Re: [RFC] Implement basic background scanning
From: Tomas Winkler <hidden>
Date: 2008-09-16 09:15:24
On Tue, Sep 16, 2008 at 11:43 AM, Kalle Valo [off-list ref] wrote:
Helmut Schaa [off-list ref] writes:quoted
quoted
This doesn't play well at all with hardware assisted scan as far as I can tell.Correct. The patch only adapts software scan code. The hardware assisted scan is not touched at all but should also not be affected in an odd way.I would guess that some firmwares support similar scanning in hardware. In the future we might add support for background scanning in hardware with a flag in hw_scan(), or something like that.
In iwwlifi we can trigger scan anytime during association so this is
not an issue.
The common point for sw and hw is when to trigger scanning and what
are scanning parameters.
The objective is that this affect performance, therefore the scan can
be triggered on
1. On limited number of channels
a. After first scan we know which channels are active or activated
(passive channels with traffic)
b. We can scan only channels with possible roaming candidates
(same SSID or list of possible SSIDs)
2. Group scanning
Issue scanning in small group of channels and returning back to the
serving channel. The size of group
is affected by current traffic rate and quality. Size of group
effects off channel time (#channels * dwell time)
Thanks
Tomas