Re: [PATCH][RFC] nl80211/mac80211: Rounded RSSI reporting

[Johannes Berg <johannes@sipsolutions.net>]

On Fri, 2016-10-21 at 09:20 -0500, Denis Kenzior wrote:

> > It's actually not clear to me that this is really how it should be.
> > There's a point to be made that taking a more holistic "link
> > quality" would be a better choice. That's related, but maybe can be
> > a separate discussion.

> Can you elaborate on this 'link quality' idea?

Well, I didn't really want to - getting 3 system folks into a room will
result in 4 different ways of doing it - but you can take into account
not just the RSSI, but also the bitrate you can reasonably use on the
channel/with the AP, the noise you can perhaps detect (if you can), the
amount of packet loss or retransmissions you experience, etc.

I think that some systems (Android, maybe Windows) already do something
more complex than pure RSSI indicators, but I don't really know for
sure.

> > Yes, this would be ideal.
> > 
> > [...]

see my other email

> This sounds really brittle.  Furthermore, we also need a facility to 
> know when signal strength is getting low to trigger roaming
> logic.  This would mean sharing CQM facility between roaming & signal
> strength notifications.  As you wrote above, things become quite
> impractical.

This would likely go through the supplicant anyway, so it could manage
proper range overlaps etc. for this.

It does seem brittle if we just have a single value, but if we add
low/high thresholds (with hysteresis) then I think we can do this, and
gain more flexibility in the process. But let's discuss more details
over in the other email I just sent :)

johannes