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From: Chen-Yu Tsai <wens@csie.org>
Date: Wed, 22 Jul 2015 15:56:52 +0800
Message-ID: <CAGb2v65aLaHarHym6XQN_uz5nNiU8SMCuhVZ+GJ3_FVmRqk4uQ@mail.gmail.com> (sfid-20150722_095719_416837_E007E3A4)
Subject: Re: [PATCH] wireless-regdb: Update regulatory rules for Taiwan (TW)
To: Seth Forshee <seth.forshee@canonical.com>
Cc: wireless-regdb <wireless-regdb@lists.infradead.org>,
	linux-wireless <linux-wireless@vger.kernel.org>,
	Chen-Yu Tsai <wens@csie.org>
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Sender: linux-wireless-owner@vger.kernel.org

On Wed, Jul 22, 2015 at 3:40 PM, Chen-Yu Tsai <wens@csie.org> wrote:
> On Thu, Jul 9, 2015 at 11:15 PM, Seth Forshee
> <seth.forshee@canonical.com> wrote:
>> On Wed, Jul 08, 2015 at 11:07:20AM +0800, Chen-Yu Tsai wrote:
>>> > Thanks. I think there should be a written document about what the
>>> > rules should be like, or what is expected:
>>> >
>>> >   1. WiFi channel boundaries or band boundaries
>>> >   2. peak output power or peak power spectral density
>>> >
>>> > In http://lists.infradead.org/pipermail/wireless-regdb/2015-July/000856.html
>>> > you mentioned the software is smart enough to work out how to combine
>>> > different bands and what channels to use, so I see no reason to explicitly
>>> > chop up contiguous spectrum, unless there are explicit rules forbidding
>>> > combined use of bands with different regulatory rules. AFAIK the FCC
>>> > only requires one to satisfy all rules when usage crosses band boundaries.
>>> >
>>> > http://lists.infradead.org/pipermail/wireless-regdb/2015-July/000857.html
>>> > also raises a similar question.
>>
>> I was really commenting about the transmit power updates in your patch.
>> I just compared the frequency changes to the documentation you linked to
>> and those do look okay to me.
>
> I see.
>
>>> >> I would however consider an update for 5.15-5.25 GHz and 5.6-5.65 GHz
>>> >> provided that there's official documentation to substantiate the change.
>>> >> I unfortunately cannot read Chinese, so I would need some assistance to
>>> >> confirm the documentation.
>>> >
>>> > I could possibly ask around, though I'm not optimistic. The "official"
>>> > documents are just transcripts from NCC hosted Q&A sessions regarding
>>> > the latest regulations. Proposals/questions are submitted by vendors,
>>> > and the NCC responds and puts together an aggregated transcript.
>>>
>>> Just got off the phone with the NCC. Their position is, spectrum allocation
>>> is not within their purview, but the Ministry of Transportation and
>>> Communications. As noted in the patch, they have already opened up the
>>> spectrum to U-NII and low power radio usage. What remains is that the
>>> NCC revise its testing standards. Until then, their position is that,
>>> since their testing standards are modeled after FCC standards, vendors
>>> can just test under FCC standards, then convert the reports into LP0002
>>> format, and cite the FCC test report.
>>>
>>> There is no formal English version of the Q&A transcript, at least not
>>> until some foreign testing body requests it. The person in charge just
>>> asked me to translate it myself...
>>
>> If you send a patch which updates only the frequencies I would likely
>> apply that after allowing a week or so for others to either ack or nack
>> it (and running the stuff you linked to through google translate and
>> seeing if I could make any sense of the output).
>
> Got it.
>
>> I think the power updates are probably based on a misunderstanding, and
>> may not even be completely correct. For the most part after they've been
>> converted to EIRP (eirp = 10 * log10(mW)) they don't turn out to be
>> substantially different than what we have now. I think the value in
>> 5250-5350 MHz is probably incorrect however. Based on my quick skim of
>> the document you linked to it should be 50 mW rather than 250. 50 mW
>> also roughly matches to the 17 dBm which is in the database today,
>> whereas 250 mW is closer to 24 dBm.
>
> Yes. About the first part, it seems dbparse.py converts values in mW
> into EIRP anyway. However I don't think EIRT equals "peak power spectral
> density".

Sorry, this part applies to the US rules, not part of this patch.

> About the second part, yes the current values match the ones in LP0002.
> However as I stated, the regulatory body has explicitly allowed certifying
> under the latest FCC rules, which effectively raises the limits from
> 50 mW to 250 mW.
>
>> My suggestion would be update the frequencies but not the existing
>> transmit power limits, unless you discover that any of the power limits
>> are definitely incorrect.
>
> I'll split up the patch into 3:
>
>   1. Add the new 5150 - 5250 frequency band, using current LP0002
>      limits if any, otherwise FCC limits.
>
>   2. Tweak frequency boundaries for the remaining bands to make
>      them contiguous and properly reflect the regulations rather
>      than the WiFi channel frequencies.
>
>   3. Update power limits and DFS requirements to latest FCC standards.
>
> Each patch will then explain why and how the regulations changed
> along with references, in English if available.
>
> You can then decide on whether to merge all three or just the first
> two.
>
>
> Regards
> ChenYu