5GHz channel bandwidth - "20/40/80" vs "80"

[skippy_p]

Hi everyone. Would using a fixed channel bandwidth of 80MHz (for my 5GHz band) instead of the "20/40/80" option make a difference? I've separated my 2.4GHz and 5GHz bands using different SSIDs, and I don't have any devices on the 5GHz band that don't support an 80MHz channel width, although I'm not sure this really matters. I believe that even if a device only supports 20MHz or 40MHz, it will still connect despite the router being locked to 80MHz...correct me if I'm wrong. Would using the 20/40/80 option allow the router to dynamically adjust channel width based on environmental conditions such as congestion, noise, etc? For example, if there's too much noise at 80MHz, the router will automatically adjust down to 40 or 20? If so, I'll stick with that setting; otherwise I'll lock it to 80MHz. I'm already using a fixed channel (ch 149).

Thanks.

 

[Tech9]

I believe that even if a device only supports 20MHz or 40MHz, it will still connect despite the router being locked to 80MHz

Correct.

Would using the 20/40/80 option allow the router to dynamically adjust channel width based on environmental conditions such as congestion, noise, etc?

Correct.

otherwise I'll lock it to 80MHz

I have locked to 80MHz router in a condo apartment with multiple networks around, no issues. It's Synology, but Asus will work as well.

 

[Analog-1]

Stick with locked 80mhz. Also stick with a self picked and locked channel. I find letting a router roam around tends to pick the worse frequency possible.

 

[SkippyP]

Thank you both. Like I said, I’ve already locked the channel to 149. As for channel width, I like the idea of the router dynamically adjusting based on congestion and noise but I also like the idea of locking it down. Decisions decisions!

 

[Tech9]

Like I said, I’ve already locked the channel to 149.

This is what @skippy_p said. Who are you?

 

[SkippyP]

Lol. Same person. I logged into the site from a different device when I created this post, and then replied from my phone. I forgot that I already had an account when I created the new one. And I didn’t realize I had logged into my original account from that other device when I created this post. I guess I have two accounts now!

 

[EPR]

Is the noise and congestion coming from on your/my network or outside surrounding networks?

I'm set on 20/40/80, so just curious if going to 80 might have benefit.

 

[SkippyP]

Been using a fixed 80MHz for my 5GHz band for almost two weeks and everything has been working great. I live in a detached home (corner lot) so I don’t have any interference from neighbours.

 

[sfx2000]

I have locked to 80MHz router in a condo apartment with multiple networks around, no issues. It's Synology, but Asus will work as well.

Synology - you cannot lock a 5GHz channel to 80MHz only with SRM 1.3xx

 

[jayd]

This is exactly what I've been contemplating ever since I got my router. Also heard that it's not a good idea to use 40MHz on the 2.4GHz band if there are a lot of neighbors with Wi-Fi around. And they were right because I downloaded a WiFi Analyzer app on my phone and I can see the majority of them are on that band using 20MHz. You stick out like a sore thumb when you use 40MHz in a crowded area. No channel is free of people here. Lucky are the people that live far apart from their neighbors. Like you I guess.

 

[SkippyP]

@jayd - correct re the 2.4 band…leave that locked to 20MHz. For the 5GHz band, you can try locking it to 80MHz and see how that goes for a while. But if your area is congested, I’d suggest leaving it at 20/40/80.

 

[jayd]

It's interesting because when I leave the 2.4GHz band on auto (20/40), my Android devices choose 20MHz. Does the router or the devices know when the area is congested/crowded? Or do devices just prefer 20 over 40? On 5GHz there seems to be no difference locking it to 80MHz or leaving at 20/40/80. All the devices choose 80. What I'm not sure about is if I should keep 160MHz enabled and leave it at 20/40/80/160. That's how it was in the beginning.

 

[SkippyP]

I believe it’s the router that selects the channel’s bandwidth when it’s set to 20/40 (for 2.4GHz) and 20/40/80/(160) for the 5GHz band, but I’ll defer to the experts to chime in and confirm.

