On Wednesday 08 August 2007 22:49:17 you wrote:
> Richard Jonsson wrote:
> > On Monday 06 August 2007 03:21:11 you wrote:
> >> Richard Jonsson wrote:
> >>> Isn't Desired TX power supposed to adapt so that higher bitrates are
> >>> possible, with Bit Rate going lower if that is not enough to keep a
> >>> good connection?
> >>
> >> Richard,
> >>
> >> Please grab a new copy of the port_to_mac80211 patch, and try the patch
> >> below. It boosts the desired power by up to 5 dBm as signal - noise
> >> decreases from 20 to 0.
> >>
> >> Larry
> >
> > Hard to say if there is a difference. I've noticed that signal quality
> > changes between reboots. When I first tried this patch I couldn't get
> > above 36M even at the AP, so I loaded the version without the patch. Same
> > thing. So I rebooted and then all rates worked, even 11M. Even for the
> > driver version that didn't work a few days ago.
> That is scary! That may mean that something is not being reset. The real
> question is whether warm reboots are intrinsically different than cold
> (power-off) reboots.

I've power cycled between reboots, unsure if I would get the same results on a 
soft reset.
> > New/updated observations:
> > Rate scaling seems to work, but if it gets down to 1M it will not rise
> > again unless I force it to a higher bitrate and run iperf for a few
> > seconds before setting it to auto. This is even when signal is -5dBm and
> > noise is -80dBm. I get a feeling it's a bit to sensitive as it will drop
> > quickly at a few meters away. At this distance forced 54M still works
> > well.
> > Maybe this is due to small dips (0.5sec) in traffic flow?!
> I'm surprised that you get signal values as high as -5 dBm. My maximum is
> about -35. I'm usually in the -40 range, even at 2 m from the AP.
That -5dBm signal is best case when AP's antenna is a few cm from the 
computers lid. In this position it often reads between -15 - -20dBm. If I 
move just a cm further away it drops to -30dBm which gradually decreases with 

> > With the patch applied power is reported as 27dB in debugfs. With
> > debug_xmitpower dmesg reports desired power to be 16.5 and actual 16.25.
> > This is max when I manually set power through debugfs. After a while it's
> > down to 10dB, even though only 1M works where I sit.
> >
> > Range seems to be higher for B-rates. Maybe this is just how things are,
> > I lack experience.
> The CCCK (B) encoding is much different than OFDM (G) transmissions. I
> would not be surprised to learn that its range were longer.
> The power setting that comes from mac80211 is 27 dBm, which is completely
> bogus for what is supposed to be the FCC table. The regulatory limit is 20
> dBm EIRP (a fancy acronym that means take the antenna into account). I've
> sent a fix for comment, but as is the usual case for mac80211, it will take
> several days or weeks to get a response. The maximum power that a bcm43xx
> device can use is encoded in the sprom. For most of them that quantity is
> 18.5 dBm, corresponding to the regulatory limit of 20 minus a safety factor
> of 1.5. I think that is there to prevent setting the power too high and
> flunking the certification tests. The output that goes to the radio is thus
> 18.5 less the gain of the antenna, which is also in the sprom with a usual
> value of 2 dBm. That is why you see the code setting a Desired power of
> 16.5 dBm.

I see! I expected it to go to 18dBm.
> Initially, I thought that the performance of my BCM4311 fell off as the
> power increased; however, that no longer happens. As a result, we can push
> full power at all times and there seems to be no need to use the kind of
> algorithm that you were testing. Don't tell the FCC, but we could relax

IMHO there should eventually be some power scaling, as I understand wlan takes 
a fair amount of power. Ideally there should be different modes (powersave, 
performance) preferrably as an API common to all networking, at least 
wireless. Getting offtopic, just a thought.

> that upper power limit as we will never try to get the device certified,
> but then we would use extra power, and run the risk of burning out the
> radio. If you decide to do that, please tell me the power setting at which
> it fried!

Heh, I might have tried if it was a usb stick ;) Since it's usable and since I 
got 54M/36M rate under no/high load in winxp under the same circumstances I 
believe power output is sufficient.
> With the patches that were pushed into wireless-dev a few minutes ago, I
> suggest that you try bcm43xx-mac80211. It is getting at least as good, if
> not better, performance than the BCM4301 or the softmac port to mac80211
> drivers do. We would also appreciate as much testing as possible as it will
> help getting it merged into mainstream. That driver will require V4
> firmware.
> Thanks for your report,
> Larry

Sure, I'll do that. Where do I get a current source? By git?
(I forgot to add the mailinglist in the original mail, sorry)
Bcm43xx-dev mailing list

Reply via email to