You say "switch to 5GHz, but that isn't practical for use with mobile devices" -- is the reasoning that the 5GHz signal doesn't penetrate the walls enough as you walk around with the device?
That is a factor as others have mentioned, but mostly I meant it is just that many mobile devices don't support 5GHz. And you can't just add a cheap USB dongle. That is starting to change though, so check the specs on your devices.
You say "switch to 5GHz, but that isn't practical for use with mobile devices" -- is the reasoning that the 5GHz signal doesn't penetrate the walls enough as you walk around with the device?