50 Android smartphones + ASUS RT-AC5300

[sfx2000]

Just it's Mac only, while I'm a Ubuntu user.
So
sudo iw dev wlan0 interface add mon0 type monitor flags otherbss
sudo ifconfig mon0 up promisc
sudo iw dev mon0 set channel

are my good friends

quick check on ubuntu - depends on the driver, but sudo iw <interface> scan is pretty handy...

 

[niemion]

One of the nice things that Asus has done is to enable the QBSS load stanza in the beacon frame - this shows number of client stations associated, and the channel utilization... this can help with determining overall loading (it's not the only indication, but it's good for a quick glance). Depending on what tools are on hand (screenshot below is from WiFi Explorer on Mac) - Wireshark can show this as well from a wireless PCAP file...

I have now done some testing with 24 Samsung Galaxy S7 (802.11 a/b/g/n/ac, dual-band) devices. All devices were spread in a range between 8 - 14 meters from the router.

12 were connected 5 GHz radio #1.
12 were connected 5 GHz radio #2.

WiFi Explorer reported up to 79 % utilization on 5 GHz radio #1 and up to 80 % utilization on 5 GHz radio #2.

What do you think of this? Video streaming on all devices were running very well, but I guess that adding access points is unavoidable if we were to extend from 24 devices to 50.

 

[drabisan]

If, and only if, you don't see any other SSIDs in the area of your channel (or channels if you're using 40 or 80MHz channeling space) you can add some more devices to radio #1. And monitor channel utilization.
To control even better the spectrum, make sure you're using only 1 channel (exclude channel bundling as it give little to no benefits for your setup/use only 20MHz Channel bandwidth as is called in Asus firmware) and load devices all the way to the point you're loosing streaming. That would be max you can get to and from that point forward repeat for radio #2 and, eventually, a new router on another channel per radio.

 

[sfx2000]

I have now done some testing with 24 Samsung Galaxy S7 (802.11 a/b/g/n/ac, dual-band) devices. All devices were spread in a range between 8 - 14 meters from the router.

12 were connected 5 GHz radio #1.
12 were connected 5 GHz radio #2.

WiFi Explorer reported up to 79 % utilization on 5 GHz radio #1 and up to 80 % utilization on 5 GHz radio #2.

What do you think of this? Video streaming on all devices were running very well, but I guess that adding access points is unavoidable if we were to extend from 24 devices to 50.

That traffic load sounds about right - which goes back to my original concern about airtime...

Quick question - MU-MIMO enabled or not?

2nd Quick question - IGMP Snooping enabled or not?

 

[Shonk]

If, and only if, you don't see any other SSIDs in the area of your channel (or channels if you're using 40 or 80MHz channeling space) you can add some more devices to radio #1. And monitor channel utilization.
To control even better the spectrum, make sure you're using only 1 channel (exclude channel bundling as it give little to no benefits for your setup/use only 20MHz Channel bandwidth as is called in Asus firmware) and load devices all the way to the point you're loosing streaming. That would be max you can get to and from that point forward repeat for radio #2 and, eventually, a new router on another channel per radio.

using only 20mhz of spectrum for each radio is stupid and you are limiting the peak bandwidth between said devices and the router
s7's can connect at 866mbit on 5ghz and like 192mbit on 2.4ghz

i would try 20 on one radio at 40mhz 20 on another at 40mhz
and 10 on the 2.4ghz radio at 20mhz/40mhz

 

[drabisan]

using only 20mhz of spectrum for each radio is stupid and you are limiting the peak bandwidth between said devices and the router
s7's can connect at 866mbit on 5ghz and like 192mbit on 2.4ghz

i would try 20 on one radio at 40mhz 20 on another at 40mhz
and 10 on the 2.4ghz radio at 20mhz/40mhz

A single channel in 5GHz with OFDM modulation (802.11ac) is teoretical 450mbps.
And that's plenty of bandwidth for a 1080p stream.
The reason I said 20MHz is to keep the spectrum as free as possible and to be able to avoid any unwanted interference.
For ex: using only channel 36 in 20Mhz on one radio gives you no interference whatsoever in using channel 44 on another radio. But while bundling 36 and 40 on a 40Mhz "leaks" a bit on channel 44.
But that's the theory. Why anybody would build an adapter capable of 160Mhz spacing on a low CPU device? The only answer is: cause it can, but is useless in the real world.

And I learned if you don't need more resouces for a certain task, do not allocate it and use it for some other task.

 

[Shonk]

your not thinking of the big picture though 20mhz of spectrum shared between 20 devices
40mhz of spectrum will half the load at each given frequency e.g. each device will get twice as much
throughput even if the spectrum is overloaded in comparison to 20mhz

e.g. if 20x20mhz devices can pull 3mbit each at the same time 20x40mhz should pull 6mbit each

A single channel in 5GHz with OFDM modulation (802.11ac) is teoretical 450mbps.
And that's plenty of bandwidth for a 1080p stream.
The reason I said 20MHz is to keep the spectrum as free as possible and to be able to avoid any unwanted interference.
For ex: using only channel 36 in 20Mhz on one radio gives you no interference whatsoever in using channel 44 on another radio. But while bundling 36 and 40 on a 40Mhz "leaks" a bit on channel 44.
But that's the theory. Why anybody would build an adapter capable of 160Mhz spacing on a low CPU device? The only answer is: cause it can, but is useless in the real world.

And I learned if you don't need more resouces for a certain task, do not allocate it and use it for some other task.

 

[drabisan]

I'm not arguing with your arguments here.
One of many problem in today's wireless world is the "all-in" concept.
No matter how much data a client/AP needs to send, it will use the channel/channels. And that's perfect into a constant bit-rate transmission and it's a PITA in a variable bandwidth transmission (ex. Youtube, Netflix).
And this rises a different discussion on a high density environment. And unfortunately there's no solution to suit all possible requests. In some cases highest possible bandwidth is the solution, in other cases containing the transmission in a channel and spreading the clients over many APs each using only one channel is the solution. Ultimately the number of available channels is the one it is and the right balance needs to be achieved for every use-case.

 

[sfx2000]

I don't think OP has a bandwidth problem - whether 80, 40, or even 20MHz channel (well, maybe 20MHz, but there still other AC improvements there) - but he's running into a capacity issue, which is noted by his utilization numbers...

Since all his devices (Samsung GS7) are MU capable, it would be interesting to see the numbers with MU enabled and disabled to see if there is a change in the overall channel utilization.

 

[niemion]

I don't think OP has a bandwidth problem - whether 80, 40, or even 20MHz channel (well, maybe 20MHz, but there still other AC improvements there) - but he's running into a capacity issue, which is noted by his utilization numbers...

Since all his devices (Samsung GS7) are MU capable, it would be interesting to see the numbers with MU enabled and disabled to see if there is a change in the overall channel utilization.

MU-MIMO
Default settings. I believe it is enabled in Merlin firmware RT-AC5300_380.65_2, but I will check later today and test it on / off.

IGMP Snooping
Default settings. Let me check later today.

Channels and bandwidth are set to auto. It picks 80 MHz by default in the area that we tested in, which causes slight overlapping (see screenshot). We are testing at an entirely different location today. Do you suggest setting it at 20 or 40 MHz instead?

 

[niemion]

Have just checked and both Multi-User Mimo and IGMP Snooping is disabled.