AP performance (again): txpower regulation

[Berislav Purgar]

2011/9/8 Lev Serebryakov <lev at freebsd.org>

> Hello, Adrian.
> You wrote 8 сентября 2011 г., 8:02:28:
>
> > These look fine, but I don't have as much experience with the ar5212
> > series stuff as I do with the AR5416+ series stuff.
> >>  It seems, registers are Ok. But clients don't see any difference!
> >> Maybe, it is because my Senao card is "powerful" one, with additional
> >> schematic (and power supply) to boost signal?
>
> > Hm. Well, how far away are they? You can do a bit of math to see what
>   About 7 meters and 2 concrete (internal) walls :)
>
>    I've repeated experiment when client and server were within 3 meters
>  without walls -- txpower seems to work. 30 gives about -55dB
> (accroding to InSSIDer -- I'm not sure, that this numbers could be
> used as absolute ones),txpower 15 gives about -65 and txpower 1 about
> -75.
>
>  But in any case iperf throughput is about 10-11Mbit/s with pikes up to
> 18Mbit/s.
>
>  It looks pessimistic: 18Mbit/s  in 2m direct sight. I know, that
>  54Mbit/s is half-duplex, but 18Mbit/s is less than 27Mbit/s and
>  "ifconfig wlan0 list sta" shows data like this:
>
>  00:18:de:08:e8:1d    1    9  36M 21.5    0  28696  48048 EPS  AQE     RSN
> WME
>
>  Why 36M in almost-ideal conditions!? Why -70dB in room next to my AP,
> when neighborhood AP (simple d-link, according to all data) is -65,
> and this room is furthest from other apartments)!?
>
>  Also, graph of signal strength is much smoother on small distances and
> didn't look like mountain range.
>
>  Another observation: when distance is about 5 meters txpower 30, 15 and
> 10 are almost indistinguishable (and grpahs are smooth, -75dB for 10,
> -70dB for 15, -67dB for 30), but txpower 1 gives crazy graph: it
> osscilate between -80 and -10 (!!!). Sometimes it gold on -77, but
> after 10-15 seconds raise to the sky, then drop down again, etc.
>
> > changes the TX power on the sender side would have on the receiver
> > signal level.
> > Have you ever looked at doing up a free space loss model to predict
> > what the signal level(s) should be?
>   It is too complex for me :-) And I'm not sure, that I have tool to
> measure real signal to compare with calculations.
>
> --
> // Black Lion AKA Lev Serebryakov <lev at freebsd.org>
>
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>

Hi
maybe you device  have interference with other devices in room. try to lower
.. turn off other devices if u have in room . what show ifconfig wlan0 scan
?? how much is noise level ??
i have AR5212 and it work great over 6m inside house (2 walls). transfer
rate i get is 2.4~3.2MB/s

Beri