2x2 vs 1x1 MU-MIMO on RAX 120 vs RAX 80

[sahils]

Hi everyone,

I notice that the RAX80 supports "streaming on up to four 1x1 devices at the same time"  while the RAX120 supports "four 2x2 devices".

1. Is someone able to help me to understand why there is this difference? Both devices have 8 antennas but the RAX80 supports 8 streams while the RAX120 supports 12 streams?

2. How would this impact me (having RAX80 vs RAX120) as I migrate to WiFi 6 devices? I notice that devices being released nowadays often support 2x2 MU-MIMO (e.g. smartphones, tablets). Will the RAX80 also support 2x2 devices?

[plemans]

RAX80: has 4x 2.4ghz antenna and 4x 5ghz antenna 

RAX120: has 4x 2.4ghz antenna and 8x 5ghz antenna. 

The RAX120 is a 12 stream versus the RAX80 is an 8. And the extra 4 are in the 5ghz band for 5ghz mu-mimo

[sahils]

Ah okay noted, thanks. But since RAX80 supports four streams of 1x1 devices, what about my 2x2 devices? Will RAX80 send 2 streams to my 2x2 devices? If so, how many 2x2 devices can it concurrently support?

[plemans]

If it can support 4x concurrent 1x1 devices then it should be able to support 2x 2x2 solutions. 

You can have more devices running at the same time because they're usually rarely transmitting at the same time. 

[sahils]

Right, makes sense, thanks! One more question - how do the streams work when older (non WiFi 6) devices are on the network?

[plemans]

both the access point and the client need to support mu-mimo

https://www.networkcomputing.com/wireless-infrastructure/mu-mimo-reality-check

[zeilsteen]

Yes and I tested with the RAX 120 and you can not use the 8x8 if you don't have a client that does 8x8 sounding.

I used two 4x4 clients ACwave2 with MU-MIMO enabled. And that is not using the 8x8 mimo. Only 4x4.

Also 3x 2x2 ac wave 2 with MU-Mimo enabled does not have any speed benefits from the 8x8 in throughput in my test.

So you buy into the future with this router I guess.