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<p>Let me jump in and add a bit more information.</p>
<p>I am not an RF guy - I stopped playing with radios [and TV] in
the days when they used vacuum tubes (yes, really.)<br>
</p>
<p>Many laptops share radio and <span class="q-box
qu-userSelect--text" style="box-sizing: border-box; direction:
ltr;"><span style="font-weight: normal; font-style: normal;
background: rgba(0, 0, 0, 0) none repeat scroll 0% 0%;">antenna
resources between WiFi and bluetooth</span></span>.<br>
</p>
<p>Bluetooth lives on the 2.4ghz band. Wifi presently uses both
that band and also a 5ghz band. <span class="q-box
qu-userSelect--text" style="box-sizing: border-box; direction:
ltr;"><span style="font-weight: normal; font-style: normal;
background: rgba(0, 0, 0, 0) none repeat scroll 0% 0%;">Different
antennas might be used for each.</span></span></p>
<p><span class="q-box qu-userSelect--text" style="box-sizing:
border-box; direction: ltr;"><span style="font-weight: normal;
font-style: normal; background: rgba(0, 0, 0, 0) none repeat
scroll 0% 0%;">I encountered Wi-Fi/Bluetooth contention issues
a couple of years back....<br>
</span></span></p>
<p>My home wifi has (or rather had) distinct SSIDs for Wifi on the
2.4 and 5ghz bands. It was a rough attempt at manual load and
distance balancing.<br>
</p>
<p>(Our house is in a relatively quiet area, RF wise, so there's not
really any seriously competing wi-fi - or for that matter cell
signal, broadcast TV, or FM radio.)<br>
</p>
<p>I began to notice that when I had one of my laptops on the 5ghz
WiFi and was listening to music via some bluetooth speakers that
my remote terminal keystrokes sometimes had that sluggish feel
that is familiar when doing remote terminal command-line stuff
over long paths with a lot of latency/jitter. And at the same
time the music via Bluetooth often broke up or stuttered. There
was a clear correlation between the two problems.<br>
</p>
<p>I had heard from some Linux kernel developers that deep down in
the Linux kernel the simultaneous use of Wifi on a 5ghz channel
and bluetooth on 2.4 causes a lot of thrashing and flogging of the
the radio system. I don't know, but I suspect that as a result
there are queues of outbound traffic waiting for the radio or <span
class="q-box qu-userSelect--text" style="box-sizing: border-box;
direction: ltr;"><span style="font-weight: normal; font-style:
normal; background: rgba(0, 0, 0, 0) none repeat scroll 0%
0%;">antennas</span></span> to become operational on the
channel they need. I have no idea what happens to inbound frames
when the radio system is tuned elsewhere - I never measured
whether the frames are lost or delayed.</p>
<p>I suspect similar issues are present in *BSD, MacOS, and Windows
kernels.<br>
</p>
<p>So I did some simple empirical testing to compare life with the
laptop coerced to use an SSID present only on the 2.4ghz band.
The problems went away.</p>
<p>I went back to the laptop, but coerced onto the 5ghz band for
WiFi and, voila, there was trouble.<br>
</p>
<p>I've done this with a MacBook Pro (circa 2015 model) using
various versions of MacOS and with my rather newer Linux laptops
(mostly Dell XPS units with Fedora.) Same sorts of behavior.</p>
<p>These were all i5 based units with 2 or 4 cores - plenty of CPU
power to simultaneously handle an SSH remote console client and a
music player.<br>
</p>
<p>I did not test with mobile phone or tablet platforms.<br>
</p>
<p>I do not know if the single radio issue is the result of cost
savings or some radio-engineering or <span class="q-box
qu-userSelect--text" style="box-sizing: border-box; direction:
ltr;"><span style="font-weight: normal; font-style: normal;
background: rgba(0, 0, 0, 0) none repeat scroll 0% 0%;">antenna
</span></span>issue. I do suspect that these things could
become more troublesome as WiFi 6 and/or 5G start to use some of
the higher frequency allocations around 5.9 and 6ghz.)<br>
</p>
<p>(A few weeks ago we switched our home WiFi to a WiFi 6 [Netgear
Orbi-6] mesh system that does not appear to allow separate SSIDs
for the 2.4 and 5ghz bands, so I can not repeat these tests
without constructing a test network with the now unused access
points. BTW, I did encounter the hell that is known as
"reconfiguring dozens upon dozens of different kinds of IoT
devices to use a different SSID".)</p>
<p>Looking somewhat off topic - it is my sense that we will be
seeing a lot more latency/jitter (and packet resequencing) issues
in the future as radio systems become more agile and as we begin
to use shorter (millimeter) wavelength frequencies with reduced
ability to penetrate walls that, in turn, cause more frequent
access-point transitions (with possibly distinctly different
backhaul characteristics). I've observed that these things can
cause trouble for some TCP stacks and some non-TCP based VoIP and
streaming applications.<br>
</p>
<p> --karl--<br>
</p>
<div class="moz-cite-prefix">On 10/30/20 12:08 PM, Mark Tinka wrote:<br>
</div>
<blockquote type="cite"
cite="mid:8b8fa0fe-8de0-0cec-5508-f62f0ec82c13@seacom.com">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<font face="Tahoma">Hi all.<br>
<br>
So I may have fixed this for my end, and hopefully others may be
able to use the same fix.<br>
<br>
After a tip from Karl Auerbach and this link:<br>
<br>
<a class="moz-txt-link-freetext"
href="https://developer.apple.com/forums/thread/97805"
moz-do-not-send="true">https://developer.apple.com/forums/thread/97805</a><br>
<br>
... I was able to fix the problem by disabling Bluetooth. <br>
</font> </blockquote>
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