Thanks Sam and Alistu. You both have been great help.The frequency spacing problem has been solved now. The last thing is I am unable to plot the graph i.e BER curve against received power. Afterrunning simulation for 5 iterations, when I plot the graph I get the attached plot. It does not look like its a water fall.
In previous posts Damian had mentioned that by changing the sequence length you can obtain it easily but I am unable to obtain it. Please take a look at the attached graph.