I want to make a project where people can use waiting room bell to a long distant. Here I want to use IR remote. RF transmitter with arduino will send IR signal as RF and at receiver end RF will be decoded by receiver and will produce sound with corresponding name for specific IR signal.
Have a look at the IRremote library for IR, and consider using nRF24L01 modules for the radio- there's a library called RF24 for that.
I don't see the point in trying to "send IR signal as RF". Is there any real point in doing that? Just send a single character depending on what the IR code is. If the IR code is (and here I'm making this up, I don't know what the actual codes are ) 1234567 send an "x" and if it's 9876543 send a "y". Then when you receive an "x" at the far radio play sound "abc" or play "zxc" if you receive the "y". The actual IR code is irrelevant once it's triggered process.