[wireless-regdb] Regulatory of 5.9 GHz band and OCB mode (was: [RFC 1/4] cfg80211: Add channel flags limiting availability to OCB mode only)

Luis R. Rodriguez mcgrof at suse.com
Fri Sep 5 14:52:03 PDT 2014

On Fri, Aug 01, 2014 at 04:00:34PM +0200, Michal Sojka wrote:
> Dear Luis and others,
> I work with Rostislav on the Linux support of ITS-G5. I did some
> research on the regulatory staff for 5.9 GHz band. See my findings below
> and sorry for long delay of my reply.

I'm a bit late on mine as well.

> On Tue, Jun 10 2014, Luis R. Rodriguez wrote:
> > On Mon, Jun 9, 2014 at 7:21 AM, Rostislav Lisovy <lisovy at gmail.com> wrote:
> >> Dear Luis;
> >> Thank you for the introduction in the wireless-regdb mailing-list.
> >>
> >> On Wed, 2014-06-04 at 00:18 +0200, Luis R. Rodriguez wrote:
> >>> Rostislav, can you provide documentation references which would
> >>> clarify
> >>> the stance on 802.11p and restrictions for only allowing  OCB mode?
> >>
> >> If I may cite the 802.11-2012 standard:
> >> -- 1st Quote
> >> 4.3.11 STA transmission of data frames outside the context of a BSS
> >>
> >> Communication of data frames when dot11OCBActivated is true might take
> >> place in a frequency band that is dedicated for its use, and such a band
> >> might require licensing depending on the regulatory domain. A STA for
> >> which dot11OCBActivated is true initially transmits and receives on a
> >> channel known in advance, either through regulatory designation or some
> >> other out-of-band communication.
> >> -- End of quote
> >
> > OK the spec does not rule out communication on that special band for
> > regular operation as such that special band is mentioned in the
> > context of OCB communication, but it does say that the frequency range
> > may be licensed. As it stands the public wireless-regdb only covers
> > unlicensed frequency ranges, but it obviously can support licensed
> > frequency ranges, just that the distribution mechanism and integration
> > of the wireless-regdb files then would have to be done separately
> > through separate distributors -- ie, not upstream. If the OCB bands
> > are unlicensed then we can surely add them to wireless-regdb, however
> > it remains unclear if those bands are unlicensed if we can use them
> > for regular non OCB communication.
> >
> > Follow this logic to move forward then:
> >
> >   * Poke folks to see if the US band for OCB is licensed or unlicensed
> >   * Poke folks to see if the EU band for OCB is licensed or unlicensed
> I only researched status in the EU. In summary, the band is unlicensed.
> The relevant document for Europe is 2008/671/EC (see below). This was
> confirmed to us by Czech Telecommunication Office which is responsible
> for the administration of radio frequencies in the Czech republic.
> The document can be found at
> http://www.erodocdb.dk/docs/doc98/official/pdf/2008671EC.pdf and its
> full name is "2008/671/EC, Commission Decision of 5 August 2008 on the
> harmonised use of radio spectrum in the 5 875-5 905 MHz frequency band
> for safety-related applications of Intelligent Transport Systems (ITS)".
>   Few quotes from the document:
>   Article 3 §1:
>         Member States shall, not later than six months after entry
>         into force of this Decision, designate the frequency band
>         5 875-5 905 MHz for Intelligent Transport Systems and, as
>         soon as reasonably practicable following such designation,
>         make that frequency band available on a non-exclusive
>         basis.
>         Such designation shall be in compliance with the
>         parameters set out in the Annex.
>   Annex:
>         Maximum spectral power density (mean e.i.r.p.): 23 dBm/MHz
>         Maximum total transmit power (mean e.i.r.p.):   33 dBm
>         Channel access and occupation rules:
>             Techniques to mitigate interference that provide at least
>             equivalent performance to the techniques described in
>             harmonised standards adopted under Directive 1999/5/EC
>             must be used. These require a transmitter power control
>             (TPC) range of at least 30 dB.
>   Intro (8):
>         Harmonised standard EN 302 571 [...], thus ensuring that
>         compliant ITS equipment avoids causing harmful interference.
>   The EN 302 571 standard describes in detail the technical parameters
>   mentioned above. See
>   http://www.etsi.org/deliver/etsi_en/302500_302599/302571/01.01.01_60/en_302571v010101p.pdf
>   This all means that the band in unlicensed and can be used by anybody
>   compliant with the annex parameters. This interpretation was explicitly
>   confirmed by Czech Telecommunication Office.
> I've also found the document ECC/DEC/(08)01 (see below) which predates
> 2008/671/EC, but since it also mentions 2008/671/EC it seems it is
> basically the same thing.
> ECC Decision of 14 March 2008 on the harmonised use of the 5875-5925
> MHz frequency band for Intelligent Transport Systems (ITS)
>   (ECC/DEC/(08)01) (2008/671/EC)
>   [http://www.erodocdb.dk/docs/doc98/official/Pdf/ECCDec0801.pdf]
>   The document, among others, says:
>   3. that CEPT administrations shall designate the frequency sub-band
>      5875-5905 MHz on a non-exclusive basis for ITS road safety
>      applications;
>   8. that CEPT administrations shall exempt in-vehicle ITS equipment
>      from individual licensing;

