[Make-wifi-fast] [Starlink] bloat on wifi8 and 802.11 wg

[Bob McMahon]

Here's a deck on RF topologies. This is not enough. Folks need to
understand multivariate analysis and multivariate statistics, covariance
matrices, eigenvalues & eigenvectors, etc. Know how to program in python.
Have expertise in every OS. And the list goes on.

Wi-Fi is at 20B devices on the way to 100B and more. It's a huge
undertaking and is expensive.

Bob

On Mon, Sep 2, 2024 at 10:28 AM Bob McMahon <bob.mcmahon at broadcom.com>
wrote:

> This is David's experience. It doesn't extrapolate to the industry. Our
> testing as a component supplier is quite extensive. The level of math
> required likely equals ML. The table stakes for a 2 BSS system with hidden
> nodes, etc is $80K. That's just equipment. Then test engineers with deep
> expertise of 802.11 have to be hired. And they have to continuously learn
> as 802.11 is a living standard. And now they need to learn CCAs and network
> marking planes. Then this all has to be paid for typically through
> component sells as there are no software SKUs.
>
> The cadences for new ASICs is 24 months. The cadences for OSP upgrades is
> 10 to 20 years.
>
> Of course testing is under funded. No stock b.s. to pay the bills. It has
> to come from discounted cash flows.
>
> Everyone wants the experts to work for free. Iperf2 is that already. I
> don't see any more freebies on the horizon.
>
> Bob
>
> On Sun, Sep 1, 2024, 10:05 PM David Lang via Make-wifi-fast <
> make-wifi-fast at lists.bufferbloat.net> wrote:
>
>> On Sun, 1 Sep 2024, Hal Murray via Make-wifi-fast wrote:
>>
>> > David Lang said:
>> >> It really doesn't help that everyone in the industry is pushing for
>> >> higher  bandwidth for a single host. That's a nice benchmark number,
>> but
>> >> not really  relevant int he real world.
>> >
>> >> Even mu-mimo is of limited use as most routers only handle a handful of
>> >> clients.
>> >
>> >> But the biggest problem is just the push to use wider channels and gain
>> >> efficiency in long-running bulk transfers by bundling lots of IP
>> packets
>> >> into a  single transmission. This works well when you don't have
>> >> congestion and have a  small number of clients. But when you have lots
>> of
>> >> clients, spanning many  generations of wifi technology, you need to go
>> to
>> >> narrower channels, but more  separate routers to maximize the fairness
>> of
>> >> available airtime.
>> >
>> > What does that say about the minimal collection of gear required in a
>> test
>> > lab?
>> >
>> > If you had a lab with plenty of gear, what tests would you run?
>>
>> I'll start off by saying that my experience is from practical
>> in-the-field uses,
>> deploying wifi to support thousands of users in a conference setting.
>> It's
>> possible that some people are doing the tests I describe below in their
>> labs,
>> but from the way routers and wifi standards are advertised and the guides
>> to
>> deploy them are written, it doesn't seem like they are.
>>
>> My belief is that most of the tests are done in relatively clean RF
>> environments
>> where only the devices on the test network exist, and they can always
>> hear
>> everyone on the network. In such environments, everything about existing
>> wifi
>> standards and the push for higher bandwidth channels makes a lot of sense
>> (there
>> are still some latency problems)
>>
>> But the world outside the lab is far more complex
>>
>> you need to simulate a dispursed, congested RF environment. This includes
>> hidden
>> transmitters (stations A-B-C where B can hear A and C but A and C cannot
>> hear
>> each other), dealing with weak signals (already covered), interactions of
>> independent networks on the same channels (a-b and c-d that cannot talk
>> to each
>> other), legacy equipment on the network (as slow as 802.11g at least, if
>> not
>> 802.11b to simulate old IoT devices), and a mix of bulk-transfers
>> (download/uploads), buffered streaming (constant traffic, but buffered so
>> not
>> super-sentitive to latency), unbuffered streaming (low bandwidth, but
>> sensitive
>> to latency), and short, latency sensitive traffic (things that block
>> other
>> traffic until they are answered, like DNS, http cache checks, http main
>> pages
>> that they pull lots of other URLs, etc)
>>
>> test large number of people in a given area (start with an all wireless
>> office,
>> then move on to classroom density), test not just one room, but multiple
>> rooms
>> that partially hear each other (the amount of attenuation or reflection
>> between
>> the rooms needs to vary). The ultimate density test would be a
>> stadium-type
>> setting where you have rows of chairs, but not tables and everyone is
>> trying to
>> livestream (or view a livestream) at once.
>>
>> Test not just the ultra-wide bandwidth with a single AP in the rooms, but
>> narrower channels with multiple APs distributed around the rooms. Test
>> APs
>> positioned high, and set to high power to have large coverage areas
>> against APs
>> positioned low (signals get absorbed by people, so channels can be reused
>> at
>> shorter distances) and set to low power (microcell approach). Test APs
>> overhead
>> with directional antennas so they cover a small footprint.
>>
>> Test with different types of walls around/between the rooms, metal studs
>> and
>> sheetrock of a modern office have very little affect on signals,
>> stone/brick
>> walls of old buildings (and concrete walls in some areas of new
>> buildings)
>> absorb the signal, the metal grid in movable air walls blocks and
>> reflects
>> signals
>>
>> Remember that these are operating in 'unlicensed' spectrum, and so you
>> can have
>> other devices operating here as well causing periodic interference (which
>> could
>> show up as short segments of corruption or just an increased noise
>> floor).
>> Current wifi standards interpret any failed signals as a weak signal, so
>> they
>> drop down to a slower modulation or increasing power in the hope of
>> getting the
>> signal through. If the problem is actually interference from other
>> devices
>> (especially other APs that it can't decipher), the result is that all
>> stations
>> end up yelling slowly to try and get through and the result is very high
>> levels
>> of noise and no messages getting through. Somehow, the systems should
>> detect
>> that the noise floor is high and/or that there is other stuff happening
>> on the
>> network that they can hear, but not necessarily decipher and switch away
>> from
>> the 'weak signal' mode of operation (which is appropriate in sparse
>> environments), and instead work to talk faster and at lower power to try
>> and
>> reduce the overall interference while still getting their signal through.
>> (it does no good for one station to be transmitting at 3w while the
>> station it's
>> talking to is transmitting at 50mw). As far as I know, there is currently
>> no way
>> for stations to signal what power they are using (and the effective power
>> would
>> be modified by the antenna system, both transmitted and received), so
>> this may
>> be that something like 'I'm transmitting at 50% of my max and I hear you
>> at 30%
>> with noise at 10%' <-> 'I'm transmitting at 100% of my max and I hear you
>> at 80%
>> woth noise at 30%' could cause the first station to cut down on it's
>> power until
>> the two are hearing each other at similar levels (pure speculation here,
>> suggestion for research ideas)
>>
>> > How many different tests would it take to give reasonable coverage?
>>
>> That's hard for me to say, and not every device needs to go through every
>> test.
>> But when working on a new standard, it needs to go through a lot of these
>> tests,
>> the most important ones IMHO are how they work with a high density of
>> users
>> accessing multiple routers which are distributed so there is overlapping
>> coverage and include a mix of network traffic.
>>
>> David Lang
>> _______________________________________________
>> Make-wifi-fast mailing list
>> Make-wifi-fast at lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/make-wifi-fast
>
>

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