Re: Incorrect signal levels reported using wpa_supplicant's driver_nl80211

[Dan Williams <dcbw redhat com>]

On Mon, 2009-11-02 at 23:53 +0000, Brian Morrison wrote:
> On Tue, 03 Nov 2009 01:07:22 +0200
> Maxim Levitsky <maximlevitsky gmail com> wrote:
> 
> > > This is *exactly* why 'qual' is there: so that the driver itself can
> > > figure out what the hell it's signal level is, and so that NM doesn't
> > > have to go around assuming stuff.  
> > It appears as kernel developers want to drop quality calculations
> > altogether, and report everything in dBms (right?) 
> 
> But quality does not necessarily track signal level. Consider the case
> where a second AP is on the same frequency but weaker than the AP that
> is associated with. The quality of the connection is the difference in
> signal levels (roughly the SNR) which is not the same as the signal
> level of the stronger AP.

You're only associated to one AP at a time on the same wlan device.
Thus whatever signal quality any other AP has doesn't matter.  The only
signal level or quality that matters is the one for the link through
which your packets go.  When the driver roams APs, the quality should
update to reflect the signal strength and quality of the new AP, no
matter what channel it's on.

Dan