General VHT rate-ctrl question

General VHT rate-ctrl question

[Ben Greear]

If a station and it's peer can both do VHT, is there ever a good reason
to even try HT rates?

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

Re: General VHT rate-ctrl question

[Johannes Berg]

On Tue, 2016-04-12 at 16:48 -0700, Ben Greear wrote:
> If a station and it's peer can both do VHT, is there ever a good
> reason to even try HT rates?
> 

Not really; perhaps if you could do HT greenfield preamble (which VHT
doesn't have) you could get something out of it, beyond that I don't
see a reason to try.

Unless, for some strange reason, it supports only single stream VHT and
dual-stream HT or something really weird?

johannes

Re: General VHT rate-ctrl question

[Ben Greear]

On 04/13/2016 01:01 AM, Johannes Berg wrote:
> On Tue, 2016-04-12 at 16:48 -0700, Ben Greear wrote:
>> If a station and it's peer can both do VHT, is there ever a good
>> reason to even try HT rates?
>>
>
> Not really; perhaps if you could do HT greenfield preamble (which VHT
> doesn't have) you could get something out of it, beyond that I don't
> see a reason to try.
>
> Unless, for some strange reason, it supports only single stream VHT and
> dual-stream HT or something really weird?

I was wondering if there was ever a reason that, say 450Mbps HT
would work better than MCS-1 for VHT.  Or, maybe a mid-rate HT MCS would
have more range than VHT, or something like that.

After fighting with the firmware's rate-ctrl all day, I am even more interested
in trying to make it use mistrel_ht.

Thanks,
Ben

-- 
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc  http://www.candelatech.com

Re: General VHT rate-ctrl question

[Dave Taht]

On Wed, Apr 13, 2016 at 6:18 AM, Ben Greear <greearb@candelatech.com> wrote:
>
>
> On 04/13/2016 01:01 AM, Johannes Berg wrote:
>>
>> On Tue, 2016-04-12 at 16:48 -0700, Ben Greear wrote:
>>>
>>> If a station and it's peer can both do VHT, is there ever a good
>>> reason to even try HT rates?
>>>
>>
>> Not really; perhaps if you could do HT greenfield preamble (which VHT
>> doesn't have) you could get something out of it, beyond that I don't
>> see a reason to try.
>>
>> Unless, for some strange reason, it supports only single stream VHT and
>> dual-stream HT or something really weird?
>
>
> I was wondering if there was ever a reason that, say 450Mbps HT
> would work better than MCS-1 for VHT.  Or, maybe a mid-rate HT MCS would
> have more range than VHT, or something like that.
>
> After fighting with the firmware's rate-ctrl all day, I am even more
> interested
> in trying to make it use mistrel_ht.

I just put up Andrew's old paper on minstrel, if that helps any.

http://blog.cerowrt.org/post/minstrel/

>
> Thanks,
> Ben
>
> --
> Ben Greear <greearb@candelatech.com>
> Candela Technologies Inc  http://www.candelatech.com
> --
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Re: General VHT rate-ctrl question

[Krishna Chaitanya]

On Wed, Apr 13, 2016 at 10:31 PM, Dave Taht <dave.taht@gmail.com> wrote:
>
> On Wed, Apr 13, 2016 at 6:18 AM, Ben Greear <greearb@candelatech.com> wrote:
> >
> >
> > On 04/13/2016 01:01 AM, Johannes Berg wrote:
> >>
> >> On Tue, 2016-04-12 at 16:48 -0700, Ben Greear wrote:
> >>>
> >>> If a station and it's peer can both do VHT, is there ever a good
> >>> reason to even try HT rates?
> >>>
> >>
> >> Not really; perhaps if you could do HT greenfield preamble (which VHT
> >> doesn't have) you could get something out of it, beyond that I don't
> >> see a reason to try.
> >>
> >> Unless, for some strange reason, it supports only single stream VHT and
> >> dual-stream HT or something really weird?
> >
> >
> > I was wondering if there was ever a reason that, say 450Mbps HT
> > would work better than MCS-1 for VHT.  Or, maybe a mid-rate HT MCS would
> > have more range than VHT, or something like that.
I dont think so. basically if you remove 256 QAM out of picture,
it just boils down to choosing a modulation scheme which would
be same for VHT and HT. (assuming same BW)

Only advantage is as Johannes pointed, VHT doesn't have greenfield,
so using HT greenfield preamble might be marginally good. Similarly we can
use RIFS for HT(not recommended), But again who uses RIFS/greenfield?