
that case the driver shouldn't allow AP mode, at least not in mainline
kernels. We shouldn't break the standarnd knowingly.

>From a quick grep it looks like rt2800usb enables AP mode. Is that the
case or did I misunderstood something?

-- 
Kalle Valo

Re: 5GHz 802.11n USB Adapter

[Helmut Schaa]

Am Montag, 10. Januar 2011 schrieb Kalle Valo:
> Helmut Schaa <helmut.schaa@googlemail.com> writes:
> 
> > Am Samstag, 8. Januar 2011 schrieb Jason Andryuk:
> >> Are there any limitations for rt2800usb devices?  The wiki is short on
> >> information as is rt2x00.serialmonkey.com.  Does rt2800usb support AP
> >> mode like rt2800pci?
> >
> > rt2800usb does not support bc- and mc- buffering (rt2800pci does). Hence,
> > powersaving stations might experience problems when using rt2800usb in AP
> > mode.
> 
> If some hardware models don't support broadcast/multicast buffering in
> that case the driver shouldn't allow AP mode, at least not in mainline
> kernels. We shouldn't break the standarnd knowingly.
> 
> From a quick grep it looks like rt2800usb enables AP mode. Is that the
> case or did I misunderstood something?

You're right, rt2800usb enables AP mode despite the lack of proper
mc- and bc buffering.

Helmut

Re: 5GHz 802.11n USB Adapter

[Kalle Valo]

Helmut Schaa <helmut.schaa@googlemail.com> writes:

>> If some hardware models don't support broadcast/multicast buffering in
>> that case the driver shouldn't allow AP mode, at least not in mainline
>> kernels. We shouldn't break the standarnd knowingly.
>> 
>> From a quick grep it looks like rt2800usb enables AP mode. Is that the
>> case or did I misunderstood something?
>
> You're right, rt2800usb enables AP mode despite the lack of proper
> mc- and bc buffering.

Ok, thanks. I'll try to come up with a patch which disables AP mode
for rt2800usb.

-- 
Kalle Valo

Re: 5GHz 802.11n USB Adapter

[Helmut Schaa]

Am Dienstag, 11. Januar 2011 schrieb Kalle Valo:
> Helmut Schaa <helmut.schaa@googlemail.com> writes:
> 
> >> If some hardware models don't support broadcast/multicast buffering in
> >> that case the driver shouldn't allow AP mode, at least not in mainline
> >> kernels. We shouldn't break the standarnd knowingly.
> >> 
> >> From a quick grep it looks like rt2800usb enables AP mode. Is that the
> >> case or did I misunderstood something?
> >
> > You're right, rt2800usb enables AP mode despite the lack of proper
> > mc- and bc buffering.
> 
> Ok, thanks. I'll try to come up with a patch which disables AP mode
> for rt2800usb.

Fine with me but AFAIK there are quite some users out there that use rt2800usb
in AP mode. In the end Ivo or Gertjan should have a chance to comment ;)

And furthermore Johannes Stezenbach is interested in getting rt2800usb
to do the mc- and bc buffering correctly. Not sure if he already had a chance
to investigate more.

Helmut

Re: 5GHz 802.11n USB Adapter

[Kalle Valo]

Helmut Schaa <helmut.schaa@googlemail.com> writes:

> Am Dienstag, 11. Januar 2011 schrieb Kalle Valo:
>> Helmut Schaa <helmut.schaa@googlemail.com> writes:
>> 
>> Ok, thanks. I'll try to come up with a patch which disables AP mode
>> for rt2800usb.
>
> Fine with me but AFAIK there are quite some users out there that use
> rt2800usb in AP mode.

Yeah, but they are using a broken implementation and will have random
problems because of missing broadcast and multicast packets, for
example ARP is a likely problem area. We discussed about this last
year, I think.

> In the end Ivo or Gertjan should have a chance to comment ;)

Naturally :)

> And furthermore Johannes Stezenbach is interested in getting rt2800usb
> to do the mc- and bc buffering correctly. Not sure if he already had a chance
> to investigate more.

That would be the best option, but in the mean time we should disable
AP mode.

During the years I have suffered so much from broken power save
implementations in different access points. I really do not want us to
do the same mistake.

-- 
Kalle Valo

Re: 5GHz 802.11n USB Adapter

[Johannes Stezenbach]

On Tue, Jan 11, 2011 at 05:45:41PM +0200, Kalle Valo wrote:
> Helmut Schaa <helmut.schaa@googlemail.com> writes:
> 
> > And furthermore Johannes Stezenbach is interested in getting rt2800usb
> > to do the mc- and bc buffering correctly. Not sure if he already had a chance
> > to investigate more.
> 
> That would be the best option, but in the mean time we should disable
> AP mode.
> 
> During the years I have suffered so much from broken power save
> implementations in different access points. I really do not want us to
> do the same mistake.

That's fine by me.  At this time it is not clear if and when we
will have working support for mc- and bc buffering in rt2800usb.
I have one idea to try but no idea yet how well it will work.

Johannes

Re: 5GHz 802.11n USB Adapter

[Ivo Van Doorn]

Hi,

>> Fine with me but AFAIK there are quite some users out there that use
>> rt2800usb in AP mode.
>
> Yeah, but they are using a broken implementation and will have random
> problems because of missing broadcast and multicast packets, for
> example ARP is a likely problem area. We discussed about this last
> year, I think.
>
>> In the end Ivo or Gertjan should have a chance to comment ;)
>
> Naturally :)
>
>> And furthermore Johannes Stezenbach is interested in getting rt2800usb
>> to do the mc- and bc buffering correctly. Not sure if he already had a chance
>> to investigate more.
>
> That would be the best option, but in the mean time we should disable
> AP mode.

Ok, but please don't restrict only to rt2800usb then. Basically _all_ rt2x00 USB
drivers are not functioning. Also I assume it means that also Mesh
mode, Secondary,
and Ad-hoc should also be disabled?

Ivo

Re: 5GHz 802.11n USB Adapter

[Kalle Valo]

Ivo Van Doorn <ivdoorn@gmail.com> writes:

>> That would be the best option, but in the mean time we should disable
>> AP mode.
>
> Ok, but please don't restrict only to rt2800usb then. Basically
> _all_ rt2x00 USB drivers are not functioning. Also I assume it means
> that also Mesh mode, Secondary, and Ad-hoc should also be disabled?

AFAIK Mesh and Ad-Hoc don't use power save mode so not not being able
to buffer bc/mc shouldn't be a problem.

-- 
Kalle Valo

Re: 5GHz 802.11n USB Adapter

[Jason Andryuk]

On Sat, Jan 8, 2011 at 2:21 PM, Jason Andryuk <jandryuk@gmail.com> wrote:
> I am looking for a linux-supported dual band 802.11n USB Adapter that
> can operate at both 2.4GHz and 5GHz.

I was hoping for a little more feedback on the status of different drivers.

In the meantime, I found http://www.wikidevi.com/ which has lots of
info on the chipsets used with various wireless adapters.
Specifically http://www.wikidevi.com/wiki/Special:BrowseData which
allow one to search by way of various parameters.

Hopefully others find the above site helpful.

Jason