Huge ping spikes on irregular interval

[Draghmar]

Hi
I'm not sure when this started (probably long ago) but I've noticed huge ping spikes on my wi-fi connection (BCM4352 Azurewave AW-CE123H). I pinged my router (Asus RT-AC66U) and results were weird - most of the time there was 1ms but from time to time it go up to 40-60ms for one or two checks. I also noticed that spikes always happens when I open list of available wireless networks from systray (not sure how this icon is called because I'm at work right now).
For the record - I was playing online game with my wife so we were on the same local network but one was on LAN and second on WAN and wired didn't have problems when wireless has.
I found somewhere that Windows (Windows 7 here) built-in software for wireless config can cause this issue.

What can I do to narrow down possibilities and eliminate this irritating behavior?

 

[azazel1024]

That is because your adapter is taking the time to scan the local networks, which means it has to scan across the frequencies and possibly bands.

It cannot be transmitting or receiving on it's current wifi connection while it is doing that. Hence the spike in ping times.

All wireless adapters will periodically do this under the right circumstances. Generally it is only when you are doing a network scan or if your signal strength drops below a certain level, your wifi adapter will occasionally scan local wifi networks to see if there is a stronger access point on the same network to connect to. Up to the driver/OS on how frequently it'll choose to scan if the signal strength drop low enough, but I suspect it is about every 2-10 seconds.

Only takes a few dozen miliseconds to do, but it is a few dozen miliseconds it can't be doing something else.

If you are noticing this just within games, either you have very poor wifi connection, interference from other sources causing dropped packets or else you just have a bad internet connection to the server in use.

 

[System Error Message]

ping is a low priority task. When the bandwidth of a medium is being used or filled up ping times increase because pings arent used to measure performance but to diagnose network connectivity. If you truely want to use ping as a benchmark than you will need to set ping on the test device to the highest priority so that even with heavy traffic it will still be fast.

Dont expect to get a ping of 1ms when you are transferring files or playing games and if your upload is full than your pings will be high.

Because wifi is a shared medium ping spikes are common on wifi as the medium gets used up. Every application on the network has its own latency so an application that says its own latency is more accurate than what pings show

 

[stevech]

Other than scanning, long ping times can be caused by CSMA/CA (clear channel assessment) delays. WiFi is a listen-before-transmitting protocol at the lower level (MAC layer). If a signal is detected, transmission is delayed. The delay is exponentially longer with more successive channel is busy detections.

A non-WiFi signal, e.g., an analog video signal near your WiFi channel, can create an almost-always-busy condition. This is because the WiFi CSMA/CA process is to minimize the chance of two 802.11 devices transmitting simultaneously. The 802.11 signals are brief "pulses" or data frames. Some non-WiFi signals like video (baby monitors in 2.4GHz) are not bursty with data frames.

As well, a very busy channel within 2-3 channels of yours (20MHz mode) can cause much more frequent CSMA/CA delays. This can be a neighbor streaming data/HD TV and using a large percentage of the air time.

If you change to channel 1, 6 or 11, you may see a decrease.

 

[Draghmar]

Thanks for your replies. Interesting things you've said. I forgot to mention that my WiFi card is connected on 5GHz and beside my phone there is nothing around at that frequency and channel I've chosen. But the 2.4GHz is still on so that could still cause problems.
I have to check if there's a way to disable 2.4Ghz on laptop and see if that would change anything.

BTW If this is OS doing then maybe something that I red somewhere would apply - disabling Windows as a WiFi configuration service and use some 3rd party tool. What do you think? Are there even things like that?

There has to be something I could do. There are laptops made for gaming with WiFi card in them - do they all cause lags like this?

 

[azazel1024]

If you are experiencing lag spikes in gaming, try connecting with a wire to your router and run that way for a bit. Still experiencing lag spikes, then it has nothing to do with wifi.