BER VS SNR OF OFDM LTE AWGN (TRANSMITER AND RECIEVER)

GENERAL PROGRAM CAN SIMULATE FOR ANY FFT SIZE

clc;
clear all;
close all;
% Initializing parameters
Nfft=input('fft size N = ');
Nused=input('Number of OFDM symbols used m = ');
M=input('constellation size M = ');
Type=input('Type of Mapping (1 for PSK) and (2 for QAM) = ');
Phase_Offset=input('phase offset = ');

Ncp=input('cyclic prefix samples Ncp = ');

% Transmitter

if Type == 1
Tx = modem.pskmod('M',M,'PhaseOffset',Phase_Offset,'SymbolOrder','gray');
Rx = modem.pskdemod('M',M,'PhaseOffset',Phase_Offset,'SymbolOrder','gray');
else
Tx = modem.qammod('M',M,'PhaseOffset',Phase_Offset,'SymbolOrder','gray');
Rx = modem.qamdemod('M',M,'PhaseOffset',Phase_Offset,'SymbolOrder','gray');
end

% data generation
Tx_data=randi([0 M-1],Nused,Nfft);
% modulation
mod_data=modulate(Tx,Tx_data);
% Serial to Parallel
s2p=mod_data.';
% insertion of pilots (upsmapling)
upsampled=upsample(s2p,1);
% Amplitude modulation (IDFT using fast version IFFT)
am=ifft(upsampled,Nfft);
% Parallel to serial
p2s=am.';
% Cyclic Prefixing
CP_part=p2s(:,end-Ncp+1:end); % this is the Cyclic Prefix part to be appended.
cp=[CP_part p2s];

% Reciever

% Adding Noise using AWGN
SNRstart=3;
SNRincrement=2;
SNRend=11;
c=0;
r=zeros(size(SNRstart:SNRincrement:SNRend));
for snr=SNRstart:SNRincrement:SNRend
c=c+1;
noisy=awgn(cp,snr,'measured');
% Remove cyclic prefix part
cpr=noisy(:,Ncp+1:Nfft+Ncp); %remove the Cyclic prefix
% serial to parallel
parallel=cpr.';
% Amplitude demodulation (DFT using fast version FFT)
amdemod=fft(parallel,Nfft);
% Down-Sampling

downsampled=downsample(amdemod,1);
% Parallel to serial
rserial=downsampled.';
% demodulation
Umap=demodulate(Rx,rserial);
% Calculating the Symbol Error Rate
[n, r(c)]=symerr(Tx_data,Umap);

end
snr=SNRstart:SNRincrement:SNRend;
% Plotting SER vs SNR
semilogy(snr,r,'-ok');
grid;
title('OFDM Symbol Error Rate vs SNR');
ylabel('Symbol Error Rate');
xlabel('SNR [dB]');