Wi-Fi channels - the ongoing debate?

[TheLyppardMan]

From what I can see, there is still some ongoing debate as to which channels should be used for Wi-Fi, particularly in the 2.4 GHz band.

If I set my ASUS RT-AX88U to “Auto”, it currently chooses channel 8 for the lower band and channel 100 for the upper band (Amazon Fire TV Stick now supports the DFS channels, whereas it didn’t when I checked previously). I also ran a test using my new ISP-supplied router (FRITZX!Box 7530 AX) and that allocated the 2.4 GHz band to channel 6 (I can’t remember which channel it allocated for the 5.0 GHz band, but it was in the region of 130-150 in the DFS channels). So, what is someone like me to make of all this, given the different opinions? I usually set my router to use channel 11, but if I set it to “Auto”, what would be the best way to evaluate the performance of each setting?

I’m uploading a couple of screenshots, showing the nearby Wi-Fi networks. Mine are the top three, which I have named after my new ISP service (Zen Internet) starting later this week.

 

[OzarkEdge]

From what I can see, there is still some ongoing debate as to which channels should be used for Wi-Fi, particularly in the 2.4 GHz band.

If I set my ASUS RT-AX88U to “Auto”, it currently chooses channel 8 for the lower band and channel 100 for the upper band (Amazon Fire TV Stick now supports the DFS channels, whereas it didn’t when I checked previously). I also ran a test using my new ISP-supplied router (FRITZX!Box 7530 AX) and that allocated the 2.4 GHz band to channel 6 (I can’t remember which channel it allocated for the 5.0 GHz band, but it was in the region of 130-150 in the DFS channels). So, what is someone like me to make of all this, given the different opinions? I usually set my router to use channel 11, but if I set it to “Auto”, what would be the best way to evaluate the performance of each setting?

I’m uploading a couple of screenshots, showing the nearby Wi-Fi networks. Mine are the top three, which I have named after my new ISP service (Zen Internet) starting later this week.

I set a fixed control channel and the recommended max bandwidth, and then monitor noise, DFS status, and client/node connection details/quality in the Wireless Log. If you can't settle on a fixed control channel with the least noise <-84dBm and best connections, then leave it on ch Auto to let the router vary the control ch and bw for your ambient radio conditions. Get 80MHz bw working with a non-DFS control channel (for legacy clients) before experimenting with 160MHz bw.

OE

 

[TheLyppardMan]

When you say, "monitor noise, DFS status, and client/node connection details/quality in the Wireless Log", how do I find that information and what exactly am I looking for? If you mean the router's log, then there is tons of information in there, so I would need to have some idea of how to find the relevant data.

 

[OzarkEdge]

When you say, "monitor noise, DFS status, and client/node connection details/quality in the Wireless Log", how do I find that information and what exactly am I looking for? If you mean the router's log, then there is tons of information in there, so I would need to have some idea of how to find the relevant data.

Start by looking at the router Wireless Log... ASUSWRT lists the information I mentioned... it's a bit cryptic but you should be able to figure it out... ch/bw; noise per band; DFS active or not; and then the client/node connection details for each band, number of streams, protocol, physical link rate, bw, Tx rate... it's there.

OE

 

[TheLyppardMan]

I've searched a saved copy of the log for the words noise, DFS and dB, but nothing was found.

 

[tallytr]

I've searched a saved copy of the log for the words noise, DFS and dB, but nothing was found.

You sure, under the SSID, there is a line, in my case for 5GHz, 160MHz disabled, manual non DFS channel 149 (155) selected...
noise: -86 dBm Channel: 149/80

 

[TheLyppardMan]

Got it - I was looking in the wrong log! I'll have a look and see what information I can find now that I am in the right place.

 

[tallytr]

Got it - I was looking in the wrong log! I'll have a look and see what information I can find now that I am in the right place.

All that info is super sketchy to me, it probably all makes sense, still... you can see the clients connected at the bottom.. the RSSi (signal strength), what band width (20,40,80, 160 MHz) and so on....

 

[TheLyppardMan]

I spent much of my life working with noise/decibels, albeit noise from nuisance neighbours in my role as Senior Technical Officer in Environmental Health, so I should be OK with this I should hope. The term signal to noise ratio reminds me of the old Hi Fi stuff in the 70's and 80's. I can't remember the specific references, but I have a feeling it had to do with the quality of cassette/open-reel tape recordings and pickup cartridges, etc

 

[drinkingbird]

From what I can see, there is still some ongoing debate as to which channels should be used for Wi-Fi, particularly in the 2.4 GHz band.

If I set my ASUS RT-AX88U to “Auto”, it currently chooses channel 8 for the lower band and channel 100 for the upper band (Amazon Fire TV Stick now supports the DFS channels, whereas it didn’t when I checked previously). I also ran a test using my new ISP-supplied router (FRITZX!Box 7530 AX) and that allocated the 2.4 GHz band to channel 6 (I can’t remember which channel it allocated for the 5.0 GHz band, but it was in the region of 130-150 in the DFS channels). So, what is someone like me to make of all this, given the different opinions? I usually set my router to use channel 11, but if I set it to “Auto”, what would be the best way to evaluate the performance of each setting?

I’m uploading a couple of screenshots, showing the nearby Wi-Fi networks. Mine are the top three, which I have named after my new ISP service (Zen Internet) starting later this week.

