Thanx Dhiman sir for ur kind reply..i think u are asking about the frequency spacing??
i am giving 100 Ghz spacing between the four transmitted frequencies…i am also using wdm mux with 15 Ghz bandwidth..bcoz somewhere on the forum i read it gives u better results so i increazed it to 15 which i think is nt dat much…i hope i am not doing wrong…dhiman sir i hv one query abt plotting graphs for all 4 receivers on the same graph for ber abd q factr…bt m nt able to do it at a time fr all..cn u plz tel me if i can do it..i vil b very much thankful…thanx in advnce