Re: [ath9k-devel] Radar Detection and DFS status

Re: [ath9k-devel] Radar Detection and DFS status

[Luis R. Rodriguez]

2009/2/11 mementux <mementux@gmail.com>:
> Hi!
>
> I would like to make an outdoor radio link at 5GHz between my house and one
> of my neighbors. Because I live near an airport, I've looked for European in
> force regulation regarding radar detection. I've discovered that ETSI has
> released a new normative on Dicember 2008 (EN 301 893 v1.5). This normative
> requires that WLAN devices with DFS capability must detect pulse width down
> to 0.8us across the bands from 5250 to 5350MHz and from 5470 to 5725 MHz;
> moreover they must detect staggered Pulse Repetition Frequency (PRF) radars
> with 3 PRF value (I don't excactly know what it means).
>
> I have two devices with Atheros 5414 radio module, so I've looked for
> support of radar detection (and 802.11h) in madwifi driver. I've seen that
> the -dfs branch supports the EN 301 893 v1.4.1 and it implements 802.11h
> protocol. Looking into the madwifi-dfs code I've seen that the hardware does
> the pulse detection and the driver detects the radar recognizing the pulse
> patterns (ath/if_ath_radar.c and ath/if_ath_radar.h).
>
> Because the pulse detection is done in hardware, I suppose that for
> detecting pulse width down to 0.8us I need radio modules with newer chipset
> like AR9xxx. Is it right? Can't I use my AR5414 radio modules?
> So, I've searched in the code of ath9k and mac80211 but I don't find any
> implementation of radar detection and 802.11h. Am I wrong? I've read on
> http://wireless.kernel.org/en/users/Drivers/ath9k that 802.11h is a feature
> of ath9k driver (and consecutively of mac80211, right?).
>
> I there any way to make an outdoor radio link at 5GHz compliant to the
> European regulation with Linux? :-)

mac80211 or ath9k does not yet have radar detection support so
therefore no mac80211 driver will allow you to use any beaconing mode
(AP | IBSS | Mesh) mode on DFS channels yet.

Note that not all 5 GHz channels require radar detection though so you
could try using one of the non-DFS channels. Check 'iw list' for that.

ath9k STA should work with DFS but I didn't work on that myself so
will leave someone else to comment on that.

  Luis

Re: [ath9k-devel] Radar Detection and DFS status

[Sujith]

Luis R. Rodriguez wrote:
> mac80211 or ath9k does not yet have radar detection support so
> therefore no mac80211 driver will allow you to use any beaconing mode
> (AP | IBSS | Mesh) mode on DFS channels yet.
> 
> Note that not all 5 GHz channels require radar detection though so you
> could try using one of the non-DFS channels. Check 'iw list' for that.
> 
> ath9k STA should work with DFS but I didn't work on that myself so
> will leave someone else to comment on that.

Yep, STA mode should work fine, since 802.11h CSA support was added to
mac80211 recently.

Sujith
-- 
http://sujith-m.blogspot.com

Re: [ath9k-devel] Radar Detection and DFS status

[Alberto Pollastro]

On Wed, Feb 11, 2009 at 10:41 PM, Luis R. Rodriguez <mcgrof@gmail.com> wrote:
>
> mac80211 or ath9k does not yet have radar detection support so
> therefore no mac80211 driver will allow you to use any beaconing mode
> (AP | IBSS | Mesh) mode on DFS channels yet.
>
> Note that not all 5 GHz channels require radar detection though so you
> could try using one of the non-DFS channels. Check 'iw list' for that.

I've checked in regdb (2009.01.30) an it reports that I can use these
frequencies (in Italy):

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

I'm not sure, but in Italy the range 5170 - 5250 can be used only
indoor. Are indoor/outdoor channels treated differently by mac80211
and/or ath9k?

Regarding 802.11h, is its development for beaconing modes scheduled?

Thanks,
Albert.

Re: [ath9k-devel] Radar Detection and DFS status

[Luis R. Rodriguez]

On Thu, Feb 12, 2009 at 4:56 AM, Alberto Pollastro
<a.pollastro@gmail.com> wrote:
> On Wed, Feb 11, 2009 at 10:41 PM, Luis R. Rodriguez <mcgrof@gmail.com> wrote:
>>
>> mac80211 or ath9k does not yet have radar detection support so
>> therefore no mac80211 driver will allow you to use any beaconing mode
>> (AP | IBSS | Mesh) mode on DFS channels yet.
>>
>> Note that not all 5 GHz channels require radar detection though so you
>> could try using one of the non-DFS channels. Check 'iw list' for that.
>
> I've checked in regdb (2009.01.30) an it reports that I can use these
> frequencies (in Italy):
>
> 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
>
> I'm not sure, but in Italy the range 5170 - 5250 can be used only
> indoor. Are indoor/outdoor channels treated differently by mac80211
> and/or ath9k?

Yes, we have indoor and outdoor channel flags. You can supply a patch
or provide a reference to the regulatory information you are reading
to determine this and we can patch it up.

> Regarding 802.11h, is its development for beaconing modes scheduled?

I believe this will be worked on but we have no exact schedule.

  Luis

Re: [ath9k-devel] Radar Detection and DFS status

[Alberto Pollastro]

On Thu, Feb 12, 2009 at 4:53 PM, Luis R. Rodriguez <mcgrof@gmail.com> wrote:
> Yes, we have indoor and outdoor channel flags. You can supply a patch
> or provide a reference to the regulatory information you are reading
> to determine this and we can patch it up.

I've read the European Directive 2007/90/EC:

http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2007:041:0010:01:EN:HTML

I think that the EC directive has been acknowledged by the Italian
legislation as reported in the following table at page 28 (it's in
Italian, sorry):

http://www.comunicazioni.it/binary/min_comunicazioni/piano_nazionale_ripartizione_frequenze/03%20tabella_B.pdf

I hope I'm not wrong.

Thanks,
Albert.

Re: [ath9k-devel] Radar Detection and DFS status

[Luis R. Rodriguez]

On Thu, Feb 12, 2009 at 12:39:51PM -0800, Alberto Pollastro wrote:
> On Thu, Feb 12, 2009 at 4:53 PM, Luis R. Rodriguez <mcgrof@gmail.com> wrote:
> > Yes, we have indoor and outdoor channel flags. You can supply a patch
> > or provide a reference to the regulatory information you are reading
> > to determine this and we can patch it up.
> 
> I've read the European Directive 2007/90/EC:
> 
> http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2007:041:0010:01:EN:HTML
> 
> I think that the EC directive has been acknowledged by the Italian
> legislation as reported in the following table at page 28 (it's in
> Italian, sorry):
> 
> http://www.comunicazioni.it/binary/min_comunicazioni/piano_nazionale_ripartizione_frequenze/03%20tabella_B.pdf
> 
> I hope I'm not wrong.

Thanks the details, Michael, what do you think?

  Luis