I am trying to run a basic ofdm code from 'MIMO-OFDM Wireless Communication with Matlab' book using Matlab but I keep getting a blank simulation page. Can I know what is the problem with the code?

%OFDM_basic.m
clear all
NgType=1;                       %NgType=1/2 for cyclic prefix/zeropadding
if NgType==1, nt='CP'; elseif NgType==2, nt='ZP';
end
Ch=0;                           %Ch=0/1 for AWGN/multipath channel
if Ch==0, chType='AWGN'; Target_neb=100; else chType='CH'; Target_neb=500; end

figure(Ch+1),clf
PowerdB=[0 -8 -17 -21 -25];     %channel tap power profile 'dB'
Delay=[0 3 5 6 8];              %channel delay 'sample'
Power=10.^(PowerdB/10);         %Channel tap power profile 'linear sample'
Ntap=length(PowerdB);           %Channel tap number
Lch=Delay(end)+1;               %Channel length
Nbps=4; M=2^Nbps;               %Modulation order =2//4/6 for QPSK/16QAM/64QAM
Nfft=64;                        %FFT SIZE
Ng=Nfft/4;                      %GI(Guard interval)length(Ng= for no GI)
Nsym=Nfft+Ng;                   %Symbolduration
Nvc=Nfft/4;                     %Nvc=0: noVC(Virtual Carrier)
Nused=Nfft-Nvc;                 
EbN0=[0:5:30];                  %EbN0
N_iter=1e5;                     %Number of iterations for each EbN0
Nframe=3;                       %Number of symbols per frame
sigPow=0;                       %Signal power initialization
file_name=['OFDM_BER_' chType '_' nt '_''GL' num2str(Ng) '.dat'];
fid=fopen(file_name,'w+');
norms=[1 sqrt(2) 0 sqrt(10) 0 sqrt(42)];   %BPSK 4-QAM 16-QAM
for i=0:length(EbN0)
  rng(0,'v5uniform'); rng(0,'v5normal');
  Ber2=ber(); %BER initialisation
  Neb=0; Ntb=0;                %Initialise the number of error/total bits
  for m=1:N_iter
      %Tx__________________________________________________________________
      X=randi(1,Nused*Nframe,M);    %bit:integer vector
      Xmod=qammod(X,M,0,'gray')/norms(Nbps);
      if Ngtype~=2, x_GI=zeros(1,Nframe*Nsym+Ng);
          %Extend an OFDM symbol by Ng zeros
      end
      kk1=[1:Nused/2]; kk2=[Nused/2+1:Nused]; kk3=1:Nfft;kk4=1:Nsym;
      for k=1:Nframe
          if Nvc~=0, X_shift=[0 Xmod(kk2) zeros(1, Nvc-1) Xmod(kk1)];
          else
              X_shift=[Xmod(kk2) Xmod(kk1)];
          end
          x=ifft(X_shift);
          x_GI(kk4)=guard_interval(Ng,Nfft,NgType,x);
          kk1=kk1+Nused; kk2=kk2+Nused;kk3=kk3+Nfft; kk4=kk4+Nsym;
      end
      if Ch==0, y=x_GI;             %No channel
      else                          %multipath Fading
          channel=(randn(1,Ntap)+j*randn(1,Ntap)).*sqrt(Power/2);
          h=zeros(1,Lch); h(Delay+1)=channel;%cir:channelimpulse response
          y =conv(x_GI,h);
      end
      if 1i==0                       %only to measure signal power for adding AWGN noise
          y1= y(1:Nframe*Nsym); sigPow=sigPow+y1*y1'; continue;
      end
      %Add AWGN noise________________________________________________
      snr = EbN0(i)+10*(Nbps*(Nused/Nfft)); %SNR vs Eb/N0 by Eq.(4.28)
      noise_mag = sqrt((10.^(-snr/10))*sigPow/2);
      y_GI = y+ noise_mag*(randn(size(y)) +1j*randn(size(y)));
      %Rx________________________________________________________________________
      kk1=(NgType==2)*Ng+[1:Nsym]; kk2=1:Nfft;
      kk3=1:Nused; kk4=Nused/2+Nvc+1:Nfft; kk5(Nvc~=0)+[1:Nused/2];
      if Ch==1
          H=fft([h zeros(1,Nfft-Lch)]); %Channel frequency response
          H_shift(kk3)=[H(kk4) H(kk5)];
      end
      for k=1:Nframe
          Y(kk2)= fft(remove_GI(Ng,Nsym,NgType,y_GI(kk1)));
          Y_shift= [Y(kk4) Y(kk5)];
          if Ch==0, Xmod_r(kk3)=Y_shift;
          else 
              Xmod_r(kk3)= Y_shift./H_shift; %Equaliser-channel compensation
          end
          kk1=kk1+Nsym; kk2=kk2+Nfft; kk3=kk3+Nused; kk4=kk4+Nfft; kk5=kk5+Nfft;
      end
      X_r=qammod(Xmod_r*norms(Nbps),M,'gray');
      Neb=Neb+sum(sum(de2bi(X_r,Nbps)~=de2bi(X,Nbps)));
      Ntb=Ntb+Nused*NFrame*Nbps; %[BER,Neb,Ntb] =ber(bit_Rx,bit,nbps);
      if Neb>Target_neb,break;end
  end
  if 1i==0,sigPow=sigPow/Nsym/Nframe/N_iter;
  else
      Ber =Neb/ntb;
      fprintf('EbN0=%3d[db],BER=%4d/%8d=%11.3e\n', EbN0(1i),Neb,Ntb,Ber)
      fprintf(fid,'%d\t%11.3e\n', EbN0(1i), Ber);
      if ber<1e6, break; end
  end
end
if(fid~=0),fclose(fid); end
plot_ber(file_name,Nbps);

[GAJANAND]

hello any one can answer the error problem in this code

[Walter Roberson]

ber and plot_ber are not part of any Mathworks toolbox, and I do not find them in the File Exchange either. I am not finding it via Google either.

[Elkor]

First,You have to change to Ber2=Ber(). Second,You have to use routines for GI,BER(PROGRAM 4.3)for their initilatization All routines must be in the same folder as ofdm-basic.m(e.g., guard_interval.m,remove_GI.m,plot_ber.m,function_ber.m,function_Q.m).All credits go to my smart colleague.

Answer 1

[GAJANAND]

hey krish if you find the solution kindly send on [e-mail] will be thankful

Answer 2

[Long Cao]

hey krish if you find the solution kindly send on [e-mail] will be thankful

Answer 3

[Nico]

I think the randi-parameters are wrong.

In original code it was

X= randint(1,Nused*Nframe,M); % bit: integer vector

ought to be like

X= randi([0 M-1],Nused*Nframe,1); % bit: integer vector

in recent Matlab.

I get plots, but simulation deviates heavily from analytic result with configuration same as above code. Did anyone get more satisfying results?

[Ilhem]

Can you give the code please

[José]

Hola Nico,

estoy trabajando el mismo código. Si quieres contrastamos resultados.

jose.antonio.saavedra ... gmail.

Saludos!

Answer 4

[廷刚 赵]

I got the result by modifying the code, but there is a deviation from the result in the book