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From: David Lang <david@lang.hm>
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Subject: Re: [Cerowrt-devel] [bufferbloat-fcc-discuss] arstechnica confirms
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On Sat, 12 Mar 2016, Adrian Chadd wrote:

> On 12 March 2016 at 11:14, Henning Rogge <hrogge@gmail.com> wrote:
>> On Sat, Mar 12, 2016 at 3:32 PM, Wayne Workman
>> <wayne.workman2012@gmail.com> wrote:
>>> I understand that Broadcom was paid to develop the Pi, a totally free board.
>>>
>>> And they already make wireless chipsets.
>>
>> The question is how easy would it be to build a modern 802.11ac
>> halfmac chip... the amount of work these chips do (especially with 3*3
>> or 4*4 MIMO) is not trivial.
>
> It's not that scary - most of the latency sensitive things are:
>
> * channel change - eg background scans
> * calibration related things - but most slow calibration could be done
> via firmware commands, like the intel chips do!
> * transmit a-mpdu / retransmit
> * transmit rate control adaptation
> * receiving / block-ack things - which is mostly done in hardware anyway
> * likely some power save transition-y things too

you are ignoring MU-MIMO, the ability to transmit different signals from each 
antenna so that the interference patterns from the different signals result in 
different readable data depending on where the receiver is in relation to the 
access point is not a trivial thing.

But it's one of the most valuable features in the spec.

David Lang