rayleigh_fading.m

這個檔案裡面的matlab的m函數

function [Ts, z_dB] = rayleigh_fading(f_D, t, f_s)

if f_s<1000,f_s=1000;
end
N = ceil(t*f_s);
Ts = linspace(0,t,N);
if mod(N,2) == 1,N = N+1;
end

f = linspace(-f_s, f_s,N);

Gfi_p = randn(2,N/2);
Gfq_p = randn(2,N/2);
CGfi_p = Gfi_p(1,:)+i*Gfi_p(2,:);
CGfq_p = Gfq_p(1,:)+i*Gfq_p(2,:);
CGfi = [conj(fliplr(CGfi_p)) CGfi_p];
CGfq = [conj(fliplr(CGfq_p)) CGfq_p]; 

P_r = 1;
S_r=P_r/(4*pi)./(f_D*sqrt(1-(f/f_D).^2));
idx1=find(f>f_D);
idx2=find(f<-f_D);

S_r(idx1) = 0; 
S_r(idx2) = 0;
r_I = N*ifft(CGfi.*sqrt(S_r));
r_Q = -i*N*ifft(CGfq.*sqrt(S_r));
z = sqrt(abs(r_I).^2+abs(r_Q).^2);
z_dB = 20*log10(z);
z_dB =z_dB(1:length(Ts));