Well, you could just use a more powerful laser and make your own line-of-sight - that's the Skunk Works approach.

Seriously, there is one technique that uses inexpensive ASK hardware but double modulates the signal. Philips uses it with the RF on their top of the line Pronto touch screen universal remotes. It is explained briefly at the bottom of this web page...
If you know anyone with an RF signal strength meter, you might be able to get an idea of the noise frequencies you are dealing with.