compex WLM200NX (ath9k) dual band issue

Christian Lamparter chunkeey at googlemail.com
Tue Nov 20 19:21:46 EST 2012


Hello Walter,

On Wednesday, November 21, 2012 12:22:20 AM Walter Robert Ditzler wrote:
> sorry form y weak description. i saw some examples running a hostapd setup
> with one card simultaniously on both freq (2.4 and 5).
Ah, can you tell me where you saw this example? 

> in my case i just doesnt work. from your comment bellow, is it true that
> this is not possible? if it is possible can you help me with a hint how
> to proceed?
No, unfortunately it's not possible with any "run-off-the-mill" hardware
I known. In your case, the chip on the WLM200NX seems to be a AR9220,
which is part of the AR9280 series. the public specs can be found at:
<http://www.atheros.com/technology/technology.php?nav1=47&product=85>

Of course the textblob there isn't particular helpful (in fact it's
confusing), but there's a "key" sentence in there:

"Single-chip, 802.11n compliant wireless LAN client solution with
integrated MAC, baseband and dual 2.4/5 GHz radios"

What this means is: The solution has dual 2.4/5GHz radios, it only 
has one media access controller (MAC) to drive either one of them.
[The MAC deals with CSMA/CA, hw de-/encryption, bits of aggregation, ... 
so you can't live without one]. And because there's only one MAC,
the other radio is simply switched off and can't be used.  [Is this
useful? Or do you need more technical details?]

Note: dual-band routers usually have two independent wifi chips!
So, if you have an empty minipci-slot you could add another AR9220
(or go for a cheaper 2.4GHz-only AR9223). This way you can make your
own "simultaneous dual-band" platform.
If this is not an option, then you could add an additional ath9k_htc
<http://linuxwireless.org/en/users/Drivers/ath9k_htc> usb adapter
to your system and run the 5GHz AP from the WLM200NX. [your call]

Regards,
	Chr


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