[maemo-users] Steve's Ranty Review #1: N800 ogg support

From: Kalle Valo Kalle.Valo at nokia.com
Date: Sat Oct 20 10:24:25 EEST 2007
"ext Frederic Crozat" <fred at crozat.net> writes:

> Just curious : is the n800 really supposed to last "days" when connected
> via Wifi (with full WLAN Power Save mode enabled), without any
> disconnect timeout and anything doing network access on the wifi link ?

Short answer: Yes, even with the default WLAN PSM settings.

Long answer: It depends on your network. Here are few items which
mostly affect WLAN power consumption:

o N800 transmitting something periodically (once in a minute is not
  bad, once in a second is really bad, Google talk has 30s interval
  which is ok).
o Buggy AP which does not support WLAN PSM properly.
o distance to AP (WLAN background scan will kick in if the signal level is
  -75 dBm or less)
o Lots of broadcast and multicast packets on the network (like
  Windows samba broadcasts).

Also WLAN settings (beacon and DTIM interval) affect power
consumption, but not before the issues I have listed above are ruled
out. And this was only about issues related to WLAN, if there are
other processes waking up the CPU that will naturally affect the
standby time.

For the background scan there are going to be some optimisations in
OS2008, for example the limit will be lowered to -85 dBm.

> When I check battery applet (which is really great btw), I'm never sure
> if the "in use" time is applicable when being idle AND wifi connected.

The applet does not provide WLAN standby time at all, sorry.

> I know I disable network auto-connect and set disconnect timeout to 5min
> because I had bad experience with first IT2007 version (before full WLAN
> Power Save mode gconf key were given here). Maybe I should try it
> again..

I think you should, you might be pleasently surprised. If not, I would
guess that after a bit of investigation you might find what's causing
the high power consumption. tcpdump is your friend. And if you have
any questions, post them here.

Kalle Valo

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