Index exceeds matrix dimensions (how to fix it )

hello and thank u all for reading and healping me

i do have a prblm with this code i didnt find the erreur + im sur that it's a small mistake wich i couldn't notice

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Index exceeds matrix dimensions.

Error in Untitled2 (line 121)

semilogy(SNR,BER(2,:),'ro-' ,'LineWidth',2); hold on

%% ________________________________________________________________________

%% ________________________________________________________________________
clc; clear; close all;
%% ________________________________________________________________________
%% SIMULATION PARAMETERS __________________________________________________
par.B      = 128;           % NUMBER OF BASE-STATION ANTENNAS (B >> U)
par.U      = 16;            % NUMBER OF SINGLE-ANTENNA USERS 
ModType    = {'64QAM','BPSK', 'QPSK','8PSK','16QAM','64QAM'};       % MODULATION TYPE : 'BPSK', 'QPSK','8PSK'
                            %                  '16QAM','64QAM'
Precoders  = {'ZF'};  % PRECODERS  LIST {'MRT','ZF'}                            
NRuns      =  1e3;          % NUMBER OF MONTE-CARLO RUNS
SNR        = -10:2:20;      % SNR [dB]
      
%% ________________________________________________________________________
%% MAPPING PREPARATION ____________________________________________________
for o             = 1:length(ModType)    
switch (ModType{o})
case 'BPSK' 
      par.Symbols   = [ -1 1 ];
        
case 'QPSK' 
      par.Symbols   = [ -1-1i,-1+1i,+1-1i,+1+1i ];      
        
case '8PSK'
      par.Symbols   = [ exp(1i*2*pi/8*0), exp(1i*2*pi/8*1), ...
                        exp(1i*2*pi/8*7), exp(1i*2*pi/8*6), ...
                        exp(1i*2*pi/8*3), exp(1i*2*pi/8*2), ...
                        exp(1i*2*pi/8*4), exp(1i*2*pi/8*5) ];      
          
case '16QAM'
      par.Symbols   = [ -3-3i,-3-1i,-3+3i,-3+1i, ...
                        -1-3i,-1-1i,-1+3i,-1+1i, ...
                        +3-3i,+3-1i,+3+3i,+3+1i, ...
                        +1-3i,+1-1i,+1+3i,+1+1i ];
                    
case '64QAM'
      par.Symbols   = [-7-7i,-7-5i,-7-1i,-7-3i,-7+7i,-7+5i,-7+1i,-7+3i, ...
                       -5-7i,-5-5i,-5-1i,-5-3i,-5+7i,-5+5i,-5+1i,-5+3i, ...
                       -1-7i,-1-5i,-1-1i,-1-3i,-1+7i,-1+5i,-1+1i,-1+3i, ...
                       -3-7i,-3-5i,-3-1i,-3-3i,-3+7i,-3+5i,-3+1i,-3+3i, ...
                       +7-7i,+7-5i,+7-1i,+7-3i,+7+7i,+7+5i,+7+1i,+7+3i, ...
                       +5-7i,+5-5i,+5-1i,+5-3i,+5+7i,+5+5i,+5+1i,+5+3i, ...
                       +1-7i,+1-5i,+1-1i,+1-3i,+1+7i,+1+5i,+1+1i,+1+3i, ...
                       +3-7i,+3-5i,+3-1i,+3-3i,+3+7i,+3+5i,+3+1i,+3+3i ];  
end
end
%% ______________________________________________________________________
%% 
% compute symbol energy
par.Es     = mean(abs(par.Symbols).^2);
% precompute bit labels
par.bps    = log2(length(par.Symbols));            % number of bits per symbol
par.bits   = de2bi(0:length(par.Symbols)-1,par.bps,'left-msb');
%% ________________________________________________________________________
%% PREALLOCATION __________________________________________________________
BER        = zeros(length(Precoders),length(SNR)); % BER
EVM        = zeros(length(Precoders),length(SNR)); % EVM
%% ______________________________________________________________________

