[maemo-users] Power consumption and WLAN APs

From: Kalle Valo kalle.valo at nokia.com
Date: Wed Jul 23 22:57:43 EEST 2008
"ext Andrew Daviel" <advax at triumf.ca> writes:

> Excellent writeup, thanks :-)

You welcome.

> So, what devices apart from the Nokia tablets use PSM ?

Nokia phones (N95, N81 etc) use WLAN PSM. They might even have more
aggressive PSM tablets have.

> iPhone ? 

I once (like a year ago) played with an iPhone. What it did was that
it disassociated (ie. disconnected) from the AP few minutes after the
display was turned off. But I haven't looked at it since.

> Palm ? Windows Mobile devices like the UTstarcom PocketPC ?

No idea. I haven't had access to those kind of devices.

> I opened a ticket with Proxim; not sure if our contract includes
> support but maybe I'll get a reply.

I wish you luck.

> Is there anything for the tablets that can log wireless traffic in
> enough detail to show whether PSM is working ? airodump-ng ??
> How about on laptops ? Airmagnet drivers perhaps (which we don't have)

Good question. I should write something about this as well because
having proper airlogs would help a lot with these kind of problems. I
just don't have the time to do it right now :/

But basically you use can set the driver to monitor mode (iwconfig
wlan0 mode monitor), set the correct channel (iwconfig wlan0 channel
7) and use tcpdump to save the log to a file (tcpdump -i wlan -w
wlandump.cap). The cap file can be read with wireshark and you can see
all the WLAN frames trasmitted over the air.

Please note that not all drivers support monitor mode or they have
some quirks using it. Here's a link to page describing how to use
monitor mode with madwifi:


> I have an ancient Orinoco Gold card on a Dell Latitude, and a slightly
> less old Thinkpad with (I think) madwifi driver, and a new Lenovo on
> the way (Windows, though)

I have used madwifi to sniff WLAN frames quite a lot, but nowadays I
use iwl3945 because it's fully Open Source.

Kalle Valo

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