Awesome work

> >   * If the bands are *not licensed* there is one corner case that I
> > still think should be reviewed by regulatory folks: having an OCB
> > frequency range unlicensed under the current reading of the
> > specification of 802.11-2012 means that 802.11 devices *can* use them
> > for OCB, however if OCB is not enabled on the device it seems to be
> > that OCB bands can be used for non OCB communication. Furthermore
> > 4.3.11 seems to be saying that it is only optional to use a dedicated
> > frequency for OCB, OCB can happen on other frequency ranges.
> I see it similarly.
> The use of OCB is not a regulatory requirement. As it was mentioned by
> Rostislav, IEEE 802.11-2012 specifies in section "E.2.4 5.9 GHz band in
> Europe (5.855–5.925 GHz)":
>     STAs shall have dot11OCBActivated set to true.
> Section 4.3.11 then reads:
>     When dot11OCBActivated is true, a STA is not a member of a BSS and
>     it does not utilize the IEEE 802.11 authentication, association,
>     or data confidentiality services.
> Note that magic words like "shall" or "should" are not present in this
> text.
> I would interpret this as that OCB mode should be forced in the
> 5.855–5.925 GHz band (i.e. hard-coded in the Linux kernel) and that no
> other modes should be allowed there.

There I disagree, if its not a regulatory requirement forcing something
on Linux is prone to be hacked around, so to avoid issues also with
regulatory bodies what we do is enable R&D folks to use certain features
undera CONFIG_CFG80211_CERTIFICATION_ONUS so I think a reasonable compromise
is that by default Linux ships with what you say but we enable researchers
and developers to customie their kernels and use the OCB bands for other
purposes. That doesn't mean we need to support it -- it just means if
someone wants to hack on the code to do it we should give them the freedom
to do so. That means we can ignore OCB bands for non-OCB purposes for now
completely and just let whoever wants to do something different to use
CONFIG_CFG80211_CERTIFICATION_ONUS. I can also see conflicts with non
OCB devices on OCB bands so its importan for us to not fuck with that
loosely too.

> Section 10.20 uses proper words:
>     When a STA joins a BSS, it shall set dot11OCBActivated to false. The STA
>     shall keep dot11OCBActivated false while joined with the BSS or while
>     the STA is the AP within a BSS. If a STA does not include the
>     dot11OCBActivated MIB attribute, the STA shall operate as if the
>     attribute is false.
> The other question is whether OCB mode should be allowed in other
> frequency bands. As far as I know, nothing prevents it.

OK -- again CONFIG_CFG80211_CERTIFICATION_ONUS :) if someone decides
to tinker lets let them. But Linux by default should be have IEEE
compliant and regulatory compliant.

> >> -- 2nd Quote
> >> Annex E (normative) Country elements and operating classes
> >> E.2.3 5.9 GHz band in the United States (5.850–5.925 GHz)
> >> ...
> >> STAs shall have dot11OCBActivated set to true.
> >
> > So all STAs in the US wil have OCB activated? I fail to understand how
> > Annex E should be read in the context of operating classes.
> >
> >> E.2.4 5.9 GHz band in Europe (5.855–5.925 GHz)
> >> STAs shall have dot11OCBActivated set to true.
> >
> > Ditto.
> I understand that dot11OCBActivated can be changed at runtime. STAs
> operating in the mentioned band "shall have dot11OCBActivated set to
> true".

Cool, thanks for all your work on this. Folks -- hope this helps,
chug on.


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