On Fri, 2014-05-30 at 18:56 +0200, Rostislav Lisovy wrote:
> IEEE 802.11p operates in its own 5.9GHz band. When there will
> be a record for the 5.9GHz band in the regulatory daemon,
> it must be limited to the OCB mode only -- using the newly
> added flags.
Is this really a *regulatory* limitation? Rather than a limitation
elsewhere, e.g. the spec?
johannes
On Tue, Jun 03, 2014 at 10:01:33PM +0200, Johannes Berg wrote:
> On Fri, 2014-05-30 at 18:56 +0200, Rostislav Lisovy wrote:
> > IEEE 802.11p operates in its own 5.9GHz band. When there will
> > be a record for the 5.9GHz band in the regulatory daemon,
> > it must be limited to the OCB mode only -- using the newly
> > added flags.
>
> Is this really a *regulatory* limitation? Rather than a limitation
> elsewhere, e.g. the spec?
Our engaged and capable *real* regulatory folks in the community are:
* Liraz Perelmooter <[email protected]>
* Michael Green <[email protected]>
Additionally we have the wireless-regdb mailing list [0] which we should
Cc for inquiries and verification on things like this. We hope for their
participation as they are our real experts who grind away at the specs.
Rostislav, can you provide documentation references which would clarify
the stance on 802.11p and restrictions for only allowing OCB mode?
Also your patches seem to refer to the 802.11p ammendment work to 802.11,
but it is now merged as of IEEE 802.11-2012 as per Jouni's last update to us
on the standards work [1]. As per Jouni's slides 802.11p-2010 made it as an
ammendment into 802.11-2012 and this work is rerrred to as "Wireless Access
for the Vehicular Environent". It would be *useful* if you'd refer to the IEEE
802.11-2012 standard then and document as part of your patches the exact
sections and references that about Wireless Access for the Vehicular
Environment.
For reference to others this comes in as a full patch series by Rostislav
to add some form of "802.11p" support using OCB (Outside the Context of BSS)
mode. This mode of operation allows devices to send frames not connected
to a BSS. The patch in question above is for the regulatory flag that is
being proposed to be added, the full series of the other patches can be
seen on the mailing list archive [2]. Rostislav clarifies that when OCB
mode is used all the STAs communicate with each other without the need
for a coordinator. The 5.9 GHz band is being clarified to be used for 802.11p,
the patch series also is specifying that when 5.9 GHz is enabled only
OCB mode of operation is allowed on that band. No references are made to
the specific 802.11 ammendment / IEEE 802.11 sections or more importantly it is
not being made clear if the OCB mode is something that differs depending
on regulatory bodies at this point.
Since 802.11p was designed for cars in mind I suspect regulatory bodies
likely do want proper rules followed, but its unclear what countries
that follow either IEEE 802.11 or the ISO equivalent want OCB mode of
operation and if they also have the same restrictions of only allowing
5.9 GHz operation only for OCB. I can also imagine for example of regulatory
bodies that may want to allow 5.9 GHz for non OCB mode, specially if they
need the spectrum. One particular use case which provides a compromise
could be for example to have APs/P2P GOs look for OCB communication and
if its detected to disallow it. Not like I would recommend this given
that it would then introduce crazy regulatory compliance silliness
such as seen with DFS and that pushed crazy implementation and designs,
but -- its certainly possible.
So is this an IEEE compliance thing or regulatory thing? If its a generally
accepted IEEE compliance thing for 802.11-2012 then I don't see why we
don't just hard code this restriction on cfg80211 for the band. That
after all would be the much more saner thing to do than all the silly
mess of discrepencies betwen regulatory bodies. After all cfg80211 is for
802.11, and if we follow the specs and if its mentioned clearly there I
see no resason why not to hard code this. If folks want to override this
(I envision university environments doing research on this) the patch can
add a Kconfig option that depends on CONFIG_CFG80211_CERTIFICATION_ONUS
which will make the check permissive on 5.9 GHz instead of fully enforced.
[0] http://lists.infradead.org/mailman/listinfo/wireless-regdb
[1] http://wireless.kernel.org/en/developers/Summits/Barcelona-2012?action=AttachFile&do=view&target=ieee80211-barcelona-2012.pdf
[2] http://comments.gmane.org/gmane.linux.kernel.wireless.general/121022
Luis
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
-- 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.
E.2.4 5.9 GHz band in Europe (5.855–5.925 GHz)
STAs shall have dot11OCBActivated set to true.
-- end of quote
Regards;
Rostislav
On Mon, Jun 9, 2014 at 7:21 AM, Rostislav Lisovy <[email protected]> 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
* If the bands are licensed then the wireless-regdb changes that
would be needed imply that a wireless-regdb needs to be provided to
whatever customer by whomever is licensing that entity for usage of
that band, that is, we upstream can be removed from the equation of
the distribution. The upstream kernel however would require a flag for
frequency ranges for OCB frequency ranges. Although the regulatory
classes specify a few for the US and EU, this can likely change. I
forget if the regulatory class can be interpreted through IEs, if so
and if the specification is going to remain static I can envision the
ability to hard code the OCB frequency ranges upstream but you'd then
need to parse these things.
* 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.
> -- 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.
Luis