Best thing to do us to run the 1522 in AP mode and run a wire from the host router to the 1522. Run the 5Ghz radio on the 1522 if your connecting devices support 5Ghz. Be aware that 5Ghz is susceptible to building materials, walls, doors and such and will lower the signal strength. Due to the high frequency of 5Ghz, it's best to be line of site or maybe one wall away. You can use the same SSID as the AirPort Extreme, however just make sure the channel is different on between the 2 wifi's.
FYI, Having so many other WiFi routers using 2.4Ghz near by is causing WiFi congestion and thus free, clear and open channels are being used up and thus causing router disconnection as the routers are trying to find a good channel to use. We are seeing this in more populated areas.