802.11ac lower extension channel

[Michal Kazior]

On 16 May 2016 at 09:08, Sebastian Gottschall <s.gottschall at dd-wrt.com> wrote:
> Am 16.05.2016 um 07:35 schrieb 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.
>
> for your own reference. this one here is working
>
> vht_oper_chwidth=1
> vht_oper_centr_freq_seg0_idx=106
> channel=100
>
> you're right i swapped center and control
>
> according to the documentation of ath10k. the distance of center and
> control. is "6" for vht80. and not 4

It's an oversimplification and works for channels that are first in a
segment (e.g. 36).


> the problem now is, it wont work for lower
>
> so the following hostapd snipped wont work
> vht_oper_chwidth=1
> vht_oper_centr_freq_seg0_idx=102
> channel=108

This is incorrect configuration. You can't use channel 102 as center
channel for vht80. See the channel allocation map I've linked in my
previous email.

Valid VHT80 center channels (seg0_idx) are: 42, 58, 106, 122, 138, 155.

If you want to use channel 108 as control channel you need to use
seg0_idx=106 with HT40+.
You should be able to use channel=104 (and seg0_idx=106) with HT40- as well.


Michał