bit error rate calculation

can anybody suggest how to calculate bit error rate for a signal x=cos(wt) transmitted along with random noise, and detected as y.

AWR has an example for that, you can check it.

could you please explain me what is AWR?

AWR is a System and Circuit simulator.If you don't know, forget about it..( It's hard to learn from scratch..
You can also do this simulation with MatLab. I hope you know MatLab..