On Tue, Sep 26, 2017 at 03:54:45PM -0400, Seth Forshee wrote: > On Thu, Aug 24, 2017 at 11:17:44AM -0500, Seth Forshee wrote: > > On Thu, Aug 24, 2017 at 09:13:42AM +0200, Sven Eckelmann wrote: > > > On Mittwoch, 23. August 2017 15:52:40 CEST Seth Forshee wrote: > > > [...] > > > > > +# Source > > > > > +# https://www.imda.gov.sg/~/media/imda/files/regulation%20licensing%20and%20consultations/ict%20standards/telecommunication%20standards/radio-comms/imdatssrd.pdf?la=en > > > > > +# page 12-14 > > > > > +# The EIRP for 5250 – 5350 can be increased by 3dB if TPC is implemented. > > > [...] > > > > > + # 5470 - 5725 is only allowed when TPC is implemented > > > > > + # (5470 - 5725 @ 160), (30), DFS > > > > > > > > I'm not sure that the lack of a specific provision for operating without > > > > TPC in this range means that it cannot be used. As I understand it, TPC > > > > would only result in a reduction in EIRP of 3 dB, so as long as we use > > > > a power limit of half of the maximum allowed we will be safe. > > > > > > > > If this is incorrect I'd appreciate it if someone more knowledgable on > > > > the topic could chime in. > > > > > > I would also be happy about feedback regarding this part. But my current > > > settings are based on the document [1] mentioned in this change. > > > > > > Let us look at the range 5250 – 5350 on page 13. There are two entries for the > > > same frequency range. > > > > > > * 28: > > > - up to 200 mW > > > - requires TPC for 5250 – 5350 Mhz > > > * 29: > > > - up to 100 mW > > > - requires *no* TPC for 5250 – 5350 Mhz > > > > > > This is exactly the 3(.01029995...) dB difference which you've talked about. > > > Now to the frequency range 5470 - 5725 MHz on page 14. > > > > > > * 30: > > > - up to 1000 mW > > > - requires TPC for 5470 - 5725 MHz > > > > > > There is no extra exception rule for non-TPC mode. > > > > > > Now let us check what IEEE 802.11h-2003 [2] says about TPC. > > > > <snip detailed analysis> > > > > > My current change now assumes following strict interpretation: > > > > > > * Singapore provides a mitigation factor of 3 dB for 5250 – 5350 Mhz (see > > > table entry 28 + 29) > > > * Singapore provides now mitigation factor for 5470 - 5725 MHz and requires > > > TPC > > > > > > I am currently unsure whether it is now valid to say that the default > > > mitigation factor would be 3 dB and thus there is an implicit table entry (let > > > us call it 30b) which would be: > > > > > > * 30b: > > > - up to 500 mW > > > - requires *no* TPC for 5470 - 5725 MHz > > > > > > Countries like AU or regions like ETSI (ETSI EN 301 893) seem to have this > > > mitigation factor always specified in their rules. But Singapore is missing it > > > for this specific frequency range. > > > > So on the one hand I'm in agreement, it would be good to know where the > > 3 dB attenuation comes from and whether it's really universal. So far > > it's been something I've taken on faith from folks a lot more familiar > > with the subject than me. > > > > However, it seems the same lack of information would also anyone who > > does want to support TPC. The information about how much to attenuate > > must either be provided on a per-regulatory-domain basis or else it must > > be standardized somehow. If it's the former then it seems odd that > > Singapore does not include this information. > > > > Hopefully someone more knowledgable will chime in to help us understand > > better. > > I was going through old messages in my inbox and realized that we've > never done anything about this. Unless someone speaks up soon I guess > I'll play it safe apply the patch as is, with the range commented out. Applied, thanks!
