clc, clear, close all
N = 2048; %N=symbol size
M=8; % 8-PSK
CP=64; %Cyclic prefix insertion
Min_snr=0;
Max_snr=14;
delta_snr=1;
num_frames=1000;
SNR_dB=zeros(1,Max_snr-Min_snr);
total_errors=zeros(1,Max_snr-Min_snr);
num_errors=zeros(1,num_frames);
BER_Q=zeros(1,Max_snr-Min_snr);
%Transmitter
k=1;
for snr=Min_snr:delta_snr:Max_snr %in dB
% for snr=12;
SNR=10.^(0.1*snr);
% Generate random 8-PSK symbols
for frame=1:num_frames;
msg = randsrc(3,N,[0,1]);
% Create 8-PSK modem object
h = modem.pskmod('M',8, 'PhaseOffset',0, 'SymbolOrder','gray', 'InputType', 'bit');
% Modulation
D_m = modulate(h,msg);
%Do ifft to generate orthogonal carriers
d = sqrt(N)* ifft(D_m,N);
%Addition of cyclic prefix
x = [d((N-CP+1):N) d];
sigma=sqrt(1/(6*SNR));
% channel option
w=sigma*(randn(1,length(x))+1j*randn(1,length(x)));%generate noise
%add AWGN
y=x+w;
%END Transmitter
%Reciever
% Remove the CP
r = y(CP+1:end);
D_est = 1/sqrt(N)* fft(r,N);
% Demodulation
H = modem.pskdemod('M',8, 'PhaseOffset',0, 'SymbolOrder','gray', 'OutputType', 'bit');
D_de = demodulate(H,D_est);
num_errors(frame)=biterr(msg,D_de);
end
SNR_dB(k)=snr;
total_errors(k)=sum(num_errors);
%BER theory
BER_theory=(1/2)*(2/log2(M))*erfc(sqrt(2*log2(M)*(sin(pi/M))^2*SNR)/sqrt(2));
BER_Q(k)=BER_theory;
k=k+1;
fprintf('Current SNR = %d\n',snr);
fprintf('Total number of errors = %d\n',sum(num_errors));
fprintf('BER = %12.8f\n',sum(num_errors)/(3*N*num_frames));
fprintf('BER_theory = %12.8f\n',BER_theory);
% eyediagram(D_est,8) % plot eye-diagram
end
BER=total_errors/(3*N*num_frames);
figure(1),
semilogy(SNR_dB,BER_Q,'-');
hold on;
semilogy(SNR_dB,BER,'o'),grid, xlabel('snr (dB)'), ylabel('BER');
figure(2), plot(D_est,'o');
