Which part of a WIFI router's stack causes jitter?

[dr_sacha_k]

Hello!

Thanks in advance for your help.

The diagram below plots the differences between times of arrival at the receiving end of a wifi link.
Most packets seem to take exactly 2ms to arrive, but there are wide variations below and above this standard arrival time.
Would anyone know which part of the system causes these variations, and if there is a way to minimise them?

Thank you!

All the best,
- Sacha

 

[RMerlin]

Wifi is a shared medium among all devices using the same frequency. If the router or a client wants to send a packet and sees there is already someone else sending traffic, it will have to wait before it can have its turn at sending traffic. That will cause latency spikes.

 

[sfx2000]

The diagram below plots the differences between times of arrival at the receiving end of a wifi link.
Most packets seem to take exactly 2ms to arrive, but there are wide variations below and above this standard arrival time.
Would anyone know which part of the system causes these variations, and if there is a way to minimise them?

Normal for WiFi... much depends on other traffic on the same AP - snapshot below...

 

[dr_sacha_k]

Many thanks to you all for your replies, much appreciated!

@RMerlin:
Your answer is the closest to what I am after.

There is actually a single client sending traffic through that router: it is a small development board (ESP32) sending RTP packets to a laptop.
The router is unplugged from the WAN, the system is
ESP32 ~~wifi~~> router D-Link DIR-882 --Ethernet cable--> laptop
nothing else plugged in but potentially some spectrum competition from surrounding routers.

Which part of the router's software stack will make the decisions to delay or not, is it the scheduler or the radio chip or something else? (E.g. automatic channel switching?)
From that standpoint, apart from QoS settings which are inoperant in this case because there is no competing traffic, is there any setting that can be optimised in the router's software stack to minimise the spikes?

Thank you!

 

[thiggins]

Wi-Fi Ping Spikes: Causes and Fixes - SmallNetBuilder

Wi-Fi ping spikes aren't always caused by a poor connection. Your router settings could be to blame.

www.smallnetbuilder.com

 

[RMerlin]

Which part of the router's software stack will make the decisions to delay or not

The radio.