[OpenWrt-Devel] [OpenWrt] 2.4Ghz limited to 50mW in DFS-ETSI

Atanas Vladimirov vlado at bsdbg.net
Wed Jul 29 12:21:37 EDT 2015 

https://dev.openwrt.org/ticket/20201

On BB I used 20dBm for both 2.4 and 5GHz on the same router.

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On 29 юли 2015 г. 18:40:10 Ben West <ben at gowasabi.net> wrote:

> This is what I observe running Barrier Breaker on UBNT M5 products, too.  I
> believe the 17dBm limit is intentional, i.e. per regulation.  The 30dBm tx
> power limit applies to channels 149 and above, I believe.
>
> >  Also (kind of off-topic): Do you know why 5Ghz channels 36-48 are forced
> >  to be 17dBm only on the WNDR3800? I found two possible explanations:
> >  either because of the factory calibration
>
>
> On Wed, Jul 29, 2015 at 10:25 AM, Gerald Matzka <mgerald21 at yahoo.de> wrote:
>
> > Well, it looks like the txpower of your wdnr3800 is limited to 17dBm
> > because of the hardware reg-domain settings.
> >
> > Kind regards,
> >
> > ... sent from my iPhone
> >
> > > Am 29.07.2015 um 10:43 schrieb Nicola von Thadden <nico at vthadden.de>:
> > >
> > > Hi,
> > >
> > > I have this strange behaviour down below, for which I also opened a
> > > ticket because I think this should not be like that ;)
> > >
> > > Does anyone have an idea where the problem could originate from and how
> > > to fix it?
> > >
> > > Thanks
> > > Nico
> > >
> > >> On 07/29/2015 12:37 AM, OpenWrt wrote:
> > >> #20222: 2.4Ghz limited to 50mW in DFS-ETSI
> > >> ----------------------+----------------------------------
> > >> Reporter:  nicoduck  |      Owner:  developers
> > >>     Type:  defect    |     Status:  new
> > >> Priority:  normal    |  Milestone:  Chaos Calmer (trunk)
> > >> Component:  kernel    |    Version:  Trunk
> > >> Keywords:  wndr3800  |
> > >> ----------------------+----------------------------------
> > >> I have got a Netgear WNDR 3800 running with openwrt since quite a while.
> > >> I now upgraded to the latest version (trunk) and wanted to use WLAN
> > within
> > >> the regulations here in Germany but also wanted to max out the output
> > >> power (within the regulations).
> > >> Switching the country to Germany limits the maximum output power to
> > 17dBm,
> > >> although it does show as being limited on 20dBm:
> > >> root at OpenWrt:/# iwinfo wlan0 txpower
> > >>    0 dBm (   1 mW)
> > >>    1 dBm (   1 mW)
> > >>    2 dBm (   1 mW)
> > >>    3 dBm (   1 mW)
> > >>    4 dBm (   2 mW)
> > >>    5 dBm (   3 mW)
> > >>    6 dBm (   3 mW)
> > >>    7 dBm (   5 mW)
> > >>    8 dBm (   6 mW)
> > >>    9 dBm (   7 mW)
> > >>   10 dBm (  10 mW)
> > >>   11 dBm (  12 mW)
> > >>   12 dBm (  15 mW)
> > >>   13 dBm (  19 mW)
> > >>   14 dBm (  25 mW)
> > >>   15 dBm (  31 mW)
> > >>   16 dBm (  39 mW)
> > >> * 17 dBm (  50 mW)
> > >>   18 dBm (  63 mW)
> > >>   19 dBm (  79 mW)
> > >>   20 dBm ( 100 mW)
> > >>
> > >> What I did: reset the device, flash it with various builts from trunk
> > and
> > >> try to figure out what was going on.
> > >> I now modified my regdb and was able to isolate the source of the
> > problem:
> > >> country DE: DFS-ETSI
> > >>         # entries 279004 and 280006
> > >>         (2400 - 2483.5 @ 40), (100 mW)
> > >>         # entry 303005
> > >>         (5150 - 5250 @ 80), (200 mW), NO-OUTDOOR, AUTO-BW
> > >>         # entries 304002 and 305002
> > >>         (5250 - 5350 @ 80), (100 mW), NO-OUTDOOR, DFS, AUTO-BW
> > >>         # entries 308002, 309001 and 310003
> > >>         (5470 - 5725 @ 160), (500 mW), DFS
> > >>         # 60 gHz band channels 1-4, ref: Etsi En 302 567
> > >>         (57000 - 66000 @ 2160), (40)
> > >> Thas does not work and has the mentioned behaviour, 2.4Ghz is limited at
