Re: Prevent auto scan in wireless devices (Aloisio Almeida)

[Howard Chu <hyc symas com>]

Dan Williams wrote:
> On Wed, 2009-01-14 at 12:51 -0800, Howard Chu wrote:
> > Howard Chu wrote:
> > > I think you need to acknowledge that single AP deployments are a very common
> > > occurrence. Yes, there are offices and hotels and other large buildings that
> > > deploy multiple APs throughout a campus, where roaming is an issue. But you're
> > > trying to force NM to act as a one-size-fits-all solution and that frankly
> > > isn't reality.
> > Perhaps a workable approach would be to check for multiple APs with the same
> > SSID at the beginning of an association; if more than one is seen, then keep
> > background scanning enabled...
>
> One thought I had to fix your case, where scanning interrupts a stream,
> is to use a sliding window to look at the number frames
> transmitted/received, and if there is a significant number of them in
> the past, oh, 30 seconds, postpone the scan for a bit.  If there's a
> postponed scan and the number of tx/rx frames drops below a certain
> number, let the scan proceed.  Thus, as long as your download or VOIP
> conversation or streaming movie is going, the scan might get postponed,
> but when it stops, the scan can occur.

That sounds promising. Is getting the frame count a cheap operation? Then it's 
just a matter of figuring out what the threshold between "busy streaming" and 
"not" is.

--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/