802.11ac lower extension channel

[Michal Kazior]

On 14 May 2016 at 06:37, Sebastian Gottschall <s.gottschall at dd-wrt.com> wrote:
> Hello
>
> a long time ago i discovered that ath10k doesnt seem to support lower
> extension channel configuration which raises also a bug report for DD-WRT in
> my case.
> when will this issue be fixed?
> if i set channel 100 and extension channel to 106 (and ht40+) in hostapd,
> all is working

You probably mean 100 and 104. There's no control channel 106.

106 could be used as center channel/frequency for vht80 across 100 and 112.


> but channel 108 and extension channel 102 (-6) and ht40- it will be refused

Again, you probably mean 108 and 104. There's no 102 control channel.

Anyway, this is forbidden by the spec (IEEE 802.11n Annex J.). See
this channel allocation map:

 http://twimgs.com/networkcomputing/news/2013/10/graphic-80211-acChannels-all.png

You can find references to this in a few places in
hostap/wpa_supplicant code. Just grep for:

  36, 44, 52

.. and you'll find e.g.

  https://w1.fi/cgit/hostap/tree/src/common/hw_features_common.c#n91
  https://w1.fi/cgit/hostap/tree/src/common/hw_features_common.c#n120


Michał