Any Downside To Enabling Multi-User MIMO and OFDMA/802.11ax MU-MIMO?

[Morris]

I said minimal overlap, not no overlap. Besides, if the APs can't hear each other there is really no need for them to avoid each other. In reality, in the home environment, it is unlikely you could turn these Asus routers down low enough in the GUI that they won't see each other. Your clients will lose "sight" of them long before they'll lose each other. Just as many problems can be caused by two nodes too close to each other with too much power as ones that are too far away.

Best WiFi design with minimal overlap has circles around the APs that overlap just enough to leave no holes, they circle comes nonplace near the adjacent AP. This is accomplished by Propper AP placement and power levels. This is WiFi design 101

 

[drinkingbird]

Best WiFi design with minimal overlap has circles around the APs that overlap just enough to leave no holes, they circle comes nonplace near the adjacent AP. This is accomplished by Propper AP placement and power levels. This is WiFi design 101

Agreed - that's exactly what I was saying. Of course for the average home user, getting that exactly right probably isn't possible, but with trial and error you can minimize major overlaps.

 

[pgershon]

Isn't there also a question of speed? From my experience, the placement necessary to create the overlapping circles for 2.4 WiFi will leave holes in 5 gHz coverage. And similarly, getting good 5gHz coverage, which has been my goal, leaves lots of overlapping 2.4 zones.

 

[Morris]

Isn't there also a question of speed? From my experience, the placement necessary to create the overlapping circles for 2.4 WiFi will leave holes in 5 gHz coverage. And similarly, getting good 5gHz coverage, which has been my goal, leaves lots of overlapping 2.4 zones.

It depends on your applications and design goals. In most cases, I'd think 2.4-GHz client need coverage and 5-Ghz might need speed and of cause you don't want holes. With your 5-GHz application's speed needs in mind, design for appropriate coverage to provide the necessary speed. Overlap in the 2.5-GHz band will affect when a client will change APS. This may not be matter as those old clients are probably IOT with basic connectivity as there only need.

 

[pgershon]

Thanks. That’s basically the route I took. I have one problematic room on the wing of my house. The wing has two bedrooms and a bath in between. I put an AP in the nearer bedroom room and it gives coverage to center of house / stairs and sometimes the far room. RSSI values on 5gHz in the far bedroom are in the -85 area. Trying to supplement with 5gHz AP in far bedroom too, and using different fixed channel on 5gHz for it. My issue is getting devices that are connected to the near bedroom to release WiFi and connect to the stronger signal in far bedroom. I have used the ASUS roaming assistant, set to release when wifi is less than -65, but I see iPads staying on the ASUS network at RSSI -77 despite being in proximity to strong signal in far bedroom (other AP is a TP-Link EAP670).

 

[drinkingbird]

Thanks. That’s basically the route I took. I have one problematic room on the wing of my house. The wing has two bedrooms and a bath in between. I put an AP in the nearer bedroom room and it gives coverage to center of house / stairs and sometimes the far room. RSSI values on 5gHz in the far bedroom are in the -85 area. Trying to supplement with 5gHz AP in far bedroom too, and using different fixed channel on 5gHz for it. My issue is getting devices that are connected to the near bedroom to release WiFi and connect to the stronger signal in far bedroom. I have used the ASUS roaming assistant, set to release when wifi is less than -65, but I see iPads staying on the ASUS network at RSSI -77 despite being in proximity to strong signal in far bedroom (other AP is a TP-Link EAP670).

Roaming assistant and similar tricks can only kick the client off. The client is welcome to reconnect to the same AP immediately after. Apple devices are known to be particularly "sticky".

 

[Morris]

Thanks. That’s basically the route I took. I have one problematic room on the wing of my house. The wing has two bedrooms and a bath in between. I put an AP in the nearer bedroom room and it gives coverage to center of house / stairs and sometimes the far room. RSSI values on 5gHz in the far bedroom are in the -85 area. Trying to supplement with 5gHz AP in far bedroom too, and using different fixed channel on 5gHz for it. My issue is getting devices that are connected to the near bedroom to release WiFi and connect to the stronger signal in far bedroom. I have used the ASUS roaming assistant, set to release when wifi is less than -65, but I see iPads staying on the ASUS network at RSSI -77 despite being in proximity to strong signal in far bedroom (other AP is a TP-Link EAP670).

I lead a group that built one of the first campus wireless networks in 2000 and we won an Intel award for the network implementation. Apple devices did not work properly on WiFi back then and it's sad to learn that they still don't. It is the client's job to chose what AP to connect to and when to roam. You should complain to Apple and start an add campaign to get every Apple user to complain and then after another 23 years they might just fix it. My android phones and tablets and also Windows Laptops roam as they should. Don't use roaming assistant as all it dose is cause client drops.

 

[drinkingbird]

I lead a group that built one of the first campus wireless networks in 2000 and we won an Intel award for the network implementation. Apple devices did not work properly on WiFi back then and it's sad to learn that they still don't. It is the client's job to chose what AP to connect to and when to roam. You should complain to Apple and start an add campaign to get every Apple user to complain and then after another 23 years they might just fix it. My android phones and tablets and also Windows Laptops roam as they should. Don't use roaming assistant as all it dose is cause client drops.

Roaming assistant/minrssi works fine as long as you understand it's strengths and weaknesses. Except apparently on apple devices, but that's not an issue for me.

 

[pgershon]

DOnt get me wrong - it works sometimes on Apple devices - not consistently. After an hour or so, the iPad finally switched APs.

 

[sfx2000]

FWIW - whethers it is DL/UL MU-MIMO or OFDMA - the AP can advertise the capabilities, but it's also the client that suggests what it can do on the probe request...

One really has to look at the Association_Response Message to see what the client and AP decide to actually do...

MU-MIMO gets a bad shake, mostly due to early 802.11ac (WiFi5) implementations with Broadcom, where if Downlink MU-MIMO was enabled on the AP side, some clients (mostly broadcom based mobile chipsets) would go into single stream...

Regarding WiFi 6/6e, there are challenges across different operating systems and clients for discovery of the 6GHz network, and even there, if common SSID, features and capabilities - 6e requires the network to be either WPA3 or nothing, whereas the "legacy" and I hate to say that work with WIFi6 - 2.4 and 5GHz has more options...

Things are getting a bit better on the AP side, but clients do need some work, mostly as the OS level, Apple/Google/Microsoft and even the GNU-Linux community - it's the chipset drivers, the WiFi supplicants, pretty much everything...

 

[Volt]

Just for information, I tested various MU-MIMO/OFDMA settings today on RT-AX56U (2x2, 80MHz) by running iperf (over Wi-Fi) between Galaxy S21 and a Dell laptop with AX211, and noticed that with the "DL/UL OFDMA + MU MIMO" setting, I get the slowest speeds between two Wi-Fi6 devices - only about 100-120MBits/s (channel 100, no other APs using this channel in vicinity). The best result is with "DL OFDMA" or "Disable" - approx. 260-270 MBits/s. Maybe this is model-specific and routers with more spatial streams do not have this issue, but that's what I got in my tests.