What is MU-MIMO

MU-MIMO

MU-MIMO was introduced with the wave 2 version of the 802.11ac wireless standard and this  is a feature that's used in modern wi-fi routers. And what this does is that it allows multiple  wireless devices to communicate with a wi-fi  router at the same time. Now previously routers  communicated with devices using SU-MIMO which stands for single-user, multiple input, multiple  output. Now this was used with the previous wireless technology which was 802.11n. Now this  also allowed wi-fi routers to communicate with  multiple devices but only with one device at a  time. So each device would have to wait their turn to communicate with the router. So as more devices  connected to the wi-fi router, congestion happens. Now this is not really a big deal if these  devices were just using low data applications such as browsing the internet. However if  they were using high data applications, such as streaming videos, then the result  would be a slow down in the internet speed 

MU-MIMO

which would cause lag and buffering. So basically  SU-MIMO works on a first come first serve basis. However a router that's usingMU-MIMO all the  devices that are connected to it won't have to wait their turn because it allows communication  to multiple devices all at the same time. It breaks up the internet bandwidth and pushes it  to the connected devices. So with this technology  you will see a significant improvement in the  speed of your internet especially if you're doing things that require a lot of bandwidth,  such as streaming videos or downloading. It reduces lag to the connected devices because  the connection is never interrupted, which increases performance. So it's almost as  if each device had their own separate wi-fi router. So if you have a lot of wireless devices  that demand a lot of bandwidth in your home and you're experiencing slow internet performance  or choppy video, you should be using a router with MU-MIMO technology. Now MU-MIMO also takes  advantage of beamforming. Now beamforming is a technique that sends transmissions in a  specific direction which strengthens a signal. 

MU-MIMO

But without beamforming, the transmission is sent  in every direction which can weaken the signal  and this is what happens in older routers. But  with newer routers, the signal is directed to the devices that are connected to it. So basically  you can compare this technique to a flashlight versus a lantern. A lantern works without  beamforming, where light is spread out in every direction and not towards a specific device.  But a flashlight works similar to beamforming. where the light is specifically aimed at a  certain direction and targets specific devices. Now MU-MIMO routers come in different variations.  So for example, they may come in 2x2, 3x3,  or 4x4 versions. And these variations refers to  the number of streams that are created. So a 2x2  device means that it has 2 antennas that are  used for 2 simultaneous streams. A 3x3 device means it has 3 antennas for 3 streams.  And a 4x4 device will have 4 streams. Now this doesn't mean that you can't add more devices.  So for example, on a 4x4 router if you add a fifth device, then that just means that a stream  will have to be divided and shared with another device. But with the new wi-fi 6 it will have even  more dedicated streams for your devices. So the more devices you add, the streams won't have to be  shared as much. In fact some newer wi-fi 6 routers can support 12 simultaneous streams, with 4 streams  on a 2.4 GHz band and 8 streams on the 5 GHz band. 

MU-MIMO

Now not all wi-fi routers will support MU-MIMO.  Because in order to have this technology, the router must support at least the 802.11ac wave  2 standard which is known as wi-fi 5. Because the previous versions, such as the 802.11a, b, g,  and n, do not support it. And the router must specifically state that it supports MU-MIMO. And  also the devices that connect to this technology must also support it, which most modern devices  today already do. And in addition they also 

need to be able to connect to the 5 GHz band  because MU-MIMO only works in 5 GHz in wi-fi  5. So older devices that can only connect to  the 2.4 GHz band will not be able to take  advantage of MU-MIMO. And another thing  to remember is that MU-MIMO only affects  the download link and not upload and it only  supports a limit of 4 simultaneous streams.  However with the new 802.11ax standard,  which is known as wi-fi 6, it works both  in 2.4 GHz and 5 GHz and it can  support 8 or more simultaneous streams  and as I said before, with some of these newer  routers it can support 12 simultaneous streams.