Say I'd like to simulate a certain EsN0 in a baseband OFDM MATLAB modem for SER curves.

I randomize 50 QAM symbols with N subcarriers each in frequency domain, add null frequencies (guard bands) to each symbol, perform IFFT and then add CP. Then I convolve the "time domain" symbols with a certain channel with taps of my choice and then I want to add noise, but I'm not sure about how to normalize it so that it would have the right meaning of EsN0 (Energy per Symbol) and I'll get the theoretical results.

I get funky results with just MATLAB's agwn function with the 'measured' flag.

I'd like to simulate a certain $E_s/N_0$ in a baseband OFDM MATLAB modem to generate SER curves.

I randomize 50 QAM symbols with $N$ subcarriers each in frequency domain, add null frequencies (guard bands) to each symbol, perform IFFT and then add CP. Then I convolve the "time domain" symbols with a certain channel with taps of my choice and then I want to add noise, but I'm not sure about how to normalize it so that I obtain the correct SNR as generally reported in theoretical curves.

I get funky results with just MATLAB's agwn function with the measured flag.