If you can get an Access Point Per (AP) per floor, then connect them to the same router/switch. You can then use the "Bridge" function with the AP's to make them all the same network, that way you dont have to reconnect to a new AP each time you go to a different floor. The Bridge function should basically make switching APs an automatic thing. Something you might try first is just getting a single one of those APs and see if it can penitrate the concrete floor/cieling. If it can then that is pretty much all you should need to do. But if it cant, or has a week signal, then you can always buy more.