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Re: Interaction issue of intel wifi and broadcom bluetooth - it appears that nobody feels responsible for doing something

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+ Marcel, wireless list, and bt list.

On 06/05/15 07:12, Jonas Thiem wrote:
Hi Jeremiah,

thanks for responding!

I did have my mobile phone very nearby also connected to the bluetooth
headphones while my laptop was still using 11n wifi. I didn't have any
noticeable issues with bluetooth there.

But I got the feeling that my phone's android drivers + hardware for
bluetooth are tuned better than the laptop ones, so maybe that just
means the phone is just better at jumping frequencies to avoid.

I guess the best test would be the same laptop model in direct
proximity, but sadly I only own that laptop once. ;)

I hope wireless interference wouldn't rule out that some driver work
would be considered to make it work better - after all, both chips are
in the same laptop and as per the intel comment, bluetooth is supposed
to work despite of wifi activity.

Regards,
Jonas Thiem

On 06/05/2015 06:45 AM, Jeremiah Mahler wrote:
Jonas,

On Fri, Jun 05, 2015 at 01:00:32AM +0200, Jonas Thiem wrote:
Hi *,

this is my first post to this mailing list, sorry if it's not supposed
to go here. (also CC in responses would be nice since I'm not
subscribed)

I filed a bug about an intel centrino wifi interaction with broadcom's BCM2045B:
https://bugzilla.kernel.org/show_bug.cgi?id=97101

Those are some unhelpful replies :-(

Indeed. Now my reply maybe of a similar nature as my knowledge of the bluetooth part is next to nil.

In short, the two seem to kinda fight over the wireless spectrum and
both drop connections all the time - unless the 'iwlwifi' module is
loaded with 11n_disabled=1.


I guess you don't have a choice about the channel your access point is operating on. If you can you might move wifi channel to 5GHz although that will likely affect your range.

To get more info on your setup here a couple of questions.

What type of device are we talking about here?
Bugzilla mentions Thinkpad X220, is that correct?
Is your AP setup for 40MHz bandwidth?

I suppose both wifi and bt have their own antennas. When sharing antennas it needs to be coordinated who is using the antennas. This is called bt-coex. As said I don't think this is the case for your device, but if so I think there is still major development task needed as I saw email from Marcel about plans to develop a bt-coex subsystem in the kernel. Not sure if that also covers the case where bt and wifi do not share antennas.

Regards,
Arend

I don't have a solution but I think the problem is interesting.

Both Bluetooth and 11n share the same frequency band near 2.4 GHz so it
is possible that they could conflict.  If you had two laptops, and you
ran just Bluetooth on one and just 11n on the other, would they
both have problems?  This would tell as whether it was something inside
the kernel or if it was really wireless interference.

[...]

Regards,
Jonas Thiem



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