I need to insert an underwater acoustic channel model to an existing code that compared between OFDM and GFDM The acoustic channel model that I have will output the channel impulse response. However, my signal is modulated in frequency domain (by doing fft). Hence, I want to obtain a frequency response of the CIR. Question :


Can I perform FFT on the CIR which give me frequency response and then just multiply my signal with it?
If that is correct, is the diagonal of the multiplication will be my signal after passing through the channel?


 H=fft(h,sys.N);    %sys.N = total data symbols h= CIR
 Sig =H.*tf_ofdm;   %tf_ofdm = input signal
 Signal=diag(output);  %output signal


I am doing FFT with the total data symbols because the CIR has random size every time it is being used.
I modeled the the acoustic channel noise in matlab:

    % On the Relationship Between Capacity and Distance in an 
    % Underwater Acoustic Communication Channel

    Turbulence=17-(30*log10(f));
    Noise_Turbulence=  power(10,(Turbulence*0.1));

    Shipping=40+(20*(s-0.5))+(26*log10(f))-(60*log10((f)+0.03));
    Noise_Shipping= power(10,(Shipping*0.1));      

    Wind=50+(7.5*(power(w,0.5)))+(20*log10(f))-(40*log10((f)+0.4));
    Noise_Wind=power(10,(Wind*0.1));

    Thermal=-15+(20*log10(f));
    Noise_Thermal= power(10,(Thermal*0.1));      



    Noise=Noise_Turbulence+Noise_Shipping+Noise_Wind+Noise_Thermal; 
Ambient_Noise=10*log10(Noise); %the values will be converted into dB