Re: [zd1211-devs] configuring the rate

[Remco <re...@d-...>]

> Using the zd1211rw git tree with the patch to make it build on 2.6.20.
> I copied 267MB of data with various rate settings. All of the copies
> took about the same about of time. What is this setting doing? The
> nodes are both 802.11g, 5ft apart, 99% quality, 100% strength. The
> correct nodes are paired, I checked the mac address.
>
> jonsmirl@jonsmirl:~/foo$ sudo iwconfig eth1 rate 36M
> real    3m29.654s
> user    0m0.032s
> sys     0m2.712s

> jonsmirl@jonsmirl:~/foo$ sudo iwconfig eth1 rate 48M
> real    3m29.183s
> user    0m0.036s
> sys     0m2.636s

> jonsmirl@jonsmirl:~/foo$ sudo iwconfig eth1 rate 54M
> real    3m28.768s
> user    0m0.032s
> sys     0m2.488s

> jonsmirl@jonsmirl:~/foo$ sudo iwconfig eth1 rate 18M
> real    3m31.614s
> user    0m0.016s
> sys     0m2.868s

AFAICT, for wireless 802.11G, the real life possible maximum rate is likely to 
be roughly ~24Mb.
Rates > real life maximum rate give similar performance since they all max out 
at that real life maximum rate (whatever that may be in your case). When 
lowering the stick's rate to rates < real life maximum rate, it's expected 
that the rate you experience is approximately the same as the rate you 
configured.
(You should see more significant differences when lowering the rate even more)

Your real life max. rate seems to be ~ (267MB*8) / (3*60 + 30) = 10.1 Mb.
If I'm not mistaken you'll only see significant differences when lowering the 
rate below 10Mb.


BTW when I was using linux-2.6.18-rc4 / wpa_supplicant 0.4.8 a couple of 
months ago I got a performance of ~ 1.3MB/s => ~10.4 Mb. This was 
approximately half the performance of the vendor driver.