[ath9k-devel] hostAPd operating in 5Ghz channels

[Jouni Malinen <jouni.malinen@atheros.com>]

On Fri, 2009-04-03 at 01:20 -0700, Giorgio Mazzucchelli wrote:
> Allowed channel: mode=2 chan=36 freq=5180 MHz max_tx_power=17 dBm
> Allowed channel: mode=2 chan=40 freq=5200 MHz max_tx_power=17 dBm
> Allowed channel: mode=2 chan=44 freq=5220 MHz max_tx_power=17 dBm
> Allowed channel: mode=2 chan=48 freq=5240 MHz max_tx_power=17 dBm

> #These are the channels listed by 'iw list' in 5Ghz band:
>     Frequencies:
>             * 5180 MHz [36] (17.0 dBm)
>             * 5200 MHz [40] (17.0 dBm)
>             * 5220 MHz [44] (17.0 dBm)
>             * 5240 MHz [48] (17.0 dBm)
>             * 5260 MHz [52] (20.0 dBm) (passive scanning, no IBSS,
> radar detection)
...
>             * 5700 MHz [140] (20.0 dBm) (passive scanning, no IBSS,
> radar detection)

> #So, from channel 52 to 140 where did they gone?  
> #Why hostAPd can't see them?

We do not currently support radar detection in ath9k which is required
for these channels. Consequently, hostapd will not allow them to be
enabled. In addition, those passive scanning and no IBSS flags would
also prevent the channel from being used as an AP.

> #These are the frequencies that I should see and use:
> 
> country IT:
>   	(2402 - 2482 @ 40), (N/A, 20)
>  	(5170 - 5250 @ 40), (N/A, 20)
> 
>   	(5250 - 5330 @ 40), (N/A, 20), DFS
>  	(5490 - 5710 @ 40), (N/A, 27), DFS

That DFS there indicates the regulatory requirement for detecting radars
and being able to change channels if a radar is present on the selected
channel.

- Jouni