Does MU-MIMO in wireless AC wave 2 routers work with older wave 1 devices?

[thomash]

I have some questions about the benefit of a Wave 2 router when mixing devices with Wave 1 and Wave 2.

Almost all of my devices use Wave 1, but maybe a new device will have Wave 2.

The available routers from the service provider:
X is Wave 1 2x2 (866)
Y is Wave 1 3x3 (1300)
Z is Wave 2 4x4 (1733) MU-MIMO

If I mix Wave 1 and Wave 2 devices, can Z router still perform MU-MIMO, or it will not work and change back to Single User? Then the only benefit is the extra channel in 4x4 to provide higher bandwidth to more devices?

The Y router 3x3 can handle more bandwidth to more devices than X router 2x2?

Thanks

 

[bill001g]

The mu-mimo is kinda questionable how much it really helps in real world installs. You can show some benefit in certain conditions but I have not seen anyone who has tested with interference from say neighbors.

Most the problem with wifi today are not the signal levels or the bandwidth it is that there is just to many people competing for the same radio space. When you consider a single person with a tri-band router uses almost all the bandwidth by themselves and you have people putting multiple of these devices in their house. In some high density apartments wifi is almost unusable because of all the signals.

What a mu-mimo router is suppose to do it put all the devices that do not support mu-mimo into 1 group and then put other users into the other groups. So the devices that support mu-mimo should get in the other groups.

3x3 vs 2x2 first issue is that your end devices must also have 3 antenna which is not common for things like cell phones. The router quickly switches between different transmission encoding methods when talking to different devices. The number of devices supported is not directly related to the bandwidth though I guess in theory at least if they all supported 3x3 they would spend less time using the radio so more people could share. Most the problem with Wifi is the half duplex and the fact that end devices can many times not actually hear each other and will transmit at the same time and the router will not get clear data from either. The more device you have connected the more chance you have for them to overlap the signals so that tends to limit you before bandwidth does.

 

[thomash]

Suppose there are 2 devices with 2x2, and a router with 4x4, would the router be able to communicate to each of the 2 devices separately, each with its own dedicated set of 2 streams? Whereas if the router was only 2x2, both devices would have to share the same streams and bandwidth to each is cut in half?

 

[bill001g]

To some extent but idea that you can REALLY transmit multiple overlapping signals on the same frequency and then separate them out at the far end is not that simple. Even though the 4x4 would in effect be using 2 2x2 signals it is still say transmitting all that data into say channel 6. The routers with 2 5g radios would actually do better because the signal would not actually interfere because they would be on different radio channels.

This is also why you do not see 100x100 mimo. Every overlapping signal you add diminishes the amount of bandwidth you add. Going from 1-2 adds much more that going from say 2-3 or 3-4. This is all dependent on slight difference in the arrival time of the signals and that is depending on things like how the signal reflects off walls and such.