> > >> 17dBm. It also does not depend on which values are set in the regulatory
> > >> database for the 2.4Ghz channels, anything over 17dBm will be limited to
> > >> 17dBm.
> > >> running "iw phy phy0 set txpower fixed 2000" gives no error but does not
> > >> change it to 20dBm. Changing the value to anything below 17dBm works
> > >> though.
> > >>
> > >> country DE: DFS-FCC
> > >>         # entries 279004 and 280006
> > >>         (2400 - 2483.5 @ 40), (100 mW)
> > >>         # entry 303005
> > >>         (5150 - 5250 @ 80), (200 mW), NO-OUTDOOR, AUTO-BW
> > >>         # entries 304002 and 305002
> > >>         (5250 - 5350 @ 80), (100 mW), NO-OUTDOOR, DFS, AUTO-BW
> > >>         # entries 308002, 309001 and 310003
> > >>         (5470 - 5725 @ 160), (500 mW), DFS
> > >>         # 60 gHz band channels 1-4, ref: Etsi En 302 567
> > >>         (57000 - 66000 @ 2160), (40)
> > >>
> > >> Thad does work. The only change to the entry above is "DFS-FCC" instead
> > of
> > >> "DFS-ETSI". I can now select any powerlevel between 1 and 20dBm and it
> > is
> > >> also reported as being used:
> > >> root at OpenWrt:/# iwinfo wlan0 txpower
> > >>    0 dBm (   1 mW)
> > >>    1 dBm (   1 mW)
> > >>    2 dBm (   1 mW)
> > >>    3 dBm (   1 mW)
> > >>    4 dBm (   2 mW)
> > >>    5 dBm (   3 mW)
> > >>    6 dBm (   3 mW)
> > >>    7 dBm (   5 mW)
> > >>    8 dBm (   6 mW)
> > >>    9 dBm (   7 mW)
> > >>   10 dBm (  10 mW)
> > >>   11 dBm (  12 mW)
> > >>   12 dBm (  15 mW)
> > >>   13 dBm (  19 mW)
> > >>   14 dBm (  25 mW)
> > >>   15 dBm (  31 mW)
> > >>   16 dBm (  39 mW)
> > >>   17 dBm (  50 mW)
> > >>   18 dBm (  63 mW)
> > >>   19 dBm (  79 mW)
> > >> * 20 dBm ( 100 mW)
> > >>
> > >>
> > >> I have no idea why but there seems to be a bug in the code parsing the
> > DFS
> > >> regulations, limiting 2.4Ghz to lot lower values than allowed. Changing
> > it
> > >> to DFS-FCC works for using the applicaple output power but does not seem
> > >> to be in compliance which German law.
> > >>
> > >> Do you have an idea where the problem could be? I'm happy to try out
> > more
> > >> builds and future versions.
> > >>
> > >> Also (kind of off-topic): Do you know why 5Ghz channels 36-48 are forced
> > >> to be 17dBm only on the WNDR3800? I found two possible explanations:
> > >> either because of the factory calibration (is it possible to get them
> > in a
> > >> human readable form somehow? The hexdump is not really readable and I
> > have
> > >> not been able to find the code which pases them) or because these
> > channels
> > >> are considered as "edge-channels" and someone thought it would be safe
> > to
> > >> limit the power, to not disturb any other systems running on even lower
> > >> channels. The latter explanation is kind of weird because it would make
> > no
> > >> sense to limit these 4 channels but no other ones. I find it especially
> > >> strange because that is typically the job of regulatory authorities, to
> > >> define those power levels.
> > >>
> > >> --
> > >> Ticket URL: <https://dev.openwrt.org/ticket/20222>
> > >> OpenWrt <http://openwrt.org>
> > >> Opensource Wireless Router Technology
> > > _______________________________________________
> > > openwrt-devel mailing list
> > > openwrt-devel at lists.openwrt.org
> > > https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
> > _______________________________________________
> > openwrt-devel mailing list
> > openwrt-devel at lists.openwrt.org
> > https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
> >
>
>
>
> --
> Ben West
> http://gowasabi.net
> ben at gowasabi.net
> 314-246-9434
>
>
>
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