How to Include an EPA Channel in Shannon Capacity Simulation

Masters!

Please, how could I include an EPA channel in the simulation of the Shannon boundary. The simple code below was simulated for AWGN channel.

BW = 20e6;

snr_dB = -10:0.01:20;

snr = 10.^(snr_dB/10);

Rb = BW*log2(1+snr);

plot(snr_dB,Rb);

For Rayleigh fading channel:

BW = 20e6;

snr_dB = -10:0.01:20;

snr = 10.^(snr_dB/10);

Rb = BW*(exp(1./snr).*expint(1./snr)/log(2));

plot(snr_dB,Rb);

Thanks in advanced. My sincere regards.