Hi,
I understand that you want to plot Channel capacity versus length plot. The attenuation constant ‘a’ which you have considered in your code effects the trend of the plot. With higher value of ‘a’, the curve gets saturated to a constant value at a lesser length/distance. This relation can be observed from the equation in the image you’ve shared.
One possible workaround may be to consider a lesser value of attenuation constant which could give a smoother curve that decreases with length. I would suggest you to play around with different values of attenuation constant.
From the code shared by you:
SNR = (Pt_transferred - sigma);
where, “Pt_transferred” is in dBm and “sigma” is in dBm. When two values which are in dBm are subtracted the resultant value will be in dB but not in dBm. So, SNR conversion to linear can simply be done using:
SNR_linear=10.^(SNR/10);
For more information, a relevant MATLAB answer on the conversion criteria can be referred from the following link below. Hope this helps you to achieve your desired result!
