qpsk en matlab
If you are using Matlab, you can simulate in complex domain, so for qpsk, you just use exp(j(wt+phi)) to represent your signal, where phi is the phase. Many communication system simulation is performed in base band equivalent, so just exp(j phi) will do.
And at the receiver, you only have noise corrupted signal(w/wo fading), so you need to make decision based on the received signal. Usually, it's based on phase. If there is fading involved, you need to get the channel information by pilot symbols.