Initial automatic channel selection implementation

Helmut Schaa helmut.schaa
Wed May 25 07:45:45 PDT 2011

On Wed, May 25, 2011 at 4:37 PM, Luis R. Rodriguez <mcgrof at> wrote:
> On Wed, May 25, 2011 at 5:19 AM, Helmut Schaa
> <helmut.schaa at> wrote:
>> On Wed, May 25, 2011 at 12:54 AM, Luis R. Rodriguez <mcgrof at> wrote:
>>> Yes, thanks this is a lot of work already done. Now we just need a
>>> basic algorithm to parse this, quantify how ideal this channel is and
>>> then spit out a desired optimal channel.
>> That's what I've hacked some time ago (in form of the attached _ugly_ shell
>> script that does auto channel selection with rt2x00, not sure if it works
>> correct with other drivers as the survey dump differs somehow between
>> rt2x00, ath5k and ath9k, and it only does channel 1-11):
>> - Iterate over all channels and stay on each channel for some time
> Nice, yeah I was thinking of using the offchannel operation if we want
> to spend more time there for inspection and if associated. For first
> iteration it should be possible to just move around. In fact for AP
> purposes I suppose one will want to just start AP mode ASAP and then
> later do offchannel operations to do the inspection on the ideal
> channel. Otherwise we sit there idle until we complete the Automatic
> Channel Selection thingy.

Correct, especially if we also consider 5Ghz channels. Offchannel operations
would be nice but how can we ensure AP mode while being offchannel?

>> - Store busy time stats for each channel
>> - Choose the channel with the lowest busy time (and on 2.4Ghz also
>> ?check the busy times on adjacent channels)
> So I was reviewing this -- if we are TX'ing or RX'ing it seems to me
> we should skip that time from the busy time, otherwise the "busy" time
> includes time we induced on TX'ing or RX'ing ourselves. So I was
> thinking of using the:
> ?(active time - rx time - tx time) ?/ busy time

Looks good ;) just one problem from a rt2x00 POV: We can't report rx/tx busy
time separately, we can only advice the hw to include or exclude rx/tx time
from the busy time statistics.


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