For 2.4, the 1/6/11 rule doesn't really apply anymore unless you're in an isolated environment that you have complete control over. These days with the saturation of the band, one of the overlapping channels may well have more capacity than 1/6/11.

I leave mine on auto, I used to hardcode but constantly had to change when other routers changed or people in the area moved in/out. Auto works well for me. You can have your router reboot every night which will have it rescan and pick the best channel each night if you want.

For 5G, generally don't use DFS unless you know you're in an area with no radar and the other channels are highly utilized. I leave 5G on auto also and it works fine, though generally hardcoding that will be ok since neighbors signals won't be nearly as strong.

At least on my AC1900 (same as 68u rev C) auto works fine on both frequencies and when comparing using another AP that can do some basic spectrum analysis, grabs channels that have the least utilization.

 

[Tech9]

For 2.4, the 1/6/11 rule doesn't really apply anymore unless you're in an isolated environment that you have complete control over. These days with the saturation of the band, one of the overlapping channels may well have more capacity than 1/6/11.

Indeed. Some people are stuck in Linksys WRT54G era though.

 

[jata]

I do think there is a use case for 160mhz (with caveats). This is for wifi backhaul nodes in an Aimesh setup.

I have an all AX setup (AX86S router with 388.1 merlin + 2 x AX58U nodes running latest stock). I use fixed channel 36 for 5Ghz and channel 1 for 2.4Ghz.

In my setup I have no issues using DFS as no radar near me and I'm not on a flight path. Also very low congestion in my area so low risk of interference.

With 160mhz on, my nodes are connected at a much higher speed - with a 30% increase in actual data throughput over 80mhz.

I have tested this using iperf from a pc (mac) connected wired to my node with the node using wifi backhaul to the router. My iperf server is a RPI4 connected directly to my router with a wired 1Gbit connection.

I did have issues with 160mhz on previous 386 firmware but I think Asus have made some improvements in 388

A couple of other weird (but good) observations I noticed is that:

1. Overall 5Ghz network noise is lower (-86 dBm on160mhz vs -91 dBm on 80mhz)
2. RSSI for the nodes is lower (-68 dBm on 160mhz vs 72 dBm on 80mhz)

So (for me) there are some benefits of enabling 160mhz

 

[Tech9]

I did have issues with 160ghz

there are some benefits of enabling 160ghz

Is this Wi-Fi 10?

 

[jata]

haha sorry. I mean 160mhz.

will update my post to avoid further teasing (and confusion)

 

[TheLyppardMan]

1. Overall 5Ghz network noise is lower (-86 dBm on160mhz vs -91 dBm on 80mhz)

Are you sure you've got this the right way round as I would have thought that -91 dBm was a lower noise level than -86 dBm?

To check my theory, I did a quick Google search and found this:

"The dBm reading you refer to is called the "noise floor" and lower negative numbers are better.

Eg there's an 8dB difference between -85 and -93dBm which means the noise level at 85dBm is roughly 7 times higher than at -93dBm.In practical terms it makes little difference which you choose once its past -80dBm.

As its power rather than voltage we're dealing with then a 3dB difference equates to either a doubling or halving of the signal power.

Eg (again) : 0dBm = 1mW of power; 3dBm = 2mW of power; -3dBm = 0.5mW of power."

 

[jata]

Are you sure you've got this the right way round as I would have thought that -91 dBm was a lower noise level than -86 dBm?

To check my theory, I did a quick Google search and found this:

"The dBm reading you refer to is called the "noise floor" and lower negative numbers are better.

Eg there's an 8dB difference between -85 and -93dBm which means the noise level at 85dBm is roughly 7 times higher than at -93dBm.In practical terms it makes little difference which you choose once its past -80dBm.

As its power rather than voltage we're dealing with then a 3dB difference equates to either a doubling or halving of the signal power.

Eg (again) : 0dBm = 1mW of power; 3dBm = 2mW of power; -3dBm = 0.5mW of power."

Not sure. Above my pay grade. I was just applying same logic as RSSI. Lower negative number is stronger/better.

could be totally wrong. Will keep using 160mhz for now and see how it goes!

 

[TheLyppardMan]

Some odd behaviour with these settings: I tried forcing 160 MHz in auto channel mode and it used the non-DFS channels, but if I set it to auto 20/40/60/80 with DFS enabled, it used the DFS channel 100 but only 80 MHz.

 

[OzarkEdge]

Not sure. Above my pay grade. I was just applying same logic as RSSI. Lower negative number is stronger/better.

could be totally wrong. Will keep using 160mhz for now and see how it goes!

Less negative dBm is stronger power.

160mhz should be 160MHz. m=milli M=Mega

OE

 

[OzarkEdge]

Some odd behaviour with these settings: I tried forcing 160 MHz in auto channel mode and it used the non-DFS channels, but if I set it to auto 20/40/60/80 with DFS enabled, it used the DFS channel 100 but only 80 MHz.

I find I that I need to Apply intermediate ch and bw settings in order to be able to select 'other' final settings. Quirky webUI logic.

When you set 20/40/80, you are setting 80MHz max bandwidth. And you do not force 160MHz bw... you set it and router may or may not use it, depending on RADAR/DFS.

OE

 

[TheLyppardMan]

Less negative dBm is stronger power.

160mhz should be 160MHz. m=milli M=Mega

OE

I thought we were talking about noise levels and not the transmit/receive power. The dB readings work the opposite way to each other (in terms of signal quality), depending on which you are applying them to.