So i was looking at some new NANOHD ap for my house and began reading up on MU-MIMO and there are some conflicting reports on how it works and clients needing support for it also.
https://unifi-nanohd.ui.com/
If you do not need to increase throughput to one device but instead are looking at being able to serve multiple devices at the same time. Would MU-MIMO allow this or do all the devices have to support that standard? Many of the articles i have read are all based on gaining throughput to a single device and that device needing to support it. I am looking more towards serving multiple devices at the same time on an AP that has high traffic. Any related links or people out there who deal with this in real world situation let me know what you think and or have seen.
MU-MIMO allows downloads to multiple devices simultaneously at fraction of speed if both devices and AP support it.
e.g. if you have 2 devices you could just as easily transmit to one, at full speed (instead of half) and then to another at full speed (instead of half).
It’s really not the thing that cures cancer like marketing would like you to believe it was
…that said, wave 2 ac consumer devices that are all 4x4 MU-MIMO and other fancy acronyms, are expected to have better radio firmware and are expected to have evolved and hopefilly improved their antenna design for handling all kinds of 802.11ac (and usually they do)
uap nanohd itself is actually a really really nice ap that does 802.11ac regular mimo really really well (as well as mu-mimo that’s of limited use)
So although there are 4 antennas for 5ghz in the nano it still has to split the bandwith between the devices talking to it at that particular time?
So heres the problem with this grandiose idea from a radio engineers perspective. It doesnt work in practice even if both devices support it. The primary issue is while multiuser mimo adds multiple access capabilities to mimo it doesnt really talk to two devices simultaneously. What it does is in 802.11ac and earlier standards is that it allows you to send multiple messages (unidirectionally) in different spatial streams because thats what OFDM allows it to do. The problem with this comes down to something I dont expect most to know and that is channel precoding. In order to properly take advantage of it you would have to do something called Space Division Multiple Access and this happens in AC particularly where things are split over spatial streams. It can also use the same precoding by telling the clients to return with it and multiple receive but the clients themselves still send one at a time. So far MIMO has been station only effectively but ax changes that. Furthermore the antenna must be explicit designed this i.e the multiple antenna array must all have the same wavelength spatial separation etc otherwise the precoding fails. So its a bit fragile. Not to mention even if a device is using multiple spatial streams to talk only one device can still talk at a time. Its why MU-MIMO did not help wireless AC much
This however changes in 802.11ax (ratified). OFDMA allows for full multiple access support in the modulation mechanism. This translates to taking advantage of MIMO.
However in prior standards it was minimally effective at best from real world testing. Which is ultimately fine since what you are concerned with is throughput and bandwidth anyways
Ok so what I am gathering from this is I need to stick with my ac lites and wait a few years for ax to take a hold and get the bugs worked out?
That would be your wisest decision yes
In fact waiting for technology to mature is usually the best decision as a whole. Its the approach the enterprise sector makes most often. They dont buy HD’s because they are HD’s they buy it for the mature management software
@sanfordvdev and @risk ive yet to expand our radio wikis to talk about them. This is a WIP
Best way to support more devices if you really need to, is to get another additional access point and install it close to where you need wifi, or even next to existing one (not glue them together but 0.5m close) and give it another set of non overlapping channels.
Basically you’re stuck on 350-500mbps max over wifi, unless you have fancy laptops or desktops on wifi and think you can use 3x3 or 4x4 or VHT160 today (probably not I’m guessing).
802.11ax (WiFi 6 , ugh) devices are just starting to show up - my best guess: you don’t have to think about upgrading APs until late 2021.
This is a very accurate statement. I am drafting posts on both MIMO and WiFi 6 so haha its funny you have the same logic 