On Mon, Dec 16, 2019 at 12:= 54 PM Tim Higgins <tim@smallnetbuilder.com> wrote:

On 12/16/2019 12:59 PM, Toke H=C3=B8iland-J=C3=B8rgensen= wrote:

Tim Higgins <tim@smallnetbuilder.com&g=
t; writes:

Hi all,

Dave T=C3=A4ht suggested that I post the discussion we've started to this=
 broader
group.

I've been spending the past few months trying to develop methods to verif=
y one
of the key promises of OFDMA; improved efficiency.
The tests have mostly focused on trying to see improvement in total throu=
ghput
using various traffic mixes using four OFDMA STAs.

I've been using Samsung S10e's as STAs and primarily iperf3 TCP/IP and UD=
P
traffic.  I did some work with the Intel AX200 as a STA using both Window=
s 10
and Linux for RvR testing and found the Linux driver basically broken for=

uplink. (See the Win10/Linux comparison in the RAX40 section of
https://www.smallnetbuilder.com/wireless/w=
ireless-reviews/33220-wi-fi-6-performance-roundup-five-routers-tested?sta=
rt=3D1

FWIW, Johannes was debugging some TCP issues on Intel =
802.11ax the other
day, and was getting ~1.4Gbps of throughput:
https://lore.kernel.org/linux-wireless/90485ecbfa2a13c4438=
b840c8a9d37677e833ea5.camel@sipsolutions.net/T/

So I guess maybe there are improvements coming in that space?

TH: Yes, I'm monitoring that thread. I'm about to try a 5.2.14 kernel with this patch
https://patchwor= k.kernel.org/patch/11253471/

I think there are others in the works. Hope the end product will be available in a backport.

So, for now, I'm limited to using the Samsung S10 as=
 STAs.=20

ANYWAY, I haven't been having much luck finding total throughput gains, s=
o
thought I'd bang my head against a different wall for awhile, which bring=
s me
to latency.=20

My initial work was pretty simple, just running pings to four OFDMA STAs =
with
OFDMA on/off on the AP, which showed no improvement. That's once I realiz=
ed
the large ping times and variation I was seeing initially was due to
aggressive power-save kicking in on the STAs with no traffic running. So =
I
also tried various TCP rates starting at 1 Mbps per STA to keep the STA a=
wake.

Coincidentally, Dave reached out the other day and suggested I look at th=
e
toolsets used for the make-wifi-fast project. =20

I've spent a few hours looking at the flent and rrul sites and  I'm inter=
ested
in exploring using the tools/techniques used for the make-wifi-fast work =
to
date to see if AX adds anything to the latency improvement party.  If any=
one
is willing to provide some pointers on the proper use of the tools, I'd
appreciate it.

I think the Flent batch file used to run the tests are=
 part of the data
file at the bottom of this page:
https://www.cs.kau.se/tohojo/airtime-fairnes=
s/

TH: Thanks for the reference, I'll look into that

The setup I was using had a server that ran the tests,=
 which was one
Ethernet hop from the AP. The clients were passive, run running
'netserver' so the server could run 'netperf' against each of them. This
flips up/down in the tests but otherwise works fairly well. I used a
separate (wired) control network for telling the clients to
connect/disconnect...

More details about the setup here:
https://blog.toh=
ojo.dk/2017/11/building-a-wireless-testbed-with-wires.html

TH: Again, thanks.

For example, I didn't see mention of the bitrates us=
ed for the traffic streams
in the tests. Do I just tell each stream to run full blast (1 Gbps)?

Well for TCP tests, yeah. The only UDP tests I did wer=
e flood tests,
where I just had iperf blasting away at way above the link rate, then
measured how many packets made it through.

TH: Got it. Blast away on both TCP and UDP. Not sure how that will work with OFDMA trying to split that bandwidth into multiple RUs that have smaller bandwidth, but guess I'll find out.

Also, since most implementations of (consumer at lea=
st) OFDMA require multiple
STAs to trigger OFDMA frames, I could use some help understanding whether=

multiple streams should be applied per STA, or spread among the 4 STAs I'=
m
using in my testing.

Why not just try both and see what works? :)

TH: Why didn't I think of that? :) OK.

Also (2), has anyone used Android STAs for make-wifi=
-fast testing?

Nope. But if you can get netperf cross-compiled it sho=
uld be simple
enough to run 'netserver' on them, I would think?

TH: Unfortunately, that requires more skills than I have. Maybe someone else on this list has already done it?

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