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From: Don Y <blockedofcourse@foo.invalid>
Newsgroups: sci.electronics.design
Subject: Re: "Safe" cell phone WiFi capabilities?
Date: Mon, 20 May 2024 11:39:21 -0700
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On 5/20/2024 10:03 AM, Dan Purgert wrote:
>>> It's almost like "the base" isn't what you want then.
>>> [...]
>>> Which is why you toss in an 802.11ax AP (or 802.11ac, if the ax units
>>> are prohibitively expensive for your house/office/whatever), and leave
>>> it up to the client device to negotiate for the best common option.
>>
>> And, when you want to pass a gigabit of data to the phone each second,
>> how does that AP help the phone GET the data when the pipe TO THE HANDSET
>> is considerably narrower?!
> 
> Then I buy a phone that can support 802.11ac Wave2 with 160 MHz channel
> width, and at least 3x3 spatial streams. Assuming, of course:
> 
>    - that the AP supports those minimum requirements as well, AND
>    - The conditions allow for negotiation of MCS8 (~2300 mbps link rate,
>      ballpark 1gpbs sustained data rate, but WiFi math is "fun") AND
>    - There aren't other devices also requesting airtime (especially ones
>      using slower options -- 2x2 streams, 802.11n, MCS5,  etc.) AND
>    - The server has enough bandwidth (incl. read buffers, disk I/O, etc.)
>      to sustain that 1gpbs transfer to my phone.
>    - The phone has enough bandwidth (incl. write buffers, "disk" I/O,
>      etc.) to sustain a 1gbps transfer from the server.

Etc.  But, I don't want to FORCE you to buy capabilities that you
don't ALREADY HAVE -- hence the question as to the prevalence of
a particular "minimum" WiFi standard in current phones.

E.g., I can replace gigabit with whatever I decide the application
requires.  Or, design the application to use the capabilities
*expected*.

> Or, I don't use WiFi (to a phone or otherwise) because if I *need*
> 1gpbs, then a wire's gonna give me that without any of the conditions
> imposed by half-duplex radio communications.

Then you're stuck with a cable.

>>> It's not like an 802.11ax AP doesn't support a/b/g/n/ac ...
>>
>> You're missing the point, completely.
> 
> It's almost like the whole reason I've repeatedly asked "what do you
> *REALLY* want to know" is because your question is vague.

I WANT TO KNOW WHAT SET OF WiFi CAPABILITIES I CAN EXPECT FROM
PHONES CURRENTLY IN USE.  What's so vague about that?

Find every phone currently in use.  Determine its WiFi capabilities
based on its published specifications.  Tabulate these results.
Identify any patterns observed.

I could similarly ask for the nominal WEIGHT of phones currently in
use.  Or, size.  Or, color.  Or, ...   The approach would be the same.
Would it MATTER how I was using this information?  Or, why?  Would
the data CHANGE??

Had I (or YOU!) personal experience DESIGNING cell phones, I
could enumerate the criteria that were used in selecting the
feature set for the phone and extrapolate that to other manufacturers.

    "Do we want the WiFi bandwidth to be comparable to the available
    cellular data rate?  What do we envision the user relying on the
    WiFi connection for, given the existing data capability?  Etc."

But, I don't KNOW how manufacturers (designers) set these features.
I don't see phones advertised highlighting their WiFi capabilities;
instead, it's OS, 4G/5G, camera, screen size, battery life.  And, I
suspect if I were to canvas phone owners and ask them what THEIR phones'
WiFi capabilities are, I would get a blank stare from most.

[Gee, does this mean WiFi is a useless feature?]

>    - If you're building some form of WiFi access point --> who cares,
>      the phone will negotiate with the AP for the best common mode
>      between them given local conditions (e.g. 802.11n @ MCS2)
> 
>    - If you're building some form of application that needs some minimum
>      data rate --> you can't really guarantee you're going to get that
>      rate, unless it's less than 1Mbps (802.11a/b/g) or MCS0
>      (802.11n/ac/ax; exact rate varies depending on available spatial
>      streams).

Or, unless you control the environment that the phone is operating in.
Didn't that occur to you?  Or, are you limited by your ASSUMPTIONS
about how the phone would be used?

I'm an engineer.  Assume I can "do engineering".  I asked a question
to gather opinions as to a survey of available *equipment*.  If you
can't provide that information, that's understandable.