Low WiFi rates (Hardy 64Bit, Intel Pro Wireless 3945)

[Marius Gedminas]

On Sat, Apr 26, 2008 at 11:11:51AM +0200, Phil Bieber wrote:
> Since I switched to Hardy, I had quite low WiFi rates, but it didn't
> bother me as I was able to surf and load with ~70 - 100 Kbit/s. But
> now it dropped down to 700KBit/s, so it cant be the surrounding setup.
> In the Ubuntu Forums I saw someone fixing this by issuing "iwconfig
> wlan0 rate 54M", but that didn't help me.

Not for an Intel 3945ABG, no.

Try 'iwpriv eth1 set_mode 4' instead, it might help if the slowdown is
caused by this bug: https://bugs.launchpad.net/ipw3945/+bug/103210

On the other hand if you're not using the ipw3945 driver (Hardy prefers
iwl3945 instead), this may not help and you may need to look for a
different cure.

> According to WICD (WiFi
> Manager alternative to the network manager), the signal strength is
> good, and that is confirmed by Windows. Also the problem stays when
> manually connecting via System->Administration->Network. With gutsy
> everything was OK and I could surf fast as well!

Strangely enough, I used to get the slowdown in Gutsy, but not, so far,
in Hardy.  Hey, hardy uses a different wifi driver (iwl3945 instead of
ipw3945), maybe that's why.

Anyway, as far as I understand, the problem is caused when the signal
quality drops temporarily -- the ipw3945 driver reduces speed, and then
forgets to increase it again when the signal quality rises.

> The card is an Intel Pro Wireless 3945ABG inside a DELL Inspiron 640m.

I've the same card in my Lenovo T61, although I run the 32-bit version
of Ubuntu.  (Back when I installed it I hadn't realized Intel Core 2 Duo
CPU supports the instruction set known as "AMD64".)

Marius Gedminas
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