2013-05-09 18:31:39

by Felix Fietkau

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Subject: Re: [PATCH 2/8] mac80211: fix various components for the new 5 and 10 MHz widths

On 2013-05-09 8:10 PM, [email protected] wrote:
> From: Simon Wunderlich <[email protected]>
>
> This is a collection of minor fixes:
> * don't allow HT IEs in IBSS for 5/10 MHz
> * don't allow HT IEs in Mesh for 5/10 MHz
> * consider 5 and 10 MHz channels when downgrading
> * don't try HT rates for 5 and 10 MHz channels when selecting rates
Why? HT rates work with 5/10 MHz just fine.

- Felix



2013-05-09 19:46:28

by Simon Wunderlich

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Subject: Re: [PATCH 2/8] mac80211: fix various components for the new 5 and 10 MHz widths

Hello Felix,

On Thu, May 09, 2013 at 08:31:36PM +0200, Felix Fietkau wrote:
> On 2013-05-09 8:10 PM, [email protected] wrote:
> > From: Simon Wunderlich <[email protected]>
> >
> > This is a collection of minor fixes:
> > * don't allow HT IEs in IBSS for 5/10 MHz
> > * don't allow HT IEs in Mesh for 5/10 MHz
> > * consider 5 and 10 MHz channels when downgrading
> > * don't try HT rates for 5 and 10 MHz channels when selecting rates
> Why? HT rates work with 5/10 MHz just fine.

Hm, to be honest I did not try - IEEE 802.11-2012 only mentions 5 and
10 MHz channels in section 18 (OFDM PHY) according with timing and other
parameters, but nothing like this (as far as I see) is mentioned in
Section 20 (High Throughput PHY).

On the other hand, it appears that AR9xxx based chipsets also support
2.4 GHz rates (DSSS, ERP-OFDM), so I can imagine also HT rates can
be supported as well.

The question is, how would we handle that? Allow HT IEs also for 5 and
10 MHz, and behave like it would be a 20 MHz channel? Are there any
other WiFi chipsets which support 5/10 MHz, should we consider them
(maybe they don't support that)? And what do others think about deviate
from standard? Personally, I don't mind, it would be cool to use HT rates
on these bandwidths too. :)

Cheers,
Simon


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2013-05-09 20:33:04

by Felix Fietkau

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Subject: Re: [PATCH 2/8] mac80211: fix various components for the new 5 and 10 MHz widths

On 2013-05-09 9:46 PM, Simon Wunderlich wrote:
> Hello Felix,
>
> On Thu, May 09, 2013 at 08:31:36PM +0200, Felix Fietkau wrote:
>> On 2013-05-09 8:10 PM, [email protected] wrote:
>> > From: Simon Wunderlich <[email protected]>
>> >
>> > This is a collection of minor fixes:
>> > * don't allow HT IEs in IBSS for 5/10 MHz
>> > * don't allow HT IEs in Mesh for 5/10 MHz
>> > * consider 5 and 10 MHz channels when downgrading
>> > * don't try HT rates for 5 and 10 MHz channels when selecting rates
>> Why? HT rates work with 5/10 MHz just fine.
>
> Hm, to be honest I did not try - IEEE 802.11-2012 only mentions 5 and
> 10 MHz channels in section 18 (OFDM PHY) according with timing and other
> parameters, but nothing like this (as far as I see) is mentioned in
> Section 20 (High Throughput PHY).
>
> On the other hand, it appears that AR9xxx based chipsets also support
> 2.4 GHz rates (DSSS, ERP-OFDM), so I can imagine also HT rates can
> be supported as well.
>
> The question is, how would we handle that? Allow HT IEs also for 5 and
> 10 MHz, and behave like it would be a 20 MHz channel?
Yes, I had 5/10 MHz running that way with a debugfs hack just fine.

> Are there any
> other WiFi chipsets which support 5/10 MHz, should we consider them
> (maybe they don't support that)?
No idea.

- Felix