test_snr.m.bak

clear all;
close all;
clc;

FLAG_ADD_TIME   = 1 ; 
FLAG_ADD_FREQ   = 0 ;
FLAG_ADD_NOISE  = 1 ;
SNR = 50;%4:0.2:12;
freqOffset = 20e3 ; % 10e3;
ppm = 0.2 ; %0.02

numFrames = 1;
samplesPerSymbol= 12;
Ns = samplesPerSymbol ;
symbolsPerFrame = 16 ;
Nf = symbolsPerFrame ;
fSample = 192e6;
%fSample = 32e6;
fSymbol = 16e6 ;
fs = fSample ;
Ts = 1.0/fs ;









    %------------------------------------------------------------------------
    % Generate and modulate data
    %------------------------------------------------------------------------
    %txBits = randi([0 1],symbolsPerFrame,1);
    err_num = zeros(length(SNR),1) ;
    sum_err_num = zeros(length(SNR),1) ;
    total_bits = zeros(length(SNR),1) ;
    err_rate = zeros(length(SNR),1) ;
for ii = 1:length(SNR)
for jj = 1:1e6 % frame iteration
    snr = SNR(ii) ;
    chAWGN = comm.AWGNChannel(...
    'NoiseMethod','Signal to noise ratio (Eb/No)', ...
    'EbNo',snr,...
    'SignalPower',1, ...
    'SamplesPerSymbol',samplesPerSymbol);
    hLen = 5000 ;
    headBits = randi([0 1],1,hLen);
    tailBits = randi([0 1],1,hLen);
    txBits1 = [0 1 0 0 0 1 0 0 1 1 0 0 1 1 0 1] ;
    txBits = [headBits txBits1 tailBits] ;
    txSymPr = mskmod(txBits,samplesPerSymbol);
    %txSym = [txSymPr,zeros(1,2048-192),txSymPr,zeros(1,2048-192),txSymPr,zeros(1,2048-192)]
    txSym=txSymPr;
    %------------------------------------------------------------------------
    % Transmit through channel
    %------------------------------------------------------------------------
    if FLAG_ADD_NOISE
        rxchan = chAWGN(txSym);
    else
        rxchan = txSym ; 
    end    
    %
    % Add timing offset
    if FLAG_ADD_TIME
        Frac = 1000; 
        timingOffset = round(ppm*Frac) ;
        rxSigTimingOff = resample(rxchan,Frac+timingOffset,Frac) ;
        %     varDelay = dsp.VariableFractionalDelay;
        %     rxSigTimingOff = varDelay(rxchan,0.2);
        stem(real(rxchan(1:192)));
        hold on;
        stem(real(rxSigTimingOff(1:192)),'r') ;
    else
        rxSigTimingOff = rxchan ; 
    end    
    %
    % Add carrier frequency and phase offset
    %rxSigCFO = pfo(rxSigTimingOff);
    if FLAG_ADD_FREQ
        Len = length(rxSigTimingOff) ;
        rxSigCFO = rxSigTimingOff.*exp(-1*j*2*pi*freqOffset*[0:Len-1]*Ts) ;
    else
        rxSigCFO = rxSigTimingOff ;
    end    
    %
%     scatterplot(txSym(1:samplesPerSymbol:end));
%     scatterplot(rxSigCFO(1:samplesPerSymbol:end)) ;
    % Pass the signal through an AWGN channel
    shift = 0; 
    rxSig = [rxSigCFO(shift+1:end),zeros(1,shift)];
    
    %%%get the corr for ppm estimation
    for tt=1:70
        rxCorr = rxSig((tt-1)*Ns*Nf+1:(tt)*Ns*Nf+0) ;
        ppm_est = time_est(rxCorr,Ns) ;
        fprintf("ppm estimation is %f\n",ppm_est) ;
    end
    %
    % Save the transmitted signal for plotting
    plot_rx = rxSig;
    
   
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
	rx_demod=mskdemod(rxSig,12);
    [err_num(ii) tt] = biterr(rx_demod(1:end-1),txBits(1:end-1)) ;
    sum_err_num(ii) = sum_err_num(ii)+err_num(ii);
    total_bits(ii) = total_bits(ii) + length(txBits) ;
    
    fprintf("SNR is %f and FRAME NUMBER is %d\n" , snr , jj ) ;
    if( sum_err_num(ii) > 100 ) || (jj>1000) % at least 10-5
        break ;
    end  
end    
      
    err_rate(ii) = sum_err_num(ii)/total_bits(ii) ;
    ideal_rate(ii)=1/2*erfc(sqrt(10.^(snr/10)/2));
end

semilogy(SNR,err_rate);
hold on ;
semilogy(SNR,ideal_rate,'r');
keyboard ;