[SOLVED] is it possible to have 4x4 MIMO with 80+80MHz in Wifi 5GHz?

[natiya3]

I've read this: "An AP with 4 antennas shall run on MIMO 4x4 mode, unless when it needs the maximum bandwidth and request 80+80Mhz. in that case, it shall run in MIMO 2x2 mode for each one of the channels"

But I don't understand: can we get more throughput using 2x2 MIMO with 80+80MHz than doing 4x4 MIMO with 80+80MHz? Or maybe is not possible to do 4x4 MIMO with 80+80MHz?

 

[bill001g]

Not sure that is likely some proprietary implementation.

The latest 802.11ax (ie wifi6) can use 160mhz channels. It can also run 4x4 mimo on that. I am pretty sure it can split the 160 over 2 blocks rather than contiguous but it still runs as 1 communication. I not have spent the time to understand it but it appears it can skip blocks that get interference. It would get more total bandwidth running 4x4 over the 80+80 and that is one of the supposed big advantages of this new wifi.

What you are talking about sound like more deception by wifi manufactures. What they likely mean is running 2 devices one on each 80mhz block at 2x2 mimo will give more bandwidth. Key is it is 2 different devices. This is the same crap as them adding together the speeds of the 2 5g radios in a tri-band router.

In some ways it makes sense since trying to cram 4 overlapping signals into a radio channels is much harder the 2.

If you are even considering stuff like this I would buy the new wifi6 equipment since that is at least based on a standard. It is so new it is hard to say if it is going to live up to all the hype.

 

[natiya3]

Not sure that is likely some proprietary implementation.

The latest 802.11ax (ie wifi6) can use 160mhz channels. It can also run 4x4 mimo on that. I am pretty sure it can split the 160 over 2 blocks rather than contiguous but it still runs as 1 communication. I not have spent the time to understand it but it appears it can skip blocks that get interference. It would get more total bandwidth running 4x4 over the 80+80 and that is one of the supposed big advantages of this new wifi.

What you are talking about sound like more deception by wifi manufactures. What they likely mean is running 2 devices one on each 80mhz block at 2x2 mimo will give more bandwidth. Key is it is 2 different devices. This is the same crap as them adding together the speeds of the 2 5g radios in a tri-band router.

In some ways it makes sense since trying to cram 4 overlapping signals into a radio channels is much harder the 2.

If you are even considering stuff like this I would buy the new wifi6 equipment since that is at least based on a standard. It is so new it is hard to say if it is going to live up to all the hype.

but if the 2x2 MIMO with 80MHz refers to 2 devices, that will be MU-MIMO instead of MIMO, right?

 

[bill001g]

Mu-mimo is mostly smoke and mirrors. It more a matter of semantics based on the definitions of "simultaneous" you want to use. Say a router has 100mbps of bandwidth and 2 machines each which has a 1500 byte packet to send. Lets also assume mu-mimo can actually split this 100mbps into 2 equal parts...which it can't. So you have the option of sending pc1 at 100mbps and then pc2 data at 100mbps. Or you can send pc1 and pc2 data at 50mbps. In the end the data transfer takes the same amount of time. The difference is pc2 has to wait .0012ms more for his data to start being sent in the first option. In the real world mu-mimo makes so little difference most people can't even tell.

You have to be very careful a lot of this stuff has changed in wifi 6. It has the actually ability to chop the bandwidth up into sub channels. Again it has not been around long enough to see how much this really help when you look at real world installations.