Subject: RE: [Fwd: Re: [manet] Power Saving in 802.11]

From: "David Holmer" <[email-masked]>
Date: Fri, 14 Nov 2003 10:34:45 -0500

The several available power levels you are talking about for the Cisco
cards (that are discussed in the paper) are the different TRANSMIT power
levels. The power levels being discussed in the Intersil document are
different levels of SLEEP. While most wireless drivers I've looked at
can control transmit power levels, probably even on a per packet basis,
I have yet to find a driver that seems to be aware of the multiple sleep
levels. The only sleep related settings that seem to be wide spread are
related to configuring the built in PSM power saving modes. This is the
case in the Atheros drivers as well (transmit power settable, but no
sleep power settings beyond PSM).

- David Holmer

-----Original Message-----
From: Miguel Sanchez [mailto:[email-masked]] 
Sent: Thursday, November 13, 2003 9:44 AM
To: [email-masked]
Cc: [email-masked]; 'Peter Pham'
Subject: Re: [Fwd: Re: [manet] Power Saving in 802.11]

Hi,

You may want to look for tech specs of Aironet Cisco 340 and 350 series
adapters.
I think 340 allow 4 power levels and 350 six different power levels,
software selectable. I haven't researched how long does a power change
to become effective though.

I think this paper
[http://black1.csl.uiuc.edu/~prkumar/ps_files/compow.pdf] uses these
cards to adapt transmission power level.  They did a real implementation
using Linux. I guess the paper will give you some of the details my
answer is lacking.

Best regards,

Miguel Sánchez
Polytechnic University of Valencia, Spain

dholmer wrote:

>...
>
>Now for your other question on how feasible is it to control the power
>saving state of an actual NIC card. I haven't had that much experience
>with attempting that yet. The real question is if that functionality is
>available at the driver level, or if it is only a firmware controlled
>feature. A quick search through the Linux open source orinoco driver
>(which actually supports many types of cards) yielded no promising
leads
>for manual power control. However many options for enabling the default
>802.11 PSM and tweaking its parameters were available. In a pinch, it
>may be possible to switch the card in and out of PSM with very long
>beacon intervals, but some in depth experimentation would be necessary
>to test this out.
>
>David Holmer
>
>PS I had trouble locating a link to the Intersil application note. If
it
>has been removed, people can email me directly for a copy.

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