MIMO and Client count for an Access Point

[nips]

Hi,

As per the MU-MIMO definition AP can serve simultaneous multiple clients in same time. If it is 4x4 AP, it can serve 4 number of simultaneous clients same time. In theory it says maximum per radio 200 simultaneous users can be connected to a AP, then all simultaneous users are 400. I have a confusion what is the difference between MIMO simultaneous users and AP simultaneous users. Could anyone please explain this ?

[Rich R · Accepted solution]

You're confusing connected/associated users which have joined the AP with the number of users which can simultaneously transmit/receive to/from the AP.  MU-MIMO addresses the latter which is about managing the radio bandwidth/throughput at any given moment. It's a fundamental basis of WiFi that the airwaves are a shared medium so you can never have every client tx/rx at the same time.

[Haydn Andrews · Accepted solution]

the 4x4 also refers to spacial streams some clients use more than 1 things like laptops may be 2x2 so in that case 2 clients at same time.

As stated before the difference between connected and transmitting clients 

[nips]

@Rich R  @Haydn Andrews  Thanks for your clarifications. 

That means although many number of users are connected to the AP, only the simultaneous users that are allowed in MIMO can transfer data at the same time. What about others who want to transfer data? Do they need to wait until the airwaves are free from currently using clients ?

[Rich R]

Short answer - yes. 
That's what the WiFi 802.11 standards are all about and there have been various enhancements and improvements over the years which is what all the suffix letters after 802.11 are,

https://en.wikipedia.org/wiki/IEEE_802.11