Devices on roaming network not connecting to nearest access point

Jeremy, you are just on the target here!

The device should measure quality of the service needed at the different APs and choose the one that can provide the service with best quality

This is exactly what a phone in a 3G or LTE network do, it finds the best base station all the time.

I guess the WiFi network standard is to stupid to measure quality of service in a good way, only avaliable service seems to be: Start look around for another AP if your signal strengths starts falling down to a certain limit (set by the manufacturer). What irritates me most is the case when my iPhone 5S take the decition to turn my wireless off too late instead of using 3G or LTE. It does that at a very very low WiFi threshold (when I am far away from my house) it totally destroy my over all user experience. Be able to set this threshold would be awesome.

I have seen some articles about coming standards like carrier grade WiFi and Hotspot 2.0. But I think it should be able to solve the roaming network issue better already now, at least if the user have an "apple only" environment.

Stuart, I found this article stating -70dBm for iOS8

iOS 8: Wireless roaming reference for enterprise customers - Apple Support

also "iOS 8 selects target BSSIDs whose reported RSSI is 8 dB or greater than the current BSSID’s RSSI if the client is transmitting or receiving data. Clients not sending or receiving data, for example sitting idle in a pocket, use a 12 dB differential."

Interesting article, but it is not talking about normal WiFi in a normal home environment.....instead, it talking about enterprise service, used by a tiny fraction of home users.

As far as iOS8 in a home environment, the iPad here continues to refuse to switch access points as it moves from one end of the house to the other. My 5 year old Mac laptop switches consistently, quickly, and reliably as it moves about.

I had the same problem. You are repeating yourself without diagnosing the actual issue OP is dealing with.

I have a roaming network. My older Airport Extreme recently died after seven years of service. I replaced it with the newer, wider-range Airport Extreme.

With this new Airport Extreme, from the far end of my property, the Airport Extreme can actually reach my office (the old one could not at all), where I located an ethernet-connected Airport Express to extend my network using the Roaming Network configuration.

However, my Internet speeds plummeted with the new Airport Extreme. I opened Airport Utility to see if I could figure out what was up. My Mac is a client of the Airport Extreme 150 feet and five walls away. My iPhone is a client of the Office Airport Express 5 feet away. My iPhone gets 20 MBPS download speed. My Mac gets 1 MBPS- BECAUSE IT IS DIRECTLY CONNECTED TO THE AIRPORT EXTREME FAR FAR AWAY.

Yes, it is "one seamless network" but no the switching logic does not evidently guarantee each client device negotiates a connection with the best possible base station on the network.

I've googled the **** out of this and there does not seem to be any user-facing way to prioritize the strongest signal base station. It's a bummer. I had to create a second network with a different SSID to make it work.