[Bloat] [Cake] [Make-wifi-fast] [Starlink] [Cerowrt-devel] Due Aug 2: Internet Quality workshop CFP for the internet architecture board

David Lang david at lang.hm
Mon Aug 2 23:12:12 EDT 2021

I guess it depends on what you are intending to test. If you are not going to 
tinker with any of the over-the-air settings (including the number of packets 
transmitted in one aggregate), the details of what happen over the air don't 
matter much.

But if you are going to be doing any tinkering with what is getting sent, and 
you ignore the hidden transmitter type problems, you will create a solution that 
seems to work really well in the lab and falls on it's face out in the wild 
where spectrum overload and hidden transmitters are the norm (at least in urban 
areas), not rare corner cases.

you don't need to include them in every test, but you need to have a way to 
configure your lab to include them before you consider any settings/algorithm 
ready to try in the wild.

David Lang

On Mon, 2 Aug 2021, Bob McMahon wrote:

> We find four nodes, a primary BSS and an adjunct one quite good for lots of
> testing.  The six nodes allows for a primary BSS and two adjacent ones. We
> want to minimize complexity to necessary and sufficient.
> The challenge we find is having variability (e.g. montecarlos) that's
> reproducible and has relevant information. Basically, the distance matrices
> have h-matrices as their elements. Our chips can provide these h-matrices.
> The parts for solid state programmable attenuators and phase shifters
> aren't very expensive. A device that supports a five branch tree and 2x2
> MIMO seems a very good starting point.
> Bob
> On Mon, Aug 2, 2021 at 4:55 PM Ben Greear <greearb at candelatech.com> wrote:
>> On 8/2/21 4:16 PM, David Lang wrote:
>>> If you are going to setup a test environment for wifi, you need to
>> include the ability to make a fe cases that only happen with RF, not with
>> wired networks and
>>> are commonly overlooked
>>> 1. station A can hear station B and C but they cannot hear each other
>>> 2. station A can hear station B but station B cannot hear station A 3.
>> station A can hear that station B is transmitting, but not with a strong
>> enough signal to
>>> decode the signal (yes in theory you can work around interference, but
>> in practice interference is still a real thing)
>>> David Lang
>> To add to this, I think you need lots of different station devices,
>> different capabilities (/n, /ac, /ax, etc)
>> different numbers of spatial streams, and different distances from the
>> AP.  From download queueing perspective, changing
>> the capabilities may be sufficient while keeping all stations at same
>> distance.  This assumes you are not
>> actually testing the wifi rate-ctrl alg. itself, so different throughput
>> levels for different stations would be enough.
>> So, a good station emulator setup (and/or pile of real stations) and a few
>> RF chambers and
>> programmable attenuators and you can test that setup...
>>  From upload perspective, I guess same setup would do the job.
>> Queuing/fairness might depend a bit more on the
>> station devices, emulated or otherwise, but I guess a clever AP could
>> enforce fairness in upstream direction
>> too by implementing per-sta queues.
>> Thanks,
>> Ben
>> --
>> Ben Greear <greearb at candelatech.com>
>> Candela Technologies Inc  http://www.candelatech.com

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