flat_fad_channel.m

%simulate the BER of a QPSK modulated siganal using an AWGN channel
%with flat rayleigh fading.
%with sigma = awgn_sigma
%G. Anbarjafari (Shahab) .....  shahab.jafari[AT]emu.edu.tr
 
clear all;
N_loop = 1000;
N_sym = 120;
N_bit=2*N_sym;
awgn_sigma = sqrt(0.5);
Eb_dB=0:10:40;
 
Eb = 10.^(Eb_dB/10);
sqrt_Es = sqrt(2*Eb);
 
BER = zeros(1,length(Eb));
normalized = 1/sqrt(2);
 
 
for n=1:N_loop;
   Rf=randn(1,N_sym) + j*randn(1,N_sym);
   V=var(Rf);
   H=Rf/sqrt(V);
   D =(floor(2*rand(1,N_sym)));
   Tx_data =(2*D-(1)); %*normalized; 
   Noise=(randn(N_sym,length(Eb_dB)));%+j*randn(N_sym,length(Eb_dB))); %10,000  5
   Rsignal= (transpose(Tx_data) * sqrt_Es).* (transpose(H) * ones(1,length(Eb_dB))) + Noise;
   Rx= (conj(transpose(H) * ones(1,length(Eb_dB))));
   Rx_data=(Rx./Rxm) .* Rsignal;
   Recov_data = 0.5*((1+sign(real(Rx_data))));%+ j * sign(imag(Rx_data))));
   BER = BER+sum((abs(Recov_data-transpose(D)*ones(1,length(Eb_dB)))).^2)/N_bit;
end
BER = BER/N_loop;
 
semilogy(Eb_dB,BER,'b*--');
xlabel('Eb/N0 (dB)');
ylabel('BER');