clear all;
close all;

bits_tr = 10000;
% SNR in dB
SNR_dB=1:1:10;
% SNR on linear scale
SNR=10.^(SNR_dB/10);

ber_net = zeros(1, length(SNR_dB));
for curr_SNR=1:1:10

    %Quadrature Component of Signal
    SQ=2*(round(rand(1,bits_tr))-0.5);
    %InPhase Component of signal
    SI = 2*(round(rand(1,bits_tr))-0.5);
    % Signal = Inphase Component + jQuadrature Component
    S = SI + j*SQ;
    % Add Additive White Gaussian Noise to the Signal
    % The snr is SNR_dB and "measured" is passed inorder to measure
    % signal power of input signal, else defaulted to 0
    % Thus signal recieved is S + AWGN
    R = awgn(S,curr_SNR,'measured');
    %Extract inphase and quadrature of recieved signal using signum
    %function
    SI_y=sign(real(R));
    SQ_y=sign(imag(R));
    % Bit Error in inphase component
    ber_inphase=(bits_tr-sum(SI==SI_y))/bits_tr;
    % Bit Error in quadrature component
    ber_quad=(bits_tr-sum(SQ==SQ_y))/bits_tr;
    % Net Bit Error
    ber_net(curr_SNR)=mean([ber_inphase ber_quad]);
    disp(ber_net)
end

semilogy(SNR_dB,ber_net,'-mh')

xlabel('Signal to noise ratio (dB)');
ylabel('Bit error rate');

title('QPSK with AWGN');


grid on;