Hi,
15 feet is kinda pushing it with ir... have you considered normal wireless? or bluetooth?
What?
15 feet is only like 3 m.
15 m should be quite reachable without even trying, 25 m is attainable with a little sweat and using lenses and parabolic reflectors (and skillfull aiming),
1.5 km is possible.
Now try that with Bluetooth