addition of guassion noise and fading simulation is generic to and type od signal .
you need to generate random noise either by command or in simulink .
also by adding delayed ( by particular amount of samples) version of the signal in original signal you can also see the multipath fading effects on your signal.as in equation.
multipath version=s+a s(n-k)
a lies between 0 to 1
k depends upon your model which yuo choose for simulation
more details can be found in simon haykin book for digital communication.