This program is for random data,followed by its FEC coding , DPSK modulation for OFDM transmission

Question

aheesh gaur 2011-8-28

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/14672-this-program-is-for-random-data-followed-by-its-fec-coding-dpsk-modulation-for-ofdm-transmission

回答： rohun pandraka 2015-2-10

      *THIS PROGRAM IS FOR DESIGNING AN OFDM TRANSMITTER*
    %======================
    %TRANSMITTER SECTION
    %======================
    %OFDM parameters
    ifftsize = 128;    %Total no. of sub-carriers
    NumCarr = 120;    % Number of data sub-carriers
    Tg = 0.012    ;% Guard Interval
    Tu = 4*Tg      ;% OFDM symbol period
    T = Tg+Tu      ;% Total OFDM symbol duration
    delf = 1/Tu    ;% Sub-carrier spacing
    BW = ifftsize*delf    ;% Net Bandwidth occupied
    fs = ifftsize/Tu    ;% Baseband sampling frequency
    r = 40;      % Up sampling ratio
    fs1 = r*fs      ;% Pass band sampling frequency
    ber2 = [];
    s2 = [];
    ber1_1 = [];
    % TRANSMITTER LOOP BEGINS
    for sp = 0.2:0.4:1.8
      s = [];
      ber= 0;
      ber1=0;
    end
    for iter = 1:2
      clc  
    end
      % Random data generion
      data_in = round(rand(400,1));
      % Convolution Coding
      trellis = poly2trellis(7,[133 171]);
      coded_data = convenc(data_in,trellis);
      msg_bits_out = coded_data;
      % Puncturing
      msg_bits_out(4:6:end)=[];  % puncturing 1/2 to 3/4   
      msg_bits_out(4:5:end)=[];  % puncturing 1/2 to 3/4
      numsymb = ceil(length(msg_bits_out)/NumCarr);
      OutWordSize = 1;
      % Serial to Parallel Conversion
      if length(msg_bits_out)/NumCarr ~= numsymb,
         Datapad = zeros(1,numsymb*NumCarr);
         Datapad(1:length(msg_bits_out)) = msg_bits_out;   
         DataOut = Datapad;
      else
         DataOut = msg_bits_out;
      end
         clear Datapad;
      DataOut = reshape(DataOut,NumCarr,numsymb);
      numsymb = size(DataOut,1)+1;
      wordsize=1;
      % DPSK Modulation
      PhaseRef = round(rand(120,1))+1;
      DPSKdata = zeros(size(DataOut,1)+1,size(DataOut,2));
      DPSKdata(1,:) = PhaseRef;
      for k = 1:numsymb -1
         DPSKdata(k+1,:) = mod((DataOut(k,:)+DPSKdata(k,:)-1),(2^wordsize))+1;
      end
      [X,Y] = pol2cart(DPSKdata*(2*pi/(2^wordsize)),ones(size(DPSKdata)));
      CarrCmplx = X+1i*Y;
      % OFDM Carrier Setting
      CarrSpacing = 1;
      StartCarr = 4;
      FinCarr= 123;
      carriers = (StartCarr:CarrSpacing:FinCarr)+1;
      NumCarr = length(carriers);
      % Adding Null Sub Carriers
      TxSpectrums = zeros(numsyb,ifftsize);
      for k = 1:numsymb
         TxSpectrums(k,carriers) = CarrCmplx(k,:);
      end
      
      % OFDM Symbol  Generation- IFFT
      BaseSignal = ifft(TxSpectrums);
      % Insertion of CYCLIC PREFIX
      cp= round((1/4)*ifftsize);
      BaseSignal=[BaseSignal(end-cp+1:end,:);BaseSignal];
      % Parallel to Serial Conversion
      BaseSignal = reshape(BaseSignal,1,size(BaseSignal,1)*size(BaseSignal,2));
      % UP-Sampling
      BaseSignal1 = interp(real(BaseSignal),r);
      BaseSignal2 = interp(real(BaseSignal),r);
      t=0:1/fs1:T*numsymb-1/fs1;
      length(t)
      % Loading Onto carrier
      carc = cos(2*pi*30000*t);
      cars = sin(2*pi*30000*t);
      TxSignal=sp*((BaseSignal1.*carc)+(BaseSignal2.*cars));
      % Adding Preamble
      pre=0.4*lpwm(0:1/fs:0.01,30000,0.01,34000);
      pkt=2*[pre zeros(1,ceil(0.05*fs1)) TxSignal];
      %Spectrum of Transmitted Signal
      l= length(TxSignal);
      p=fft(TxSignal,l);
      f=fs1*(1:l)/l;
      f1 = figure(1);
      set(f1,'color',[1 1 1]);
      plot(f,abs(p(1:length(f))));
      xlabel('Frequency (Hz)');
        ylabel('Magnitude')
      clear l p f
    %%=====================================================
    %%Invoking N! 6110 DAQ through DAQ toolbox
    %%=====================================================
      ai = analoginput('nidaq',1);
      addchannel(ai,0);
      ai.Channel.InputRange = [0.01 0.01];
      set(ai,'SampleRAte',fs1);
      set(ai,'SamplesPertRigger',lengt(pkt)+fs1*0.1)
      ao = analogoutput('nidaq',1);
      cahns=addchannel(ao,0);
      set(ao,'SampleRate',fs1);
      tempao=ger(ao,'Channel');
      apkt = abs(pkt);
      apkt1 = apkt>0.7;
      apkt2 = apkt1.*pkt;
      pkt = pkt-apkt2+sign(apkt2)*0.7;
      set(tempao,OutputRange,[-0.7,0.7])
      putdata(ao,pkt)
      start([ai ao])
        rxdata = getdata(ai);
        stop([ai ao])
      delete([ai ao])