Up to you if you want to keep 160 enabled or not, but my experience with it enabled is that it was far too unreliable. To trigger 160 without using any DFS channels, the router locks to one of the lower channels (36-48). Those channels operate at a lower transmit power compared to the upper channels (149-161)…approx 5x lower! Lowers transmit with 200mW while uppers transmit with ~1W. That results in noticeably less range when using one of the lowers.

I disabled 160 and locked to channel 149 (one of the uppers) and I have excellent signal range throughout the house, backyard, and driveway. My throughput with an 80MHz channel width is consistently 750-780 Mbps throughout most of the house; 500-600 in my backyard; and 300-400 on my driveway.

 

[OzarkEdge]

It's interesting because when I leave the 2.4GHz band on auto (20/40), my Android devices choose 20MHz. Does the router or the devices know when the area is congested/crowded? Or do devices just prefer 20 over 40? On 5GHz there seems to be no difference locking it to 80MHz or leaving at 20/40/80. All the devices choose 80. What I'm not sure about is if I should keep 160MHz enabled and leave it at 20/40/80/160. That's how it was in the beginning.

I've always assumed that clients decide/connect with their best wireless mode, authentication method, and bandwidth permitted by the router. The 20/40/80/160MHz setting lets the router narrow the max permissible bandwidth to reduce interference and maintain throughput... 160MHz/DFS is not a sure thing (for more than one reason) (and requires lower Tx power bands)... 20/40/80MHz will likely permit 80 max most/all of the time depending on your radio space... 80 (fixed/locked) will stay 80 max all of the time... clients will still connect at their max bandwidth permitted by the router.

For the 2.4 band, assume congestion somewhere out there and restrict your use to the minimum 20MHz bandwidth to be courteous.

I cover this somewhat cryptically for my use in my install notes. So for my US region, my 2.4/5.0 max Channel Bandwidth and Control Channel are of 2.4 Fixed and 5.0 Fixed-1,3.

OE

 

[sfx2000]

I can't recommend 160MHz for the 5GHz band for a few reasons...

1) 160MHz is going to need DFS, and in many regions, it's going to have to happen down in the UNII-1 band, where clients may be restricted in Tx power

2) 160MHz effectively cuts the Tx power on the AP down by 3dB - 3dB is half of the Tx power, and this affects all clients, as Tx power covers all channel widths

3) There are AP's and Clients - when going 160MHz channel width, you might find the number of spatial streams cut in half - a 4 stream AP might drop down to 2-streams which affects all clients, and some clients may drop from 2-stream to 1-stream, which effectively negates any benefit of the wider channel.

People obviously are free to explore settings on their own - it's a free country, and your mileage may vary...

 

[sfx2000]

I've always assumed that clients decide/connect with their best wireless mode, authentication method, and bandwidth permitted by the router. The 20/40/80/160MHz setting lets the router narrow the max permissible bandwidth to reduce interference and maintain throughput.

20/40/80 is fine here - 80MHz will define the upper limit, and all client stations are required to support the 80MHz channel width, they are not required to support 160...

As you have noted - just because the AP is set to 80MHz, the clients can dynamically adjust both the number of spatial streams as well as channel bandwidth - mostly to reduce power consumption, but also when out on the edge of the footprint, the client firmware will adjust accordingly for the best rate, usually based on downlink frame errors, along with uplink retransmit requests from the AP.

 

[SkippyP]

@sfx2000 - that’s interesting. So if individual clients can dynamically adjust channel bandwidth, I’m curious as to why even use the “20/40/80” option on the router? Why leave it up to the router to dynamically adjust the channel for ALL clients when individual clients can do this themselves based on their specific conditions? Best to lock the router to 80, no?

 

[L&LD]

Yes. And if you can lock the router to 160MHz bandwidth (in your environment and router's capabilities), it works equally well.

 

[SkippyP]

But locking it to 160 also means using one of the lower channels (36-48) around these parts. And those lower channels have significantly less transmit power, resulting in poorer coverage. Locking to 80 and also locking to one of the upper channels (149-161) would provide a better balance of coverage and performance, no?

 

[L&LD]

Yes. And if you can lock the router to 160MHz bandwidth (in your environment and router's capabilities), it works equally well.