% BER for BPSK in a Flat Fading Rayleigh channel

clc
clear all
close all

% Number of Bits
N = 10^6; 

% SNR in dB scale
SNR_dB = [0:50]; 

% SNR in Linear scale
SNR = 10.^(SNR_dB./10);  
Eb = 1;                    % Average Signal Energy 
No = Eb./SNR;              % Average Noise Energy 

for i = 1:length(SNR)
    
    % Generate BPSK signal
    x = randsrc(1,N);     
    
    % Complex AWGN with Mean = 0 and Variance = No
    n = sqrt(No(i)/2)*[randn(1,N) + j*randn(1,N)]; 
    
    % Rayleigh channel with Mean = 0 and Variance = 1 (Fade Power = 1) 
    h = sqrt(0.5)*[randn(1,N) + j*randn(1,N)]; 
%     h=GenerateFade_Jakes(1,N,0.01);
    
    % Received Signal
    y = h.*x + n;
    
    % Equalization
    y_hat = y./h;
    
    % BPSK Demodulation
    y_re = real(y_hat); 

    x_hat(find(y_re < 0)) = -1;
    x_hat(find(y_re >= 0)) = 1;

    % Error Counter
    n_err(i) = size(find([x- x_hat]),2);

end

% Simulated BER Rayleigh
sim_BER_ray = n_err./N; 

semilogy(SNR_dB,sim_BER_ray,'-*r','LineWidth',2);
axis([0 50 10^-6 0.5])
grid on
legend('Rayleigh');
xlabel('SNR (dB)');
ylabel('BER');
title('BER for BPSK in a Flat Fading Rayleigh channel');