A little late to this conversation, but I've been trying to learn about similar things for a residential setup.
I think Ronski makes one key point: otherwise unaided, a client will try to cling on to whatever AP it has itself hooked up to. Even if there is another AP with a better signal available. Even if that AP has the same SSID. Roaming can therefore be a problem.
The better commercially-oriented equipment appears to have features that force a device to switch, or make switching invisible, but I haven't worked out details of how they work, nor how well they work - but nothing appears to be perfect. There are components to the WiFi standards that would help, if only they were widely implemented.
It needs to be noted that roaming has another consequence to behaviour: Commercial AP's seem to be designed to work as a team. There is an expectation that, long before a device gets to the extremities of an AP's range, it would have handed over to a new AP instead. Residential AP's expect to work alone, so expect to need to work with devices at the edges of coverage. These expectations can affect design choices - particularly about the highest power configurations can be.
As an example, Ruckus has a low-end line of "xclaim" models that are meant to be simple to use, and targeted at small businesses. The power available on these models seems to be higher than the new models in the Ubiquiti line (AC-Lite and AC-LR) - yes, higher than Ubiquiti's "long range" model.
Perhaps it is only better to resort to decent commercial equipment when you can expect to saturate the space with plenty of APs - in which case, raw power is not an advantage. Otherwise decent residential equipment is needed - but has to be chosen in the knowledge that roaming will not be easy.
There seems to be quite a set of trade-offs when considering issues of power/range/coverage.
- Aside: An issue I'm seeing with my Xclaim is that I have a choice of channels in the 5GHz band: "anything", or an individual channel. Setting the device to use one of channels 100-140 allows it to use extra power (up to 30dBm is allowed instead of 23 dBm, 1 Watt instead of 200mW), so can achieve better range.
Unfortunately, these channels also require the AP to monitor for radar, so it can sometimes switch channel on you if it thinks it has detected radar. The AP can suddenly switch from channel 100 ... but almost always defaults back to channel 36 or 40 when it does so. This is one that allows less power, so range is reduced. They are also the channels that the neighbour's VM superhubs also seem to pick - so you are more likely to collide.
Anyway ...
I was originally trying to get my wireless working using the same SSID for 2.4GHz and 5GHz, so the devices could choose which to be on. With an AP that should steer devices to 5GHz, this should work well, right?
Things didn't seem to work out that way - but being named the same made it hard to determine whether a device really was on 2.4GHz or 5GHz. Then I swapped to separate SSID's, and suffered from @ronski's problem: the device would hang on to a dire signal at 2.4GHz, when a nearby 5GHz signal was a much better choice.
In the end, I too went for an app to help the situation, rather similar to Ronski's: "5 wifi", which attempts to switch to a 5 GHz signal if decent.
