[Make-wifi-fast] Uplink vs downlink latency

[Dave Taht]

throughput and latency are interrelated, whats the throughput?

On Wed, Apr 29, 2020 at 2:40 PM Tim Higgins <tim at smallnetbuilder.com> wrote:
>
> Hi all,
>
> I finally have my testbed working the way I want and am starting to run tests to see if OFDMA does anything useful.
>
> This will all be covered in detail in an upcoming SmallNetBuilder article. But I wanted to sanity check something with this esteemed group.
>
> The tests are basically the flent rtt_fair_var up and down tests ported to the octoScope platform I use for WiFi testing.
> The initial work was done on flent, with a lot of hand-holding from Toke. (Thank you, Toke!)
>
> Using 4 Intel AX200 STAs on Win10. iperf3 is running traffic using TCP/IP with unthrottled bandwidth. I've taken Bjørn's idea and have each STA using a different DSCP priority level, but with TCP/IP traffic, not UDP. I'm sticking to using CS0-7 equivalents and confirmed that the iperf3 --dscp values properly translate to the intended WiFi priority levels.  Each STA has a different priority, either CS0,3,5 or 6 (best effort, excellent effort, video and voice).
>
> Ping is used to measure latency and always runs from AP to STA. Only TCP/IP traffic direction is reversed between the down and uplink tests.
>
> One thing that jumps out immediately is that uplink latencies are *much* lower than downlink, with either OFDMA on or off. Attached are three examples. The CDFs are average latency of the 4 STAs.
>
> The NETGEAR R7800 is a 4x4 AC Qualcomm-based. I'm using this as a baseline product.
>
> The NETGEAR RAX15 is 2x2 AX Broadcom-based. You can see what I mean when I say OFDMA doesn't help.
>
> Does this much difference between up and downlink latency pass the sniff test?
>
> ===
> Tim
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-- 
Make Music, Not War

Dave Täht
CTO, TekLibre, LLC
http://www.teklibre.com
Tel: 1-831-435-0729