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From: b.K.il.h.u+tigbuh@gmail.com
Date: Fri, 26 Jan 2024 12:36:58 +0100
Message-ID: <CAPuHQ=F5QXXaELZLApK7WiveXSDoUeH-YEHM4RrZy6qLkibS8Q@mail.gmail.com>
Subject: Re: WiF Transmit Power Control (TPC) Regulatory Requirements?
To: Petko Bordjukov <bordjukov@gmail.com>
Cc: wireless-regdb <wireless-regdb@lists.infradead.org>, 
	linux-wireless <linux-wireless@vger.kernel.org>, thomas.huehn@hs-nordhausen.de
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Yes, I've read their research when it was published and I view it as
influential results. Their approach jointly optimizes transmit rate
and power for each and every frame (i.e., for each link and each
direction every time).

However, we are talking about much lower hanging fruit if all you want
is an attic mounted access point that tries not to interfere too much
with the neighbors while still dealing with blind spots within the
house. I still think that the periodic global adjustment method also
used by Cisco should be legal and very easy to implement on OpenWrt.

On Fri, Jan 26, 2024 at 11:46=E2=80=AFAM Petko Bordjukov <bordjukov@gmail.c=
om> wrote:
>
> Hi,
>
> The only project I've heard of that implements such functionality is
> https://github.com/thuehn/Minstrel-Blues.
>
> On Thu, Jan 4, 2024 at 12:02=E2=80=AFPM <b.K.il.h.u+tigbuh@gmail.com> wro=
te:
> >
> > Ideally, TPC should be a fully automatic mechanism that reduces
> > transmit power between the two points to as low of a level as possible
> > while delivering the same quality of service. The purpose is to reduce
> > the excess headroom in each link. I.e., if you could still link with
> > 65Mb/s towards a given direction using 14dBmW, you should not transmit
> > with 20dBmW.
> >
> > Some only set the AP TX power globally (i.e., same towards all of its
> > connected clients at the moment) to tackle the hidden/exposed node
> > problem, but again must do this adaptively and change this constantly
> > without human intervention. There exist multiple advanced algorithms
> > for this, some proprietary tuned for corporate deployment.
> >
> > Actually, if we accepted automatically retuning tx power with iw based
> > on actual link stats of momentarily connected clients every 60s with
> > cron, this could be added to OpenWrt pretty easily.
> >
> > > Class A devices control their transmit power within =C2=B13 dB and cl=
ass B devices control their power within =C2=B19 dB.
> >
> > - https://www.litepoint.com/blog/wi-fi-6-ofdma/
> > - https://www.cisco.com/c/en/us/td/docs/wireless/controller/technotes/8=
-3/b_RRM_White_Paper/tpc.html
> >
> > > On Thu, 2024-01-04 at 10:07 +0100, b.K.il.h.u+tigbuh@gmail.com wrote:
> > > > You can find a wording in most such regulations that if TPC is not
> > > > supported, the maximal TX power must be reduced by 3 dBmW. Hence in
> > > > all such cases, the entries in db.txt contain 3 less than the maxim=
um.
> > > >
> > > > If, on the other hand, you know of a country that specifies that
> > > > devices lacking TPC may not use the band at all, all such band entr=
ies
> > > > must be omitted (commented out along with a URL).