Creating a physical layer with variable data rates?

I am trying to create a very simple physical layer in Simulink with two different data rates. The general diagram of this system would be two different modulation schemes (for example BPSK and QPSK) leading into some simple channel coding, then through a fading function (eg. f(x)) and a AWGN. On the other side of the channel is a channel decoder, and the same demodulation schemes. The variable data rate would be chosen based on the fading function. Is there a way to implement this in Simulink?