I looked into Ubiquiti options and apparently all their wireless devices require this "controller" you mentioned. It's either software or additional expensive hardware. If they have a simple plug in wireless add on, I haven't found it. This pretty much makes Ubiquiti wireless a non-option for me. Seriously, what kind of company has these kind of requirements for software in 2018? Java? Google? Really? I guess I'll have to look into other options.
As I said, this is starting to get into enterprise networking territory. It add complexity but you also get added benefits. If this is kind of stuff is beyond your knowledge, then avoid it.
Part of my job is designing networks for a living. We set this kind of stuff up for clients so they just use it and it works, but there is a lot of planning and expertise that goes into it in the beginning.
It doesn't actually have to run continuously for basic operation - despite what Halcyon said
Once again, you have failed to read and/or understand what I've said. If you read back to what I said, I mentioned the access point or points
get their config from a controller at boot-up and the controller manages the wireless network. On other enterprise networks such as Cisco, Motorola and Aruba, the controller continuously monitors the wireless network and makes adjustment in real-time, particularly in relation to channel selection, IDS/IPS etc...
The Ubiquti AP's can run without a controller but only once the initial boot has completed and it has received the config from the controller, from that point they continue running as per the config until such time a reboot happens. However these are not autonomous access points, they are still managed radios. Autonomous access points either store the config themselves and restore it during boot or they feature their own built-in mini-controller of sorts (such as the Arubu IAP series).