% generate random bit stream (antenna x bit x trial)
bits       = randi([0 1],par.U,par.bps,NRuns);
%% ________________________________________________________________________
%% MONTE-CARLO LOOP _______________________________________________________
for i      = 1:NRuns  
    % DATA GENERATION (AS DECIMAL)
    idx    = bi2de(bits(:,:,i),'left-msb')+1;
    % MAPPING (MODULATION)
    s      = par.Symbols(idx).';
    % CHANNEL MATRIX GENERATION
    H      = sqrt(0.5)*(randn(par.U,par.B) + 1i*randn(par.U,par.B));
    % NOISE VECTOR GENERATION
    n      = sqrt(0.5)*(randn(par.U,1) + 1i*randn(par.U,1));
    %% ____________________________________________________________________
    %% PRECODING ALGORITHMS LOOP __________________________________________
    for j             = 1:length(Precoders)       
        %% ________________________________________________________________
        %% SNR LOOP _______________________________________________________
        for k         = 1:length(SNR)
            % NOISE VARIANCE
            N0        = 10.^(-SNR(k)/10);                        
            % PRECODING TECHNIQUES 
            switch (Precoders{j})                        
            % MRT 
            case 'MRT',[x, beta] = PRECODER_1_MRT(s, H);   
            % ZF 
            case 'ZF', [x, beta] = PRECODER_2_ZF(par, s, H);                                                                   
            end
            % CHANNEL EFFECT AND NOISE
            Hx        = H*x;
            y         = Hx + sqrt(N0)*n;
            % NORMALIZATION OF RECEIVED SIGNAL BY beta
            shat      = beta*y;                   
            % SINGLE USER-DETECTION
            [~,idxhat]= min(abs(shat*ones(1,length(par.Symbols)) ... 
                        - ones(par.U,1)*par.Symbols).^2,[],2);
            bithat    = par.bits(idxhat,:);            
            % COMPUTE BER AND EVM
            err       = (idx~=idxhat);
            BER(j,k)  = BER(j,k)+...
                        sum(sum(bits(:,:,i)~=bithat))/(par.U*par.bps);
            EVM(j,k)  = EVM(j,k)+100*norm(shat - s)^2/norm(s)^2;
            
         end %  END OF NORMALIZED TRANSMIT POWER LOOP _____________________ 
     end %  END OF PRECODING ALGORITHMS LOOP ______________________________
end % END OF MONTE-CARLO LOOP _____________________________________________

%% ________________________________________________________________________  
%% RESULTS NORMALISATION __________________________________________________
BER     = BER/NRuns;
EVM     = EVM/NRuns;

%% ________________________________________________________________________  
%% PLOT RESULTS ___________________________________________________________

%% PLOT BER
figure(1)

 semilogy(SNR,BER(1,:),'bo-' ,'LineWidth',2); hold on
 semilogy(SNR,BER(2,:),'ro-' ,'LineWidth',2); hold on
% semilogy(SNR,BER(3,:),'go-' ,'LineWidth',2); hold on
% semilogy(SNR,BER(4,:),'ko-' ,'LineWidth',2); hold on
% semilogy(SNR,BER(5,:),'yo-' ,'LineWidth',2); hold on
% semilogy(SNR,BER(6,:),'mo-' ,'LineWidth',2); 


% semilogy(SNR,BER(2,:),'rs--','LineWidth',2); 
xlabel('SNR [dB]','FontSize',12)
ylabel('BER','FontSize',12);
axis([min(SNR) max(SNR) 1e-4 1]);
legend('MRT Precoder','ZF Precoder','location','NorthEast')
  
%% PLOT EVM    
% figure(2)
% semilogy(SNR,EVM(1,:),'bo-' ,'LineWidth',2); hold on
% semilogy(SNR,EVM(2,:),'rs--','LineWidth',2); 
% xlabel('EVM','FontSize',12)
% ylabel('BER','FontSize',12);
% %axis([min(SNR) max(SNR) 1e-4 1]);
% legend('MRT Precoder','ZF Precoder','location','NorthEast')       
%% ________________________________________________________________________ 

Answer 1

[KALYAN ACHARJYA]

In this case

>> whos BER
  Name      Size            Bytes  Class     Attributes

  BER       1x16              128  double              

Haing single row only, how can you acess the 2 row

  semilogy(SNR,BER(2,:),'ro-' ,'LineWidth',2); hold on
  %................^..this is error, BER haing 1x16, you trying to access 2 row

Correct one, may be

 semilogy(SNR,BER,'ro-' ,'LineWidth',2); 

>>whos SNR

Name      Size            Bytes  Class     Attributes

  SNR       1x16              128  double    

try it the error will not occur again, on that line.

[taleb imed]

i fix it ,merci KALYAN

BER        = zeros(length(ModType),length(SNR)); % BER

[KALYAN ACHARJYA]

Preallocated BER as follows

BER=zeros(length(Precoders),length(SNR));

%%

BER=zeros(length(Precoders),length(SNR))
BER =
     0     0     0     0     0     0     0     0     0     0     0     0     0     0     0     0

BER size depends on length(Precoders) and length(SNR), here it is 1x16

In your case .................^=1 ............................^=16

After canlucation of BER from the following

BER(j,k)  = BER(j,k)+...
                        sum(sum(bits(:,:,i)~=bithat))/(par.U*par.bps);

>> whos BER

Name Size Bytes Class Attributes

BER 1x12 96 double

Now you have figure out from the j,k value how BER going to 6x16

[KALYAN ACHARJYA]

@taleb imed Bienvenue